The salient question addressed in this work is whether and how photovoltaic-biased photoelectro-catalysis(PV-PEC) can fairly and practically beat photovoltaic-powered electrocatalysis (PV-EC) for solar-driven carbon dioxide reduction (CO2RR). First, it was argued that to fairly evaluate PV-PEC and PV-EC CO2RR approaches in terms of techno-economy, the two devices should be driven by the same PV cell and produce the same group of products for the same series of Faradaic efficiency for each product. For this condition, PV-PEC CO2RR was shown to surprisingly have higher solar-to-chemical conversion efficiency, and thereby more competitive, than PV-EC. This non-trivial performance was achieved by leveraging novel design of light management presented in this work and careful choice of PV and PEC cells achievable in literature. Furthermore, the framework generalized in this work is also applicable to other solar-driven catalytic processes with various different products such as productions of H2O2 by water oxidation and ammonia by nitrogen fixation.
Keywords CO2 reduction, photoelectrocatalysis, electrocatalysis, solar fuel, techno-economy