Luận án tiến sĩ Kỹ thuật hóa học: Nghiên cứu chế tạo vật liệu Ag

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TÓM TҲ7/8Ұ1È1

BiӃn tính TiO2 bҵng kim loҥi có khҧ QăQJ JLD WăQJ KRҥt tính xúc tác quang hóa cӫa TiO2, mӣ rӝng vùng hoҥWÿӝng cӫa TiO2 tӯ vùng tӱ ngoҥLÿӃn khҧ kiӃn &iFNӃWTXҧQJKLrQFӭXFKRWKҩ\$JAu, Pt, Pd, Rh, Cu và 1LOjFiFNLPORҥLbiӃQtính vào TiO2 FKRNӃWTXҧ hoҥWWính xúc tác quang cӫD7L22 là WӕWQKҩW

/XұQiQÿmFKӃWҥRWKjQKF{QJYұWOLӋX$JTiO2 EҵQJSKѭѫQJSKiSFKLӃX[ҥWLDJCo-60 và OҫQÿҫXWLrQFKӃWҥRWKjQKF{QJYұWOLӋX7L22 ÿӗQJELӃQWtQK$JYj1LYӟLVӵKӛWUӧFӫDEӭF[ҥJDPPDWӯQJXӗn Co-ĈӗQJWKӡL[iFÿӏQKÿһFWUѭQJFҩXWU~FFQJKRҥWtính [~FWiFTXDQJKyDSKkQKӫ\FiFFKҩWKӳXFѫFӫDKDLYұWOLӋXQj\

&iFYұWOLӋX[~FWiF$J7L22 và Ag-Ni/TiO2 ÿLӅX FKӃ WUrQ Fѫ Vӣ 7L22 (P25) có kích WKѭӟFKҥW- QPEҵQJSKѭѫQJSKiSFKLӃX[ҥ tia JCo-7KjQKSKҫQSKDNtFKWKѭӟFKҥWGLӋQWtFKEӅPһWULrQJQăQJOѭӧQJYQJFҩPQăQJOѭӧQJOLrQNӃW«FӫDFiFYұWOLӋXÿѭӧF[iFÿӏQKEҵQJFiFSKѭѫQJSKiSQKLӉX[ҥWLD;;5' NtQKKLӇQYLÿLӋQWӱTXpW6(0 NtQKKLӇQYLÿLӋQWӱWUX\ӅQTXD7(0 GLӋQWtFKEӅPһW%(7SKәWiQVҳFQăQJOѭӧQJWLD;('; SKәTXDQJÿLӋQWӱWLD;;36 «

.ӃWTXҧSKkQWtFKFҩXWU~FYұWOLӋX$J7L22 YӟLKjPOѭӧQJ$JELӃQWtQKWURQJNKRҧQJWӍ OӋ NKӕL OѭӧQJ $J7L22 Wӯ  -  FKR WKҩ\ YұW OLӋX Qj\ Fy FҩX WU~F SKD 7L22 DQDWDVHYjUXWLOHYӟLNtFKWKѭӟF- QPYj$JNLPORҥLNtFKWKѭӟFNKRҧQJ- 3 nm 1ăQJOѭӧQJYQJFҩP FӫDFiFPүX$J7L22 EҵQJYjH9 ÿӅXWKҩSKѫQVRYӟL7L22 EDQÿҫXEҵQJH9 

.ӃW TXҧ SKkQ WtFK FҩX WU~F FӫD FiF PүX YұW OLӋX $J-Ni/TiO2 YӟL WӍ OӋ NKӕL OѭӧQJAg/TiO2 và Ni/TiO2 Wӯ± FKRWKҩ\FҩXWU~FSKDQJRjLSKD anatase và rutile FӫD 7L22 EDQ ÿҫX FzQ $JYj 1LNLPORҥLYӟLNtFKWKѭӟFQDQR NKRҧQJ-QPQăQJOѭӧQJYQJFҩPFӫDFiFPүX$J-Ni/TiO2 EҵQJ3,151; 3,123; 3,102; 3,024 eV) ÿӅXWKҩSKѫQVRYӟLPүX7L22 EDQÿҫX

+RҥWWtQK[~FWiFTXDQJKyDFӫDKDLYұWOLӋXFKӃWҥRÿѭӧFWKӇKLӋQYӟLKDLFKҩWKӳXFѫPHWK\OUHGYjUKRGDPLQH%.ӃWTXҧFKRWKҩ\$J7L22 và Ag-Ni/TiO2 ÿӅXFyKRҥWWtQKxúc tác quang hoá FDRKѫQ7L22 EDQÿҫXWURQJFQJÿLӅXNLӋQSKҧQӭQJ1JX\rQQKkQ

