Tailoring the Pore Structure of Porous Ni-Sn Alloys for Boosting Hydrogen Evolution Reaction in Alkali Solution

Abstract

Ni-based alloy is an ideal candidate for its application in the field of hydrogen evolution of water splitting due to its good durability, excellent catalytic properties and low hydrogen evolution overpotential. In this paper, porous Ni-Sn alloy materials were prepared by activation reaction sintering, and the pore structure was tailored by adjusting Sn content. The effects of Sn content and electrolyte temperature on the hydrogen evolution properties of porous Ni-Sn alloy electrodes in 6 mol·L−1 KOH solution were studied by electrochemical measurement methods, such as cyclic voltammetry (CV) curves, electrochemical impedance spectroscopy (ESI) and linear sweep voltammetry, and the mechanism of hydrogen evolution was further discussed. The experimental results reveal that when Sn content is 45 wt%, porous Ni-Sn alloy exhibits the best catalytic performance for hydrogen evolution with a Tafel slope of 164.69 mV·dec−1 and an overpotential of 170 mV. The tested electrode also shows good stability for hydrogen evolution in alkaline solution, and the apparent activation energy calculated at room temperature is 29.645 kJ·mol−1. The catalytic mechanism of hydrogen evolution is as follows: the addition of Sn significantly reduces the dissociation degree of M-H bonds, thereby reducing the overpotential of hydrogen evolution; with the increase of Sn content, the porous Ni-Sn electrode displays a higher electrochemical active surface area (ECSA), which makes porous Ni-Sn alloy exhibit good hydrogen evolution catalytic performance.