Quantum effect modulates the Bi-Ov active sites of S-scheme heterojunction for efficient CO2 photoreduction to CH4

Quantum dot (QD) heterojunctions have demonstrated great promise in CO 2 photocatalysis due to their unique quantum confinement effects. However, precise regulation of the electronic structure and enhancement of product selectivity remain major challenges. Herein, we report a novel ZnO@Bi 2 O 3 quantum dot S-scheme heterojunction photocatalyst synthesized via a space-confinement strategy. Under visible light irradiation, the ZnO@Bi 2 O 3 QDs heterojunction achieves a remarkable CH 4 production rate of 30.4 μmol g −1 h −1 (99 % C-selectivity), which is 2-fold and 9.2-fold higher than those of pristine ZnO and Bi 2 O 3 , respectively. Experimental and theoretical analyses revealed that the superior photocatalytic performance was attributed to the quantum confinement effect modulating the Bi-O v active sites of heterojunction, thereby accelerating charge carrier separation and the formation of the key intermediate *CH 3 O. This work highlights the pivotal role of quantum effects in modulating heterojunction electronic structures and offers new insights into the rational design of high-performance photocatalysts for artificial photosynthesis. • The spatial confinement strategy is used to synthesize a novel QDs S-scheme heterojunction. • The yield of CH 4 in QDs S-scheme heterojunction was 2 and 9.2 times higher than ZnO and Bi 2 O 3 , respectively. • S-scheme mechanism of heterojunction effectively drive the migration of photogenerated carriers and generate higher photocurrent. • Quantum confinement effect modulates the Bi-O v active center, thereby promoting the CO 2 activation and the formation of *CH 3 O.