ỦY BAN NHÂN DÂN THÀNH ĐỒN TP HỒ CHÍ MINH THÀNH PHỐ HỒ CHÍ MINH TRUNG TÂM PHÁT TRIỂN SỞ KHOA HỌC VÀ CÔNG NGHỆ KHOA HỌC VÀ CÔNG NGHỆ TRẺ CHƯƠNG TRÌNH KHOA HỌC VÀ CƠNG NGHỆ CẤP THÀNH PHỐ BÁO CÁO TỔNG HỢP KẾT QUẢ NHIỆM VỤ NGHIÊN CỨU KHOA HỌC VÀ CÔNG NGHỆ NGHIÊN CỨU TỔNG HỢP VẬT LIỆU NỀN CẤU TRÚC NANO Ti0.7W0.3O2 CHO XÚC TÁC PLATINUM (Pt) ỨNG DỤNG TRONG PIN NHIÊN LIỆU Cơ quan chủ trì nhiệm vụ: Trung tâm Phát triển Khoa học Công nghệ Trẻ Chủ nhiệm nhiệm vụ: ThS Phạm Quốc Hậu Thành phố Hồ Chí Minh – 2019 ỦY BAN NHÂN DÂN THÀNH ĐỒN TP HỒ CHÍ MINH THÀNH PHỐ HỒ CHÍ MINH TRUNG TÂM PHÁT TRIỂN SỞ KHOA HỌC VÀ CÔNG NGHỆ KHOA HỌC VÀ CÔNG NGHỆ TRẺ CHƯƠNG TRÌNH KHOA HỌC VÀ CƠNG NGHỆ CẤP THÀNH PHỐ BÁO CÁO TỔNG HỢP KẾT QUẢ NHIỆM VỤ NGHIÊN CỨU KHOA HỌC VÀ CÔNG NGHỆ NGHIÊN CỨU TỔNG HỢP VẬT LIỆU NỀN CẤU TRÚC NANO Ti0.7W0.3O2 CHO XÚC TÁC PLATINUM (Pt) ỨNG DỤNG TRONG PIN NHIÊN LIỆU (Đã chỉnh sửa theo kết luận Hội đồng nghiệm thu ngày 21/05/2019) Chủ nhiệm nhiệm vụ (ký tên) Chủ tịch Hội đồng nghiệm thu (Ký ghi rõ họ tên) ThS Phạm Quốc Hậu Cơ quan chủ trì nhiệm vụ GS TS Nguyễn Cửu Khoa Đồn Kim Thành THÀNH ĐỒN TP HỒ CHÍ MINH TRUNG TÂM PHÁT TRIỂN KHOA HỌC VÀ CƠNG NGHỆ TRẺ CỘNG HOÀ XÃ HỘI CHỦ NGHĨA VIỆT NAM Độc lập - Tự - Hạnh phúc ., ngày tháng năm 200 BÁO CÁO THỐNG KÊ KẾT QUẢ THỰC HIỆN NHIỆM VỤ NGHIÊN CỨU KH&CN I THÔNG TIN CHUNG Tên nhiệm vụ: Nghiên cứu tổng hợp vật liệu cấu trúc nano Ti0.7W0.3O2 cho xúc tác Platinum (Pt) ứng dụng pin nhiên liệu Thuộc: Chương trình/lĩnh vực (tên chương trình/lĩnh vực): Vườn ươm Sáng tạo Khoa học Công nghệ trẻ Chủ nhiệm nhiệm vụ: Họ tên: Phạm Quốc Hậu Ngày, tháng, năm sinh: 17/06/1993 Nam/ Nữ: Nam Học hàm, học vị: Thạc Sĩ Chức danh khoa học: Chức vụ: Nghiên cứu viên Điện thoại: Tổ chức: Nhà riêng: Mobile: 097 9798 111 Fax: E-mail: phamquochau11819@gmail.com Tên tổ chức công tác: Viện Kỹ Thuật Công Nghệ Cao Nguyễn Tất Thành Địa tổ chức: 300A Nguyễn Tất Thành, Phường 13, Quận 4, TP HCM Địa nhà riêng: Hẻm 230 cũ, đường Lê Văn Thọ, Gò Vấp, TP HCM Tổ chức chủ trì nhiệm vụ: Tên tổ chức chủ trì nhiệm vụ: Trung tâm Phát Triển Khoa Học Công Nghệ Trẻ Điện thoại: (028)38 233 363 Fax: E-mail: Website: Địa chỉ: Số 1, Phạm Ngọc Thạch, P Bến Nghé, Quận 1, TP HCM Họ tên thủ trưởng tổ chức: Đoàn Kim Thành Số tài khoản: 3713.0.1083277.00000 Kho bạc: Kho bạc Nhà Nước Quận 1, TP Hồ Chí Minh Tên quan chủ quản đề tài: Sở Khoa Học Cơng Nghệ TP.HCM II TÌNH HÌNH THỰC HIỆN Thời gian thực nhiệm vụ: - Theo Hợp đồng ký kết: từ tháng 06 năm 2018 đến tháng 04 năm 2019 - Thực tế thực hiện: từ tháng 06 năm 2018 đến tháng 04 năm 2019 - Được gia hạn (nếu có): - Lần từ tháng… năm… đến tháng… năm… - Lần … Kinh phí sử dụng kinh phí: a) Tổng số kinh phí thực hiện: 90 tr.đ, đó: + Kính phí hỗ trợ từ ngân sách khoa học: 90 tr.đ + Kinh phí từ nguồn khác: tr.đ b) Tình hình cấp sử dụng kinh phí từ nguồn ngân sách khoa học: Số TT Theo kế hoạch Thời gian Kinh phí (Tháng, năm) (Tr.đ) Thực tế đạt Thời gian Kinh phí (Tháng, năm) (Tr.đ) Ghi (Số đề nghị toán) … c) Kết sử dụng kinh phí theo khoản chi: Đối với đề tài: Đơn vị tính: Triệu đồng Số TT Nội dung khoản chi Trả công lao động (khoa học, phổ thông) Nguyên, vật liệu, lượng Thiết bị, máy móc Xây dựng, sửa chữa nhỏ Chi khác Tổng cộng Theo kế hoạch Tổng NSKH Thực tế đạt Nguồn khác Tổng 53,253 53,253 27,130 27,130 9,617 90,000 9,617 90,000 NSKH Nguồn khác - Lý thay đổi (nếu có): Đối với dự án: Đơn vị tính: Triệu đồng Số TT Nội dung khoản chi Theo kế hoạch Thực tế đạt Tổng NSKH Nguồn khác Tổng NSKH Nguồn khác Thiết bị, máy móc mua Nhà xưởng xây dựng mới, cải tạo Kinh phí hỗ trợ cơng nghệ Chi phí lao động Ngun vật liệu, lượng Thuê thiết bị, nhà xưởng Khác Tổng cộng - Lý thay đổi (nếu có): Các văn hành q trình thực đề tài/dự án: (Liệt kê định, văn quan quản lý từ công đoạn xét duyệt, phê duyệt kinh phí, hợp đồng, điều chỉnh (thời gian, nội dung, kinh phí thực có); văn tổ chức chủ trì nhiệm vụ (đơn, kiến nghị điều chỉnh có) Số TT … Số, thời gian ban hành văn Tên văn Ghi Tổ chức phối hợp thực nhiệm vụ: Số TT Tên tổ chức đăng ký theo Thuyết minh Tên tổ chức tham gia thực Nội dung tham gia chủ yếu Sản phẩm chủ yếu đạt Ghi chú* - Lý thay đổi (nếu có): Cá nhân tham gia thực nhiệm vụ: (Người tham gia thực đề tài thuộc tổ chức chủ trì quan phối hợp, khơng q 10 người kể chủ nhiệm) Số TT Tên cá nhân đăng ký theo Thuyết minh Phạm Quốc Hậu Hồ Thị Thanh Vân Tên cá nhân tham gia thực Phạm Quốc Hậu Hồ Thị Thanh Vân Nội dung tham gia 1,2,3,4,5,6,7 2,5,7 Sản phẩm chủ yếu đạt Ghi chú* Nguyễn Trường Sơn Huỳnh Thiên Tài Nguyễn Văn Ất Phan Thị Thúy Vi Mai Ngọc Trâm Anh Nguyễn Trường Sơn Huỳnh Thiên Tài Nguyễn Văn Ất Phan Thị Thúy Vi Mai Ngọc Trâm Anh 1,3,5,7 1,2,3,5,6,7 1,2,3,5,6,7 2,3,5,6 2,3,5,6 - Lý thay đổi ( có): Tình hình hợp tác quốc tế: Số TT Theo kế hoạch (Nội dung, thời gian, kinh phí, địa điểm, tên tổ chức hợp tác, số đoàn, số lượng người tham gia ) Thực tế đạt (Nội dung, thời gian, kinh phí, địa điểm, tên tổ chức hợp tác, số đoàn, số lượng người tham gia ) Ghi chú* - Lý thay đổi (nếu có): Tình hình tổ chức hội thảo, hội nghị: Theo kế hoạch Số (Nội dung, thời gian, kinh phí, địa TT điểm ) Thực tế đạt (Nội dung, thời gian, kinh phí, địa điểm ) Ghi chú* - Lý thay đổi (nếu có): Tóm tắt nội dung, công việc chủ yếu: (Nêu mục 15 thuyết minh, không bao gồm: Hội thảo khoa học, điều tra khảo sát nước nước ngoài) Số TT Thời gian (Bắt đầu, kết thúc - tháng … năm) Theo kế Thực tế đạt hoạch Nội dung 1: Tổng quan tài 06/2018 – 06/2018 liệu pin nhiên liệu 07/2018 hạn chế gặp phải việc thương mại hóa Nội dung 2: Khảo sát nghiên cứu 07/2018 – 07/2018 – tổng hợp vật liệu cấu trúc nano 08/2018 08/2018 Ti0.7W0.3O2 phương pháp solvothermal nhiệt độ thấp Các nội dung, công việc chủ yếu (Các mốc đánh giá chủ yếu) Người, quan thực Nội dung 3: Khảo sát, đo đạc tính chất vật liệu nano Ti0.7W0.3O2 tổng hợp Nội dung 3.1: Đo đạc cấu trúc vật liệu cấu trúc nano Ti0.7W0.3O2 phương pháp nhiễu xạ tia X (XRD), XPS Nội dung 3.2: Đo đạc tính chất hình dạng, kích thước, phân bố hạt nano vật liệu phương pháp phân tích TEM thành phần nguyên tố phương pháp SEM/EDX mapping, XRF Nội dung 3.3: Đo đạc diện tích bề mặt riêng vật liệu cấu trúc nano Ti0.7W0.3O2 phương pháp BET độ dẫn điện phương pháp bốn mũi dò Nội dung 4: Viết báo cáo phần tổng hợp tính chất vật liệu cấu trúc nano Ti0.7W0.3O2 08/2018 – 10/2018 08/2018 – 09/2018 10/2018 – 11/2019 10/2018 Nội dung 5: Nghiên cứu tổng hợp xúc tác nano Pt/Ti0.7W0.3O2 phương pháp khử NaBH4 kết hợp với Ethylene glycol phương pháp polyol có hỗ trợ vi sóng Nội dung 6: Khảo sát, đo đạc tính vật liệu xúc tác nano Pt/Ti0.7W0.3O2 tổng hợp 11/2019 – 01/2019 11/2019 – 12/2019 01/2019 – 02/2019 01/2019 – 02/2019 Nội dung 6.1: Khảo sát, đo đạc cấu trúc vật liệu xúc tác Pt/Ti0.7W0.3O2 phương pháp XRD, XPS Nội dung 6.2: Đo đạc tính chất hình dạng, kích thước, phân bố hạt nano Pt vật liệu cấu trúc nano Ti0.7W0.3O2 phương pháp phân tích TEM, XRF, SEM/EDX mapping Nội dung 6.3: Đo đạc tính chất điện hóa xúc tác Pt/ Ti0.7W0.3O2 