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 H 2 O/CO 2 activation and carriers’ severe recombination impede photocatalytic CO 2 reduction reaction. Herein, this work innovatively proposes an “interfacial H 2 O dissociation” strategy on a MoN/Mo 2 N (MN) dual-plasmon heterojunction for achieving interface structure-dependent active *H generation in the CO 2 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 H 2 O 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 CO 2 reduction. Without cocatalysts and sacrificial reagents, the MN metallic heterojunctions exhibit an efficient CO 2 photoreduction activity with a CH 4 evolution rate of 8.2 μmol h –1 . This work offers an atomic-level insight into H 2 O dissociation and the design of metallic heterojunction for CO 2 reduction.