Ultrafine SnO2/010 Facet-Exposed BiVO4 Nanocomposites as Efficient Photoanodes for Controllable Conversion of 2,4-Dichlorophenol via a Preferential Dechlorination Path.

Abstract

It is a great challenge for achieving efficiently controllable conversion of chlorinated organics through BiVO4-based photoelectrochemical methods by improving the selective adsorption of such organics and charge separation. Herein, we have successfully fabricated SnO2/010 facet-exposed BiVO4 nanocomposites by a series of hydrothermal processes and further used as efficient photoanodes. The resulting photoanode exhibits about 6.3 times higher photoelectrochemical activity than bulk-BiVO4, especially with the efficiently controllable conversion of 2,4-dichlorophenol (2,4-DCP) to the nontoxic valuable intermediates such as catechol and pyrogallol by preferential dechlorination. Based on the 2,4-DCP adsorption curves, in situ diffuse reflectance infrared spectra, transient-state surface photovoltage responses, and photocurrent action spectra, it was clearly confirmed that the exceptional performance could be mainly attributed to the promoted selective adsorption of 2,4-DCP for efficiently modulating holes by the strong coordination interactions between -Cl with lone-pair electrons in 2,4-DCP and Bi- with empty orbits on (010) facet-exposed BiVO4 nanoflakes and to the coupled nano-SnO2 for prolonging the charge lifetime of BiVO4 by acting as the high-energy-level electron-accepting platform. This work provides a feasible strategy to develop excellent BiVO4-based photoelectrochemical methods for efficiently controlling the conversion of chlorinated organics simultaneously with energy production and recovery.