Facile assembly of a graphitic carbon nitride film at an air/water interface for photoelectrochemical NADH regeneration

The development of a metal-free photoelectrode film is of great significance. Herein, graphitic carbon nitride (g-C3N4) nanosheets with a concentration of up to 36 mg mL−1 were first obtained on a large scale using a wet ball-milling method. The obtained g-C3N4 nanosheets exhibit 6- and 8-times higher activity in terms of photocatalytic H2 evolution and nicotinamide adenine dinucleotide (NADH) regeneration than bulk g-C3N4, respectively. Furthermore, a uniform g-C3N4 film electrode was fabricated via the interfacial self-assembly of nanosheets at the air/water interface, which can be transferred onto various substrates. By coupling with graphene nanosheets, a g-C3N4/graphene hybrid film electrode was assembled at the interface, showing improved photoelectrochemical coenzyme NADH regeneration efficiency. The photoelectrochemical system uses water as the electron donor, which avoids the drawback of using additional sacrificial agents. This work presents a novel and facile method to prepare high-quality g-C3N4 hybrid films, and also provides a sustainable route for renewable energy conversion and biocatalytic applications.