Construction of Efficient P-Type C3n4 Modified Ni@Nis Cocatalyst for Photocatalytic Hydrogen Production Reaction

Abstract

Carbon nitride (C3N4) has been regarded as one of the hottest topics for photocatalytic hydrogen production. However, the charge transfer of pure C3N4 is obstructed and the recombination rate is rapid resulted from the poor inherent crystallinity. Meanwhile, the photogenerated holes transfer to the surface of n-type adverse to the photocatalytic H2 reaction. In this study, we successfully synthesized the p-type C3N4 (Li-K) by molten salt method to adjust the energy band structure that allows photogenerated electrons to migrate towards the surface of C3N4 (Li-K), followed by loading Ni@NiS core-shell cocatalyst to capture the photogenerated electrons. Thereby, the optimized NiS-5 exhibits the excellent photocatalytic H2 rate of 18.18 mmol h-1 g-1, which is approximately 33 and 2.5 times higher than that of C3N4 (Li-K) and NiS-0 under visible light. This result is attributed to the smooth transmission of separated photogenerated charges from C3N4 (Li-K) to Ni then to NiS because of the matched energy band between C3N4 (Li-K) and NiS, thus improving photogenerated carrier separation efficiency. This work paves a rewarding pathway towards synthesizing efficient p-type carbon nitride based photocatalyst.

Keywords: p-type C3N4, Ni@NiS, H2 production, photogenerated charges