One-Step Synthesis of Ni-Mo2C/N-Biochar Heterojunction Bifunctional Electrocatalyst from Waste Grapefruit Peel for Efficient Overall Water Electrolysis
摘要
Amidst escalating global energy crises and environmental degradation, biomass resources offer a critical pathway for energy transition through their inherent renewability, carbon neutrality, and abundance. However, efficient conversion of waste biomass remains impeded by compositional complexity and suboptimal process energetics, constraining scalable industrial implementation. Building on this, we innovatively utilize waste grapefruit peel as a multifunctional precursor to construct Ni-Mo₂C heterojunction nanocomposites (Ni-Mo₂C/NGC) on a biomass-derived N-doped graphene-like carbon matrix (NGC) via an in situ one-step pyrolysis strategy. Electrocatalytic evaluation reveals that the nanocomposite exhibits outstanding bifunctional activity for both oxygen and hydrogen evolution reactions (OER/HER) in alkaline electrolyte, achieving low overpotentials (η) of 260 mV for OER and 120 mV for HER at a current density of 10 mA cm⁻², with corresponding Tafel slopes of 48 and 52 mV dec⁻¹, respectively. Density functional theory (DFT) calculations elucidate that synergistic interfacial electron coupling between Ni and Mo₂C at the heterojunction significantly elevates the density of exposed catalytic active sites, optimizes the adsorption free energy of key reaction intermediates, and accelerates interfacial charge transfer kinetics, thereby cooperatively enhancing the intrinsic bifunctional electrocatalytic activity. This study establishes a novel strategy for the high-value-oriented preparation of high-performance electrocatalysts from waste biomass, providing insights into the construction of non-precious metal bifunctional heterojunction catalysts.
Graphical Abstract