Carbon-mediated electron transfer channel between SnO2 QDs and g-C3N4 for enhanced photocatalytic H2 production

Graphitic carbon nitride (g-C3N4y) is a promising material for photocatalytic water splitting but suffers from the self-agglomeration and fast recombination of photogenerated electron-hole pairs. Tin oxide (SnO2) has a high electron extraction ability and can play a key role in the charge separation and transfer dynamics of composites. Herein, we report a 0D/2D heterostructure of carbon-encapsulated SnO2 quantum dots (SnO2@C QDs) anchored on g-C3N4 nanosheets (SnO2@C/CN). The construction of interface between SnO2@C and g-C3N4 dramatically increases the surface area and the number of active sites for photocatalytic hydrogen evolution reaction (HER) and provides a driving force for efficient charge separation/transfer kinetics. The carbon layer encapsulating SnO2 QDs acts as a bridge that facilitates electron transfer from g-C3N4 to SnO2 QDs. The champion SnO2@C/CN achieves an exceptional HER rate of 2,544.3 mu mol g(-1) h(-1) (with 3 wt% Pt) with an apparent quantum efficiency of 9.63 % (lambda = 420 nm) and excellent photostability. A photoactivity enhancement mechanism is proposed based on the interfacial energy band alignment. This work provides insights into the designing of heterostructured photocatalysts of enhanced charge separation via interface engineering.

Automated summary

The heterostructure of graphitic carbon nitride and tin oxide shows exceptional performance in photocatalytic hydrogen evolution reaction, with enhanced charge separation efficiency through interface engineering. The proposed mechanism explains the enhancement in photoactivity.