Porous MoP nanosheets chemically bonded with ultrathin P-doped carbon coating for highly efficient and stable hydrogen evolution in acidic and alkaline media

Transition metal-based catalysts have garnered significant interest as viable alternatives to noble metal catalysts for the electrocatalytic hydrogen evolution reaction (HER) in both acidic and alkaline environments. Nevertheless, challenges such as surface oxidation, corrosion, and the leaching of active components critically affect their stability and catalytic efficacy. In this study, a non-exogenous strategy is proposed to fabricate P-doped carbon-coated transition metal phosphide catalyst. By topologically phosphating two-dimensional (2D) MoC nanosheets, the endogenous carbon atoms in MoC thermally migrate to the surface to form an ultrathin P-doped carbon shell that chemically bonds with MoP. The resulting P-doped carbon shell has a thickness of 1–2 nm (3–4 graphene layers) and creates a robust built-in electric field with the MoP core. Optimization of the surface and interface electronic structures markedly improves the HER activity and stability in both alkaline and acidic media (η₁₀ = 95/98 mV, Tafel = 59/57 mV dec⁻¹), respectively, along with excellent stability (at 500 mA cm⁻² for over 120 h). The results provide valuable insights into the phase separation engineering for the design and fabrication of catalysts with high stability and catalytic activity. © 2025 Elsevier B.V.