Synthesis And Electrocatalytic Performance Of Co,V,Fe,Mo-Based Metal Compounds

The excessive exploitation of fossil energy and the pollution caused by it become one of the major problems that plague humans in the world.Due to the non-renewable primary energy sources and low energy conversion efficiency,it is obviously unable to meet the energy consumption of modern society in rapid development demand.As a representative of the clean new energy research field,new hydrogen energy sources are being widely concerned by the scientific community.There are many ways to prepare hydrogen,among which electrolytic water is one of the most popular ways to obtain hydrogen energy.However,direct electrolyzed water needs to cross high energy barriers.Most catalysts usually show high activity in different media,or when two types of catalysts are paired in the same electrolyte solution,incompatible integration leads to a reduction in the efficiency of the overall water electrolysis.Therefore,the development of a novel dual-functional electrocatalyst that can efficiently decompose water into hydrogen and oxygen in the same electrolyte is the focus of current research.High-efficiency electrocatalysts have the following characteristics:high intrinsic activity,optimal electronic state modulation,large contact between electrolyte and catalyst,and rapid electron conduction.In this paper,iron-doped cobalt vanadate Co_3?1-x?Fe_3xV₂O₈?x=0?0.9?and cobalt vanadate and molybdenum disulfide nano-array composite Co₃V₂O₈/MoS₂ were designed for the above problems and strategies,and their catalytic performance in electrolysis was investigated.The specific research content is as follows:1.Through a one-step hydrothermal method,a series of different iron doping amounts of cobalt vanadate(Co_3?1-x?Fe_3xV₂O₈)were synthesized by adding different molar ratios of iron and cobalt,and their structures and electrocatalytic properties were also studied.With a certain amount of Fe doping,the tuning becomes good to the electronic structure of Co,thereby effecting the catalytic activity.The results of electrochemical tests show that Co_3?1-x?Fe_3xV₂O₈ is an oxygen evolution catalyst,and its electrocatalytic properties satisfy similar volcanic curve rules.Co₁.5Fe₁.5V₂O₈ possesses the best oxygen evolution performance and an initial potential of 260 mV.Tafel's slope is 32.8 mV dec-1.When Co₁.5Fe₁.5V₂O₈ is used as a hydrogen evolution catalyst,only a low overpotential is also required.When Co₁.5Fe₁.5V₂O₈ was used for two-electrode total hydrolysis,the electrode began to undergo total electrolysis at 1.59 V?vs.RHE?.When the current density reached 10 mA cm-2,the required voltage was about 1.66 V,Co₁.5Fe₁.5V₂O₈ was used as the anode and cathode for the full hydrolytic stability test.During the long-term stability measurement,the system maintained a stable current density,and the structure did not change after the stability test.2.The Co₃V₂O₈/MoS₂ nanocomposite array?Co₃V₂O₈/MoS₂/CC?was synthesized in situ on a carbon cloth by a two-step hydrothermal method,and its performance of electrocatalytic oxygen evolution and hydrogen evolution was studied.First,the MoS₂ nanosheet array?MoS₂/CC?is vertically grown in situ on a carbon cloth substrate by a hydrothermal method,followed by a second step of growth under mild hydrothermal conditions,that is,continued growth on MoS₂/CC.then grow Co₃V₂O₈ nanoparticles on that,namely Co₃V₂O₈/MoS₂/CC.By constructing such a special morphology,it exposes more active sites and makes full contact with the electrolyte,eliminating the use of a binder and co-catalyzing the electrolysis of water.Electrocatalytic tests show that the Co₃V₂O₈/MoS₂/CC composite nanosheet array has good catalytic activity for hydrogen evolution and oxygen evolution in an alkaline environment,and can work stably and efficiently at low overpotential.And in the two-electrode full water test,it demonstrated superior catalytic activity,as well as continuous high-efficiency stability.