tổng hợp phương pháp quét vòng tuần hoàn (CV) Nội dung 7: Viết báo đăng 02/2019 – tạp chí quốc tế 04/2019 02/2019 – 04/2019 - Lý thay đổi (nếu có): III SẢN PHẨM KH&CN CỦA NHIỆM VỤ Sản phẩm KH&CN tạo ra: a) Sản phẩm Dạng I: Số TT Tên sản phẩm tiêu Đơn chất lượng vị đo chủ yếu Vật liệu Mẫu cấu trúc nano Ti0.7W0.3O2 Vật liệu xúc tác Mẫu Pt/Ti0.7W0.3O2 Số lượng Theo kế hoạch Thực tế đạt 01 mẫu vật liệu cấu trúc nano Ti0.7W0.3O2 (m=150 mg) 01 mẫu xúc tác Pt/Ti0.7W0.3O2 (m = 100 mg) Kích thước hạt < 15 nm, SBET ≥ 200 m2/g, độ dẫn điện ≥10-4 S/cm Kích thước hạt ~ 10 nm, SBET ≥ 201.48 m2/g, độ dẫn điện ≥2.20x10-2 S/cm 20 kl% Pt/Ti0.7W0.3O2 20 kl% Pt/Ti0.7W0.3O2 - Lý thay đổi (nếu có): b) Sản phẩm Dạng II: Số TT Tên sản phẩm Phương pháp tổng hợp vật liệu Ti0.7W0.3O2 phương pháp solvothermal nhiệt độ thấp Phương pháp tổng hợp vật liệu xúc tác Pt/Ti0.7W0.3O2 phương pháp khử NaBH4 kết hợp với Ethylene glycol phương pháp polyol có hỗ trợ vi sóng - Lý thay đổi (nếu có): c) Sản phẩm Dạng III: Yêu cầu khoa học cần đạt Ghi Theo kế hoạch Thực tế đạt Phương pháp rõ Phương pháp rõ 01 Phương pháp ràng, chi tiết, ràng, chi tiết, đảm bảo tính đảm bảo tính khoa học khoa học Phương pháp rõ Phương pháp rõ 02 Phương pháp ràng, chi tiết, ràng, chi tiết, đảm bảo tính đảm bảo tính khoa học khoa học Số TT Tên sản phẩm Bài báo khoa học đăng tạp chí quốc tế thuộc hệ thống ISI/Scopus Bài báo khoa học đăng tạp chí quốc tế Oral Presentation Yêu cầu khoa học cần đạt Theo Thực tế kế hoạch đạt 01 Bài báo đăng tạp chí ISI uy tín, tạp chí quốc tế thuộc ISI/Scopus 01 Số lượng, nơi cơng bố (Tạp chí, nhà xuất bản) - 01 tạp chí International Journal of Hydrogen Energy (Q1, IF = 4.229) - 02 tạp chí Journal of Nanoscience and Nanotechnology (Q2, IF = 1.354) Bài báo đăng - 01 tạp chí Solid tạp chí ISI uy tín, State Phenomena (Scopus) tạp chí quốc tế thuộc ISI/Scopus 4th International Conference Of Chemical Engineering And Industrial Biotechnology (ICCEIB 2018) - Lý thay đổi (nếu có): d) Kết đào tạo: Số TT Cấp đào tạo, Chuyên ngành đào tạo Thạc sỹ Tiến sỹ Số lượng Theo kế hoạch Thực tế đạt Ghi (Thời gian kết thúc) - Lý thay đổi (nếu có): đ) Tình hình đăng ký bảo hộ quyền sở hữu công nghiệp: Số TT Tên sản phẩm đăng ký Kết Theo kế hoạch Thực tế đạt Ghi (Thời gian kết thúc) - Lý thay đổi (nếu có): e) Thống kê danh mục sản phẩm KHCN ứng dụng vào thực tế Số Tên kết Thời gian Địa điểm Kết TT ứng dụng (Ghi rõ tên, địa nơi ứng dụng) sơ 2 Đánh giá hiệu nhiệm vụ mang lại: a) Hiệu khoa học công nghệ: (Nêu rõ danh mục công nghệ mức độ nắm vững, làm chủ, so sánh với trình độ cơng nghệ so với khu vực giới…) Nghiên cứu tổng hợp vật liệu cấu trúc nano Ti0.7W0.3O2 có tính chất vượt trội diện tích bề mặt riêng lớn, độ dẫn điện cao, độ bền cao mơi trường axit mơi trường oxi hóa, thay vật liệu truyền thống cacbon Bên cạnh đó, vật liệu cấu trúc nano Ti 0.7W0.3O2 hạt xúc tác Pt cịn có lực liên kết mạnh dẫn tới cải thiện đáng kể hoạt tính xúc tác độ bền phản ứng oxi hóa methanol so với vật liệu xúc tác thương mại Pt/C Điều này, dẫn tới cải thiện độ bền hiệu suất hoạt động pin nhiên liệu methanol trực tiếp góp phần làm giảm giá thành pin nhiên liệu b) Hiệu kinh tế xã hội: (Nêu rõ hiệu làm lợi tính tiền dự kiến nhiệm vụ tạo so với sản phẩm loại thị trường…) Hiện nay, vật liệu xúc tác Pt/C sử dụng rộng rãi pin nhiên liệu methanol trực tiếp Tuy nhiên, độ bền vật liệu cacbon lực tương tác yếu cacbon xúc tác Pt dẫn tới làm giảm hiệu hoạt động pin nhiên liệu methanol trực tiếp thời gian hoạt động lâu dài Do đó, việc tổng hợp thành cơng vật liệu cấu trúc nano Ti0.7W0.3O2 với diện tích bền mặt riêng lớn (xấp xỉ diện tích bề mặt riêng cacbon), độ bền điện hóa cao có lực tương tác mạnh với hạt xúc tác Pt dẫn tới tăng hoạt tính độ bền xúc tác cho phản ứng oxi hóa methanol, phản ứng quan trọng điện cực anode pin nhiên liệu methanol trực tiếp Hướng nghiên cứu đóng góp mặt kinh tế tăng hiệu hoạt động pin nhiên liệu methanol trực tiếp góp phần bảo vệ mơi trường khả phát thải thấp pin nhiên liệu Tình hình thực chế độ báo cáo, kiểm tra nhiệm vụ: Số TT I Nội dung Báo cáo tiến độ Lần Thời gian thực 11/12/2018 Ghi (Tóm tắt kết quả, kết luận chính, người chủ trì…) - Đã hồn thành vượt tiến độ công việc - Đã tổng hợp vật liệu cấu trúc nano Ti0.7W0.3O2 phương pháp solvothermal với diện tích bề mặt riêng lớn (> 200 m2/g) độ dẫn điện cao (0.022 S/cm – gấp 105 lần so với vật liệu TiO2) High Conductivity and Surface Area of Mesoporous Ti0.7 W0.3 O2 Materials as Promising Catalyst Support for Pt 6000 Pt(111) Pt/Ti0.7W0.3O2 Ti0.7W0.3O2 WO3 (JCPDS 020-1324) 204 105 211 200 Anatase (JCPDS 084-1286) 004 1000 60 Degree (2θ) Ti0.7W0.3O2 001 020 200 30 2000 220 200 105 204 Anatase (JCPDS 084-1286) 004 3000 Pt (JCPDS 04-0802) 211 1000 101 4000 2000 111 5000 200 Intensity (a.u.) 3000 101 measurement, the material was degassed at 150 C for h in order to completely vaporize the water molecules adsorbed in the meso/micropores of the oxide The electrical conductivity of the Ti07 W03 O2 powder was measured by a standard four-probe technique Ti07 W03 O2 powders were made into pellets, of ∼13 mm diameter and ∼1 mm thickness, by use of steel in a hydraulic press under a pressure of 300 MPa To obtain reliable electrical conductivity data, the four-point probe system was carefully placed on the Ti07 W03 O2 pellet The Pt loading on the support was determined both by energy-dispersive X-ray spectroscopy (EDX-JSM 6500F, JEOL) with an accelerating voltage of 15 kV Intensity (a.u.) Huynh et al 30 RESULTS AND DISCUSSION 60 Degree (2θ) 3.1 Characterization of Ti0.7 W0.3 O2 Support Figure X-ray diffraction patterns of Ti07 W03 O2 samples and (inset) The structure of Ti07 W03 O2 support was confirmed by X-ray diffraction patterns of 20 wt% Pt/Ti07 W03 O2 catalyst means of XRD patterns Figure shows that the diffraction peaks of Ti07 W03 O2 nanoparticles at 2 positions 25.3 ; 38.1; 47.5; 54.4 and 62.8 corresponding to was not clearly detected, confirming that Ti07 W03 O2 is a crystal plane (101); (004); (200); (105) and (204), principally a homologous solid solution with anatase-TiO2 which was slightly left shifted compared to that of stanstructure dard anatase-TiO2 structure (JCPDS 084-1286) This result As shown in Figures 3(a) and (b), uniformly sized sphercould be interpreted as the merged of W6+ ions into the ical nanoparticles of Ti07 W03 O2 supports with a diamanatase-TiO2 lattice and changed Ti4+ to form W–O–Ti eter in the range of 9–10 nm and the good distribution bonds or located at interstitial sites.18 Interesting, the were obtained via the single-step solvothermal process 95.85.71.37 On:3 Fri, 07 2018 14:04:25 three strongest diffraction peaks of IP: tungsten oxide (WO in Dec this work Moreover, the agglomeration of Ti07 W03 O2 Copyright: American Scientific Publishers (JCPDS 020-1324) at 2 position 23.0 ; 23.7 and 24.0 nanoparticles was significantly removed compared to that Delivered by Ingenta of the previous reports,15 