Intermolecular Electron Transfer in Electrochemically Exfoliated BCN-Cu Nanosheet Electrocatalysts for Efficient Hydrogen Evolution

The search for materials with superior electrocatalytic performance has attracted attention during the past few years aiming to identify a convenient material that works at a low overpotential with long-term stability. Herein, we introduce an innovative technique to fabricate two-dimensional BCN heterostructure nanosheets with various Cu:BCN weight ratios. The fabricated composites showed unique electrocatalytic properties for hydrogen evolution reaction (HER). The morphology and structure of the electrocatalysts were characterized using field emission scanning electron microscopy, Raman, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy techniques. Remarkably, this study reveals the effect of electrochemical chronopotentiometry on facilitating the electrochemical exfoliation and hence enhancing the catalytic activity of the fabricated nanosheets. This effect was further confirmed via density functional theory (DFT) calculations, unveiling the effect of the formed oxide layer on the charge transfer process. The overpotential of the 0.125 Cu-BCN composite at a current density of -10 mA/cm 2 vs RHE is 50% lower than that of pristine BCN. These findings were also affirmed by the DFT calculations, which showed that incorporating copper on BCN has significantly reduced the G H* value of the HER and subsequently accelerates the kinetics of the reaction and the overall catalytic activity of the material.