Preparation And Electrocatalytic Properties Of Several Cobalt-based Nanomaterials

Electrolysis of water mainly consists of hydrogen evolution reaction?HER?and oxygen evolution reaction?OER?.Enormous efforts have been afforded to develop catalysts to reduce the energy barrier in the process of reaction.Cobalt-based composites have emerged as promising non-noble catalysts because of their excellent electrochemical properties,earth abundant and low cost.To improve the electrochemical performance of cobalt-based nanomaterials,countless strategies have been investigated,such as the incorporation of heteroatoms,the introduction of conductive support.Simultaneously,the structure-function relationship among morphology,structures and electrocatalytic properties has been systematically discussed.The content of this work is as follows:?1?CoS nanoflowers in-situ grown on stainless steel?SLS?were synthesized?CoS@SLS?.SLS can further improve the electrochemical activity because of its containing reactive elements.Hence,the prepared CoS@SLS reveals a great activity with an overpotential of 318mV for OER at 10 mA cm^-2.After the stability test of 14 h,the electrochemical activity of materials still remains above 82%.?2?Spinel-like Mn-Co oxides?MnCo₂O₄?nanosheets grown on the entire surface of nickel foam?NF?were prepared by electrodeposition?MnCo₂O₄/NF?.It is more suitable to use nickel foam as conductive substrates than other supports because nickel can effectively catalyze HER.Nanomaterials show high HER activity by controlling the feeding ratio of manganese and cobalt salt,the deposition voltage and the deposition time.It delivers a low overpotential of 127 mV at 10 mA cm^-2 and the good stability even after 5000 s for HER.?3?Fe₃O₄-CoP_x/TiN composites were synthesized by facile electrodeposition.TiN nanoarrays are not only used as charge transfer channels,but also prevent the agglomeration of Fe₃O₄-CoP_x nanoflowers,enhancing the stability of nanomaterials.Besides,synergistic effects of the Fe₃O₄,CoP_x have great influence on morphology of Fe₃O₄-CoP_x/TiN.Therefore,nano-materials show high electrocatalytic properties with a low onset overpotential of 50 mV for HER and an overpotential of 331 mV for OER at 10 mA cm^-2.The two-electrode device for water splitting delivers a cell voltage of 1.75 V to reach the current density of 10 mA cm^-2.