Electrospinning of α fe2o3 and znfe2o4 nanofibers loaded with reduced graphene oxide (RGO) for h2s gas sensing application

MINISTRY OF EDUCATION AND TRAINING HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY Nguyen Van Hoang ELECTROSPINNING OF α-Fe2O3 AND ZnFe2O4 NANOFIBERS LOADED WITH REDUCED GRAPHENE OXIDE (RGO) FOR H2S GAS SENSING APPLICATION DOCTORAL DISSERTATION OF MATERIALS SCIENCE Hanoi – 2020 MINISTRY OF EDUCATION AND TRAINING HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY Nguyen Van Hoang ELECTROSPINNING OF α-Fe2O3 AND ZnFe2O4 NANOFIBERS LOADED WITH REDUCED GRAPHENE OXIDE (RGO) FOR H2S GAS SENSING APPLICATION Major: Materials Science Code: 9440122 DOCTORAL DISSERTATION OF MATERIALS SCIENCE SUPERVISOR: PROF PhD NGUYEN VAN HIEU Hanoi – 2020 DECLARATION OF AUTHORSHIP This dissertation has been written in the basic of my researches carried out at Hanoi University of Science and Technology, under the supervision of Prof PhD Nguyen Van Hieu All the data and results in the thesis are true and were agreed to use in my thesis by co-authors The presented results have never been published by others Hanoi, 26th May 2020 Supervisor Prof PhD Nguyen Van Hieu PhD Student Nguyen Van Hoang ACKNOWLEDGMENTS First, I would like to express my deep gratitude to my supervisor, Prof Nguyen Van Hieu, for his devotion and inspiring supervision I would like to thank him for all his advice, support and encouragement throughout my postgraduate course I am grateful to Assoc Prof PhD Nguyen Duc Hoa, Assoc Prof PhD Nguyen Van Duy, PhD Dang Thi Thanh Le, PhD Chu Manh Hung, and PhD Nguyen Van Toan for their useful help, suggestions and comments I also would like to express my special thanks to PhD and Master Students at iSensors Group for their support and shared cozy working environment during my PhD course I am thankful to the leaders and staffs of International Training Institute for Materials Science (ITIMS), Graduate School for their help and given favorable working conditions I would like to thank my colleagues at Department of Materials Science and Engineering at Le Quy Don Technical University for their support during my PhD course I gratefully acknowledge the fund from Vietnam National Foundation for Science and Technology Development (NAFOSTED) under code 103.02-2017.25 and the 911 Scholarship of Ministry of Education and Training for the financial support for my research Last but not least, I am deeply thankful to my family for their endless love and unconditional support Without them, the work would have been impossible PhD Student Nguyen Van Hoang CONTENTS CONTENTS i ABBREVIATIONS AND SYMBOLS v LIST OF TABLES vii LIST OF FIGURES viii INTRODUCTION CHAPTER OVERVIEW ON SMO NFs AND THEIR LOADING WITH RGO FOR GAS-SENSING APPLICATION 1.1 Electrospinning for NFs fabrication 1.1.1 Background on electrospinning 1.1.2 Processing – structure relationships of electrospun NFs 1.2 NFs for gas-sensing application 10 1.2.1 Electrospun SMO NFs for gas-sensing application 10 