Crafting CuxS-ReS2 semiconductor with enhanced adsorption capacity to facilitate photoelectrocatalytic ethanol production from CO2

Converting carbon dioxide into value-added fuels and chemicals is considered a promising long-term strategy to mitigate global warming and address energy supply challenges. Constrained by the slow kinetics of C–C coupling processes, ensuring efficient generation of C2 products in CO₂ catalytic reduction remains challenging. Herein, a semiconductor catalyst containing Cu9S5, Cu2S, and ReS2 was synthesized through pulse electrodeposition and high-temperature sulfurization. The incorporation of Re induced the formation of Cu9S5 with high light absorption coefficient during the Cu sulfidation process, and spontaneous loss of Cu ions led to the high density of holes in Cu9S5 that might result in improved photoelectrochemical performance of the semiconductor catalyst. More importantly, the composite of CuxS and ReS2 enhanced the adsorption capacity of CO2 at the interface, effectively reducing the activation energy barrier for CO2 molecules. Simultaneously, the adsorption of CO on the surface of composite catalyst was also strengthened to a certain extend, the retention of CO intermediates promoted C–C coupling and high-efficient conversion of CO2 to ethanol. As a result, the optimized CuxS-ReS2/TiO2NTs (TiO2 nanotubes) heterojunction achieved an increased generation rate in the liquid system, with ethanol yield of 30.12 μmol cm−2 after 5 h of photoelectrocatalysis. Even after five cycles of photocatalytic reactions, the ethanol production maintained at 8.08 μmol cm−2. The absence of new phases on the surface further indicates the stability of this semiconductor catalyst. This work provides an effective strategy for the catalyst design aimed at achieving the efficient conversion of CO2 and selective synthesis of ethanol and other multi-carbon products.