16 19 which could be predicted corresponding to a crystal plane (001), (020) and (200) Figure The 20 wt% Pt/Ti07 W03 O2 was synthesized by chemical reduction process J Nanosci Nanotechnol 19, 877–881, 2019 879 High Conductivity and Surface Area of Mesoporous Ti0.7 W0.3 O2 Materials as Promising Catalyst Support for Pt Huynh et al Figure Pore diameter of Ti07 W03 O2 support and (inset) comparison of the surface area between Ti07 W03 O2 and others materials in the previous reports 3.2 Characterization of Pt/Ti0.7 W0.3 O2 Catalyst The formation of crystalline Pt nanoparticles in Pt/Ti07 W03 O2 catalyst was confirmed by means of the Figure (a) TEM images; (b) SEM images, and (c) EDS of X-ray diffraction (XRD) pattern Figure (inset) shows Ti07 W03 O2 nanoparticles that the diffraction peak of Pt metal at 2 positions 39.76; 46.2 and 67.45 corresponding to a crystal plane (111), that the high surface area of the Ti07 W03 O2 catalyst (200) and (220) of the face-centered cubic (fcc) Pt (JDCPS support 04-0802) was determined This result suggested that Pt Energy-dispersive X-ray spectroscopy (EDX) (Fig 3(c)) nanoparticles successfully anchored on the Ti07 W03 O2 shows that the proportion of Ti atom and W atom is support Furthermore, the diffraction peak of mesoporous 69.44 and 30.56, respectively, which closely agree with the Ti07 W03 O2 support was not changed, which implied that IP: W 95.85.71.37 On: Dec 2018 14:04:25 expected atom ratio of 70:30 for Ti resultFri, 07 07Copyright: 03 O2 This high stability of mesoporous Ti07 W03 O2 American Scientific Publishers suggested that the ingredient of Ti07 W03 O2 nanoparticles Delivered by Ingenta The morphology of 20 wt% Pt/Ti07 W03 O2 samples can be easily controlled through adjusting the percentage was investigated by the transmission electron microscopy of TiCl4 and WCl6 precursors Importantly, the diffrac(TEM) measurements and scanning electron microscopes tion peaks of tungsten oxide were not detected by the (SEM) measurements Figures 6(a), (b) illustrates that the X-diffraction (XRD), whilst EDX measurements indicate spherical Pt nanoparticles are shape of ∼9 nm in diamethat the atom ratio of tungsten atom into Ti07 W03 O2 supter were deposited uniformly on the mesoporous support port is 30.56 This suggested that tungsten atom may be This result could be interpreted as the high surface area of successfully incorporated into anatase-TiO2 structure mesoporous Ti07 W03 O2 materials affecting to a high level The surface area plays an important role in the catalyst of dispersion of nanosized catalysts.22 support materials The surface area of Ti07 W03 O2 support Figure 6(c) indicates that the percentage of Pt nanoparwas measured by the BET measurements The high surticles anchored on the surface of Ti07 W03 O2 catalyst face area up to 201.481 m2 /g, which is definitely higher support is 19.35 wt%, which agrees closely with the than that of anatase-TiO220 (83 m2 /g) and W-doped TiO210 (91.71 m2 /g) Interestingly, Ti07 W03 O2 also exposed the porous structure with a diameter about 2.02 nm (Fig 4) indicating the Ti07 W03 O2 support is mesoporous materials, which is a promising support material for the deposition of platinum nanoparticle catalysts The electronic conductivity of mesoporous Ti07 W03 O2 was confirmed by a standard four-probe technique As a result, the electronic conductivity of Ti07 W03 O2 (0.022 S/cm) is much higher than that of the TiO2 nanoparticles (137 × 10−7 S/cm)17 and other materials of the previous reports16 17 21 (Fig 5) This result suggested that the mesoporous Ti07 W03 O2 materials can satisfy the requireFigure Comparison of the electronic conductivity between mesoment of support materials for electrochemical, particularly porous Ti07 W03 O2 materials in this work and others materials in the PEMFCs previous reports 880 J Nanosci Nanotechnol 19, 877–881, 2019 Huynh et al High Conductivity and Surface Area of Mesoporous Ti0.7 W0.3 O2 Materials as Promising Catalyst Support for Pt catalyst support to alternative carbon-support materials for Proton-exchange membrane fuel cells (PEMFCs) Acknowledgments: This research is financially supported by Youth Innovative Science and Technology Incubation Programme, managed by Youth Promotion Science and Technology Center, Hochiminh Communist Youth Union, HCMC, Vietnam References and Notes Z.-M Zhou, Z.-G Shao, X.-P Qin, X.-G Chen, Z.-D Wei, and B.-L Yi, Int J Hydrogen Energy 35, 1719 (2010) L Li, L Hu, J Li, and Z Wei, Nano Research 8, 418 (2015) V T T Ho, K C Pillai, H.-L Chou, C.-J Pan, J Rick, W.-N Su, B.-J Hwang, J.-F Lee, H.-S Sheu, and W.-T Chuang, Energy and Environmental Science 4, 4194 (2011) D Gubán, A Tompos, I Bakos, Á Vass, Z Pászti, E G Szabó, I E Sajó, and I Borbáth, Int J Hydrogen Energy 42, 13741 (2017) C.-J Pan, M.-C Tsai, W.-N Su, J Rick, N G Akalework, A K Figure (a) TEM images; (b) SEM images; and (c) EDS of 20 wt% Agegnehu, S.-Y Cheng, and B.-J Hwang, Journal of the Taiwan Pt/Ti07 W03 O2 catalysts Institute of Chemical Engineers 74, 154 (2017) J.-H Kim, G Kwon, H Lim, C Zhu, H You, and Y.-T Kim, calculated 20 wt% Pt, which implied that the Pt nanoparJ Power Sources 320, 188 (2016) A Bharti and G Cheruvally, J Power Sources 363, 413 (2017) ticle easily anchored on the surface of mesoporous M Kim, C Kwon, K Eom, J Kim, and E Cho, Scientific Reports support Ti07 W03 O2 via chemical reduction process uti7, 44411 (2017) lizing NaBH4 reducing agent without any surfactants or X Liu, X Wu, and K Scott, Catal Sci Technol 4, 3891 (2014) stabilizers 10 E O Oseghe, P G Ndungu, and S B Jonnalagadda, Journal of Photochemistry and Photobiology A: Chemistry 312, 96 (2015) 11 W Sangkhun, L Laokiat, V Tanboonchuy, P Khamdahsag, and CONCLUSION IP: 95.85.71.37 On: Fri, 07 Dec 2018 14:04:25 N Grisdanurak, Superlattices Microstruct 52, 632 (2012) Copyright: American Publishers 12 H Tian, J Ma, K Li, and J Li, Mater Chem Phys 112, 47 (2008) In summary, mesoporous Ti07 W03 O2 materials were easily Scientific Delivered Ingenta Y Wang, T Chen, and Q Mu, J Mater Chem 21, 6006 (2011) synthesized via a one-step solvothermal process with low- by13 14 D.-M Chen, G Xu, L Miao, L.-H Chen, S Nakao, and P Jin, temperature utilizing only titanium tetrachloride (TiCl4 J Appl Phys 107, 063707 (2010) and tungsten hexachloride (WCl6 as precursors As a 15 C V S D Wang, H Wang, E Rus, F J DiSalvo, and H D Abruña, result, mesoporous Ti07 W03 O2 materials have a uniformly J Am Chem Soc 132, 10218 (2010) 16 Q Z Chinmayee, V Subban, A Hu, T E Moylan, F T Wagner, spherical nanoparticles morphology of 10 nm diameter and F J DiSalvo, J Am Chem Soc 132, 17531 (2010) and pores with 2.02 nm, resulting in the high surface 17 V T Ho, C J Pan, J Rick, W N Su, and B J Hwang, J Am area up to 201.481 m /g Moreover, the agglomeration Chem Soc 133, 11716 (2011) nanoparticles were significantly prevented compared to 18 Y Yang, H Wang, X Li, and C Wang, Mater Lett 63, 331 (2009) that of Ti07 W03 O2 catalyst support in the previous reports 19 L Zheng, L Xiong, Q Liu, J Xu, X Kang, Y Wang, S Yang, J Xia, and Z Deng, Electrochim Acta 150, 197 (2014) Interesting, the high electrical conductivity of meso20 G Cabello, R A Davoglio, and E C Pereira, J Electroanal Chem porous Ti07 W03 O2 (0.022 S/cm) is significantly higher 794, 36 (2017) than that of others materials, which plays an impor21 Y.