NiSe₂–FeSe Double-Shelled Hollow Polyhedrons as Superior Electrocatalysts for the Oxygen Evolution Reaction

Rational design and construction of hollow structured hybrid electrocatalysts are impressive for efficient and sustainable water splitting process. This study emphasizes a MOF-based self-templating approach to synthesize NiSe2–FeSe double-shelled hollow polyhedrons (DHPs) for efficient oxygen evolution reaction (OER) in alkaline solutions. Starting from MIL-88A, this study demonstrates a self-templating approach followed by etching, coprecipitation, and selenization treatments to construct NiSe2–FeSe DHPs. Due to the double-shelled hollow structure and compositional merits, the resulting NiSe2–FeSe DHPs exhibit excellent OER performance with a small overpotential of 280 mV to reach a current density of 10 mA cm–2, a small Tafel slope of 58 mV dec–1, and outstanding stability (over 88% current retention for at least 24 h), which significantly outperforms the benchmark RuO2 catalyst. The notable improvement in efficiency along with stability is attributed to abundant electrocatalytic active sites, large surface area, and the synergistic effect of heterostructure interfaces.