Study of the Kinetics of Hydrogen Evolution Reaction on Raney Nickel Composite‐Coated Electrode by AC Impedance Technique

Abstract

The hydrogen evolution reaction on the Raney nickel composite-coated electrode is investigated in 1.04M NaOH aqueous solution at 70~ by ac impedance technique. In case of the chemically activated electrode material, the easiest pathway for the hydrogen evolution reaction (HER) is the Volmer-Tafel mechanism, and the controlling step is the Volmer reaction with a small contribution of the Heyrovsky reaction. The electrode material becomes more electrocatalytic towards the HER after an electrochemical activation. In this case, the easiest pathway for the HER is the Volmer-Heyrovsky mechanism, both steps being rate-controlling.

Uncoupled non-linear equations method for determining kinetic parameters in case of hydrogen evolution reaction following Volmer–Heyrovsky–Tafel mechanism and Volmer–Heyrovsky mechanism

“…Comparing Figs. 5 and 7,x 1 increases with increase iñ m 4 and is independent ofm 3 .x 2 andx 4 increase andx 3 decreases with increase inm 3 .…”

“…With increase ofm 3 ,x 2 andx 4 increase andx 3 decreases for a givenm 4 . With increase inm 4 ,x 1 andx 3 increase andx 2 andx 4 decrease for a givenm 3 . With increase in q 1 ,x 1 increases.…”

“…For simple reaction like hydrogen ion discharge, the symmetry factors b v and b h are usually assumed to be approximately 0.5 [2]. The charge required for complete surface coverage, q 1 is determined through empirical means as the value obtained through independent sources like experimental measurement or theoretical calculations generally does not result in best fit [3]. Empirical value of q 1 is chosen such that best fitting is obtained between experimental data and simulated data using obtained kinetic parameters at all overpotentials [4].…”

Novel Fe–Ni-Graphene composite electrode for hydrogen production

“…Analysis of the HER mechanism for FeeNi and FeeNi-G composite coatings have been made based on the Tafel slope (b c ) values [62]. For this analysis, the values of Tafel slope given in the work of Choquette et al for different HER mechanisms were taken as the reference (up to 66 mV dec À1 indicate HeyrovskyeVolmer mechanism; neighbourhood of 118 mV dec À1 indicate VolmereTafel mechanism and above 200 mV dec À1 indicate Tafel mechanism) [63].…”

Shape-controlled synthesis of nickel phosphide nanocrystals and their application as hydrogen evolution reaction catalyst

“…However, since the high cost and the limited reserve of Pt, extensive research has also been devoted to the development of non-Pt materials used as HER electrocatalysts [25]. At present, Ni is one of the active non-precious metal HER catalysts, but it's HER activity is limited so far [26][27][28]. Therefore, it is very important to prepare Ni-based catalysts and further enhance their HER activity.…”