Formation of NiCo Alloy Nanoparticles on Co Doped Al<sub>2</sub>O<sub>3</sub> Leads to High Fuel Production Rate, Large Light‐to‐Fuel Efficiency, and Excellent Durability for Photothermocatalytic CO<sub>2</sub> Reduction
Shaowen Wu, Yuanzhi Li, Qian Zhang, Qianqian Hu, Jichun Wu, Chongyang Zhou, Xiujian Zhao
Abstract
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.