Boosting photocatalytic hydrogen evolution via regulating Pt chemical states

As a cocatalyst, chemical states of Pt have significant effects on hydrogen evolution activity of photocatalysts, but the effects have not been elucidated. Herein, we report an effective strategy to greatly improve hydrogen production via regulating the chemical states of Pt. A highly efficient C 3 N 4 photocatalyst with high Pt 0 proportion (denoted as 1.0%-Pt/CN-BH-H) is successfully prepared. Under visible-light condition (λ ≥ 420 nm), 1.0%-Pt/CN-BH-H (Pt 0 proportion is 60.1%) affords ∼2.316 mmol h −1 g −1 of hydrogen, approximately four-fold higher than that obtained by a photodeposited sample 1.0%-Pt/CN-P (Pt 0 proportion is 8.2%, ∼0.605 mmol h −1 g −1 of hydrogen). Atmospheric treatment increases the amount of Pt 0 species by causing electrons transfer from N element to Pt 2+ in 1.0%-Pt/CN-BH-H, as proved by in situ experimental investigation and DFT calculations. Mass formation of the Pt 0 species facilitates charge separation. In addition, Pt 0 has a lower hydrogen adsorption energy than that of Pt 2+ ; therefore, photocatalysts containing Pt 0 show an improved hydrogen-evolution performance.