High-efficiency charge separation of Z-scheme 2D/2D C3N4/C3N5 nonmetal VdW heterojunction photocatalyst with enhanced hydrogen evolution activity and stability

Abstract

The interfacial charge transfer control is a key and arduous issue for propelling the migration/separation of photogenerated carriers for heterojunction photocatalysts. Here, a new 2D/2D C3N4/C3N5 nonmetal van der Waals (VdW) heterojunction is fabricated by the simple self-assembly technique in acidic medium, whose charge separation efficiency is promoted dramatically, thus being endowed with the high-efficiency photocatalytic hydrogen evolution (PHE) performance. The PHE rate reaches up to 3.33 mmol h−1 g−1 under the visible light and the apparent quantum efficiency (AQE) of 20.6% is achieved at 420 nm on the optimal 2D/2D C3N4/C3N5-5% sample. Furthermore, the 2D/2D C3N4/C3N5 nonmetal VdW heterojunction also exhibits the desired stability because there was no significant decrease after PHE reaction of 10 cycles with total 40 h. Such outstanding PHE activity and stability originate from the impelled separation of photoinduced charge carriers and the powerful interfacial interaction through forming Z-Scheme charge transfer path and π-π coupling effect between C3N4 and C3N5 nanosheets. This work takes a significant guiding and demonstration for designing and exploiting other novel nonmetallic polymer-based VdW heterojunctions in the photocatalytic application field.