Assembling Heterojunction Zn_0.75Cd_0.25Se–CdS Quantum Dot Aerogels for Enhanced Photocatalytic CO₂ Methanation

Abstract Heterojunction engineering into quantum dot (QD) assemblies has emerged as an effective approach to optimize photocatalytic systems through enhanced charge separation and extended light‐harvesting capabilities. Nevertheless, fabricating QD heterojunctions with robust interfacial coupling remains challenging due to stringent morphological and lattice matching constraints. Here, a class of atomically fused ZnCdSe–CdS aerogels with tailored heterointerfaces is reported for superior solar‐driven CO₂ reduction. The high lattice compatibility between ZnCdSe and CdS enables seamless heterojunction formation with strong electronic coupling, while strategic Cd doping in ZnSe extends optical absorption to maximize solar utilization. The optimized aerogels exhibit exceptional CO₂ photoreduction activity, achieving a CH₄ production rate of 240 µmol g⁻¹ h⁻¹ with 87% selectivity and an apparent quantum yield (AQY) of 1.2% under visible light. Combined spectroscopic characterization and density functional theory (DFT) simulations elucidate that suppressed carrier recombination at the engineered interface serves as a key mechanistic determinant for enhanced performance. This work establishes a universal platform for designing interfacial‐engineered QD aerogels, advancing their applicability in high‐efficiency solar fuel generation systems.