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A nanocomposite of Co/Co–Al2O3 nanosheets shows a high light-to-fuel efficiency and fuel production rate for photothermocatalytic CO2 reduction using CH4.

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Unique nanocomposites of NiCo alloy nanoparticles with Ni/Co molar ratios of 1.86, 1.60, and 0.38 supported on Co‐doped Al2O3 nanosheets are prepared by a facile approach. Very high fuel production rates of CO (rCO) and H2 (rH2) (70.53 and 63.46 mmol min−1 g−1) and light‐to‐fuel efficiency (η, 29.7%) are achieved via photothermocatalytic CO2 reduction by methane (CRM) on Ni1.60Co/Co‐Al2O3 simply utilizing focused UV‐visible‐infrared (UV‐vis‐IR) illumination. Ni1.60Co/Co‐Al2O3 also demonstrates high rCO and rH2 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‐Al2O3 samples has an important effect on the photothermocatalytic durability. The samples of Ni1.60Co/Co‐Al2O3 and Ni1.86Co/Co‐Al2O3 with a higher Ni/Co molar ratio demonstrate excellent photothermocatalytic durability, while the Ni0.38Co/Co‐Al2O3 with a lower Ni/Co molar ratio has less durability. This is attributed to carbon deposition rate being significantly reduced on Ni1.60Co/Co‐Al2O3 and Ni1.86Co/Co‐Al2O3 as compared to its single metal counterparts.