ZIF-8 Derived ZnO/Au Plasmonic Photocatalyst Boosts CO2 Reduction to MeOH Generation

Abstract

Photocatalytic CO₂ conversion into renewable solar fuels offers a dual solution for reducing greenhouse gas emissions and meeting sustainable energy demands. To employ this, plasmonic nanoparticles (PNPs) are one of the best candidates which exhibit exceptional broadband optical absorption and localized surface plasmon resonance-mediated electromagnetic field confinement, enabling precise photochemical energy conversion to enhance solar-driven catalytic CO₂ reduction efficiency. In this report, ZIF-8-derived ZnO is synthesized at controlled pyrolysis process, and heterostructure formed with Au nanoparticles to develop plasmonic Au_x/ZnO (AZN) photocatalyst. The hybrid heterostructure catalyst with very low Au-loaded (AZN0.1) exhibits CO₂ reduction to methanol with rate of 211.95 μmol g⁻¹ h⁻¹, which is nearly four times higher than the pristine ZIF-8 derive ZnO. The electron paramagnetic resonance signals’ observed g-values in ZnO are characteristic of surface defect like oxygen vacancies and trends of decreasing defect are also observed in photoluminescence spectroscopy after incorporation of Au NPs on the surface of defective ZnO. Here, Au co-catalyst forms a Schottky junction with ZnO, enhancing charge separation by donating plasmon mediated hot electrons. Therefore, this study infers new insight for plasmon-mediated preparation of Au/ZnO heterojunction for efficient photocatalytic CO₂ reduction to MeOH.