W2N3 nanodot/2D C3N4 heterostructures with interfacial covalent bonding toward Pt-free photocatalytic hydrogen evolution

Abstract

Graphitic carbon nitride is a promising photocatalyst for hydrogen evolution, but its performance is severely limited by rapid carrier recombination and the reliance on noble-metal (e.g., Pt) cocatalysts. To address this challenge, we develop a supramolecular assembly strategy enabling in situ growth of ultra-small tungsten nitride (W₂N₃) nanodots (∼5 nm) on 2D atomic-layered carbon nitride (W₂N₃ND–2DCN). This approach leverages hydrogen bonding and coordination interactions between supramolecular precursors to suppress metal agglomeration and enable low-temperature in situ nitridation, while forming strong interfacial covalent bonds between W₂N₃ and 2D C₃N₄. Systematic characterization and density functional theory calculations reveal that the interfacial bonding accelerates charge transfer, suppresses carrier recombination, and optimizes the hydrogen adsorption free energy (). Coupled with a high specific surface area (124 m² g⁻¹), W₂N₃ND–2DCN achieves an exceptional hydrogen evolution rate of 1785 μmol h⁻¹ g⁻¹ under visible light, which is comparable to the Pt-decorated benchmark (1694 μmol h⁻¹ g⁻¹). This work provides a feasible route to high-performance Pt-free photocatalysts for sustainable hydrogen production.