Photoelectrochemical Oxidation of Glycerol to Dihydroxyacetone Over an Acid-Resistant Ta:BiVO₄ Photoanode

Abstract

The conversion of glycerol, a major byproduct of the biodiesel industry, into value-added chemicals is a topic of significant academic and industrial importance because it can potentially decrease production costs and waste amounts. This process may become even greener if the conversion of glycerol is driven by renewable energy in ambient temperature instead of conventional thermochemical reactions. Herein, we have developed an energy-efficient method for the photoelectrochemical oxidation of glycerol to dihydroxyacetone (DHA), a high-value-added chemical, over a Ta-doped BiVO4/WO3/F-doped tin oxide (FTO) (Ta:BiVO4) photoanode with higher acid resistance than a conventional non-doped BiVO4/WO3/FTO photoanode (BiVO4). The DHA selectivity of the Ta:BiVO4 anode was close to 100%, and the amounts of undesirable products, such as glyceraldehyde and formic acid, were negligible. By tuning the acidity and composition of the reaction solution, the Faradaic efficiency for the oxidation of glycerol to DHA over the acid-resistant Ta:BiVO4 photoanode increased from 61% for a 25 mM H2SO4 solution to 80% for a 100 mM H2SO4 solution to 96% for a 100 mM H2SO4 solution containing acetone. Conversely, the undoped BiVO4 photoanode was unstable in the 25 mM H2SO4 solution, and its current density decreased by 27%.