Anchored Li2MnO3 nanoparticles on ZnO nanosheets photocatalyst for effective CO2 reduction to CH3OH upon visible illumination

Abstract

Photocatalytic reduction of CO₂ has garnered significant attention as a sustainable and clean process for producing fuels and chemicals. Various heterojunction-based photocatalysts are explored to effectively reduce CO₂ to valuable chemicals. In this study, porous ZnO sheets are fabricated through a hydrothermal process using polyvinylpyrrolidone as a pore builder. Moreover, Li₂MnO₃ NPs were incorporated into the ZnO nanosheet via the impregnation method with varying Li₂MnO₃ contents (5–20 %). Li₂MnO₃ NPs are uniformly dispersed on the porous ZnO sheets, which enhances the photocatalytic performance. The resulting Li₂MnO₃/ZnO photocatalyst demonstrates an improved CO₂ photocatalytic reduction to CH₃OH under visible illumination. The 15 % Li₂MnO₃/ZnO photocatalyst achieves a maximum formation rate of CH₃OH at approximately 156.04 μmol g^-1h^-1, which is 15.85 times greater than that of bare ZnO. Furthermore, the photocatalytic ability after five cycles of reactions remains remarkably stable due to its exceptional stability during CO₂ reduction. The enhanced photocatalytic performance of the Li₂MnO₃/ZnO photocatalyst is attributed to the modification of the bandgap structure, strong visible light response, improved CO₂ adsorption, high electronic reduction capability, and effective charge transport capacity. This work contributes to the novel design of highly effective S-scheme mechanisms for the photoreduction of CO₂.