Porous Plate-like MoP Assembly as an Efficient pH-Universal\nHydrogen Evolution Electrocatalyst

Abstract

Molybdenum\nphosphide is one of the most potential electrocatalysts\nfor the hydrogen evolution reaction (HER), whereas it is still challenging\nto achieve an efficient molybdenum phosphide-based catalyst that performs\nwell over a wide pH range. Herein, a porous nanoplate composed of\nsmall MoP flakes confined in thin N, P, S-triple-doped carbon (MoP@NPSC)\nwas prepared by the assembly of phosphomolybdic acid (H₃PMo₁₂O₄₀·<i>n</i>H₂O, {PMo₁₂}) and egg white, followed by phosphorization.\nGiven its small size (ca. 1 nm) in favor of deriving small particles\nand the oxygen-rich surface with strong coordination ability, the\n{PMo₁₂} cluster was selected to combine with egg white\nto obtain a lamellar hybrid precursor via a hydrogen bond. Through\ncontrollable phosphating, a nanoplate organized by interconnected\nMoP particles was generated, accompanied by the in situ formation\nof the N, P, S-doped carbon thin layer and pores from the pyrolysis\nof egg white. The plentiful pores, thin carbon coating, and multielement\ndoping bring about promoted electrolyte/bubble diffusion, enhanced\nconductivity and stability, and lowered adsorption energy of hydrogen/hydroxyl,\nrespectively. All of the above merits endow MoP@NPSC with prominent\nactivity with low overpotentials of 50, 76, and 71 mV at 10 mA cm^–2 toward the HER in alkaline, neutral, and acid media,\nrespectively, and nearly no attenuation after 40 h of testing. Especially,\ncompared with commercial Pt/C, MoP@NPSC exhibits similar low onset\npotential and even better at large current density in 1 M KOH. The\nelectrolyzer equipped with the MoP@NPSC cathode and the NiFe-LDH anode\nrequires only 1.52 V to deliver 10 mA cm^–2 and can\nbe powered by a solar cell (1.524 V) charged by sunlight.