Formation of NiCo Alloy Nanoparticles on Co Doped Al2O3 Leads to High Fuel Production Rate, Large Light‐to‐Fuel Efficiency, and Excellent Durability for Photothermocatalytic CO2 Reduction

Abstract Unique nanocomposites of NiCo alloy nanoparticles with Ni/Co molar ratios of 1.86, 1.60, and 0.38 supported on Co‐doped Al 2 O 3 nanosheets are prepared by a facile approach. Very high fuel production rates of CO ( r CO ) and H 2 ( r H2 ) (70.53 and 63.46 mmol min −1 g −1 ) and light‐to‐fuel efficiency (η, 29.7%) are achieved via photothermocatalytic CO 2 reduction by methane (CRM) on Ni 1.60 Co/Co‐Al 2 O 3 simply utilizing focused UV‐visible‐infrared (UV‐vis‐IR) illumination. Ni 1.60 Co/Co‐Al 2 O 3 also demonstrates high r CO and r H2 values (50.99 and 39.72 mmol min −1 g −1 ) as well as high η value (26.3%) under λ > 560 nm focused vis‐IR illumination. The high photothermocatalytic activity is derived from the light‐driven thermocatalytic CRM. A novel photoactivation is found to substantially promote the light‐driven thermocatalytic CRM due to the apparent activation energy being considerably reduced upon illumination. It is found that the Ni/Co molar ratio in the NiCo/Co‐Al 2 O 3 samples has an important effect on the photothermocatalytic durability. The samples of Ni 1.60 Co/Co‐Al 2 O 3 and Ni 1.86 Co/Co‐Al 2 O 3 with a higher Ni/Co molar ratio demonstrate excellent photothermocatalytic durability, while the Ni 0.38 Co/Co‐Al 2 O 3 with a lower Ni/Co molar ratio has less durability. This is attributed to carbon deposition rate being significantly reduced on Ni 1.60 Co/Co‐Al 2 O 3 and Ni 1.86 Co/Co‐Al 2 O 3 as compared to its single metal counterparts.