Ni-Doped BiVO4 with V4+ Species and Oxygen Vacancies for Efficient Photoelectrochemical Water Splitting

Dechao Kong,Jie Qi,Danyang Liu,Xiangwen Zhang,Jijun Zou,Lun Pan

doi:10.1007/s12209-019-00202-1

Abstract

Bismuth vanadate is a promising photoanode material for photoelectrochemical (PEC) water splitting, but its activity and stability need to be further improved. In this work, we synthesized Ni-doped BiVO4 abundant with V4+ species and oxygen defects through an in situ electrodeposition method. The effective doping can decrease the particle size of BiVO4 and lead to the formation of V4+ species/oxygen defects. Accordingly, the doped and defective BiVO4 showed high optical absorption and rapid charge transfer, and further showed much higher PEC activity than pure BiVO4. Specifically, 5-Ni-BiVO4 exhibits the highest activity in PEC water splitting, with a photocurrent of 2.39 mA/cm2 at 1.23 V versus RHE (the reversible hydrogen electrode), which is 2.5 times higher than pure BiVO4 (0.94 mA/cm2), and much higher incident photon-to-current efficiency (IPCE) value of 45% (while only 25% for BiVO4 at ca. 400 nm). This work provides an in situ method for the development of a high-performance photoanode.

Highlights

As the energy crisis and environmental pollution have become serious issues in the past decades [1], sustainable energy needs to be explored, and the utilization of solarDechao Kong and Jie Qi have contributed to this work.Electronic supplementary material The online version of this article contains supplementary material, which is available to authorized users.Since Fujishima and Honda [6] first applied TiO2 as a photoanode material for PEC water splitting, much research has been carried out to explore the active photoanodes, such as WO3, Fe2O3, ZnO, B iVO4 [7,8,9,10,11,12]
X-ray diffraction (XRD) characterization was applied to analyze the crystalline phase of samples with a diffractometer by Germany Brooke AXSCO
In the Raman spectra (Fig. 1c), the characteristic vibration peaks of all samples refer to the crystal structure of monoclinic scheelite BiVO4, and the Ni doping gradually decreased the crystallization of B iVO4, which may have caused surface defects

Summary

Introduction

Ni ions were applied to narrow the band gap of B iVO4 [32,33,34,35], and the atom radii difference between N i2+ (0.78 Å) and B i3+ (1.03 Å) could lead to abundant surface defects, which are beneficial to optical absorption and charge transfer [36]. The doping of Ni ions into the BiVO4 lattice decreases the particle size and causes abundant V 4+ species and oxygen defects, which shorten the migration length of charge carriers and enhance optical absorption.

Results

Conclusion