Light-driven thermocatalytic CO2 reduction by CH4 on alumina-cluster-modified Ni nanoparticles with excellent durability and high light-to-fuel efficiency promoted by the photoactivation effect

Using inexhaustible solar energy to drive efficient light-driven thermocatalytic CO 2 reduction by CH 4 (DRM) is an attractive approach that can synchronously reduce the greenhouse effect and convert solar energy into fuels. However, it is often limited by the intense light intensity required to produce high fuel production rates, and the catalyst deactivation due to severe carbon deposition generated from side reactions. Herein, a nanostructure of alumina-cluster-modified Ni nanoparticles supported on Al 2 O 3 nanorods (ACM-Ni/Al 2 O 3 ) was synthesized, displaying good catalytic performance under focused UV–vis-IR illumination. By light-driven thermocatalytic DRM on ACM-Ni/Al 2 O 3 at a reduced light intensity of 76.9 kW m −2 , the high fuel production rates of H 2 ( r H2, 65.7 mmol g −1 min −1 ) and CO ( r CO, 78.8 mmol g −1 min −1 ), as well as an efficient light-to-fuel efficiency ( η , 26.3 %) are achieved without additional heating. The r H2 and r CO of light-driven thermocatalysis are 2.9 and 1.9 times higher, respectively, compared to conventional thermocatalysis at the same temperature. We have discovered that high light-driven thermocatalytic activity originates from the photoactivation effect, significantly reducing the apparent activation energy and facilitating C* oxidation as a decisive step in DRM. ACM-Ni/Al 2 O 3 possesses excellent durability and exhibits an extremely low coking rate of 4.40 × 10 −3 g c g catalyst −1 h −1 , which is 26.8 times lower than that of the reference sample without Al 2 O 3 cluster modification (R-Ni/Al 2 O 3 ). This is owing to a decrease in activation energies (E a ) of C* oxidation and an increase in E a of C* polymerization by the surface modification of Ni nanoparticles with Al 2 O 3 clusters, effectively inhibiting carbon deposition.