Interlayer Spacing Regulation by Single‐Atom Indiumδ+–N4 on Carbon Nitride for Boosting CO2/CO Photo‐Conversion

Simultaneous optimization on bulk photogenerated‐carrier separation and surface atomic arrangement of catalyst is crucial for reactivity of CO2 photo‐reduction. Rare studies capture the detail that, better than in‐plane regulation, interlayer‐spacing regulation may significantly influence the carrier transport of the bulk‐catalyst thereby affecting its CO2 photo‐reduction in g‐C3N4. Herein, through a single atom‐assisted thermal‐polymerization process, single‐atom In‐bonded N‐atom (Inδ+–N4) in the (002) crystal planes of g‐C3N4 is originally constructed. This Inδ+–N4 reduces the (002) interplanar spacing of g‐C3N4 by electrostatic adsorption, which significantly enhances the separation of bulk carriers and greatly promotes the reactivity of CO2 photoreduction. The CO2 photo‐conversion performance of this resulted single‐atom In modified g‐C3N4 is significantly superior to other single atom loaded carbon nitride catalysts. Moreover, the Inδ+–N4 enhances the CO2 adsorption on g‐C3N4, reduces the *COOH formation energy, and optimizes the reaction path. It achieves a remarkable 398.87 µmol g−1 h−1 yield rate, 0.21% apparent quantum efficiency, and nearly 100% selectivity for CO without any cocatalyst or sacrificial agent. Through d(002) modulation of carbon nitride by single In atom, this study provides a ground‐breaking insight for reactivity enhancement from a double‐gain view of bulk structural control and surface atomic arrangement for CO2‐reduction photocatalysts.