Solar Hydrogen Evolution Boosted by Cu and Pt Single-Atom Sites Anchored on g-C₃N₄ via Magnetron Sputtering Deposition

Photocatalytic hydrogen (H₂) evolution offers a promising solution to environmental pollution and the global energy crisis. Among different photocatalysts, graphitic carbon nitride (g-C₃N₄), most known as melon in the literature, is distinguished by its availability, large surface area, low cost, and unique optical and electrical properties. However, the efficiency of pristine g-C₃N₄ is limited by rapid electron–hole recombination, presence of charged trapped states and high charge transference resistance. To overcome these challenges, we used a facile magnetron sputtering technique to load Cu and Pt single atoms onto g-C₃N₄, confirmed by AC-STEM, XPS, ICP-OES, and XAS characterizations. This approach not only overcomes the problems related to the charge carrier dynamics of the pristine graphitic carbon nitride but also ensures uniform, contamination-free deposition and high distribution of single atoms, thereby optimizing photocatalytic performance. Under solar irradiation (AM 1.5G) for 5 h, the Cu and Pt-loaded g-C₃N₄ demonstrated significantly improved photocatalytic activity, achieving H₂ accumulated values of 93 μmol and 173 μmol, respectively, compared to only 0.3 μmol for pristine g-C₃N₄. For comparison, Pt and Cu nanoparticles (NPs)- loaded g-C₃N₄ samples were also prepared, achieving H₂ accumulation values of 86.3 and 24.3 μmol, respectively, compared to pristine g-C₃N₄. However, these values are lower than those of Pt and Cu single-atom-loaded samples. The enhanced H₂ evolution performance is attributed to the deposition of metal single atoms acting as electron traps and active catalytic sites, thus improving electron–hole separation. These findings highlight the potential of sputter depositing single-atom to overcome the inherent limitations of g-C₃N₄, paving the way for more efficient and scalable hydrogen production systems.