Synergistic Ru Species on Poly(heptazine imide) Enabling Efficient Photocatalytic CO ₂ Reduction with H ₂ O beyond 800 nm

Abstract Photocatalytic CO 2 conversion with H 2 O to carbonaceous fuels is a desirable strategy for CO 2 management and solar utilization, yet its efficiency remains suboptimal. Herein, efficient and durable CO 2 photoreduction is realized over a Ru NPs /Ru‐PHI catalyst assembled by anchoring Ru single atoms (SAs) and nanoparticles (NPs) onto poly(heptazine imide) (PHI) via the in‐plane Ru‐N 4 coordination and interfacial Ru‐N bonds, respectively. This catalyst shows an unsurpassed CO production (32.8 µmol h −1 ), a record‐high apparent quantum efficiency (0.26%) beyond 800 nm, and the formation of the valuable H 2 O 2 . Ru SAs tune PHI's electronic structure to promote in‐plane charge transfer to Ru NPs, forming a built‐in electron field at the interface, which directs electron‐hole separation and rushes excited electron movement from Ru‐PHI to Ru NPs. Simultaneously, Ru SAs introduce an impurity level in PHI to endow long‐wavelength photoabsorption, while Ru NPs strengthen CO 2 adsorption/activation and expedite CO desorption. These effects of Ru species together effectively ensure CO 2 ‐to‐CO conversion. The CO 2 reduction on the catalyst is revealed to follow the pathway CO 2 → *CO 2 → *COOH→ *CO→ CO, based on the intermediates identified by in situ diffuse reflectance infrared Fourier transform spectroscopy and further supported by density functional theory calculations.