| Transition metal nano materials were prepared by polymer-template and polymer-stabilized methods in this work.The series of M-P-C(M are transition metal Fe,Co,Ni and Mn ternary alloy elements,P is polymer,C are carbon XC72) complex catalyst materials FeCoNi-P-C, MnCoNi-P-C,MnCoFe-P-C and MnNiFe-P-C were prepared by polymer-template method.The series of M-PVP(M are Co,Ni,Sn and Zn metals and alloy elements,PVP is polyvinylpyrrolidone K-30) catalyst materials Co-PVP,Ni-PVP,CoNi-PVP,CoNiSn-PVP and CoNiZn-PVP were prepared by polymer-stabilized method.The phase transition of prepared materials were characterized by IR,TEM and SEM-EDS determined methods.Electrocatalytic properties of prepared nano materials for ethanol electro-oxidation were studied.In alkaline medium,the properties of ethanol electro-oxidation on the electrodes with the active materials M-P-C and M-PVP were investigated by the electrochemical measurements such as Cyclic voltammetry, chronoamperometric and EIS.In alkaline medium the series of M-P-C catalysts exhibited electrocatalytic activitiy for the electro-oxidation of ethanol.The catalytic activitiy of four electrodes were compared with each other,it showed that the magnitude order of them is FeCoNi-P-C＞MnCoNi-P-C＞MnCoFe-P-C＞MnNiFe-P-C。FeCoNi-P-C material was studied thoroughly,the result of TEM indicated that the majority of the nanoparticles were between the size of 20 and 30 nm,part of which were at 10 nm.The chemical compositions of complex material was approved by SEM-EDS,then it showed that the molar ratio of Fe,Co and Ni compositions are equal.In alkaline medium FeCoNi-P-C exhibited very obviously catalytic activity for the electro-oxidation of ethanol.The result of electrochemical showed that:the anode current density of FeCoNi-P-C electrode in ethanol solution was significantly higher than that in KOH solution; When the potential reached 0.4 V,the current density of blank solution was 2.5 mA·cm-2,at the same potential it reached highly 22 mA·cm-2 in 0.5 mol/L ethanol solution,it indicated that ethanol was oxidated.When the increase of concentration of ethanol reached 1.0mol/L,the current density increased to 32 mA·cm-2.With the increase of metal content,the anode current density increased greatly.HPLC result indicated that a part of the product after the oxidation of ethanol was a mixture of acetaldehyde and acetic acid,there may be a little of CO2 gas.The series of prepared M-PVP transition metal catalistic materials showed obviously catalysis for the ethanol electro-oxidation in alkaline medium.The result of electrochemical showed that:the unitary Co-PVP showed catalysis for ethanol oxidation at worse negative potential than Ni-PVP;meanwhile the duality CoNi-PVP material showed it much more positive about 0.2 V potential,the ternary CoNiSn-PVP,CoNiZn-PVP showed a remarkable catalytic property for ethanol oxidation with an onset potential around -0.05 V on the voltammogram.CoNi-PVP catalyst material was studied thoroughly.Polymer PVP coordinated with CoNi were determined by IR,it protected the nanometal aggregation,then the result of TEM indicated that the nanolines were obtained by high polymer protection method,and the diameters of those were between 3 and 5 nm,lengths were about 100 nm;The chemical compositions of complex material was approved by SEM-EDS,then it showed that the molar ratio of Co and Ni compositions are equal.For contrast,the noble metal Ru cluster nano-materials Ru-PVP, RuCo-PVP,RuNi-PVP and RuCoNi-PVP were prepared by polymer-stabilized method.The result of electrochemical showed that:Ru cluster nano-materials showed much more better catalysis for ethanol oxidation than others.At the same time,Co,Ni were joined into Ru material which formed duality and temary catalyst.The catlysis for ethanol electro-oxidation much more better than Ru-PVP.It indicated that as the adode catalysis of the ethanol fuel cell,there is a disparity between of free-noble metal and noble metal materials. |
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