Multi-shelled CoS2-MoS2 hollow spheres as efficient bifunctional electrocatalysts for overall water splitting

The exploration of highly efficient non-precious electrocatalysts is essential for water splitting devices. Herein, we synthesized CoS2-MoS2 multi-shelled hollow spheres (MSHSs) as efficient electrocatalysts both for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) using a Schiff base coordination polymer (CP). Co-CP solid spheres were converted to Co3O4 MSHSs by sintering in air. CoS2-MoS2 MSHSs were obtained by a solvothermal reaction of Co3O4 MSHSs and MoS4 anions. CoS2-MoS2 MSHSs have a high specific surface area of 73.5 m(2) g(-1). Due to the synergistic effect between the CoS2 and MoS2, the electrode of CoS2-MoS2 MSHSs shows low overpotential of 109 mV with Tafel slope of 52.0 mV dec(-1) for HER, as well as a low overpotential of 288 mV with Tafel slope of 62.1 mV dec(-1) for OER at a current density of 10 mA cm(-2) in alkaline solution. The corresponding two-electrode system needs a potential of 1.61 V (vs. RHE) to obtain anodic current density of 10 mA cm(-2) for OER and maintains excellent stability for 10 h. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.