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.