Interlayer Spacing Regulation by Single-Atom Indium(delta+)-N-4 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 (In delta+-N-4) in the (002) crystal planes of g-C3N4 is originally constructed. This In delta+-N-4 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 In delta+-N-4 enhances the CO2 adsorption on g-C3N4, reduces the *COOH formation energy, and optimizes the reaction path. It achieves a remarkable 398.87 mu mol 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.