Formation of Ni–Fe Mixed Diselenide Nanocages as a Superior Oxygen Evolution Electrocatalyst

Exploring effective electrocatalysts is a crucial requirement for boosting the efficiency of water splitting to obtain clean fuels. Here, a self-templating strategy is reported to synthesize Ni–Fe mixed diselenide cubic nanocages for the electrocatalytic oxygen evolution reaction (OER). The diselenide nanocages are derived from corresponding Prussian-blue analog nanocages, which are first obtained by treating the nanocube precursor with a site-selective ammonia etchant. The resulting Ni–Fe mixed diselenide nanocages perform as a superior OER electrocatalyst, which affords a current density of 10 mA cm⁻² at a small overpotential of 240 mV; a high current density, mass activity, and turnover frequency of 100 mA cm⁻², 1000 A g⁻¹, and 0.58 s⁻¹, respectively, at the overpotential of 270 mV; a Tafel slope as small as 24 mV dec⁻¹; and excellent stability in alkaline medium.

A self-templating strategy is developed to synthesize Ni–Fe diselenide nanocages with the assistance of a site-selective ammonia etchant. With structural and compositional advantages, these unique nanocages exhibit superior electrocatalytic performance for the oxygen evolution reaction in an alkaline medium.

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