Electronic modulation of PtNd alloy on S-doped g-C₃N₄ via f-d orbital coupling for enhanced photocatalytic hydrogen...

Precise control of the photogenerated charge dynamics and the electronic configuration of active sites is key to enhancing the performance of photocatalytic hydrogen-producing materials. Here, we report an efficient one-pot strategy to prepare sulfur-doped g-C₃N₄ (SCN). Furthermore, a PtNd/SCN composite photocatalyst was successfully fabricated by loading a platinum (Pt)‑neodymium (Nd) alloy onto the SCN surface via an H₂ reduction method. Using trithiocyanuric acid as a single precursor to supply C, N, and S enables uniform S doping within the g-C₃N₄ framework, broadening the light absorption range and optimizing the band structure. Pt serves as the primary hydrogen-evolving active site, while Nd acts as an "electronic co-catalyst" for Pt, forming strong electronic interactions through its unique 4f orbital structure. HRTEM and XPS analyses confirm the formation of a PtNd alloy interface and directional electron transfer from Nd to Pt, effectively modulating the Pt d-band center and optimizing the adsorption free energy of hydrogen intermediates, thereby significantly enhancing hydrogen evolution reaction (HER) kinetics. The experimental results show that the optimized PtNd/SCN composite photocatalyst exhibits a markedly enhanced photocatalytic hydrogen production rate under simulated sunlight, reaching 5468 μmol·g^-1·h^-1-5 times higher than Pt/CN (1074 μmol·g^-1·h^-1) and 1.3 times that of Pt/SCN (4076 μmol·g^-1·h^-1). PL, TRPL, and photoelectrochemical measurements confirm that the introduction of Nd promotes the migration of photo-generated electrons from SCN to Pt, thereby significantly suppressing carrier recombination. This study reveals the unique mechanism by which the rare earth element Nd acts as an electronic regulator for the d-band center of Pt, providing new insights into the design of photocatalytic systems with low Pt loading.