Direct and indirect Z-scheme heterostructure-coupled photosystem enabling cooperation of CO2 reduction and H2O oxidation

The stoichiometric photocatalytic reaction of CO₂ with H₂O is one of the great challenges in photocatalysis. Here, we construct a Cu₂O-Pt/SiC/IrOx composite by a controlled photodeposition and then an artificial photosynthetic system with Nafion membrane as diaphragm separating reduction and oxidation half-reactions. The artificial system exhibits excellent photocatalytic performance for CO₂ reduction to HCOOH and H₂O oxidation to O₂ under visible light irradiation. The yields of HCOOH and O₂ meet almost stoichiometric ratio and are as high as 896.7 and 440.7 μmol g⁻¹ h⁻¹, respectively. The high efficiencies of CO₂ reduction and H₂O oxidation in the artificial system are attributed to both the direct Z-scheme electronic structure of Cu₂O-Pt/SiC/IrOx and the indirect Z-scheme spatially separated reduction and oxidation units, which greatly prolong lifetime of photogenerated electrons and holes and prevent the backward reaction of products. This work provides an effective and feasible strategy to increase the efficiency of artificial photosynthesis.