1.2.2 Electrospun SMO NFs for H2S gas-sensing application 13 1.3 1.2.2.1 H2S gas 13 1.2.2.2 Electrospun SMO NFs for H2S gas-sensing application 13 NFs loading with RGO for gas-sensing application 14 1.3.1 Overview on RGO and its application in gas-sensing field 14 1.3.1.1 Overview on RGO 14 1.3.1.2 RGO in gas-sensing application 17 1.3.2 RGO-loaded SMO NFs in gas-sensing applications 19 1.3.2.1 RGO-loaded SMO gas sensor 19 1.3.2.2 RGO-loaded SMO NFs gas sensor 22 i 116 APPENDIX o Pure α- Fe 2O NFs@ air & 350 Fifth-order polynomial fit RSS = 3.66E-5 o 0.5 wt.% RGO @ air & 350 Fifth-order polynomial fit RSS = 3.03E-5 /Rg ) C (b) 10 o 0.5 wt.% RGO @ air & 350 Linear Fit Slope = 6.76 a C (g) 0.96 1.08 1.0 wt.% RGO@ air & 350 Fifth-order polynomial fit RSS = 2.4E-5 1.06 o 1.0 wt.% RGO@ air & 350 Linear Fit Slope = 8.66 C (c) o 1.5 wt.% RGO@ air & 350 Fifth-order polynomial fit RSS = 1.34E-5 1.00 o C 1.5 wt.% RGO@ air & 350 Linear Fit Slope = 2.44 (d) o 10 C (h) 1.04 1.02 10 (f) 0.98 Resp Base (R C Linear Fit Slope = 5.53 (a) 1.02 1.00 o Resp ( R a /R g ) 1.04 Pure α- Fe O NFs@ air & 350 C 5 C (i) 0.98 10 0.00 0.25 0.50 0.75 1.00 H 2S conc (ppm) Time (s) Figure A3.1 Fitted values of RSS and slope for DL calculation of sensors based on α-Fe 2O3 NFs loaded with different contents of RGO of (a, e), 0.5 (b, f), 1.0 (c, g), and 1.5 wt.% (d, h), respectively The sensors are tested with H2S gas at operating temperature of 350°C Table A3.1 Calculation table of DL to H S of sensors based on α-Fe O3 NFs loaded with different contents of RGO from to 1.5 wt% RGO at operating temperature of 350°C Samples RSS rmsnoise Slope DL (ppb) 3.66E-05 0.001913113 5.53 1.04 0.5 3.03E-05 0.00174069 6.76 0.78 2.40E-05 0.001549193 8.66 0.54 1.5 1.34E-05 0.001157584 2.44 1.42 117 α− α−Fe O3 Cal 400 Fifth-order polynomial fit RSS = 1.31E-5 Linear Fit Slope = 4.15 (a) o C@ H 2S & 350 o C (f) 1.00 Cal 500 o C@ air & 350 o C Fifth-order polynomial fit RSS = 5.12E-6 1.04 Resp Base (R a /R g ) 1.02 1.00 1.04 Cal 600 o C@ air & 350 o C Fifth-order polynomial fit RSS = 3.66E-5 1.02 Cal 700 o C@ air & 350 o C Fifth-order polynomial fit RSS = 2.34E-5 0.98 0.96 1.04 Cal 800 o C@ air & 350 o C Fifth-order polynomial fit RSS = 1.77E-5 1.02 Cal 500 (b) o C@ H2S & 350 oC Linear Fit Slope = 2.76 (g) Cal 600 oC@ H S & 350 o C (c) Linear Fit Slope = 5.53 (h) Linear Fit Slope = 4.48 (i) Cal 800 oC@ H S & 350 o C (e) Linear Fit Slope = 0.83 (j) 1.00 10 0.00 0.25 Time (s) Cal 700 oC@ H S & 350 o C (d) Resp (R a /Rg ) 1.02 α- Fe O Cal 400 o C@ air&350 o C 0.50 0.75 H2S conc (ppm) 1.00 Figure A3.2 Fitted values of RSS and slope for DL calculation of α-Fe 2O NFs sensors calcined at various annealing temperatures of 400 (a, f), 500 (b, g), 600 (c, h), 700 (d, i), and 800°C (e, j), respectively The sensors are tested with H 2S gas at operating temperature of 350°C Table A3.2 Calculation table of DL to H S of α-Fe2O3 NFs sensors calcined at annealing temperatures from 400°C to 800°C at operating temperature of 350°C Samples RSS rms noise Slope DL (ppb) 400oC 1.31E-05 0.001144552 4.15 0.83 500oC 5.12E-06 0.000715542 2.76 0.78 600oC 3.66E-05 0.001913113 5.53 1.04 700oC 2.34E-05 0.001529706 4.48 1.02 800oC 1.77E-05 0.001330413 0.83 4.81 118 wt% RGO Cal 400 oC@ air&350 Fifth-order polynomial fit (a) RSS = 1.67E-5 1.02 (R a /R g ) Resp Base 1.06 0.98 wt.