-J Wang, D P Wilkinson, V Neburchilov, C Song, A Guest, and tant key in catalyst support materials for PEMFCs The J Zhang, J Mater Chem A 2, 12681 (2014) 22 K.-W Park and K.-S Seol, Electrochem Commun 9, 2256 (2007) result found that mesoporous Ti07 W03 O2 are a promising Received: 17 November 2017 Accepted: 13 March 2018 J Nanosci Nanotechnol 19, 877–881, 2019 881 Article Journal of Nanoscience and Nanotechnology Copyright © 2018 American Scientific Publishers All rights reserved Printed in the United States of America Vol 18, 7177–7182, 2018 www.aspbs.com/jnn Advanced Ti07W03O2 Nanoparticles Prepared via Solvothermal Process Using Titanium Tetrachloride and Tungsten Hexachloride as Precursors Hau Quoc Pham1 , Tai Thien Huynh1 , At Van Nguyen1 , Tran Van Thuan3 , Long Giang Bach3 , and Van Thi Thanh Ho2 ∗ Bach Khoa University (BKU), Ho Chi Minh City, 700000, Vietnam Hochiminh City University of Natural Resources and Environment (HCMUNRE), 700000, Vietnam Nguyen Tat Thanh Institute of Hi-Technology, Nguyen Tat Thanh University, Ho Chi Minh City, 700000, Vietnam The degradation of Pt-based catalysts is considered as the main barrier to the commercialization of fuel cells M-doped TiO2 (M is a transition metal) has been investigated to improve the stability of electrocatalysts Recently, W-doped TiO2 materials have been found as a good catalyst support for the photocatalyst applications but their application in Proton-exchange membrane fuel cell application has rarely been reported In addition, the agglomeration of nanoparticles, which are synthesized from the organic precursor, has been reported Here, we report Ti07 W03 O2 nanoparticles prepared via a one-step solvothermal method with inorganic precursors without using surfactants or stabilizers for restricting nanoparticle agglomeration The properties of the material were measured by XRD, TEM, BET, and electronic conductivity The mean particle size of ∼5 nm, the high specific surface area of 126.471 m2 /g and a moderate electronic conductivity of 0.014 S/cm were obtained for the sample prepared at 220 C for h It was observed that using inorganic precursors to prevent particle agglomeration is more advantageous compared to organic precursors as mentioned in previous reports Keywords: Nanoparticles, Catalyst Support, Solvothermal, Ti07 W03 O2 , W-Doped TiO2 INTRODUCTION At present, Carbon Black is mainly used as a catalyst support in fuel cell systems owing to its high activity for the oxygen reduction reaction (ORR) at the cathode.1 However, the durability of carbon-based supports during the operational environment is a critical hurdle for commercialization.2 The degradation of Pt/C catalyst with long-time operations leads to a decrease in the performance of fuel cells, which can be expounded by two mechanisms.1 Firstly, the exceedingly weak interaction (van der Waals forces) between Pt catalyst and carbon support leads to Pt agglomeration and Pt nanoparticle detachment.3 Secondly, the corrosion of carbon-based supports occurs by thermodynamic reaction at the cathode of Proton-exchange membrane fuel cell (PEMFC) (ECO = /C 0207 V versus NHE at T = 298 K) at high electrode ∗ Author to whom correspondence should be addressed J Nanosci Nanotechnol 2018, Vol 18, No 10 potentials.4 In order to solve these problems, carbon materials, which are mostly of graphitic nature, such as graphene,5 carbon nanofibers,7 and carbon nanotubes,9 are used as alternative carbon-based supports As a result, they show better durability than that of Carbon Black in the operating conditions of PEMFC Nevertheless, they are still electrochemically corroded at high potentials.10 At present, titanium oxide (TiO2 is widely used in applications such as sensors,11 12 dye-solar cells,13 14 and photocatalysts15 owing to its commercial availability, nontoxicity, high stability, and the possibility to control size and structure of particles.16–19 However, a low electrical conductivity of 137 × 10−7 S/cm20 is a critical hindrance for its use in fuel cells To overcome this problem, doping strategies have been attempted.20–24 For example, Ti07 Mo03 O2 ,20 Ti07 Ru03 O2 ,24 Nb-doped TiO2 ,22 and Ta-doped TiO2 25 show higher CO-tolerance than carbon-based supports Recently, W-doped TiO2 materials have been studied as catalyst materials in photocatalyst 1533-4880/2018/18/7177/006 doi:10.1166/jnn.2018.15720 7177 Advanced Ti07 W03 O2 Nanoparticles Prepared via Solvothermal Process Using Titanium Tetrachloride Table I The summary of Ti07 W03 O2 samples synthesized in this work Sample Temperature ( C) 180 200 220 220 220 Time (h) Denote 4 T1804 T2004 T2204 T2202 T2206 applications.26–28 Nevertheless, to the best of our knowledge, these materials have rarely been tested in lowtemperature fuel cells Some previous studies, fabricating W-doped TiO2 for fuel cells, found it to be a challenging task For example, Wang et al.29 synthesized Ti07 W03 O2 by the sol–gel method by compromising the durability and higher CO-tolerance than carbon-based supports Nonetheless, the agglomeration of Ti07 W03 O2 nanoparticles leads to the inhomogeneous catalyst dispersion, resulting in the low performance of fuel cells In addition, several works29 30 have synthesized W-doped TiO2 nanostructure from organic precursors showing that the nanoparticles are easily agglomerated by grafted organic macromolecules.31 In this study, for the first time, Ti07 W03 O2 nanoparticles were synthesized by the one-step solvothermal process without using surfactants or stabilizers The utilization of inorganic precursors including titanium tetrachloride and tungsten hexachloride was aimed to restrict the agglomeration of Ti07 W03 O2 nanoparticles The samples were characterized by XRD, TEM, BET, and electrical conductivity As a result, Ti07 W03 O2 synthesized at 220 C for h formed a solid solution with anatase-TiO2 structure The morphology of Ti07 W03 O2 sample showed a uniform spherical shape with approximately nm of particles size resulting in a high surface area of 126.471 m2 /g, which is Figure 7178 Pham et al higher than that reported previously.26 28 Importantly, the electronic conductivity of Ti07 W03 O2 sample in our study was 0.014 S/cm, which was significantly higher compared to that of undoped TiO2 nanoparticles (137 × 10−7 S/cm) These results open a new approach for synthesizing the Ti07 W03 O2 nanostructure from inorganic precursors via the solvothermal method and introduce it as a promising catalyst