Design of faceted 0D/1D CeO2/ZnO S-scheme heterostructures for solar-driven methanol production

Abstract

Efficient solar-driven conversion of CO₂ into value-added chemical presents a promising approach to addressing climate change and energy scarcity. However, sluggish charge carrier kinetics remain a significant barrier to effective CO₂ photoreduction. In this study, a solvothermal method is employed to synthesize facet-engineered CeO₂/ZnO nanorod (NRs) S-scheme heterojunctions for the selective photoreduction of CO₂ to methanol under mild conditions. Comprehensive characterization confirms the successful deposition and stability of CeO₂ nanoparticles on the surface of ZnO NRs. Among the synthesized photocatalysts, the composite with 0.2 mmol CeO₂ exhibits the best performance, yielding 111 µmol·g^₋1, 176 µmol·g^₋1, 311 µmol·g^₋1, and 304 µmol·g^₋1·h^₋1 for H₂, CO, CH₄, and CH₃OH, respectively, with a notable CO₂ selectivity of approximately 89 %. Mechanistic analysis reveals that optimized CeO₂ loading induces an internal electric field, facilitating an S-scheme heterojunction charge-transfer pathway that enhances electron mobility from the ZnO NRs to CeO₂. In-situ FT-IR spectroscopy further identifies key intermediates (HCOO* and H₃CO*) involved in the transformation of CO₂ to CH₃OH. This work demonstrates a novel photocatalyst design that leverages precise CeO₂ loading onto ZnO NRs, offering a promising strategy for efficient and selective CO₂ photoreduction.