% RGO Cal 400 Cal 500 1.00 1.04 Cal 800 o C@ air & 350 o C Fifth-order polynomial fit RSS = 9.0E-6 1.02 Time (s) o (f) C@ H 2S & 350 oC (g) Linear Fit Slope = 8.66 10 Linear Fit Slope = 3.15 (i) 10 10 Cal 800 o C@ H 2S & 350 o C (j) Linear Fit Slope = 0.14 0.25 10 (h) Cal 700 o C@ H 2S & 350 o C 0.00 10 Cal 600 o C@ H 2S & 350 o C (e) C@H 2S&350 o C Linear Fit Slope = 3.68 Cal 700 o C@ air & 350 o C (d) Fifth-order polynomial fit RSS = 4.0E-5 1.02 o Linear Fit Slope = 6.00 Cal 600 o C@ air & 350 o C Fifth-order polynomial fit (c) RSS = 2.40E-5 1.04 1.00 C Cal 500 o C@ air & 350 o C (b) Fifth-order polynomial fit RSS = 1.21E-5 1.02 1.00 o Resp (R a /Rg ) 1.04 10 0.50 0.75 H2S conc (ppm) 1.00 Figure A3.3 Fitted values of RSS and slope for DL calculation of 1.0 wt.% RGO-loaded αFe O3 NFs sensors calcined at various annealing temperatures of 400 (a, f), 500 (b, g), 600 (c, h), 700 (d, i), and 800°C (e, j), respectively The sensors are tested with H S gas at operating temperature of 350°C Table A3.3 Calculation table of DL to H2 S of 1.0 wt.% RGO-loaded α-Fe2O3 NFs sensors calcined at annealing temperatures from 400°C to 800°C at operating temperature of 350°C Samples RSS rms noise Slope DL (ppb) 400o C 1.67E-05 0.001292285 0.65 500o C 1.21E-05 0.0011 3.68 0.90 600o C 2.40E-05 0.001549193 8.66 0.54 700o C 4.05E-05 0.002012461 3.12 1.94 800o C 9.00E-06 0.000948683 0.14 20.33 119 Table A4.1 Average nanograin sizes determined by Scherrer formula and integrated intensity of (311) diffraction peak of ZFO-NFs calcined at different conditions Samples β (FWHM) (radian) Crystallite sizes (nm) Integrated intensity 400o C 0.62 13.53 20.24 500o C 0.55 15.16 22.44 600o C 0.46 18.08 35.39 700o C 0.35 23.92 84.24 0.5 h 0.51 16.32 24.68 3h 0.46 18.08 35.39 12 h 0.38 21.82 69.01 48 h 0.36 23.28 108.82 0.5 oC/min 0.46 18.08 35.39 2oC/min 0.68 12.25 29.19 5oC/min 0.61 13.63 35.29 20o C/min 0.55 15.23 46.58 120 Table A4.2 Response and response-recovery time to ppm H2S gas at the operating temperature of 350°C of the ZFO NFs sensors calcined at different annealing temperatures (400−700°C), annealing time (0.5−48 h), heating rates (0.5−20°C/min), electrospinning time (10−120 min) S τres τrec 1ppm (s) (s) 400o C 8.5 47 423 500o C 61 261 600o C 102 206 700o C 21.8 129 0.5 h 34 217 3h 102 206 12 h 42.3 63 48 h 15.4 40 0.5oC/min 102 206 2o C/min 19.9 53 5o C/min 53.4 68 20oC/min 7.4 12 122 Samples 121 Resp Base (R a /Ra ) 1.04 o C@ H 2S & 350 o C Linear Fit Slope = 8.32664 Cal 500 oC@ air & 350 oC Fifth-order polynomial fit RSS = 3.69E-5 (b) 1.02 Cal 400 Cal 400 o C@ air & 350 oC Fifth-order polynomial fit RSS = 1.37E-5 (a) Cal 500 o 10 (e) C@ H 2S & 350 o C Linear Fit