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

Abstract

Graphitic carbon nitride (g-C3N4) 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 μmol g−1 h−1 (with 3 wt% Pt) with an apparent quantum efficiency of 9.63 % (λ = 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.