Hydrogen Evolution Reaction in Alkaline Media: Alpha-\nor Beta-Nickel Hydroxide on the Surface of Platinum?

Reducing the energy\nconsumption of a hydrogen evolution reaction\n(HER) at a platinum (Pt) electrode is important for the hydrogen economy.\nHerein, we report the loading of alpha- or beta-nickel hydroxide (α-\nor β-Ni­(OH)<sub>2</sub>) nanostructures on the surface of a\nPt electrode to improve its catalytic activity and stability for HER\nin alkaline electrolytes. Both experimental and theoretical studies\nreveal that β-Ni­(OH)<sub>2</sub> is a better co-catalyst of\nPt than α-Ni­(OH)<sub>2</sub> for promoting the HER, attributed\nto the higher water dissociation ability of β-Ni­(OH)<sub>2</sub>, as well as the stronger interactions between β-Ni­(OH)<sub>2</sub> and the Pt electrode. Particularly, the overpotential of\nthe HER in 0.1 M KOH at 10 mA cm<sup>–2</sup> is decreased\nfrom 278 mV at the Pt electrode to 92 mV at the β-Ni­(OH)<sub>2</sub>/Pt electrode, and the Tafel slope decreased from 62 to 42\nmV dec<sup>–1</sup>, correspondingly. The performance of the\nβ-Ni­(OH)<sub>2</sub>/Pt catalytic electrode surpasses that of\nmost of the previously reported electrodes for the same purpose.