A novel three-dimensional graphitic carbon nitride/palladium phosphide heterojunction photocatalyst for enhanced hydrogen production and treatment of industrial dye-polluted water under visible light irradiation

Photocatalytic water splitting for H2 production and dye decomposition over a suitable catalyst has led to seek for suitable photocatalysts. Herein, a novel strategy is proposed by stabilizing palladium phosphide (PdP2) in its type II heterojunction with cyano-rich mesoporous three-dimensional graphitic carbon nitride (3D g-C3N4) structure to obtain a suitable photocatalyst. This strategy has efficiently alleviated the active surface area of the suffering g-C3N4 and has well reduced the rate of photoinduced charges carrier recombination through the spatial charge separation phenomena of the heterojunction. In addition, the PdP2 loading has effectively improved the optical properties of 3D g-C3N4 by reducing the band gap and electrochemical resistance for fast interfacial charge migration. Furthermore, the g-C3N4/PdP2 heterojunction has surprisingly increased the amount of H2 production to ∼402 μmol h-1 over the g-C3N4/PdP-3 % heterojunction catalyst as compared to the misery directly calcined g-C3N4 i.e., T(g-C3N4) sample with negligible amount of only ∼7 μmol h-1. The apparent quantum efficiency (AQE) is also remarkably achieved to the value of 23 % over g-C3N4/PdP-3 % heterojunction catalyst, which is ∼26 times higher than that of 3D g-C3N4 (0.88 %). Furthermore, the results show that the g-C3N4/PdP-3 % sample has excellent photocatalytic decomposition efficiency (∼99 %) towards methylene blue and is more favorable for cationic dyes than anionic dyes decomposition. The reusability and stability test result further confirmed that the g-C3N4/PdP-3 % heterojunction is highly stable for long-term H2 production and industrial dye decomposition.