Emerging hollow artificial photosynthetic system with S-scheme heterojunction sandwiched between layered redox cocatalysts for overall CO2 reduction and H2O oxidation

The development of artificial photosynthesis is challenged by nonstoichiometric photocatalytic reaction of CO2 with H2O. Herein, a delicate hollow multi-shelled nanoreactor with S-scheme heterojunction sandwiched between layered noble-metal-free redox cocatalysts is fabricated, which exhibits excellent photocatalytic performance for overall CO2-to-CO reduction and H2O-to-O2 oxidation with stoichiometric ratio of the evolved reduction and oxidation products. The synergy of the sandwiched heterojunction and spatially separated dual cocatalysts on the inner/outer sides: (i) promotes the separation and transfer of powerful photoexcited charges towards opposite directions; (ii) maneuvers the occurrence of surface redox reactions in different spaces through lowering the thermodynamic barriers, and (iii) hinders the occurrence of side reactions and photocorrosion on the semiconductor surface. Consequently, the charge separation, transfer and consumption are well balanced, and the photocatalytic activity, selectivity and stability are perfectly optimized. It is expected that this novel design can be extended to other semiconductor heterojunctions towards high-efficient photoredox catalysis.