Boosting Photoelectrochemical Ethanol Evolution on Reduced Graphene Oxide Functionalized Photocathode

Herein, a reduced graphene oxide (rGO) functionalized photocathode is studied for selective production of solar liquid fuels depending on dark and solar light illumination condition. rGO functionalized photocathode with p–n junction at the core–shell interface of ZnO@ZnTe is prepared with a three‐step synthetic process. Preparation of ZnO nanorod, formation of ZnTe on ZnO nanorod by anion‐exchange and then, finally, rGO layers are functionalized on the surface of ZnO@ZnTe photocathode. The photoelectrochemical (PEC) system of BiVO4∥KHCO3∥ZnO@ZnTe@rGO combination is introduced for selective solar liquid fuel production by CO2 reduction reaction (CO2RR). Functionalization of rGO layers on photocathode enables the multi‐electron shuttling function for the enhanced charge transfer efficiency due to its large charge capacitance, which results in producing liquid fuels such as HCHO and EtOH selectively as solar liquid fuels. These results in this work clearly demonstrate a possibility of solar liquid fuel product selectivity by PEC CO2RR. Photo‐electrochemical CO2 conversion into useful products such as formaldehyde and ethanol is demonstrated in this work by using reduced graphene oxide (rGO) functionalized ZnO@ZnTe photocathode. Selective product formation is a challenging task, and it is controlled by an electron transfer process with and without rGO for EtOH and HCHO, respectively. These results help to understand the fundamentals behind product selectivity for the CO2 reduction reaction.