Preparation And Electrocatalytic Performance Of Cobalt Based Nanosheets/Conductive Material Nanocomposites

The efficient catalytic reaction of water splitting plays an important role in the artificial photosynthetic systems and solar fuel.It remains severe challenging to develop hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)catalysts with low cost and high activity under mild conditions.Herein,novel nanocomposites have attracted much attention based on ultrathin Cobalt-containing nanosheets and chemical properties.These are widely used in the field of electrocatalysis because of its unique chemical and physical properties.However,they showed low electrochemically active surface area(ECSA)due to its conducivity and aggregation.In order to achieve the better application,we used two strategies to improve the electrocatalytic performance of those materials.Research contents are as follows:1.Here,a new nanocomposite is prepared based on 2D(D=dimension)ultrathin Co3O4 nanosheets and 2D reduced graphene oxide(rGO)through a one-pot hydrothermal strategy.The ultrathin Co3O4/rGO nanocomposite exhibits excellent stability under alkaline conditions and shows overpotential of 290 mV with Tafel slope of 68 mA dec-1,which is smaller than that of bare Co3O4 catalyst.Extensive experiments were also carried out using 0D carbon spheres(CS),1D carbon nanotubes(CNTs)in place of the 2D rGO.The oxygen vacancies,electrochemically active surface area and OER performance of asprepared nanocomposites were improved with the increase of the dimension of nanocarbons,suggesting the electrochemistry activity is closely related to the surface area of carbon subtrates.Adding carbon materials can enhances the electronic transmission rate of the material and also prevents the agglomeration of the active nanosheets,which can form the synergistic catalyst.Compared with other Co3O4-containing nanocomposites reported so far,the Co3O4/rGO nanocomposite shows excellent performance.2.In situ synthesis of ordered ultrathin Cobalt-containing nanosheets arrays with Ni foam,which result in the formation of the ordered ultrathin Co3O4/Ni foam,CoS/Ni foam,CoP/Ni foam nanocomposites.On application of these nanocomposites for water splitting,it was found that the CoP/Ni foam shows high electrocatalytic activity for OER with overpotential of 265 mV under alkaline solution.The high activity is attributed to the formation of the CoP/CoOx under catalytic conditions.The CoP/Ni foam also exhibits highly active for hydrogen evolution with overpotential of 165 mV.As a result,the bifunctional catalyst can achieve 20 mA cm-2 by a voltage of only 1.61 V.