Synthesis Of Platinum-based Nano-Catalysts And Study On Electrocatalytic Oxidation Kinetics

Direct ethanol fuel cell（DEFC）,as a new energy conversion device,has attracted wide attention because of its advantages such as low operating temperature,high efficiency and environmental protection.However,as the direct ethanol fuel cells with low catalytic activity of catalysts and kinetics of ethanol catalytic oxidation process is not clear,which seriously hindered the direct ethanol fuel cell commercialization process,therefore,the development of ethanol oxidation catalyst with high catalytic activity,clear ethanol catalytic oxidation kinetics is a key problem for promoting the development of the fuel cell quickly.In this paper,a series of nano-catalysts with high catalytic activity for the oxidation of ethanol were prepared by using ethylene glycol and formic acid as co-reducing agents,and the kinetic process of ethanol catalytic oxidation was investigated by using modern electrochemical testing methods.In order to synthesize Pt/RGO nano-catalyst with high catalytic activity for ethanol oxidation,a series of Pt/RGO nano-catalyst were successfully synthesized by impregnation and liquid-phase reduction method in this paper.A series of Pt/RGO nano-catalyst were successfully synthesized by adding formic acid as the second reducing agent on the basis of ethylene glycol as the single reducing agent and lowering the reaction temperature.The effect of ethylene glycol concentration on the microstructure and catalytic performance of Pt/RGO nano-catalyst was investigated.A series of catalysts were characterized by XRD,SEM,TEM and electrochemical workstation.The results show that when the volume concentration of reducing agent ethylene glycol is 66%,the catalytic performance of the prepared Pt/RGO_EG-66 nano-catalyst is the best,and the reduced Pt nanoparticles are uniformly distributed on the graphene carrier.The average particle size was 2.58 nm,the electrochemical active surface area was 102.94 m²/g,the peak current density value was 88.67 m A/cm²,and the steady-state current density value was 34.38 m A/cm².After 500 depletion tests,the current density retention rate was the highest.It is suggested that adjusting the concentration of reducing agent is an important way to synthesize Pt/RGO nanocrystalline catalysts with high catalytic activity.In order to clarify the kinetic process of ethanol catalytic oxidation,the influence of sulfuric acid concentration,ethanol concentration,scanning speed and temperature on the kinetic process of ethanol electrocatalytic oxidation was investigated by using electrochemical testing methods,and the related kinetic parameters were calculated.The results showed that with the increase of sulfuric acid solution concentration,the oxidation peak potential showed a negative shift to a certain extent,which affected the catalytic oxidation kinetics of ethanol.The peak current density increased with the increase of the concentration of ethanol.The response of the second oxidation peak to the electrocatalytic oxidation of ethanol was stronger than that of the first oxidation peak,and the reaction order of each oxidation peak was obtained.The peak current density increases with the increase of sweep speed,and the two oxidation peaks are controlled by the diffusion process.The peak current density also increases with the increase of temperature,and the apparent activation energy corresponding to the oxidation peak is calculated.According to Tafel slope and activation energy calculation results,the reaction energy barrier of Pt/RGO_EG-66 catalyst prepared in this paper is lower than that of commercial Pt/C catalyst.