Effective Near-Infrared\nLight-Driven Photocatalytic\nReduction of CO<sub>2</sub> by Dual-Site Doped Carbon Nitrides

g-C<sub>3</sub>N<sub>4</sub> is a nontoxic, stable, and\nnonmetal\nphotocatalyst that mostly absorbs solar energy in the ultraviolet\nregion. The photocatalytic activity of g-C<sub>3</sub>N<sub>4</sub> was considerably restricted by its low quantum efficiency and fast\ncarrier recombination. In this work, we present a novel P–S\ncodoped black carbon nitride (PSCN) prepared by the solvothermal method.\nThe physicochemical and photoelectrical properties of the prepared\ncatalysts were studied by SEM, XRD, XPS, UV–vis DRS, and PL\ntechniques. By introducing P and S heteroatoms to the C<sub>3</sub>N<sub>4</sub> framework, its bandgap was reduced significantly from\n2.71 eV (GCN) to 1.79 eV (PSCN), and its light absorption extended\nfrom the UV zone (λ < 420 nm) to the NIR zone (800–1500\nnm). When exposed to near-infrared laser radiation (λ = 808\nnm), the catalyst demonstrates an unusual photothermal conversion,\nas evidenced by IR thermography. The CO yields with a PSCN photocatalyst\n(58.5 μmol·h<sup>–1</sup>·g<sup>–1</sup>) under NIR light (λ > 800 nm) are comparable to that irradiated\nby UV–vis light (300 < λ < 800 nm, 57.0 μmol·h<sup>–1</sup>·g<sup>–1</sup>), while the CO yield with\nGCN under full-spectrum is only 6.2 μmol·h<sup>–1</sup>·g<sup>–1</sup> (UV–vis–NIR). According\nto DFT simulations, PSCN can lower the energy required to produce\nCOOH*. Furthermore, compared to CO desorption, the energy barriers\nfor forming HCO* on PSCNs were much higher; thus, the selectivity\nof CO<sub>2</sub> reduction to CO was enhanced. Our research provides\na new approach for constructing nonmetal photocatalysts with a wide\nspectral response range and photothermal synergistic catalysis.