Enhanced electrocatalytic full water-splitting reaction by interfacial electric field in 2D/2D heterojunction

[Display omitted] •2D/2D heterostructure of two well-defined carbon matrices.•Interfacial activity of the g-C3N4 film on the rGO layer.•Modified electronic states on the interface for superior OER and HER activity.•DFT simulation on the plane-averaged charge density difference.•Resolving the local pH reduction problem and electron transport. To increase the productivity of hydrogen and oxygen generation, the carbon-based electrocatalyst with 2D/2D structure, graphitic carbon nitride with reduced graphene oxide (g-C3N4/rGO), was synthesized via a facile electrostatic self-assembly method and was used as electrocatalyst for full water-splitting. In the alkaline electrolyte, g-C3N4/rGO showed lower overpotential and Tafel slope of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively, than the other 2D structured materials. The DFT calculation simulates the spontaneous electron transfer, low charge transfer resistance, and internal electric field of g-C3N4/rGO electrocatalysts. Especially, the internal electric field between the g-C3N4 and rGO is beneficial in solving the local pH reduction problem and electron transport. Consequentially, our study elucidates that 2D/2D structure, inducing the internal electric field, is an effective way to enhance the performance of the full water-splitting system.