Polyoxometalates combined polypyrrole induced bimetallic phosphides for electrocatalytic hydrogen evolution

Abstract

The gradual depletion of fossil fuels and rapid consumption of energy have greatly advanced the development of sustainable energy sources. Transition metal phosphides (TMPs) show high catalytic properties and durability for water-splitting. In this work, a carbon-coated porous nanosphere electrocatalyst (MoP/MoNiP@C) is prepared by combining polypyrrole, phosphomolybdate (PMo₁₂) and nickel ions as supramolecular precursors through mutual electrostatic attraction, followed by a one-step high-temperature calcined phosphating process. The hydrogen evolution activities and stability of MoP/MoNiP@C and control samples are tested in 0.5 M H₂SO₄ and 1.0 M KOH solutions. MoP/MoNiP@C exhibits high HER activity with overpotentials of 138 (0.5 M H₂SO₄) and 132 (1.0 M KOH) mV with a current density of 10 mA cm⁻² and corresponding Tafel slopes of 61 and 88 mV dec⁻¹, respectively. The synergistic effect between MoP and MoNiP greatly improves the HER activity of MoP/MoNiP@C and the porous structure accelerates the charge transfer rate during the electrochemical process. Furthermore, the special doping properties of polypyrrole can enhance the conductivity by doping with transition metal ions, thereby improving the hydrogen evolution properties. This study provides experimental guidance for the preparation of polypyrrole based electrocatalysts for application in energy conversion and storage fields.