Photocatalytic CO₂ Reduction to Acetone by Chiral HgS/CuO Heterojunctions

The efficient conversion of CO₂ into value-added C₃ chemicals is highly desirable yet remains challenging due to the complex multi-electron transfer and C-C coupling processes involved. In particular, acetone is an industrially important solvent and chemical feedstock, and its direct synthesis from CO₂ via photocatalysis represents a sustainable alternative to fossil-based routes. Herein, we report chiral CuO/HgS heterojunction photocatalysts for additive-free photocatalytic CO₂ reduction to acetone. Chiral CuO and HgS were synthesized using chiral molecules as symmetry-directing agents and subsequently assembled into heterojunctions with controlled handedness combinations. Structural and spectroscopic analyses confirm the successful construction of chiral interfaces. Photocatalytic tests reveal that the heterojunction catalysts exhibit significantly enhanced CO₂ conversion efficiency and acetone selectivity compared to single components. The optimized system delivers improved charge separation efficiency, increased photocurrent response, and prolonged carrier lifetimes. This work demonstrates an effective heterojunction design strategy for promoting C₃ product formation from CO₂ and provides a sustainable approach for green acetone synthesis.