Over a 15.9% Solar-to-CO Conversion from Dilute CO2 Streams Catalyzed by Gold Nanoclusters Exhibiting a High CO2 Binding Affinity

Development of efficient and selective electro-catalysts is a key challenge to achieve an industry-relevant electrochemical CO2 reduction reaction (CO2RR) to produce commodity chemicals. Here, we report that Au-25 clusters with Authiolate staple motifs can initiate electrocatalytic reduction of CO2 to CO with nearly zero energy loss and achieve a high CO2RR current density of 540 mA cm(-2) in a gas-phase reactor. Electrochemical kinetic investigations revealed that the high CO2RR activity of the Au-25 originates from the strong CO2 binding affinity, leading to high CO2 electrolysis performance in both concentrated and dilute CO2 streams. Finally, we demonstrated an 18.0% solar-to-CO conversion efficiency using a Au-25 electrolyzer powered by a Ga0.5In0.5P/GaAs photovoltaic cell. The electrolyzer also showed 15.9% efficiency and a 5.2% solar-driven single-path CO2 conversion rate in a 10% CO2 gas stream, the CO2 concentration in a typical flue gas.