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

Abstract

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 (r_H2) and CO (r_CO) (61.69 and 63.80 mmol min⁻¹ g⁻¹) are achieved on Ni₅Cu₂/Al₂O₃. The high r_H2 and r_CO 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.