Work Function Engineering of Carbon-Coated Antiperovskite Ni3ZnC0.7/g-C3N4 Mott–Schottky Heterojunctions for Accelerating Photocatalytic Hydrogen Evolution

The development of high-performance Mott–Schottky photocatalysts via work function engineering is of great significance for highly active and stable photocatalytic solar-fuel conversion. In this work, we developed a novel carbon-coated antiperovskite Ni3ZnC0.7-modified g-C3N4 Mott–Schottky heterojunction photocatalyst (Ni3ZnC0.7@C/g-C3N4) for efficient hydrogen evolution. The results showed that the carbon layer could enhance the work function of Ni3ZnC0.7 to serve as a powerful promoter for the rapid migration of photogenerated charges between g-C3N4 and Ni3ZnC0.7. The Schottky barrier that formed in the Ni3ZnC0.7@C/g-C3N4 heterojunction was conducive to inhibiting the recombination of photogenerated charges. Density functional theory (DFT) calculations further demonstrated that the introduction of Ni3ZnC0.7@C not only promoted an increase in the density of states in Ni3ZnC0.7@C/g-C3N4 but also shortened the HOMO–LUMO band gap and enabled the spatial separation of the HOMO–LUMO, thus facilitating the transfer and effective separation of photogenerated charges. The optimized hydrogen adsorption energy (ΔGH*) and decreased water dissociation energy barrier were both conducive to the progress of the photocatalytic reaction. The optimized Ni3ZnC0.7@C/g-C3N4 photocatalyst exhibited an excellent photocatalytic hydrogen evolution reaction performance under visible light, with a hydrogen evolution rate as high as 1021.65 μmol·g–1·h–1, 3.6 times that of 1% Pt/g-C3N4. This work confirmed the significant potential of antiperovskite bimetallic carbides (BTMCs) as a cocatalyst for photocatalytic hydrogen evolution, offering new insights to effectively design highly efficient photocatalysts for solar-driven conversion devices.