MOF-derived CoSe2 microspheres with hollow interiors as high-performance electrocatalysts for the enhanced oxygen evolution reaction

Abstract

Electrocatalytic water splitting has been recognized to be one of the most promising routes to acquire hydrogen. However, the high-efficiency water splitting is limited by the sluggish kinetics of the anodic oxygen evolution reaction (OER). Metal–organic frameworks (MOFs) have been extensively utilized as precursors to synthesize high-performance electrocatalysts. Herein, a facile template-engaged strategy is adopted to fabricate hollow microspheres derived from a Co-MOF. After a thermally induced selenylation process under an argon atmosphere, the Co-MOF is successfully converted into CoSe₂ microspheres at different temperatures. The optimized CoSe₂-450 microspheres display excellent OER electrocatalytic performance in 1.0 M KOH aqueous solution, exhibiting 10 mA cm⁻² at η = 330 mV with a small Tafel slope of 79 mV dec⁻¹, even superior to those of a commercial IrO₂ catalyst. Moreover, CoSe₂-450 shows excellent durability without obvious decay after 1000 cyclic voltammetry cycles. This is due to the hollow interior of CoSe₂ microspheres and well-distributed active sites, which can effectively offer space for fast mass transport and electron transfer.