Advanced Energy Materials | Repairing Oxygen-Defect-Induced Surface Traps Unlocks High Photovoltage in BiVO₄ Photoanodes

Article Highlights

To overcome the low photovoltage caused by Fermi-level pinning in oxygen-vacancy-rich BiVO₄ photoanodes, this study combines fluorine-atom doping with the in situ deposition of a NiCoBi cocatalyst to repair oxygen-defect-induced surface trap states. Fluorine doping tunes the electronic structure, raises the work function and shifts the Fermi level positively, while NiCoBi passivates surface defects and relieves Fermi-level pinning. Together they increase the photovoltage of F–BiVO₄₋ₓ/NiCoBi by 37.78% relative to pristine BiVO₄₋ₓ. The photoanode reaches 5.60 mA cm⁻² at 1.2 V_RHE, keeps interfacial charge recombination below 10% at 0.4 V_RHE, delivers nearly 100% glucose conversion with an 82% glucaric-acid yield, and shows only 2.56% decay during long-term operation with a Faradaic efficiency close to 100%. DFT calculations and in situ characterization confirm that the strategy preserves the benefits of oxygen vacancies while substantially improving charge separation, injection and stability.

Introduction

In April 2026, Advanced Energy Materials published the latest photoelectrochemical research from Associate Professor Kai-Hang Ye’s team at Guangdong University of Technology. The work reports a general strategy that couples F-atom doping with in situ NiCoBi cocatalyst deposition to repair oxygen-defect surface traps and markedly improve the photovoltage and photoelectrocatalytic performance of BiVO₄ photoanodes. Wenhao Zou of Guangdong University of Technology, Xin Ding of Xiamen University and Hengjun Xie of Guangdong University of Technology are co-first authors. The corresponding authors are Kai-Hang Ye of Guangdong University of Technology, Kun Wang of Sun Yat-sen University, Shuang Xiao of Shenzhen Technology University and Songcan Wang of Northwestern Polytechnical University.

Background

Photoelectrochemical (PEC) technology is a key route for next-generation solar-energy conversion and the green synthesis of high-value chemicals. It has important potential for addressing global energy shortages and environmental pollution. Oxidation at the photoanode involves slow multielectron transfer, and this kinetic bottleneck directly limits practical PEC-cell performance. Bismuth vanadate (BiVO₄), with a suitable bandgap and high theoretical photocurrent density, is a promising photoanode for solar water splitting and value-added chemical synthesis.

Over the past decade, cocatalyst loading, heterojunction construction and defect-state engineering have improved BiVO₄ performance, but many approaches work only under specific conditions and do not provide a general design rule. Introducing oxygen vacancies (O_V) can tune the bandgap and surface electronic structure and improve light absorption, charge separation and charge transfer. Excess O_V, however, can become recombination centers, intensify Fermi-level pinning, weaken band bending and hamper carrier transport. Controlling the concentration and distribution of O_V is therefore central to maximizing their benefits while suppressing their adverse effects.

The study shows that oxygen vacancies not only improve bulk charge-separation efficiency and shift the onset potential negatively, but also raise the bands and Fermi level, creating room for a higher photovoltage (V_ph). F-atom doping and in situ photoelectrochemical deposition of NiCoBi are consequently combined to regulate the Fermi level of BiVO₄₋ₓ and alleviate surface-defect-induced Fermi-level pinning. The resulting F–BiVO₄₋ₓ/NiCoBi photoanode retains the high charge-separation efficiency and negative onset-potential shift associated with oxygen vacancies while substantially increasing photovoltage, suppressing interfacial recombination and delivering strong performance in both water and organic oxidation.

Equipment Used in This Study

Figures and Analysis

Summary

This work addresses inadequate photovoltage in oxygen-vacancy-containing BiVO₄ photoanodes by combining F-atom doping with in situ NiCoBi cocatalyst deposition. Oxygen vacancies optimize the bandgap, improve charge separation and shift the onset potential negatively, but excessive surface defects constrain photovoltage. F doping creates a dipole field, raises the work function and lowers the Fermi level; NiCoBi bonds with surface Bi and O, repairs defects and relieves Fermi-level pinning. The resulting F–BiVO₄₋ₓ/NiCoBi photoanode reaches 0.1827 V photovoltage—37.78% above BiVO₄₋ₓ—with 98.52% bulk charge-separation efficiency and less than 10% interfacial recombination at 0.4 V_RHE. It delivers more than 5.60 mA cm⁻² at 1.2 V_RHE in both water and glucose oxidation, almost complete glucose conversion, an 82% glucaric-acid yield and only 2.56% long-term decay. The strategy offers a broadly applicable route to defect regulation and electronic-structure optimization in high-performance photoelectrodes.

Author Profile

Kai-Hang Ye

Associate Professor, Guangdong University of Technology

Professor Ye has worked on photoelectrocatalysis since 2013 and joined the School of Chemical Engineering and Light Industry at Guangdong University of Technology in July 2022. His research addresses photocurrent-density bottlenecks in photoanodes through work-function regulation and heterojunction design, with the aim of improving photovoltage, light absorption, photogenerated-charge separation and catalytic efficiency.

He has led projects supported by the China Postdoctoral Science Foundation and the National Natural Science Foundation of China. As first or corresponding author, he has published 21 SCI papers in journals including Nature Communications, Energy & Environmental Science, Applied Catalysis B: Environment and Energy, Carbon Energy, Chemical Engineering Journal and Nano Energy. His papers have received more than 2,500 citations; seven are ESI Highly Cited Papers, and his H-index is 25.

Research group: gdutist.cn

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