Issue 12, 2021

Reinforcement of a BiVO4 anode with an Fe2O3 underlayer for photoelectrochemical water splitting

Abstract

To understand the consequence of an Fe2O3/BiVO4 heterojunction simply, we fabricated an FTO/Fe2O3/BiVO4 composite photoanode for photoelectrochemical (PEC) water oxidation. We discovered that forming a heterojunction between the Fe2O3 underlayer and BiVO4 upper layer dramatically increased the photocurrent in the low bias region. This photocurrent density increased six-fold from 0.15 mA cm−2 at 0.6 V vs. the reversible hydrogen electrode (RHE) for BiVO4 to 0.95 mA cm−2 at 0.6 V vs. RHE for BiVO4 with the Fe2O3 underlayer. The faradaic efficiency of PEC water splitting was close to 100%, and the molar ratio of the generated hydrogen to oxygen was 2 : 1. However, the photocurrent did not improve in the high bias region; at higher than 1.23 V vs. RHE, the photocurrent density of the FTO/Fe2O3/BiVO4 electrode was lower than that of the bare BiVO4 electrode. The effects of the Fe2O3 underlayer greatly improved the charge separation efficiency, but such improvements were noted only in the low bias region. In addition, the PEC performance was observed to depend on the thickness of the Fe2O3 underlayer. The optimised FTO/Fe2O3/BiVO4 electrode was achieved when the Fe2O3 underlayer was approximately 350 nm thick and when the BiVO4 upper layer had approximately the same thickness as the underlayer.

Graphical abstract: Reinforcement of a BiVO4 anode with an Fe2O3 underlayer for photoelectrochemical water splitting

Supplementary files

Article information

Article type
Paper
Submitted
03 mar 2021
Accepted
20 apr 2021
First published
20 apr 2021

Sustainable Energy Fuels, 2021,5, 3102-3114

Reinforcement of a BiVO4 anode with an Fe2O3 underlayer for photoelectrochemical water splitting

S. Ho-Kimura and W. Luo, Sustainable Energy Fuels, 2021, 5, 3102 DOI: 10.1039/D1SE00310K

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