Dual doping-induced gradient charge polarization in a single non-centrosymmetric photocatalyst for efficient hydrogen production and organic oxidation

Artificial photosynthesis for sustainable hydrogen production in pure water using organic photocatalysts has long been hindered by inherent tightly-bound excitons and poor charge transfer. Charge polarization engineering in non-centrosymmetric organic photocatalysts such as triazole-based carbon nitride (C₃N₅) can introduce in-plane dipole electric field to promote charge separation and facilitate transfer of photogenerated free carriers. Nonetheless, heteroatom doping with non-metal elements of differing electronegativity further modulates charge distribution and local charge density. In this work, we developed phosphorus- and oxygen-dual doped C₃N₅ (P,O-C₃N₅) which exhibits gradient charge polarization within a single-component photocatalyst, significantly suppressing self-trapped charge carriers and enhancing local charge separation. First-principles density functional theory (DFT) calculations confirm that O and P doping induces distinct charge accumulation and depletion regions, leading to asymmetric polarized active sites. As a result, photocatalytic pure water splitting was achieved with a remarkable H₂ evolution rate of 33.18 μmol g⁻¹ h⁻¹ and an apparent quantum yield (AQY) of 0.12 % in pure water under 420 nm monochromatic irradiation using a single-light absorber organic photocatalyst. Furthermore, the versatility of P,O-C₃N₅ extends beyond pure water splitting, offering a promising approach for the sustainable transformation of glycerol into value-added derivatives coupled with hydrogen evolution reactions.