support to deal with current technical barrier relating to carbon-based supports EXPERIMENTAL DETAILS 2.1 Chemical All reagents and solvents were commercially procured and used without further purification Tungsten hexachloride (WCl6 , 99.9%) was purchased from Sigma-Aldrich, USA Titanium tetrachloride (TiCl4 , 99.5%) were purchased from Aladdin, Shanghai, China Ethanol (99.9%) and Acetone (99.9%) were obtained from Merck, Belgium 2.2 Synthesis of Ti07 W03 O2 Nanoparticles In a typical experiment, Ti07 W03 O2 nanoparticles were synthesized by a one-step solvothermal process using WCl6 and TiCl4 as precursors with W and Ti at a molar ratio of 3:7, without using surfactants or stabilizers At first, 0.238 g of WCl6 was dissolved in absolute ethanol followed by adding 0.155 mL TiCl4 The so formed blue transparent solution was transferred to a Teflon-lined autoclave with stainless steel shell and heated to 180 C, 200 C and 220 C for h, h and h (Table I) in an oven and then cooled to room temperature The product was washed with acetone, deionized water, and centrifuged several times until the pH of washings was neutral Finally, the precipitates were dried at 80 C in the oven overnight for further analysis Ti07 W03 O2 nanoparticles synthesis process following the one-step solvothermal method J Nanosci Nanotechnol 18, 7177–7182, 2018 Pham et al Advanced Ti07 W03 O2 Nanoparticles Prepared via Solvothermal Process Using Titanium Tetrachloride (a) 6000 T2004 4000 T1804 WO3 (JCPDS 020-1324) 20 40 215 116 220 204 200 105 211 Anatase (JCPDS 084-1286) 004 101 2000 001 020 200 Intensity T2204 60 80 Degree (2θ) (b) 8000 T2204 T2004 RESULTS AND DISCUSSION T1804 020 200 4000 001 Intensity (a.u.) 6000 and morphology of Ti07 W03 O2 nanoparticles were evaluated by transmission electron microscopy (TEM) on an FEI-TEM–2000 microscope operated at an accelerating voltage of 3800 V The specimens were prepared by ultrasonically suspending the NPs in ethanol; the suspension was then applied to a copper grid and dried in an oven The Brunauer-Emmett-Teller (BET) surface area of the Ti07 W03 O2 support was obtained from N2 adsorption isotherms at 77 K (Porous Materials, BET–202A) Before the BET measurement, the material was degassed at 150 C for h in order to completely vaporize the water molecules adsorbed in the meso/micropores of the oxide The electrical conductivity of the Ti07 W03 O2 powder was measured by a standard four-probe technique Ti07 W03 O2 powders were made into pellets of ∼13 mm diameter and ∼1 mm thickness by using steel in a hydraulic press under a pressure of 300 MPa To obtain reliable electrical conductivity data, the four-point probe system was carefully placed on the Ti07 W03 O2 pellet WO3 (JCPDS 020-1324) 101 2000 Anatase (JCPDS 084-1286) 20 22 24 26 28 30 Degree (2θ) Figure (a) XRD patterns of T1804 (180 C, h), T2004 (200 C, h), and T2204 (220 C, h) (b) High-quality XRD patterns of T1804 (180 C, h), T2004 (200 C, h), T2204 (220 C, h) in the range of 20–30 2.3 Material Characterization The powder X-ray diffraction (XRD) patterns of Ti07 W03 O2 nanoparticles were obtained by a D2 PHASER diffractometer using the CuKR radiation and Ni as a filter at 30 kV and 100 mA The data were collected from 20 to 80 at the 2 scale The particle size Figure Ti07 W03 O2 nanoparticles were synthesized by the one-step solvothermal method using TiCl4 and WCl6 as the precursors of Ti and W, respectively, without using any surfactantor stabilizer (Fig 1) Figure 2(a) describes the XRD patterns of Ti07 W03 O2 samples synthesized at different temperatures The diffraction peaks of Ti07 W03 O2 at 2 positions of 25.1, 38.1, 47.5, 54.4 , and 62.8 were observed, which were slightly shifted to the left side compared to that of the pure anataseTiO2 (JCPDS 084–1286) due to the tungsten doping Furthermore, as shown in Figure 2(b), the three strongest peaks of WO3 (JCPDS 020–1324) at 2 position 23.0; 23.7 and 24.0 corresponding to (001), (020) and (200) facets were not clearly detected in the XRD profiles of the three samples: T2204, T2004, T1804 The results suggest a possibility of the formation of a solid solution Moreover, the position of the highest peak among the XRD profiles of the three samples slightly shifted to the left (at 2 position 25.1 compared to that of the anatase TiO2 (JCPDS 084–1286) at the 2 position of 25.3 This phenomenon TEM images of all sample at different temperatures of (a) T1804, (b) T2004, and (c) T2204 J Nanosci Nanotechnol 18, 7177–7182, 2018 7179 Advanced Ti07 W03 O2 Nanoparticles Prepared via Solvothermal Process Using Titanium Tetrachloride (a) 8000 6000 T2204 4000 T2202 20 40 215 116 220 204 Anatase (JCPDS 084-1286) 105 211 004 200 WO3 (JCPDS 020-1324) 101 2000 001 020 200 Intensity (a.u.) T2206 80 60 Degree (2θ) (b) 8000 6000 T2204 T2202 020 200 4000 001 Intensity (a.u.) T2206 WO3 (JCPDS 020-1324) 2000 101 Anatase (JCPDS 084-1286) 20 22 24 26 28 30 Degree (2θ) Figure (a) XRD diffraction of T2202 (220 C, h), T2204 (220 C, h), and T2206 (220 C, h) (b) High quality XRD diffraction of T2202 (220 C, h), T2204 (220 C, h), and T2206 (220 C, h) in the range of 20–30 could be explained by the result of W doping into anatase TiO2 lattices In order to accurately determine the nanoparticle size, the samples were measured by the transmission electron microscopy (TEM) Figure depicts the TEM Figure 7180 Pham et al images of all samples at a different temperature As for sample T1804, the morphology is unclear with agglomeration phenomena It could be attributed to the low crystallinity resulting from the low solvothermal temperature When reaction temperatures rose up to 220 C, the crystallinity increased considerably as can be seen from Figure 3(c) It is well-known that the electronic conductivity has a strong correlation with the crystallinity of the material Thus the reaction temperature of 220 C was chosen to further investigate the impact of reaction time on the material properties by allowing the reaction for 2, 4, and h (Fig 4) Regardless of the increase in the reaction time, all samples were still found in the anatase phase However, as shown in Figure 4(b), it is obvious that some diffraction peaks related to WO3 could be observed when the reaction time reaches h This result indicates the formation of mixed oxides after extending the reaction time beyond h at 220 C Therefore, we can further confirm that the suitable preparation condition is 220 C for h Figure shows the TEM images of all samples prepared at different reaction time When reaction time was increased from h to h, there was a considerable improvement in crystallinity without a significant increase in the particles size However, the particles size rose strongly from nm to 20 nm with respect to the increase in the reaction time from h to h In the present investigation, the agglomeration of nanoparticles was clearly prevented compared to that of Ti07 W03 O2 