Highly Selective Photoreduction of CO2 with Suppressing H2 Evolution by Plasmonic Au/CdSe-Cu2O Hierarchical Nanostructures under Visible Light

Here, the photocatalytic CO2 reduction reaction (CO2RR) with the selectivity of carbon products up to 100% is realized by completely suppressing the H-2 evolution reaction under visible light (lambda > 420 nm) irradiation. To target this, plasmonic Au/CdSe dumbbell nanorods enhance light harvesting and produce a plasmon-enhanced charge-rich environment; peripheral Cu2O provides rich active sites for CO2 reduction and suppresses the hydrogen generation to improve the selectivity of carbon products. The middle CdSe serves as a bridge to transfer the photocharges. Based on synthesizing these Au/CdSe-Cu2O hierarchical nanostructures (HNSs), efficient photoinduced electron/hole (e(-)/h(+)) separation and 100% of CO selectivity can be realized. Also, the 2e(-)/2H(+) products of CO can be further enhanced and hydrogenated to effectively complete 8e(-)/8H(+) reduction of CO2 to methane (CH4), where a sufficient CO concentration and the proton provided by H2O reduction are indispensable. Under the optimum condition, the Au/CdSe-Cu2O HNSs display high photocatalytic activity and stability, where the stable gas generation rates are 254 and 123 mu mol g(-1) h(-1) for CO and CH4 over a 60 h period.