Study On The Preparation Process And Electrohydrolysis Performance Of Transition Metal Cobalt Compound Composite

The energy crisis has become one of the most worrying problems in the world.Due to the increasing consumption of traditional fossil fuels and the depletion of resources,the problem of environmental pollution with traditional fossil fuels is deteriorating.People are trying to explore clean energy and gradually increase its proportion in the energy structure.Among many clean energy sources,such as solar energy,geothermal energy,tidal energy,water energy and hydrogen energy,hydrogen energy（H₂）is considered to be one of the most promising clean energy sources in this century because of its high combustion calorific value,clean combustion and rich resources.Among many hydrogen production methods,the decomposition of water by electricity only depends on electric energy and does not need traditional fossil energy,which is considered to be a sustainable and promising way to produce hydrogen.However,the low energy conversion rate of ordinary electrolytic water limits its large-scale application.Therefore,electrocatalytic decomposition of water is considered to be a sustainable and promising way to convert electric energy into clean and renewable hydrogen source.Compared with precious metals,transition metals have attracted extensive attention because of their excellent properties,low price,rich active centers and abundant reserves.Among them,cobalt based catalysts are considered as potential non noble metal catalytic materials because of their environmental protection,low cost and large-scale preparation.Therefore,in this paper,we explore the related electrocatalysts.Copper based materials have attracted more and more attention as electrocatalysts because of their controllable micro/nano structure,non toxicity and rich reserves.In this paper,we utilized ammonium sulfate,urea,copper hydroxide and copper foam as precursors to prepare heterogeneous Cu/Cu O@Co/Co₃O₄ nanorod-thorns structure on copper foam（CF）through a simple hydrothermal process and afterwards reduction in H₂/Ar atmosphere.As a self-supported nanostructure,Cu/Cu O@Co/Co₃O₄ electrode possesses unique hierarchical nanorod-thorns structures,excellent conductivity and synergetic effect,which could enhance the catalytic activity,accelerate the bubble release from its surface,leading to the improved catalytic activity.It is worth remarkable that polymeric binders such as Nafion,etc.,which may weaken the electrocatalytic performance of materials,can be avoided.As a result,Cu/Cu O@Co/Co₃O₄ exhibited considerable catalytic activity in 1.0M KOH electrolyte with small overpotentials of 82 m V(η₁₀),along with low Tafel slopes of 48 m V dec^-1.Impressively,Cu/CuO@Co/Co₃O₄ can consecutively generate H₂ with 93%of its initial performance after 35 hours in 1.0 M KOH electrolyte.Nickel matrix composites have gradually entered the vision of researchers because of their rich reserves,excellent properties,low price,stable existence in alkaline electrolyte and controllable composition and morphology.In this paper,we report a fast preparation method of an integrated 1D nanowire-2D nanosheet hierarchical core-shell nanostructured nanocomposite by electrodepositing Co Ni-LDH nanosheet arrays directly onto Cu_xO nanorods（denoted as Cu_xO@Co Ni-LDH/CF）as a self-supporting electrocatalytic electrode for high efficiency electrochemical OER.The unique hierarchical core-shell nanostructure can enhance electron transport rate and provide more open-channels for effective oxygen release.Meanwhile,the intimated contact between the Cu_xO core and Co Ni LDH shell provides synergistic effects to increase the catalytic activity.Consequently,the optimized Cu_xO@Co Ni-LDH/CF exhibits a low overpotential of 207 m V in 1 M KOH（PH=13.7）solution at the 10 m V cm^-2 current density,with a small Tafel slope of 50.1 m V dec^-1.After 60 hours of long-term stability test,the overpotential increased only slightly.