Porous CoS2 nanostructures based on ZIF-9 supported on reduced graphene oxide: Favourable electrocatalysis for hydrogen evolution reaction

The research and developments of porous, highly active non-noble metal cathode materials are the current hot spots. In our work, ZIF-9 (Zeolitic imidazolate framework-9) as a cobalt source provide porous structure, we have sulfurized the ZIF-9 into CoS2 by a simple hydrothermal method. Ultimately, the porous CoS2/RGO cathode material was obtained. Through a series of characterization analyses (powder X-ray diffraction, X-ray photoelectron spectroscopy), it is confirmed that the CoS2/RGO composite was successfully formed. Furthermore, electrochemical tests demonstrated that the pursued catalyst exhibited remarkable hydrogen evolution reaction (HER) activities with a favorable overpotential (only 180 mV for 10 mA cm−2 vs reversible hydrogen electrode), a low Tafel slopes (75 mV decade−1) and high stability in acidic condition (more than 18 h).