Prussian Blue Analogue-Assisted Formation of Iron–Nickel Selenide Porous Nanosheets for Enhanced Oxygen Evolution

The development of active and stable electrocatalysts made from earth-abundant elements to accelerate the oxygen evolution reaction (OER) kinetics is of great significance for improving the efficiency of overall water splitting. Herein, a Prussian blue analogue (PBA)-assisted strategy to synthesize FeSe–NiSe nanosheets is reported. With this approach, porous FeSe–NiSe nanosheets supported on conductive Ni foam (NF) are fabricated via controlled chemical etching of Ni(OH)2/NF with Fe(CN)63– and subsequent selenylation treatment. The as-derived FeSe–NiSe/NF electrode with unique interpenetrated porous three-dimensional (3D) network architecture successfully combines the desired merits including high conductivity and a large specific surface area. As a result, it exhibits enhanced electrocatalytic OER performance in alkaline media, which requires overpotentials of only 234 and 268 mV to deliver current densities of 10 and 100 mA cm–2, respectively, outclassing its counterpart NiSe/NF. Furthermore, the catalyst possesses a very low Tafel slope (22 mV dec–1) and excellent durability.