Fe-doped Co9S8@CoO aerogel with core-shell nanostructures for boosted oxygen evolution reaction

The efficiency and stability of electrocatalysts for oxygen evolution reaction (OER) generally depends on the intrinsic catalytic activity and extrinsic active sites. To intrinsically and extrinsically improve OER performance, herein, we present a novel OER catalyst of Fe-doped Co9S8@CoO aerogel with core-shell nanostructures via structural/electronic modulation strategy. The structural modulation is realized by 3D porous aerogel and core-shell nanoarchitecture which provides rich exposed active sites and guarantees effective ion diffusion and O2 release, and the amorphous shell layer of CoO can effectively prevent the corrosion of Co9S8 by the electrolyte during OER process. The electronic modulation is realized by Fe heteroatom doping for Co9S8 and oxygen vacancies in CoO layer was caused by partial oxidation process, which facilities the transfer of electrons during OER process. These merits make Fe-doped Co9S8@CoO an efficient and stable OER catalyst: it requires only a low overpotential of 296 mV to obtain 10 mA cm−2 and it delivers a low Tafel slope of 65 mV dec−1 with good stability, which are even better than those of commercial RuO2. This work presents an effective structural/electronic modulation strategy to develop efficient and stable OER catalysts for water splitting.