Hierarchically porous nanoarchitecture constructed by ultrathin CoSe2 embedded Fe-CoO nanosheets as robust electrocatalyst for water oxidation

Abstract The sluggish kinetics and high cost of the noble-metal based electrocatalyst for oxygen evolution reaction (OER) still seriously limits the efficiencies of water splitting. Herein, for the first time, we rationally design a porous hierarchical nanoarchitecture, constructed by ultrathin CoSe2 embedded Fe-CoO nanosheets (CoSe2@Fe-CoO), which is synthesized via self-assembly hydrolysis driven in-situ synergetic selenization of Fe/Co/O/Se precursor followed by Ostwald ripening. As an OER catalyst, the porous CoSe2@Fe-CoO hybrid with abundant CoOOH electroactive sites delivers a small Tafel of 56.2 mV/dec with very low onset overpotential of 280 mV@10 mA/cm2 and excellent long-term physicochemical stability till 62 h without obvious decay, which outperforms well-established benchmark electrocatalysts (RuO2). The boosted OER performance of CoSe2@Fe-CoO nanosheets is mainly attributed to its iron-doping effect, porous nanoarchitecture, and multicomponent synergetic/interfacial effect between ultrathin cobalt (II) oxide and conductive cobalt selenide (CoSe2) nanoframework. This work presents a facile construction strategy to find a nonprecious hybrid OER electrocatalyst with excellent performance and long-term stability.