Formation of NiCo Alloy Nanoparticles on Co Doped Al2O3Leads to High Fuel Production Rate, Large Light-to-Fuel Efficiency, and Excellent Durability for Photothermocatalytic CO2Reduction

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 (eta, 29.7%) are achieved via photothermocatalytic CO(2)reduction by methane (CRM) on Ni1.60Co/Co-Al(2)O(3)simply utilizing focused UV-visible-infrared (UV-vis-IR) illumination. Ni1.60Co/Co-Al(2)O(3)also demonstrates highr(CO)andr(H2)values (50.99 and 39.72 mmol min(-1)g(-1)) as well as high eta value (26.3%) under lambda > 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 Ni1.60Co/Co-Al(2)O(3)and Ni1.86Co/Co-Al(2)O(3)with a higher Ni/Co molar ratio demonstrate excellent photothermocatalytic durability, while the Ni0.38Co/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 Ni1.60Co/Co-Al(2)O(3)and Ni1.86Co/Co-Al(2)O(3)as compared to its single metal counterparts.