nanoparticles synthesized by organic precursors.29 30 The size of nanoparticles of T2204 was considerably uniform and significantly smaller compared to that in the previous reports (Table II) For example, Wang et al.29 and Subban et al.30 used the sol–gel process for fabricating Ti07 W03 O2 from organic precursors, resulting in a nanoparticles size of approximately 50 nm The agglomeration of Ti07 W03 O2 nanoparticles synthesized by sol–gel was also reported by Zheng et al.32 The T2204 sample was subjected to the surface area (BET) measurement, which showed the highest surface area of TEM images of (a) T2202, (b) T2204 sample, and (c) T2206 sample J Nanosci Nanotechnol 18, 7177–7182, 2018 Pham et al Advanced Ti07 W03 O2 Nanoparticles Prepared via Solvothermal Process Using Titanium Tetrachloride Table II The comparison of the nanoparticle size between Ti07 W03 O2 nanoparticles (T2204) in this work and Ti07 W03 O2 nanoparticles synthesized earlier electronic conductivity offers Ti07 W03 O2 the best promoting catalyst support for fuel cells CONCLUSION Samples Synthesis method Precursors Nanoparticles size (nm) Ti07 W03 O2 Sol–gel Organic precursors 20–50 nm ∼50 nm Ti07 W03 O2 Sol–gel Organic precursors Aggregated Ti07 W03 O2 Sol–gel Inorganic precursors Ti07 W03 O2 particles of several micrometers ∼5 nm Ti07 W03 O2 Solvo- Inorganic (T2204) thermal precursors Reference [29] [30] [32] In this work Table III Comparison of the surface area between T2204 samples and W-doped TiO2 synthesized in other works as well as anatase-TiO2 Sample Anatase-TiO2 W-doped TiO2 W-doped TiO2 Ti07 W03 O2 (T2204) Synthesis method Hydrothermal Precursor Organic precursors Hydrothermal Inorganic precursors Sol–gel Organic precursors Solvothermal Inorganic precursors Surface area (m2 /g) Reference 83 [33] 76.61 [28] 91.71 [26] 126.471 In this work 126.471 m2 /g This value is extremely higher than that of anatase-TiO2 and W-doped TiO2 nanoparticles of other researchers26 28 33 (Table III) due to the advantages of inorganic precursors in preventing particle agglomeration (Fig 6) The electronic conductivity of Ti07 W03 O2 synthesized at 220 C for h was measured at 0.014 S/cm, which is significantly higher than that of the undoped TiO2 (137 × 10−7 S/cm)20 and Ti07 Mo03 O2 20 (28 ×10−4 S/cm) A high Figure Comparison of the surface area between T2204 sample in this work and anatase-TiO2 as well as W-doped TiO2 in others works J Nanosci Nanotechnol 18, 7177–7182, 2018 In conclusion, Ti07 W03 O2 was synthesized by the one-step solvothermal process without using surfactants or stabilizers We found that Ti07 W03 O2 nanoparticle agglomeration could be prevented by the utilization of inorganic precursors As a result, Ti07 W03 O2 was successfully synthesized with the anatase-TiO2 structure The Ti07 W03 O2 morphology showed a uniform spherical shape with a particles size of nm, resulting in a high surface area of 126.471 m2 /g Moreover, a high electronic conductivity at 0.014 S/cm was observed These results not only open a new approach for synthesizing Ti07 W03 O2 nanostructure from inorganic precursors but also introduces a promising catalyst support for Ti07 W03 O2 for further utilization in fuel cells Acknowledgments This research is financially supported by Youth Innovative Science and Technology Incubation Programme, managed by Youth Promotion Science and Technology Center, Hochiminh Conmunist Youth Union, HCMC,Vietnam References and Notes L Li, L Hu, J Li, and Z Wei, Nano Res 8, 418 (2015) Z.-M Zhou, Z.-G Shao, X.-P Qin, X.-G Chen, Z.-D Wei, and B.-L Yi, Int J Hydrogen Energy 35, 1719 (2010) Y Liu, S Shrestha, and W E Mustain, ACS Catal 2, 456 (2012) L Castanheira, W O Silva, F H B Lima, A Crisci, L Dubau, and F Maillard, ACS Catal 5, 2184 (2015) E Antolini, Appl Catal B: Environmen 123–124, 52 (2012) Y Li, Y Li, E Zhu, T McLouth, C Y Chiu, X Huang, and Y Huang, J Am Chem 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Microstructures 52, 632 (2012) 28 H Tian, J Ma, K Li, and J Li, Mater Chem Phys 112, 47 (2008) 29 C V S D Wang, H Wang, E Rus, F J DiSalvo, and H D Abruña, J Am Chem Soc 132, 10218 (2010) Pham et al 30 Q Z Chinmayee, V Subban, A Hu, T E Moylan, F T Wagner, and F J DiSalvo, J Am Chem Soc 132, 17531 (2010) 31 E M Hotze, T Phenrat, and G V Lowry, J Environ Quality 39, 1909 (2010) 32 L Zheng, L Xiong, Q Liu, J Xu, X Kang, Y Wang, S Yang, J Xia, and Z Deng, Electrochim Acta 150, 197 (2014) 33 G Cabello, R A Davoglio, and E C Pereira, J Electroanal Chem 794, 36 (2017) Received: 28 July 2017 Accepted: November 2017 7182 J Nanosci Nanotechnol 18, 7177–7182, 2018 Solid State Phenomena ISSN: 1662-9779, Vol 279, pp 181-186 doi:10.4028/www.scientific.net/SSP.279.181 © 2018 Trans Tech Publications, Switzerland Submitted: 2018-05-17 Accepted: 2018-06-19 Online: 2018-08-17 Comparison the Rapid Microwave-Assisted Polyol Route and Modified Chemical Reduction Methods to Synthesize The Pt Nanoparticles on the Ti0.7W0.3O2 Support Hau Quoc Pham1,a, Tai Thien Huynh1,2,b, At Van Nguyen1,c, Anh Tram Ngoc Mai1,d, Vi Thuy Thi Phan1,e, Long Giang Bach3,f, Duy Trinh Nguyen3,g, Van Thi Thanh Ho2,h* Ho Chi Minh City University of Technology (HCMUT), Vietnam Hochiminh City University of Natural Resources and Environment (HCMUNRE), Vietnam NTT Institute of Hi-Technology, Nguyen Tat Thanh University, Ho Chi Minh City, Vietnam a phamquochau11819@gmail.com, bhttai@hcmunre.edu.vn, cnguyenat95@gmail.com, maitramanh97@gmail.com,ephanthithuyvyheocon@gmail.com, fblgiangntt@gmail.com, g nguyenduytrinh86@gmail.com, hhttvan@hcmunre.edu.vn d Keywords: Ti0.7W0.3O2, W-doped TiO2, solvothermal process, rapid microwave-assisted polyol, modified chemical reduction Abstract The tungsten-modified titanium dioxide, which prepared through the one-pot solvothermal process, exhibited the large specific surface area (~ 202 m2/g) and greater electrical conductivity (~ 0.022 S/cm) Furthermore, for the comparison purpose to find appropriate approach for the synthesis 20 wt % Pt NPs/Ti0.7W0.3O2 catalyst, the modified chemical reduction utilizing NaBH4 and the rapid microwave-assisted polyol using ethylene glycol were employed without any surfactants or stabilizers The characterization of Pt-based electrocatalyst was investigated through XRD, SEM-EDX, TEM measurements As result, the platinum nanocatalyst formation with the face-centered cubic structure (fcc) and the amount loading on Ti0.7W0.3O2 support approximately 20 wt % of two synthesized methods However, the diameter size and distribution of Pt nano-forms have clearly classified in two reduction route For example, the Pt nanocatalyst, which was created by the rapid microwave-assisted polyol at 160 oC for min, exhibited the good distribution on support with ~3 nm diameter This could be ascribed to the fast and uniform heating of microwaveassisted and moderate reducing possibility of ethylene glycol These results indicate that