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Ag/TiO2 Fy KRҥW WtQK [~F WiF TXDQJ KRi FDR KѫQ 7L22 GR FiF KҥW QDQR $J NKL ÿѭӧFELӃQWtQKYjRWURQJFҩXWU~F7L22 VӁKuQKWKjQKQrQPӭFQăQJOѭӧQJPӟLYjOjPJLҧPQăQJOѭӧQJYQJFҩPFӫD7L22 và TiO2 WUӣQrQKRҥWWtQKKѫQ1JRjLUDFiFKҥWQDQRAg còn là FKҩWEҳWJLӳFiFÿLӋQWӱTXDQJVLQKOjPJLҧPNKҧQăQJWiLKӧSJLӳDOӛWUӕQJ- ÿLӋQWӱTXDQJVLQK7L22 NKLÿѭӧFELӃQWtQKÿӗQJWKӡLFҧKDLNLPORҥL$JYj1LVӁFyKRҥWWtQK[~FWiFTXDQJFDRKѫQ7L22 và Ag/TiO29uFҧKDLNLPORҥL$JYj1LVӁOjPFKҩWEҳWJLӳFiFÿLӋQWӱTXDQJVLQKWӕWKѫQWURQJWUѭӡQJKӧSFKӍFy$J'RÿyGүQÿӃQNӃWTXҧKLӋXVXҩWSKkQKӫ\TXDQJKyDFKҩWKӳXFѫFӫDYұWOLӋX$J-Ni/TiO2 FDR KѫQAg/TiO2

&iFYұWOLӋX$J7L22 và Ag-Ni/TiO2 NKLÿѭӧFFKLӃXViQJFiFÿLӋQWӱYQJKyDWUӏVӁEӏNtFKWKtFKYjGӏFKFKX\ӇQOrQYQJGүQKuQK WKjQKFһSÿLӋQWӱ- OӛWUӕQJTXDQJVLQK(e- và h+ &iFÿLӋQWӱTXDQJVLQKӣYQJGүQYjOӛWUӕQJTXDQJVLQKӣYQJKyDWUӏFyWKӇSKҧQӭQJR[\KRiNKӱYӟLFKҩWKҩSWKөWUrQEӅPһWYұWOLӋX7URQJWUѭӡQJKӧSQj\ÿLӋQWӱTXDQJVLQKNKӱ22 WҥRJӕF22- YjOӛWUӕQJTXDQJVLQKR[\KyD+22WUrQEӅPһWFKҩW[~FWiFÿӇWҥRUDFiFJӕFxOH

H2O + h+ o xOH + H+O2 + e- o O2-

&iFSKҧQӭQJQj\OjPQJăQFҧQNKҧQăQJWiLNӃWKӧSJLӳDÿLӋQWӱYjOӛWUӕQJTXDQJVLQK&iFJӕFR[\KRixOH, O2- FyNKҧQăQJSKkQKXӹFKҩWKӳXFѫ{QKLӉPWKjQKFiFKӧSFKҩWWUXQJJLDQYjFXӕLFQJSKkQKXӹKRjQWRjQWKjQK&22 và H2O

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ABSTRACT

TiO2 modified by metal can enhance the photocatalytic activity and extend the active region of TiO2 from ultraviolet to visible light Noble metals including Ag, Au, Pt, Pd, Rh, Cu and Ni have been reported to be very effective in enhancing photocatalysis of TiO2

This thesis studied the preparation and characterization of Ag/TiO2 photocatalysts by J irradiation method The first time, TiO2 were modified by Ag and Ni supported by J irradiation from the Co-60 source The resulted photocatalysts were further investigated the photocatalytic activity toward the degradation of organic compounds The Ag/TiO2 and Ag-Ni/TiO2 catalysts were prepared based on the commercial TiO2 substrates (P25) with size ranging from 20 - 40 nm by the assistance of JCo-60 irradiation The characteristics of Ag nano/TiO2 material such as: crystal phase, SDUWLFOHVL]HVSHFLILFVXUIDFHDUHDEDQGJDSELQGLQJHQHUJ\«KDVEHHQLQYHVWLJDWHGby X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), BET surface area, the diffuse reflectance spectra (DRS), energy dispersive X-ray (EDX), X-ray photoemission spectroscopy (XPS)

The modified Ag/TiO2 nanoparticles composing of 0.5 to 2.0 wt% of Ag in the composition revealed the co-existence of the TiO2 anatase and rutile phase with size of 20 - 40 nm and the Ag metallic phase with size of 1-3 nm The band gaps were of 3.330; 3.312; 3.167 and 3.295 eV which were lower than that of the pristine TiO2 substrates (3,348 eV)

The characteristics of Ag-Ni/TiO2 material composing of 0.75 to 3.0 wt% of Ag and Ni in the composition indicated two phases of anatase and rutile of TiO2 and Ag and Ni metallic phase with size of 1-3 nm The band gap was of 3.180; 3.151; 3.123; 3.102 and 3.024 eV which were lower than that of TiO2

