Harmonized Physical and Electrochemical Process Design for Densely Dispersed Cu Catalysts on Cu₂o Absorbers for Efficient Photoelectrochemical CO₂ Reduction Reaction

The photoelectrochemical CO2 reduction reaction (photo-CO2RR) is a promising technology to convert CO2 into high-value-added carbon-based chemicals using a relatively low voltage, which can economically solve the problem of CO2 emissions. Nevertheless, unlike the conventional electrochemical CO2RR approach, photo-CO2RR technology is in its initial development stage. Particularly, when sunlight is applied to photoelectrodes for photo-CO2RR, severe photocorrosion is unavoidable, resulting in the deterioration of fundamental functions including device long-term stability and conversion performance. This study proposes an innovative two-step catalyst formation strategy to enable the efficient photo-CO2RR with Cu catalysts prepared using intrinsic photocorrosion of the Cu2O absorption layer. This approach is based on the harmonized process design of the i) growth of physically generated Cu nanoparticles and ii) construction of improved photoelectrochemical Cu cluster catalysts. The vacuum-evaporated Cu seeds are designed to induce an evenly dispersed electrical path on Cu2O, and the selectively concentrated electrical field from the Cu seeds provides preferential sites for metallic Cu catalysts in subsequent photoelectrochemical reduction. This harmonized combination process of Cu catalysts on Cu2O demonstrates a synergistic performance of -1.2 mA cm(-2) at 0 V-RHE with suppression of photocorrosion and produces approximate to 95% CO product gas (0.4 V-RHE).