Enhanced Photocarrier Collection in Bismuth Vanadate Photoanode through Modulating the Inner Potential Distribution

Abstract

Photoelectrochemical (PEC) synthesis provides a promising approach to produce green fuels, while the low energy conversion efficiency limits its application due to photocarrier recombination. Photocarrier recombination can be inhibited by building potential gradients in the photoelectrode with heterojunctions. However, despite the achieved progress, only a small amount of photocarriers can be collected and take PEC reactions. One of the main reasons is that the potential gradient provided by heterojunctions is limited in the depletion region, while photocarrier recombination mainly occurrs in the charge diffusion region. To break through the limitation of band engineering technique, herein, polarized BaTiO3 nanoparticles are embedded in BiVO4 composite photoanode to modulate the inner potential distribution so that more photocarriers can be successfully collected. The results show that the energy conversion efficiency has been significantly improved, as evidenced by an improved PEC H2O2 production concentration of 836 µmol L–1 under simulated sunlight illumination, which is 2.6 times of pure BiVO4 in the same situation. This work demonstrates a feasible strategy to enhance photocarrier collection efficiency by modulating the inner potential distribution in photoelectrode with an embedded polarizer, which can significantly enhance the energy conversion efficiency without extra energy consumption.

Full-Space Potential Gradient Driven Charge Migration inside BiFeO3 Photocathode

“…16,17 However, the influence of these electric fields is mostly spatially limited to the surface or depletion area, rarely modulating the recombination process in the field-free region. 15,18,19 The depolarization field is a typical way to promote charge separation in both bulk and surface, while it is confined to ferroelectrics. 20,21 Thus, a universal approach to construct fullspace electric field through the photoelectrode is the remedial approach to inhibit carrier recombination.…”

“…Constructing an internal electric field in the natural region as an additional driving force is critical to promote photocarriers collection . So far, various strategies have been widely employed to build an electric field, such as surface tailoring, heterojunction, , and facet junction. , However, the influence of these electric fields is mostly spatially limited to the surface or depletion area, rarely modulating the recombination process in the field-free region. ,, The depolarization field is a typical way to promote charge separation in both bulk and surface, while it is confined to ferroelectrics. , Thus, a universal approach to construct full-space electric field through the photoelectrode is the remedial approach to inhibit carrier recombination.…”