Design of Palladium-Doped g-C₃N₄ for Enhanced Photocatalytic Activity toward Hydrogen Evolution Reaction

Graphitic carbon nitride (g-C3N4) has been believed to be a promising photocatalyst for water splitting due to its right band gap and band edges. However, the kinetics of hydrogen evolution on g-C3N4 is very slow. Cocatalysts are usually needed to improve the catalytic kinetics. Herein, palladium-doped graphitic carbon nitride (g-C3N4–Pd) is designed by virtue of the tenacious coordination of Pd atoms with the pyridinic nitrogen atoms of six-fold cavities in g-C3N4. The introduction of Pd does not affect the structure and morphology of g-C3N4. Palladium is found to exist as Pd ions in g-C3N4–Pd catalysts. g-C3N4–Pd catalysts exhibit clearly higher hydrogen evolution activities than g-C3N4. The highest hydrogen evolution activity on g-C3N4–Pd is 15.3 times that of g-C3N4. The improvement of hydrogen evolution activity is found to arise from both the alternation of the electron excitation manner and the acceleration of hydrogen evolution kinetics induced by Pd doping. Our findings provide a promising way to improve the photocatalytic performance for hydrogen evolution and pave a new avenue for the development of highly efficient and cost-effective photocatalysts for water splitting.