Searching for low-cost, high-efficiency, bifunctional, non-noble-metal electrocatalysts for overall water splitting is crucial to renewable energy conversion. Herein, a series of component-controllable CC/CNTs@CoSx Se2(1-x) (CC: carbon cloth, CNT: carbon nanotube) with excellent bifunctional properties in the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) were obtained by chemical vapor deposition. In this strategy, the Zif-67 precursor served as a structural inducer, which was directly grown on CC and pyrolyzed with the assistance of melamine to form multi-walled CNT-encapsulated CoSx Se2(1-x) hierarchical nanostructures. Subsequently, the electrocatalytic properties of the as-prepared materials were optimized by adjusting the S/Se molar ratio. Of note is that the lattice distortion caused by the different radii of Se and S generated a polarized electric field for easy adsorption of the intermediate products. The CoOOH generated in situ on the surface of CoSx Se2(1-x) , as well as n- and p-type domains in carbon, synergistically resulted in abundant active sites to boost the electrocatalytic activity. CC/CNTs@CoS0.74 Se0.52 exhibited overpotentials for the HER and OER of 225 and 285 mV, respectively and attained a current density of 10 mA cm-2 in alkaline solution. The as-prepared electrocatalysts could act as both cathode and anode in a water electrolyzer showing a cell voltage of 1.74 V and delivering 10 mA cm-2 , comparable to those of noble-metal-based water electrolyzers.
Keywords: chalcogenides; chemical vapor deposition; electrochemistry; nanostructures; water splitting.
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