Preparation And Ethanol Electrocatalytic Oxidation Performance Study Of Nickel-based Composites

Direct ethanol fuel cell(DEFC)is considered as a promising energy conversion device because of its high energy density,simple structure and easy fuel storage and transportation.The performance of DEFC is determined by the kinetics of ethanol oxidation reaction(EOR)at the anode.Therefore,the preparation of anodic catalyst with excellent performance is very important.In general,precious metals(Pt and Pd)and their alloys are considered ideal EOR catalysts.However,the high cost of precious metal catalysts and their susceptibility to CO poisoning have greatly limited their widespread use.Based on the above situation,the development of an efficient and inexpensive anodic catalyst is the key to improve EOR kinetics.In recent years,due to the advantages of CP(Complex,CP for short),such as rich uncoordinated metal active sites,structural modification and good stability,researchers generally believe that CP and its complexes have broad application prospects in electrochemistry.In this paper,firstly,the nickel-based complex was constructed under hydrothermal condition.Secondly,different catalysts were constructed by post-modification of nickel-based complexes.Finally,the structure of the prepared catalyst was characterized,and its electrochemical performance and catalytic performance of ethanol oxidation were systematically investigated by using the prepared composite as an anode catalyst.The main contents and results of this paper are as follows:(1)NNC was prepared by calcination with nickel-based complex as precursor,and then NNC-MOS₂ catalyst was prepared by composite with Mo S₂.Meanwhile,the effects of calcination temperature and Mo S₂ doping amount on the performance of NNC-MOS₂ catalyst were investigated.Electrochemical tests show that the optimal NNC-MOS₂ composite has excellent catalytic performance,which is attributed to the high electrochemical active surface area and good electrical conductivity of NNC-MOS₂ catalyst.2)The solution of preparing polyaniline conductive hydrogel(PANH)was directly drip-coated on the carbon cloth containing CP to synthesize the complex catalyst without binder.The structure of the composite catalyst was characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM)and X-ray photoelectron spectroscopy(XPS).Electrochemical tests showed that the current density of the optimal complex 2 was 107 m A cm^-2 at a voltage of 0.6 V and a sweep speed of 50 m V S^-1,indicating that it had good EOR activity,which was superior to the reported nickel-based catalysts.In addition,the Tafel slope and exchange current density of complex 2 are 88.9 m V Dec^-1 and 1.95×10-5 A cm-~2,respectively,indicating that complex 2 is A good EOR catalyst.Finally,after 1000 CV cycles,the current density of complex 2 was 65%of the original value.When the electrolyte was replaced with fresh electrolyte(1 M KOH+1 M Et OH),the current density returned to74%of the original.Based on the excellent electrocatalytic performance,good stability and CO toxicity resistance,complex 2 is expected to be an economical,efficient and CO toxicity resistant EOR catalyst.(3)The composite was prepared by impregnation method combining nickel base CP with carbon point(CDs).Electrochemical tests showed that the optimal CP 2-CDs@CC had a current density of 118 m A cm^-2 and a low Tafel slope and a high exchange current density,indicating that CP 2-CDs@CC had a good EOR catalytic activity.The excellent performance of CP 2-CDs@CC is mainly attributed to the addition of CDs,which improves the adsorption and charge transfer of Et OH on the catalyst surface.In addition,long-term durability tests show that CP 2-CDs@CC has good stability.Finally,by UV spectroscopy and cyclic voltammetry(CV)analysis,acetic acid is one of the products of EOR.Based on the simple preparation,high activity and stability of CP 2-CDs@CC complex,it is expected to be an economical and effective EOR catalyst.