Interface engineering: PSS-PPy wrapping amorphous Ni-Co-P for enhancing neutral-pH hydrogen evolution reaction performance

Transition metal phosphides have shown Pt-like hydrogen evolution reaction (HER) activity in acid and alkaline solution, while their HER performance in neutral-pH is really poor owing to the high resistance and inefficient mass transfer in neutral-pH electrolyte. In this work, the well-arranged core/shell PSS-PPy/Ni-Co-P growing on Cu foil, in which Ni-Co-P is the core and the mixed polymer of pyrrole and sodium polystyrene sulfonate is the shell, has been demonstrated to be a highly efficient electrocatalyst for HER in neutral-pH electrolyte. The PSS-PPy/Ni-Co-P/CF self-supporting electrode was easily synthesized by electrodeposition and chemical deposition at room temperature. According to the experiment and DFT calculation results, PSS-PPy not only improves the conductivity and hydrophilicity of Ni-Co-P, but also optimizes the electronic structure of Ni-Co-P. Thus, the PSS-PPy/Ni-Co-P shows remarkable HER activity with only overpotential of 106 and 67 mV at the current density of 10 mA cm −2 in neutral-pH and alkaline electrolytes, respectively. Furthermore, PSS-PPy/Ni-Co-P has excellent stability in neutral-pH, alkaline electrolytes and even seawater. The current surface modification method directs us to design more low-cost, high-efficiency and stable electrocatalysts for HER in neutral-pH electrolyte.