Enhanced Visible-Light H₂O₂ Production over Pt/g-C₃N₄ Schottky Junction Photocatalyst

Photocatalytic for hydrogen peroxide (H₂O₂) production is thought as a promising technology owing to its clean and green properties with the cheap and easily available raw materials of H₂O and O₂. Herein, Pt/g-C₃N₄ Schottky junction photocatalysts with ultralow Pt contents (0.025-0.1 wt %) were successfully fabricated by an impregnation-reduction method. It can efficiently reduce O₂ to generate H₂O₂ without a sacrificial agent under visible-light irradiation. The yield of H₂O₂ produced over Pt0.05/g-C₃N₄ with the optimal 0.05 wt % Pt reached 31.82 μM, which was 2.46 times that of g-C₃N₄ and higher than most of those in the literature. It also showed good stability in three repeated tests. The deposition of highly dispersed metal Pt nanoparticles with low and limited content can expose enough active Pt atoms, significantly enhance the separation efficiency of photogenerated carriers, and reduce its negative effect on H₂O₂ decomposition, resulting in improved and outstanding efficiency of H₂O₂ production. The ·O₂^- radicals were found to be the main active species. The mechanism of photocatalytic H₂O₂ production was confirmed to be a two-step single electron route (O₂ + e^-→ ·O₂^- → H₂O₂).