Unlocking Long-Lived Hot Carriers via Synergistic Quantum Confinement and P–N Sites in Graphitic Carbon Nitride for Sustainable Water Decontamination

A breakthrough in designing practical and efficient photocatalysts for water purification is achieved through the development of a novel graphitic carbon nitride architecture comodified with P-N sites and sub-2 nm nanosheets (PCNs), synthesized via a simple and scalable thermal oxidation process with a novel precursor combination. PCNs exhibited a phenol degradation rate constant that was 181-fold greater than that of bulk g-C₃N₄, excellent interference resistance across varied pH values and interfering ions, and outstanding reusability. The P(δ⁺)-N(δ^-) polarization created a built-in electric field that enhances charge separation, while quantum confinement promoted electron localization and facilitated the migration and adsorption of reactants. This synergistic mechanism prolonged the lifetime of high-energy hot carriers 10-fold compared to that of bulk g-C₃N₄, enabling exceptional performance. Moreover, the system of PCNs exhibits high performance and is straightforward, energy-efficient (180-fold reduction in EE/O), and environmentally favorable, offering a sustainable and practical paradigm for water purification.