Fabrication of a Facet-Oriented BiVO<sub>4</sub> Photoanode by Particle Engineering for Promotion of Charge Separation Efficiency
Boyang Zhang, Yao Xiang, Mei Guo, Jiaming Wang, Kaiwei Liu, Wenrui Lin, Guijun Ma
Abstract
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.