Hierarchical 0D-2D Co/Mo Selenides as Superior Bifunctional Electrocatalysts for Overall Water Splitting

Development of efficient electrocatalysts combining the features of low cost and high performance for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) still remains a critical challenge. Here, we proposed a facile strategy to construct in situ a novel hierarchical heterostructure composed of 0D-2D CoSe2/MoSe2 by the selenization of CoMoO4 nanosheets grafted on a carbon cloth (CC). In such integrated structure, CoSe2 nanoparticles dispersed well and tightly bonded with MoSe2 nanosheets, which can not only enhance kinetics due to the synergetic effects, thus promoting the electrocatalytic activity, but also effectively improve the structural stability. Benefiting from its unique architecture, the designed CoSe2/MoSe2 catalyst exhibits superior OER and HER performance. Specifically, a small overpotential of 280 mV is acquired at a current density of 10 mA center dot cm(-2) for OER with a small Tafel slope of 86.8 mV center dot dec(-1), and the overpotential is 90 mV at a current density of 10 mA center dot cm(-2) for HER with a Tafel slope of 84.8 mV center dot dec(-1) in 1 M KOH. Furthermore, the symmetrical electrolyzer assembled with the CoSe2/MoSe2 catalysts depicts a small cell voltage of 1.63 V at 10 mA center dot cm(-2) toward overall water splitting.