Slope = 67.70817 50 (f) 1.00 25 Cal 600 Cal 600 o C@ air & 350 o C Fifth-order polynomial fit RSS = 3.28E-5 (c) 1.02 o o C@ H 2S & 350 C Linear Fit Slope = 113.96252 100 (g) 1.00 50 Cal 700 Cal 700 o C@ air & 350 oC Fifth-order polynomial fit RSS = 4.78E-6 (d) 1.02 o o C@ H 2S & 350 C Linear Fit Slope = 22.34538 20 (h) 1.00 10 0 10 0.00 0.25 0.50 0.75 1.00 H2S conc (ppm) Time (s) Resp (R a /R g ) 1.06 Figure A4.1 Fitted values of RSS and slope for DL calculation of the sensors based on ZFO NFs calcined at various annealing temperatures of 400 (a,e), 500 (b,f), 600 (c,g), and 700°C (d,h), respectively The sensors are tested with H2 S gas at the operating temperature of 350°C Table A4.3 Calculation table of DL to H 2S of the ZFO NFs sensors calcined at the annealing temperature from 400°C to 700°C at the operating temperature of 350°C Samples RSS rmsnoise Slope DL (ppb) 400o C 1.37E-05 0.00117161 8.32664 0.422 500o C 3.69E-05 0.00192032 67.70817 0.085 600o C 3.28E-05 0.001810392 113.96252 0.048 700o C 4.78E-06 0.002185514 22.34538 0.093 122 Cal 400 o C@ air & 350 oC Fifth-order polynomial fit RSS = 5.05E-5 (a) 1.00 Cal 400 o 50 C@ H 2S & 350 o C Linear Fit Slope = 48.94 (e) 25 1.02 Cal 500 oC@ air & 350 oC Fifth-order polynomial fit RSS = 5.57E-5 (b) 1.00 0.98 1.04 o o Cal 600 C@ air & 350 C Fifth-order polynomial fit RSS = 3.28E-5 (c) 1.02 Cal 500 o C@ H 2S & 350 C Linear Fit Slope = 86.58 Cal 600 o 75 o 50 (f) 150 o C@ H 2S & 350 C Linear Fit Slope = 164.15 25 Resp ( R a /R g ) Resp Base (R a /Ra ) 0.98 100 (g) 50 1.00 Cal 700 o C@ air & 350 oC Fifth-order polynomial fit RSS = 5.2E-5 (d) 1.06 Cal 700 o C@ H 2S & 350 o C Linear Fit Slope = 15.25 (h) 20 10 1.04 0 10 0.00 0.25 0.50 0.75 1.00 H2S conc (ppm) Time (s) Figure A4.2 Fitted values of RSS and slope for DL calculation of the sensors based on wt% RGO loaded ZFO NFs calcined at various annealing temperatures of 400 (a,e), 500 (b,f), 600 (c,g), and 700°C (d,h), respectively The sensors are tested with H 2S gas at the operating temperature of 350°C Table A4.4 Calculation table of DL to H 2S of the wt% RGO-loaded ZFO NFs sensors calcined at annealing temperatures from 400°C to 700°C at the operating temperature of 350°C Samples RSS rmsnoise Slope DL (ppb) 400o C 5.05E-05 0.002247221 48.94 0.14 500o C 5.57E-05 0.002360085 86.58 0.08 600o C 3.28E-05 0.001811077 164.15 0.03 700o C 5.20E-06 0.002280351 15.25 0.44 123 ... MINISTRY OF EDUCATION AND TRAINING HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY Nguyen Van Hoang ELECTROSPINNING OF α- Fe2O3 AND ZnFe2O4 NANOFIBERS LOADED WITH REDUCED GRAPHENE OXIDE (RGO) FOR H2S GAS SENSING. .. Selectivity and stability 53 H2S gas sensors based on α- Fe2O3 NFs loaded with RGO 54 3.3.1 Morphologies and structures of α- Fe2O3 NFs loaded with RGO 54 3.3.2 H2S gas- sensing properties of. .. ZFO NFs and their loading with RGO 31 Table 3.1 Different nanostructures of α- Fe2O3 for H2S gas- sensing application 38 Table 3.2 α- Fe2 O3 loaded with RGO for gas- sensing application