Synergetic effects of surface plasmon resonance and structure defects in a ZnCdS2/NiMoO4@Cu Z-scheme heterojunction for enhanced photocatalytic CO2 reduction to CH4

Abstract

Photocatalytic carbon dioxide reduction to solar fuels is one of the promising strategies to solve resource depletion and global climate warming. Nevertheless, the poor product selectivity greatly limits its practical application. Herein, we present a Cu nanoparticle-modified ZnCdS₂/NiMoO₄ Z-scheme heterojunction photocatalyst that is highly selective and stable. It is worth noting that the hydrophobicity of NiMoO₄ can effectively inhibit the adsorption of water while forming a Z-scheme heterostructure with defective ZnCdS₂, and thus inhibiting hydrogen evolution and improving the separation efficiency of photogenerated carriers. Moreover, Cu nanoparticles with their surface plasmon resonance effect generate high-energy hot electrons during photoexcitation. This not only greatly increases the photogenerated electron density on the surface of the catalyst, resulting in a higher probability of multiple electron reactions or reduced state products but also effectively reduces the activation energy barrier for CO₂ reduction through the photothermal effect. Consequently, the ZCS/NMO@Cu Z-scheme heterojunction exhibits nearly 100% selectivity for CH₄ in the eight-electron reduction reaction, and outstanding CH₄ yield of 92.17 μmol g⁻¹ h⁻¹ without a sacrificial agent and co-catalyst. Furthermore, the CO₂ reduction mechanism is confirmed via in situ Fourier transform infrared (FTIR) spectroscopy analysis. This work will provide meaningful insights for designing a carbon dioxide reduction photocatalyst with high conversion and selection.