Bioinspired charge reservoir enables efficient CO₂ photoreduction with H₂O via tungsten valence oscillation

Solar-driven conversion of CO₂ and H₂O into chemicals is a promising strategy, while achieving simultaneous and efficient CO₂ reduction and H₂O oxidation remains challenging. Here, inspired by the role of plastoquinone in temporarily storing electrons during natural photosynthesis, we design a silver-modified tungsten trioxide (Ag/WO₃) that functions as a charge reservoir through reversible W⁶⁺/W⁵⁺ transitions under irradiation. When coupled with various active components, Ag/WO₃ significantly enhances their CO₂ conversion performance, indicating the universality of this strategy. Specifically, coupling Ag/WO₃ with cobalt phthalocyanine (CoPc), the CoPc/Ag/WO₃ catalyst achieves a CO production rate of ~1.5 mmol g_CoPc^-1 h^-1, representing a 100-fold enhancement over pure CoPc. Mechanistic studies reveal that electrons stored in Ag/WO₃ efficiently scavenge photogenerated holes from CoPc, thereby maintaining a high electron density at CO₂ reduction sites of CoPc. This work establishes a bioinspired charge reservoir strategy for efficient CO₂ photoreduction, providing a universal approach to solar fuel production.