Interface-Engineering-Induced Reactive Hydrogen Supply in the Dual-Plasmon Heterojunction for Efficient CO ₂ -to-CH ₄ Photosynthesis

Artificial photosynthesis is considered an ideal technology to achieve the “dual-carbon” goals. However, sluggish H2O/CO2 activation and carriers’ severe recombination impede photocatalytic CO2 reduction reaction. Herein, this work innovatively proposes an “interfacial H2O dissociation” strategy on a MoN/Mo2N (MN) dual-plasmon heterojunction for achieving interface structure-dependent active *H generation in the CO2 photoreduction process. The formation of MN heterojunctions with a low lattice mismatch diminished interfacial mass transfer obstruction and promoted charge carriers’ separation efficiency, triggering a fast H2O dissociation reaction for proton *H generation with a decreased longitudinal relaxation time of 342.40 ms from more than 600 ms and prolonging the average carriers’ lifetime to 410 ps. Theoretical calculations reveal that the strong interface coupling effect greatly decreases the energy barrier of *H generation and rate-limiting intermediate formation steps of CO2 reduction. Without cocatalysts and sacrificial reagents, the MN metallic heterojunctions exhibit an efficient CO2 photoreduction activity with a CH4 evolution rate of 8.2 μmol h–1. This work offers an atomic-level insight into H2O dissociation and the design of metallic heterojunction for CO2 reduction.