High fuel production rate and excellent durability for photothermocatalytic CO2 reduction achieved via the surface plasma effect of NiCu alloy nanoparticles

Solar energy-driven CO2 reduction is attractive for fuel production and greenhouse effect mitigation. Here, NiCu alloy nanoparticles with varying Ni/Cu molar ratios supported on Al2O3 were prepared for CH4 photothermocatalytic CO2 reduction upon focused ultraviolet-visible-infrared (UV-VIS-IR) illumination. High production rates of H2 (rH2) and CO (rCO) (61.69 and 63.80 mmol min^-1 g^-1) are achieved on Ni5Cu2/Al2O3. The high rH2 and rCO originate from efficient light-thermal conversion caused by the strong localized surface plasmon resonance (LSPR) of NiCu alloy nanoparticles. The strong LSPR effect can generate a high concentration of hot electrons, which can not only reduce the activation energy of reactants and enhance the fuel yield, but also participate in the conversion of intermediate species to reduce the carbon deposition rate. Compared with Ni5Cu2/Al2O3 and Ni/Al2O3, the samples of Ni5Cu5/Al2O3 catalysts with a lower Ni/Cu molar ratio have lower catalytic activity and a higher carbon deposition rate. This is attributed to the fact that Cu has a lower surface energy, which enables a large number of Cu atoms to aggregate on the surface of alloy nanoparticles.