Tuning of reduced graphene oxide thin film as an efficient electron conductive interlayer in a proven heterojunction photoanode for solar-driven photoelectrochemical water splitting

JOURNAL OF ALLOYS AND COMPOUNDS

卷:817

Article

Yaw, Chong Siang¹  Ng, Wen Cai¹  Ruan, Qiushi²  Tang, Junwang²  Soh, Ai Kah³  Chong, Meng Nan^1,4 

[1] Monash Univ Malaysia, Sch Engn, Chem Engn Discipline, Jalan Lagoon Selatan, Bandar Sunway 47500, Selangor Darul, Malaysia

[2] UCL, Dept Chem Engn, Torrington Pl, London WC1E 7JE, England

[3] Monash Univ Malaysia, Sch Engn, Mech Engn Discipline, Jalan Lagoon Selatan, Bandar Sunway 47500, Selangor Darul, Malaysia

[4] Monash Univ Malaysia, Adv Engn Platform, Sustainable Water Alliance, Jalan Lagoon Selatan, Bandar Sunway 47500, Selangor De, Malaysia

关键词: BiVO4;    Heterojunction;    Reduced graphene oxide;    Solar hydrogen;    Photogenerated charge carriers;   

DOI  :  10.1016/j.jallcom.2019.152721

来源: Elsevier

【 摘 要 】

Although bismuth vanadate (BiVO4) has shown excellent photoelectrochemical (PEC) properties and is a good candidate of photoanode materials, the solar-driven PEC water splitting performance is still remained below its full potential due to the fast recombination and sluggish charge mobility of photogenerated charge carriers. Previously, we have communicated a proven Type II staggered vanadium pentoxide (V2O5)/BiVO4 heterojunction photoanode that could improve the photocurrent density. This study aimed to examine the effect of introducing an rGO thin film as an efficient electron conductive interlayer in a proven V2O5/BiVO4 heterojunction photoanode, and subsequently tuning the rGO film thickness in achieving the optimum PEC performance. The resultant ternary photoanode structure of V2O5/rGO/BiVO4 was characterised by using field emission-scanning electron microscopy (FE-SEM), high resolution-transmission electron microscopy (HR-TEM), UV-vis spectroscopy, X-ray diffractometer (XRD), Raman spectroscopy and photoluminescence (PL) measurements. Results showed that the interlayer rGO thin film arising from the sequential drop cast and electrochemical reduction of 320 mu L ultrasonicated GO solution resulted in the optimal photocurrent density of 2.1 mA/cm(2) at 1.5 V vs. Ag/AgCl. Furthermore, the chemical physics surrounding the photogenerated charge carrier transfer for heterojunction V2O5/BiVO4 was validated for the structure with and without the rGO interlayer. In particular, the electrochemical impedance spectroscopy (EIS) was used to measure multiple resistances at the FTO/semiconductor, semiconductor/semiconductor and semiconductor/electrolyte interfaces. Additionally, the charge transfer (K-r) and recombination (K-r) rate constants for the heterojunction V2O5/BiVO4 with the rGO interlayer were quantified using intensity modulated photocurrent spectroscopy (IMPS). Finally, the PEC H-2 evolution rate from the ternary V2O5/rGO/BiVO4 photoanode was measured to be 32.7 mu mol/hr, which was about 3-fold higher than the bare V2O5/BiVO4 heterojunction photoanode. (C) 2019 Elsevier B.V. All rights reserved.

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