Ni(NO3)2-induced High Electrocatalytic Hydrogen Evolution Performance of Self-Supported Fold-Like WC Coating on Carbon Fiber Paper Prepared Through Molten Salt Method

Exploring high-performance and inexpensive electrocatalysts for hydrogen evolution reaction to substitute Pt based compounds is important to sustain hydrogen production. Herein, WC based self-supported catalysts doped with different concentration of nickel nitrate solution (Ni(NO3)(2)) were synthesized on carbon fiber paper (CFP) by one-step molten salt method (abbreviated as x Ni-WC@CFP). With the increasing of Ni(NO3)(2) concentration, fold-like structures were formed on the catalysts, which was conducive to active sites exposure. As Ni (NO3)(2 )concentration increased from 1M to 5M, the catalytic performance of the electrocatalyst showed a trend of increasing first and then decreasing. The optimal 4M Ni-WC@CFP showed comparable catalytic ability in 0.5M H2SO4 with a low overpotential of 73 mV at 10 mA cm(-2 )and Tafel slope of 66.4 mV dec(-1.) However, excessive nickel doping would inhibit HER performance. The density functional theory calculation further verified the experimental results. The adsorption energy of hydrogen showed a decreasing trend with the rising amount of Ni doped in, while the W-H binding energy would change in an opposite direction as over doped Ni. This work provided an insight for the preparation of high-efficiency self-supported W-based electrocatalysts and expounded the influence trend of Ni doping concentration on the performance of electrocatalysts.