Ultra-thin carbon bridged MoC quantum dots/g-C3N4 with charge-transfer-reaction highways for boosting photocatalytic hydrogen production

Abstract

Constructing heterojunction has been proved to be an efficient strategy for enhancing the photocatalytic performance of g-C 3 N 4 by prohibiting charge recombination and providing surface active sites. Herein, a novel structure of ultra-thin carbon bridged MoC quantum dots/g-C 3 N 4 nanosheets was constructed for the first time to facilitate carrier transfer and accelerate surface reactions. In our designed composites, a surface-to-surface contact has been formed between conductive carbon layer and g-C 3 N 4 nanosheet via ultrasonic assembly process. Moreover, there exist strong interfaces between MoC QDs and carbon layer because of the in-situ conversion method. As to this unique structure, the ultra-thin carbon layer functions as charge separation and migration high ways while the MoC QDs perform as noble-metal-free co-catalysts consuming the surface electrons promptly. Significantly, an optimal 40 wt% MoC QDs-C/g-C 3 N 4 photocatalyst (MCCN) is synthesized with a hydrogen evolution rate of 2989 μmol h −1 g −1 , which is 69.6 and 1.7 times higher than that of pure g-C 3 N 4 and Pt/g-C 3 N 4 , respectively. Our work provides new insights on designing highly efficient heterojunction photocatalysts for water splitting. • The hybrid MoC QDs-C/g-C 3 N 4 were prepared by ultrasonic self-assembly method. • The carbon layer acts as carrier transfer bridge to speed up the separation and migration of photo-generated charge. • The MoC QDs perform as an efficient non-noble metal co-catalysts to consume electrons efficiently. • The optimized MoC QDs-C/g-C 3 N 4 shows 69.6-fold and 1.7-fold improvement over pure g-C 3 N 4 and Pt loaded g-C 3 N 4.