Superaerophobic Composite Coating of 2D g-C₃N₄ for Efficient Photo-Assisted Water Splitting

Photo-assisted electrochemical (PAEC) water splitting represents a promising approach for efficient hydrogen and oxygen generation under solar illumination. However, catalyst delamination from the working electrode and blockage of electrochemically active sites due to gas bubble adhesion significantly hinder the performance. To overcome these issues, a 2D photocatalyst, graphitic carbon nitride (g-C₃N₄), was incorporated into a robust, highly bubble-repellent composite coating on a porous nickel foam (NF) substrate. The resultant composite prevents g-C₃N₄ delamination from the electrode surface, while its intrinsic superaerophobicity enables rapid detachment of evolved gas bubbles. Furthermore, photoexcited charge carriers in g-C₃N₄ and its photothermal enhancement effectively assist water-splitting reactions. Compared with conventional strategies involving direct photocatalyst coating on NF, with or without an additional bubble-repellent layer, the proposed composite demonstrates a significantly improved PAEC performance. It exhibits a larger electrochemically active surface area, reduced overpotentials for both hydrogen and oxygen evolution reactions, and significantly improved gas evolution yields-enhancing hydrogen and oxygen production by 51% and 44%, respectively, at reduced applied potentials relative to bare NF under simulated solar illumination. This simple yet effective approach harnesses the cooperative influence of photoactive charge stimulation, localized photothermal enhancement, and optimized bubble dynamics in achieving stable, energy-efficient photo-assisted water splitting.