Co2P@C Derived from Metal-organic Coordinate Interactions using Polyaniline as Soft Template for Electrocatalytic Hydrogen Production

Abstract Transition metal phosphides are studied widely for their excellent catalytic effect and low cost. Cobalt phosphide is considered a promising hydrogen evolution electrocatalyst in acidic solution. In this study, we synthesized the monometallic phosphide carbon-coated (Co2P@C) using polyaniline (PANI) as soft template via a high-temperature calcination and PH3 phosphating process. Therein, affluent of lone pair electrons in N atoms in PANI can coordinate with cobalt ions, resulting Co2P nanoparticles uniform distribution in the final electrocatalyst. Co2P@C exhibits satisfactory hydrogen production performance, possessing overpotential of 192 mV at 10 mA cm-2 with Tafel slope of 93 mV dec-1as well as long-term stability in acid electrolyte. The good hydrogen evolution performance can be attributed to the catalytic activity of Co2P, the porous structure, large surface area derived from PANI exposing more active sites and mass/electron diffusion as well as the carbon layer protecting Co2P@C from damage. This work may provide hints for preparing proper precursors by coordination strategy using polymer as soft templates for hydrogen evolution electrocatalyst.