Site-Specific Boron-Doped Graphitic Carbon Nitride Nanosheets with Atomic-Scale p-n Junctions via Solid-State Synthesis: Implications for Hydrogen Peroxide Photogeneration

The site-specific boron-doped graphitic carbon nitride (B-g-C₃N₄-20) has been synthesized via precise solid-state synthesis methods. Thermodynamic analysis indicates that its excellent reproducibility stems from similar activation energies of the dehydration and condensation reactions involving phenylboronic acid and melamine, as well as the dehydration polymerization of melamine with cyanuric acid. It allows both reactions to occur concurrently, leading to the orderly arrangement of intercalated molecules within the carbon nitride nanosheets, facilitating targeted boron incorporation. The boron atoms of the intercalated molecules not only form triple bonds with nitrogen atoms, horizontally arranging in an ordered manner, but also vertically interact with tertiary nitrogen atoms of the carbon nitride nanosheets. This dual-directional ordered interaction between boron and nitrogen creates atomic-scale p–n junctions at the microscopic level and exhibits a pronounced p–n junction effect at the macroscopic level. Such structural characteristics significantly improve the transport pathways for photogenerated charge carriers, resulting in a remarkable increase in photocatalytic performance with a hydrogen peroxide production rate 30 times higher than that of pure graphitic carbon nitride under neutral conditions. This work not only offers additional perspectives for advancing solid-state synthesis methods but also serves as an innovative example for the development of other functional materials.