Fabrication of a Facet-Oriented BiVO₄ Photoanode by Particle Engineering for Promotion of Charge Separation Efficiency

Facet regulation of the BiVO4 photoanode is an effective way to improve its charge separation efficiency. Herein, a BiVO4 photoanode structured by connecting a (040)-facet-oriented mono-grain layer to a conductive metal substrate was fabricated by particle engineering, namely a Langmuir–Blodgett assembly process followed by the particle transfer technique. The as-prepared electrode produced superior photocurrent and higher charge separation efficiency than that prepared by randomly accumulating the BiVO4 particles on a metal substrate. Impedance spectroscopy, time-resolved photoluminescence spectra, and theoretical analysis revealed that the (040)-facet-oriented photoelectrode had a relatively lower bulk charge transport resistance and higher electron–hole separation efficiency. Inserting Au nanoparticles into the BiVO4/substrate interlayer further enhanced its photo activity via accelerating electron transfer and preventing electron–hole recombination at the particle/substrate interface. A CoOx-loaded BiVO4/Au/Ti/Sn electrode fabricated by the particle engineering process evolved O2 by water oxidation with a Faradaic efficiency of unity. This work provides a potential scalable strategy of enhancing photoelectrochemical activity by assembly of grain orientations, which is applicable to those semiconductor photocatalysts having face-selective anisotropic electron transfer property.