Synthesis of Amorphous Ni−Zn Double Hydroxide Nanocages with Excellent Electrocatalytic Activity toward Oxygen Evolution Reaction

In spite of potential favorable electrochemical properties, reports of amorphous materials as catalysts for water oxidation are quite few. Highly efficient amorphous Ni−Zn double hydroxide nanocages as electrocatalysts for oxygen evolution reaction (OER) were prepared through a co-precipitate method. We investigated the influence of composition on electrocatalytic activity experimentally. Ni_2.7Zn(OH)_x turned out to be the optimal composition of these samples, which exhibited an OER onset overpotential as low as 0.20 V in 1 m KOH electrolyte solution. In addition, Ni_2.7Zn(OH)_x could reach a current density of 10 A g¹ at an overpotential of approximately 0.20 V. Such high mass activity should take advantage of the unique amorphous hollow nanostructure of our sample, which can provide substantial exposure of surface active atoms for remarkable catalytic activity. This amorphous Ni−Zn double hydroxide material was found to be a remarkable OER electrocatalyst and exhibited higher electrocatalytic activity than commercial IrO₂.