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As one of the advanced cobalt-based materials, cobalt sulfides with novel architecture have attracted huge interest due to the low cost, easy availability, and promising bifunctional activity for both the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), which is essential for next-generation energy storage devices. Herein, we demonstrated a facile and clean electrochemical technique to directly synthesize CoS nanosheets with high purity onto the surface of carbon cloth, and a quick thermal treatment was performed to further improve the catalytic performance (CoS-A). This novel electrochemical technique avoids the use of the binder, surfactant, and other organic additives, which may cause poor electric conductivity as well as undesirable surface wettability, exhibiting great potential of the large-scale applications. The obtained CoS-A exhibits a superior electrocatalytic performance for the OER and ORR, with a high ORR current density (-1.51 mA cm at 0.2 V), considerable OER current density (148 mA cm at 1.9 V), and excellent durability in continuous measurement for over 12 h. The approach offers a powerful yet simple method to control the phase, composition, and morphology of a highly active CoS catalyst, which provides a new idea for the design of high-performance catalysts.

The primary challenge of developing clean energy conversion/storage systems is to exploit an efficient bifunctional electrocatalyst both for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) with low cost and good durability. Here, we synthesized chlorine-doped Co(OH) in situ grown on carbon cloth (Cl-doped Co(OH)) as an integrated electrode by a facial electrodeposition method. The anodic potential was then applied to the Cl-doped Co(OH) in an alkaline solution to remove chlorine atoms (electro-oxidation (EO)/Cl-doped Co(OH)), which can further enhance the electrocatalytic activity without any thermal treatment. EO/Cl-doped Co(OH) exhibits a better performance both for ORR and OER in terms of activity and durability because of the formation of a defective structure with a larger electrochemically active surface area after the electrochemical oxidation. This approach provides a new idea for introducing defects and developing active electrocatalyst.

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Pt-Decorated highly porous flower-like Ni particles with nanopores and well-dispersed small Pt grains on petals show high activity for ammonia electro-oxidation.

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