Electrocatalytic Properties of Electroless Ni–P Coatings Towards Hydrogen Evolution Reaction in Alkaline Solution: Ni–P Coatings Deposited on Steel Substrate at Different Concentrations of Sodium Hypophosphite

Abstract

The hydrogen evolution reaction on electroless Ni–P alloy coatings on steel substrate with decreasing content of P from 8.2 to 3.4 wt% is investigated in 1 M KOH. The lowering of the P content in the alloy coating is achieved by decreasing the concentration of sodium hypophosphite in the solution for electroless deposition. Electrochemical investigations in combination with electron microscopy and radiographic analyses (SEM, EDS, XRD, TEM) reveal that the electrocatalytic activity of Ni–P coatings in regard to the hydrogen evolution reaction depends on the complex action of structure (morphology, phase composition), P content, and thickness. A change in any of these characteristics may lead to a change in other properties such as ability of the electrodes to adsorb and absorb hydrogen. Correct assessment of the contribution of individual factors is not possible due to the fact that the conditions for obtaining the coatings cannot be set in such a way as to lead to a change in only one of the factors.