How Acid Washing Nickel Foam Substrates Improves the Efficiency of the Alkaline Hydrogen Evolution Reaction

Nickel foam substrates are frequently utilised as porous 3D substrates for renewable energy applications. The preparation of these substrates usually includes an acid-washing step, but the degree to which this step affects the final electrochemical performance after spray-coating a catalyst ink is unreported. Herein, we report the effects of acid washing through physicochemical and electrochemical characterisation. The electrochemical performance was determined through repeated measurements of catalyst-coated nickel foam substrates both with and without the initial step of acid washing. It was found that acid washing increased the current density by 17.9% for the acid-treated MoS2-coated nickel foam electrode. This increment was affiliated with an electrochemically active surface area that increased by 11.2%, and a Tafel analysis indicated that the acid-treated MoS2-coated electrodes facilitated the initial water dissociation step of the hydrogen evolution reaction with greater ease. Similar effects were also discovered for acid-treated PtIr(1:3)/C-coated nickel foam substrates. The stability was also improved; the degradation rate was reduced by 18.9% for the acid-treated MoS2-coated electrodes. This demonstrates the utility of acid washing nickel foam electrodes.