Protonation of Graphitic Carbon Nitride (g-C₃N₄) for an Electrostatically Self-Assembling Carbon@g-C₃N₄ Core-Shell Nanostructure toward High Hydrogen Evolution

The development of new, appealing metal-free photocatalysts is of great significance for photocatalytic hydrogen evolution. Herein, an electrostatic self-assembly method to form a unique core-shell architecture of a colloid of carbon spheres with graphitic carbon nitride (g-C₃N₄) has been developed by a one-step chemical solution route. The chemical protonation of g-C₃N₄ solids with strong oxidizing acids (such as HNO₃) is an efficient pathway toward the sol procedure of stable carbon nitride colloids, which can cover the surface of carbon spheres via electrostatic adsorption. On account of the unique polymeric matrix of g-C₃N₄ and reversible hydrogen bonding, the carbon@g-C₃N₄ derived from the sol solution showed high mechanical stability with broadened light absorption and enhanced conductivity for charge transport. Thus, the carbon@g-C₃N₄ core-shell structure exhibited remarkably enhanced photoelectrochemical performance. This polymer system is envisaged to hybridize with desirable functionalities (such as carbon nanorods) to form unique architectures for various applications.