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.

Automated summary

In this study, WC-based self-supported catalysts doped with different concentrations of nickel nitrate were synthesized, and the effect of doping concentration on the catalyst's performance was investigated. The results showed that moderate doping of nickel can significantly enhance the catalytic activity of the electrocatalyst, while excessive nickel doping inhibits the catalyst's performance.