the rapid microwave-assisted polyol was an appropriate approach not only for synthesizing 20 wt % Pt NPs/Ti0.7W0.3O2 catalyst but also for preparing Pt-based electrocatalysts Introduction To overcome the problem of fossil fuels, which is threatening to humankind and other living creature on earth, the researcher is effort find out the alternative energy namely solar energy, wind energy as well as biomass energy Among them, the low-temperature fuel cells were considered as a promising candidate owing to energy efficiency and no CO2 emission [1] However, the poor performance of the catalyst in long operation and its high cost are main hinder to wide-spread commercialization for future At present, finding the appropriate synthesis to deposit metal catalyst with the small diameter and good distribution on support for enhanced electrocatalytic activity is still challenging work It is of great importance to determine an effortless, fast and efficient method to enhance efficient electrocatalyst for fuel cells applications Nowadays, platinum nano-forms loading on the support was commonly synthesized through the modified chemical reduction route or microwave-assisted polyol According to the previous studies [2, 3] indicated that the modified chemical reduction using a mixture sodium borohydride and ethylene glycol, which comprise to a strong reducing possibility of NaBH4 and good dispersion provided by ethylene glycol, is suitable method to create Pt nanocatalysts with the small size and good distribution on support In contrast, other studies [2-4] demonstrated that the microwaveAll rights reserved No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, www.scientific.net (#109097139-03/08/18,15:35:53) 182 Metallurgy Technology and Materials VI assisted polyol utilizing ethylene glycol, which consists of fast and homogeneous heating of microwave-assisted and moderate reducing possibility of ethylene glycol, is the appropriate route for the deposition Pt nanoparticles on support to enhance electrocatalytic activity for a Pt-based catalyst for fuel cells However, to be the best of our knowledge, there is no research for the comparison purpose of these route for synthesizing Pt nanoparticles supported on tungsten-modified titanium dioxide for low-temperature fuel cell application Herein, with the purpose find a suitable method for deposited platinum nano-forms on tungstenmodified titanium dioxide, the modified chemical reduction route using a mixture sodium borohydride and ethylene glycol and rapid microwave-assisted polyol utilizing ethylene glycol were employed All approaches in this work were not presenting any stabilizers or surfactants The characterization of Pt-based electrocatalysts was recorded through X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM) measurements As a result, the rapid microwave-assisted polyol at 160 oC for was appropriate to approach with the small diameter (~ 3nm) and good distribution of Pt catalyst on Ti0.7W0.3O2, which could ascribe to the fast reduction and the rapid formation of metal nuclei resulting in restricting further growth of the Pt nanocatalyst Furthermore, the platinum agglomeration was significantly removed in comparison with the modified chemical reduction route This indicates that the rapid microwaveassisted polyol utilizing ethylene glycol in this work is a suitable route for preparing 20 wt % Pt/Ti0.7W0.3O2 electrocatalyst in order to enhance the electrocatalytic activity of the Pt-based catalyst for fuel cell fields Experiment Details Chemical All reagents and solvents were commercially procured and used without further purification Tungsten (VI) chloride (WCl6, 99.9%) was purchased from Sigma-Aldrich, USA Titanium (IV) chloride (TiCl4, 99.5%) was purchased from Aladdin, Shanghai, China Ethanol (99.9%) and Acetone (99.9%) were obtained from Merck, Belgium Hexachloroplatinic acid (H2PtCl6) was purchased from Sigma-Aldrich, USA and ethylene glycol (EG, 99.5%) were obtained from Merck, Belgium Synthesis of Ti0.7W0.3O2 nanoparticles In this experiment, tungsten-modified titanium dioxide was prepared via single-step solvothermal process without utilizing capping agents or surfactants at 200 oC for 10 hours, which is mentioned in our research [5] Synthesis of Pt/Ti0.7W0.3O2 catalyst In this work, the 20 wt % Pt nanoparticles were anchored over the Ti0.7W0.3O2 support by the rapid microwave-assisted polyol route using ethylene glycol without using stabilizers or surfactants (denoted Pt/TWO_1) In a particular setup, 110 mg Ti0.7W0.3O2 added into ethylene glycol (25 mL, EG ≥ 99.5%) were stirred in magnetic field until full dispersion This suspension was completely dispersed by mild ultrasonication for 30 and then cooled to °C in an ice tank Next, 2.818 mL of 0.05 M H2PtCl6 was dissolved in this suspension and continue stirring for 30 Then, the pH value of the solution was adjusted by 1.0 M NaOH solution Afterward, the mixture was heated to 160 °C for in a microwave oven (ELECTROLUX EMS2047X, 800 W, 2450 MHz) with the capacity of 240W For the comparison purpose, the modified chemical reduction method only using NaBH4 as the reducing agent (denoted Pt/TWO_2) was employed At first, 2.818 mL of 0.05 M hexachloroplatinic acid was dropped into a mixture comprise to 25 mL of purified water and 0.5 mL of ethylene glycol (EG) to homogeneity solution and then the pH value was adjusted to 11 by NaOH solution After that, the Ti0.7W0.3O2 catalyst support (110 mg) was dispersed into the solution by ultrasonic for 30 Next, NaBH4 was dropped into the suspension and the constant stirring for h to the reaction completely occurred The product of two synthesis methods was Solid State Phenomena Vol 279 183 washed with acetone and deionized water Finally, the 20 wt % Pt loading on tungsten-modified titanium dioxide was dried at 80 oC in the overnight for further analysis Material Characterization The lattice structure information of the specimens was revealed by X-ray diffraction (XRD) measurement performed on a D2 PHASER-Brucker (Germany) utilizing Cu KR radiation at 30 kV The morphology and particle size of tungsten-modified titanium dioxide and 20 wt % Pt NPs loading over tungsten-modified titanium dioxide was recorded through TEM figure The nitrogen adsorption isotherms were recorded on a NOVA 1000e device to record the specific surface area of Ti0.7W0.3O2 The standard four-probe technique was taken on an MWP-6 instrument (Jandel, British) to measure the electrical conductivity of support material The SEM-coupled with EDX was recorded in order to investigate the element ratio of support as well as Pt NPs loading on the support Results and Discussion Characterization of Ti0.7W0.3O2 nanoparticles As mentioned in our previous research, the tungsten-modified titanium dioxide only exhibits the typical diffraction peaks of anatase-TiO2 structure (JCPDS 084-1286) located at 25.3o; 37.8o; 