Enabling Direct Photoelectrochemical H₂ Production using Alternative Oxidation Reactions on WO₃

Abstract

The efficient and inexpensive conversion of solar energy into chemical bonds, such as in H₂ via the photoelectrochemical splitting of H₂O, is a promising route to produce green industrial feedstocks and renewable fuels, which is a key goal of the NCCR Catalysis. However, the oxidation product of the water splitting reaction, O₂, has little economic or industrial value. Thus, upgrading key chemical species using alternative oxidation reactions is an emerging trend. WO₃ has been identified as a unique photoanode material for this purpose since it performs poorly in the oxygen evolution reaction in H₂O. Herein we highlight a collaboration in the NCCR Catalysis that has gained insights at the atomic level of the WO₃ surface with ab initio computational methods that help to explain its unique catalytic activity. These computational efforts give new context to experimental results employing WO₃ photoanodes for the direct photoelectrochemical oxidation of biomass-derived 5-(hydroxymethyl) furfural. While yield for the desired product, 2,5-furandicarboxylic acid is low, insights into the reaction rate constants using kinetic modelling and an electrochemical technique called derivative voltammetry, give indications on how to improve the system.