The photocatalytic activity of the obtained Ag/TiO2 and Ag-Ni/TiO2 nanoparticles prepared by the support of JCo-60 irradiation was investigated toward the degradation of methyl red (MR) and rhodamine B (RB) in aqueous solution The results showed

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that both the Ag/TiO2 and Ag-Ni/TiO2 nanoparticles exhibited higher photocatalytic activities compared to that of the pristine TiO2 nanoparticles under the same controlled reaction condition The reason was attributed to the ability of nano-size doped metal in lowering the band gap energy and thus shifting the optical response to the visible light region In addition, the nano-size doped Ag particles also prevented the capacity of the instinct recombination of photogenerated electrons and holes inside the catalysts, thereby increasing the catalytic efficiency Noteworthy, the Ag/Ni modified TiO2 nanoparticles exhibited the highest photocatalytic activity compared to the Ag modified TiO2 and the pristine TiO2 under the same controlled reaction condition It was accounted for the synergetic ability of both Ag and Ni metals in capturing photogenerated eletrons better than in case of solely Ag modified TiO2 As a result, the Ag-Ni/TiO2 displayed the highest photocatalytic efficiency toward the organic compound degradation

In principle, in the photocatalysts the electrons move from the valence band to the conduction band under light excitation, leading to the formation of electron ± hole pairs, denoting as e- and h+ The e- is represented for the electron in the conduction band whereas the h+ is assigned to the electron vacancy in the valance band, respectively Both these entities can migrate to the catalyst surface where they can enter in redox reactions with other species presenting on the surface of the catalysts In most cases, h+ can react easily with surface bound H2O molecules to produce ‡OH radicals, whereas, e- can react with O2 molecules to form superoxide radical anions of oxygen

H2O + h+ o xOH + H+ O2 + e- o O2-

These reactions prevent the recombination of the generated electrons and the holes The xOH and O2- produced in the above manner can then react with the organic compounds to form other species and finally, decomposes into CO2 and H2O

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1.2 Các vұt liӋu xúc tác quang hóa 6

1.3 Vұt liӋu xúc tác quang hóa TiO2 8

1.3.1 Cҩu trúc pha tinh thӇ cӫa TiO2 và các tính chҩt cӫa TiO2 8

1.3.2 TiO2 làm xúc tác quang hóa 10

&ѫFKӃ phҧn ӭng cӫa TiO2 khi làm chҩt xúc tác quang hóa 11

1.3.2.2 Các yӃu tӕ ҧQKKѭӣQJÿӃn khҧ QăQJ[~FWiFTXDQJKyDFӫa TiO2 12

1.2 Tәng quan vұt liӋu TiO2 biӃn tính 15

&ѫFKӃ [~FWiFTXDQJKyDWUrQFѫVӣ TiO2 biӃn tính 15

&iFSKѭѫQg pháp biӃn tính TiO2 16

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;iFÿӏnh liӅu xҥ trong khӱ kim loҥi 24

1.2.3.5 Áp dөng công nghӋ bӭc xҥ ÿLӅu chӃ vұt liӋu nano 25

1.3 Tình hình nghiên cӭu và sӱ dөng TiO2 biӃn tính làm chҩt xúc tác quang hóa trRQJQѭӟc 27

1.4 Tình hình nghiên cӭu và sӱ dөng TiO2 biӃn tính làm chҩt xúc tác quang hóa trên thӃ giӟi 29

1.4.1 TiO2 biӃn tính vӟi kim loҥi 29

1.4.2 TiO2 biӃn tính vӟi phi kim 32

1.4.3 TiO2 biӃQWtQKÿӗng thӡi vӟi nhiӅu nguyên tӕ 33

1.4.4 Vұt liӋu xúc tác quang hóa Ag/TiO2 34

1.4.5 Vұt liӋu xúc tác quang hóa Ag-Ni/TiO2 35

2.3 Các quy trình chӃ tҥo vұt liӋu 43

2.3.1 Quy trình chӃ tҥo Ag/TiO2 bҵQJSKѭѫQJSKiSFKLӃu xҥ 43

2.3.2 Quy trình chӃ tҥo Ag-Ni/TiO2 bҵQJSKѭѫQJSKiSFKLӃu xҥ 44

&iFSKѭѫQJSKiSSKkQWtFKWtQKFKҩt cӫa vұt liӋu 45

;iFÿӏnh cҩu trúc tinh thӇ cӫa vұt liӋu 45

2.4.2 Hình WKiLYjNtFKWKѭӟc hҥt 46

2.4.3 Thành phҫn hóa hӑc và vi cҩu trúc cӫa vұt liӋu 46

2.4.41ăQJOѭӧng liên kӃt EB (eV) 47

2.4.5 Phә khuӃch tán phҧn xҥ '56