Photoelectrochemical Decomposition of Lignin Model Compound on a BiVO4 Photoanode

The photoelectrochemical decomposition of lignin model compounds at a BiVO4 photoanode is demonstrated with simulated sunlight and an applied bias of 2.0 V. These prototypical lignin model compounds are photoelectrochemically converted into the corresponding aryl aldehyde and phenol derivatives in a single step with conversion of up to ≈64 % over 20 h. Control experiments suggest that vanadium sites are electrocatalytically active, which precludes the need for a redox mediator in solution. This feature of the system is corroborated by a layer of V2O5 deposited on BiVO4 serving to boost the conversion by 10 %. Our methodology capitalizes on the reactive power of sunlight to drive reactions that have only been studied previously by electrochemical or catalytic methods. The use of a BiVO4 photoanode to drive lignin model decomposition therefore provides a new platform to extract valuable aromatic chemical feedstocks using solar energy, electricity and biomass as the only inputs. Old dog new tricks: The photoelectrochemical decomposition of lignin model compounds at a BiVO4 photoanode is demonstrated, revealing the dual role of vanadium in BiVO4, which acts as both a photoanode material and a heterogeneous catalyst for organic transformation. This strategy highlights a new utility of photoelectrochemical cells to produce valuable chemical feedstocks from solar energy and biomass.