48.0o; 53.9o; 55.1o and 62.7o ascribed to (101); (004); (200); (105); (211) and (204) crystal planes (Figure 1) This suggests that tungsten-modified titanium dioxide is single-phase anatase solid solution with the uniformly spherical morphology about nm (Figure 1, inset) Importantly, the Ti0.7W0.3O2 nanoparticle agglomeration was significantly removed, which could attribute to the one-pot synthesis using inorganic precursors without presenting any surfactants or stabilizers Figure X-ray diffraction patterns of Ti0.7W0.3O2 NPs; inset: TEM image of Ti0.7W0.3O2 support Figure Nitrogen adsorption/desorption isotherms; inset: the electrical conductivity of Ti0.7W0.3O2 compared to that of others non-carbon materials The specific surface area and electrical conductivity are prerequisites of support for Pt-based electrocatalysts in fuel cell fields The Ti0.7W0.3O2 nanoparticles were a mesoporous material with the surface area found to be up to ~202 m2 /g, which approximately equal with the common carbon black (~240 m2/g) (Figure 2) The large specific surface area of tungsten-modified titanium dioxide could be ascribed to the small diameter and no particle agglomeration Furthermore, the electrical conductivity of tungsten-modified titanium dioxide was found about 0.022 S/cm, which is much higher than that of purified-TiO2 (~1.37x10-7 S/cm)[6] and other non-carbon materials in previous works[6-8] (Figure 2, inset) These results indicate that tungsten-modified titanium dioxide was a promising support for Pt-based electrocatalyst in fuel cells fields 184 Metallurgy Technology and Materials VI Characterization of the 20 wt % Pt/Ti0.7W0.3O2 catalyst The 20 wt % Pt loading on tungsten-modified titanium dioxide was synthesized following two different methods (Figure 3): (a) the rapid microwave-assisted polyol process with Ethylene glycol as a reducing agent (Pt/TWO_1) and (b) the modified chemical reduction route (Pt/TWO_2) with the reducing agent is NaBH4 Figure The 20 wt % Pt/Ti0.7W0.3O2 catalyst was synthesized via (a) the rapid microwave-assisted polyol method and (b) the modified chemical reduction route The lattice structure information of both the Pt/TWO_1 and the Pt/TWO_2 catalysts with 20 wt % Pt anchored were obtained by the X-ray diffraction pattern (Figure (a)) All XRD patterns of the Pt-based catalysts exhibit the typical three peak of the face-centered cubic (fcc) Pt (JDCPS 04-0802) located at 39.76 o, 46.24 o, and 67.45o corresponding to a crystal plane (111), (200) and (220) Importantly, the Pt (111) peak in Pt/TWO_1 catalyst shows the much higher intensity and broader compare that of Pt/TWO_2 catalyst, suggesting that the Pt NPs in the Pt/TWO_1 catalyst has the smaller crystallite size and the higher crystallinity Furthermore, the signal of metallic phase was not detected after the reaction in two methods, suggesting that the Ti0.7W0.3O2 NPs have the stable structures on the strong reducing environment of NaBH4 Figure (a) XRD patterns, (b, c) SEM-EDX of Pt/TWO_1 and Pt/TWO_2 catalysts, (d, e) TEM images of Pt/TWO_1 and (f, g) TEM images of Pt/TWO_2 with a different scale bar The Pt nano-forms loading on tungsten-modified titanium dioxide was measured by the Energydispersive X-ray spectroscopy (EDX) measurements As seen in Figure (b,c), the mass fraction of Pt NPs loading in Pt/TWO_1 and Pt/TWO_2 catalysts is 20.24 wt % and 19.35 wt %, respectively, which closely agree with the theoretical calculation (20 wt % Pt) This suggests that Pt NPs could be simply deposited on the mesoporous Ti0.7W0.3O2 support by both the microwave-assisted polyol route and the modified chemical reduction method The small particles and the good dispersion of Pt nanocatalyst on the support are the key requirements to improve electrocatalytic activity and efficiency of the Pt-based catalysts To investigate the particles size and the distribution of Pt NPs in the Pt/TWO_1 and Pt/TWO_2 catalysts, we used the transmission electron microscopy (TEM) measurements As shown in Figure (d, e), the Pt NPs in Pt/TWO_1 have the uniformly spherical shape with a small diameter about nm The small size and great distribution of Pt nano-forms could be attributed to the fast reduction and the rapid formation of metal nuclei resulting in restricting further growth of the Pt particles by the microwave-assisted method and ethylene glycol (EG) can serve as solvent and stabilizer [3, 4], which suggests the enhanced electrocatalytic activity of Pt/TWO_1 for fuel cell application Whilst, the Pt NPs anchored over theTi0.7W0.3O2 support via the modified chemical reduction have also the Solid State Phenomena Vol 279 185 spherical morphology with a larger diameter and particle agglomeration compared to the rapid microwave-assisted polyol (Figure (f, g)), which could be ascribed to the strong reducing possibility and right away of NaBH4 [9] resulting in the electrochemical activity of Pt NPs were significantly decreased Conclusion In summary, the tungsten-modified titanium dioxide was synthesized via effortless solvothermal low-temperature without using surfactants or stabilizers, with the purpose for the low-temperature fuel cells As a result, Ti0.7W0.3O2 is mesoporous with the spherical morphology of ~9 nm, resulting in the high surface area (~202 m2/g) and high conductivity (~0.022 S/cm), which the requirement of support materials for low-temperature fuel cells For the comparison purpose, the modified chemical reduction route and rapid microwave-assisted polyol were employed for synthesizing 20 wt % Pt loading on tungsten-modified titanium dioxide without presenting any surfactants or stabilizers As a result, the rapid microwave-assisted polyol utilizing ethylene glycol as a solvent and stabilizer at 160 oC for is an appropriate approach with the well-distributed and the smaller diameter (~ nm) of Pt nanoparticles on mesoporous Ti0.7W0.3O2 Furthermore, the Pt nanocatalyst agglomeration was significantly removed compared to that of using modified chemical reduction route, which is the key factor could significantly enhance the electrocatalytic activity and efficiency of the catalyst The smaller diameter and great distribution of Pt loading on tungstenmodified titanium dioxide could be ascribed to the fast and uniform heating of microwave-assisted and moderate reducing possibility of ethylene glycol restricting further growth of the Pt particles on support These results indicate that the rapid microwave-assisted polyol route in this work is not only a suitable approach for preparing 20 wt.% Pt/Ti0.7W0.3O2 electrocatalyst but also opens the fast, facile route for synthesizing Pt-based electrocatalysts Acknowledgments This research is financially supported by Youth Innovative Science and Technology Incubation Programme, managed by Youth Promotion Science and Technology Center, Hochiminh Communist Youth Union, 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