Solar Hydrogen Evolution Boosted by Cu and Pt Single-Atom Sites Anchored on g-C ₃ N ₄ 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.