Fast photogenerated electron transfer in N-GQDs/PTI/ZnO-QDs ternary heterostructured nanosheets for photocatalytic H2 evolution under visible light

The efficiency of photogenerated charge transport is one of the critical factors determining the photocatalytic performance in heterostructured photocatalysts. In this work, a two-dimensional conjugated polytriazine imide (PTI)-based photocatalyst was developed to achieve fast photoexcited electron transfer. These heterostructured nanosheets were synthesized by a one-pot condensation of a precursor mixture of cyanamide and N-doped graphene quantum dots (N-GQDs) in ZnCl2 containing salt melts. The ionothermal synthetic approach results in the N-GQDs/PTI in-plane heterostructured nanosheets, loaded with well-dispersed ZnO quantum dots (ZnO-QDs). Especially, the N-GQDs are coupled with PTI through the nitrogen atoms at the edge of triazine rings, forming new pi-p-pi conjugated connection units. Therefore, the obtained ternary heterostructured nanosheets can synchronously promote photoelectron transport through the new pi-p-pi conjugated networks as well as extend the optical response. Importantly, it exhibits approximately 230 and 3.6 times enhancement of H-2 evolution over pure PTI and the PTI/ZnO-QDs heterostructure under visible light irradiation, respectively.