Multimodal Synergy via Interfacial Charge Regulation Boosts Solar-Driven Photothermal CO2 Splitting in Perovskite-Ceria Composites

Abstract

Solar-driven thermochemical CO₂ splitting is a scalable and promising approach for establishing a carbon-neutral energy system. However, its extremely high conversion temperatures greatly limit its energy efficiency and widespread application. This extreme temperature requirement is fundamentally dictated by the thermodynamic bottleneck of lattice-oxygen activation. Here, we propose an interfacial charge regulation strategy that couples photogenerated carriers with thermochemical lattice-oxygen redox within a heterostructured perovskite-ceria composite. This design creates multimodal synergy among light-driven charge generation, interfacial charge regulation, and thermally activated lattice-oxygen redox. For the designed CaMn_0.875Ti_0.125O₃/CeO₂ composite, in situ characterizations and theoretical calculations reveal that charge redistribution facilitates the electronic population of metal−oxygen antibonding states. This targeted electronic population weakens specific metal−oxygen bonds, modulating the local oxygen vacancy formation energy and promoting highly reactive CO₂^·− radical anion formation. Consistent with this field-driven interfacial regulation, the composite delivers a CO yield of 1017.48 μmol g⁻¹ at a substantially lowered operating temperature of 860 °C, a 300-fold enhancement over the purely thermal baseline. Ultimately, this work moves beyond conventional charge-separation models by identifying rational interfacial field engineering as an electronic strategy to modulate local defect thermodynamics for high-efficiency CO₂-to-fuel conversion.