In situ growth of a TiO2 layer on a flexible Ti substrate targeting the interface recombination issue of BiVO4 photoanodes for efficient solar water splitting

Abstract

Unfavorable interfacial electron back-injection, sluggish surface kinetics, and poor bulk conductivity leading to remarkable recombination are the key issues which significantly hinder the solar-to-hydrogen efficiency of PEC photoanodes. In this study, Ti foil is employed as the substrate for fabricating BiVO₄ photoanodes. Surface passivation of TiO₂ is sophisticatedly designed to block interface recombination in solar water splitting for the first time, so that a significant two-fold increase in photocurrent and a large decrease in dark current are observed. In addition, to address the other two issues, CoO_x oxygen evolution catalysts (OECs) and Mo/N doping are applied to increase the photocurrent density and applied bias photon-to-current efficiency to 5.04 mA cm⁻² at 1.23 V_RHE and 1.41% at 0.75 V_RHE, respectively, under AM 1.5 G illumination, which suggests the great potential of integrating strategies to target specific issues in BiVO₄ photoanodes.