High Fuel Yields, Solar‐to‐Fuel Efficiency, and Excellent Durability Achieved for Confined NiCo Alloy Nanoparticles Using MgO Overlayers for Photothermocatalytic CO2 Reduction

Solar‐energy‐driven CO 2 reduction to produce fuel is of great importance for alleviating the greenhouse effect and energy shortage. Here, a composite of MgO overlayers confined NiCo alloy nanoparticles supported on MgO (NiCo@MgO/MgO) is prepared. Extremely high production rates of H 2 ( r H2 ) and CO ( r CO ) (112.98 and 127.13 mmol min −1 g −1 , respectively) and large solar‐to‐fuel efficiency ( η , 39.3%) are achieved on NiCo@MgO/MgO for photothermocatalytic CO 2 reduction by CH 4 under ultraviolet–visible–infrared (UV–VIS–IR) illumination. The high fuel production rates and η originate from efficient light–thermal conversion and photoactivation, which can boost the photothermocatalytic activity by reducing the activation energy. Importantly, NiCo@MgO/MgO does not show deactivation during a 90 h photothermocatalytic CO 2 reduction by the CH 4 durability test, owing to its low carbon deposition rate. Experimental evidence reveals that the NiCo alloy and MgO overlayers can inhibit CO disproportionation and accelerate the oxidation of carbon species, thereby significantly decreasing the carbon deposition rate.