Performance Of Anode Catalyst For Direct Methanol Fuel Cell Loaded On CeO₂/G Compound

Direct methanol fuel cell?DMFC?attracted much attention because of its friendly environment,high energy density and easy to carry.Platinum?Pt?is the common anodic catalyst because it can facilitate methanol oxidation most effectively in DMFC.However,Pt was easily poisoned by the CO-like intermediates during the process of MOR which would depress the catalytic activity and stability of Pt.Thus developing high performance anode catalysts is an important task for DMFC.In this paper,nano-CeO₂ and CeO₂-ZrO₂solid solution was synthesized by hydrothermal method,and synthesized catalysts Pt-CeO₂/RGO and Pt/CeO₂-ZrO₂/RGO with graphene as carrier.The microstructure and composition of the samples were characterized using XRD,TEM,BET,XPS and Raman spectrum.The application of CeO₂ and CeO₂-ZrO₂ solid solution in the electrocatalytic oxidation of methanol was studied by cyclic voltammetry and chronoamperometry.The catalysts with good catalytic performance were obtained.First of all,the application of CeO₂ and CeO₂-ZrO₂ solid solution in methanol fuel cell anode catalyst was discussed.Spherical CeO₂ and CeO₂-ZrO₂ solid solution were synthesized by hydrothermal method using citric acid as template,and Pt based catalysts were synthesized by using them as support.The results of XRD showed that Zr ions were doped into CeO₂ to form CeO₂-ZrO₂ solid solution with cubic fluorite structure.XPS analysis showed that there were large amounts of lattice oxygen and Ce³⁺in the catalysts of CeO₂ and CeO₂-ZrO₂ solid solution which the lattice oxygen and Ce³⁺content of CeO₂-ZrO₂ solid solution were the highest.Electrochemical test results show that the electrochemical active surface area of Pt/ZrO₂-CeO₂/RGO catalyst and the peak current density of electrocatalytic oxidation of methanol were the largest,which were up to 61.81m²/g and 1012 mA/mg,which were 3.27 and 6 times higher than those of commercial Pt/C catalyst,respectively.Moreover,the long-term discharge stability and anti-CO poisoning activity of Pt/ZrO₂-CeO₂/RGO catalyst were the highest,and the enhancement effect was the most obvious.In order to investigate the effect of CeO₂ morphology on the performance of anode catalyst for ethanol fuel cell,the bouquet CeO₂ was prepared by hydrothermal method with asparagine as template.It was found that when the hydrothermal reaction time was more than 5 h,the bouquet morphology was formed.When the reaction time was up to12 h,the bouquet morphology was complete,and the specific surface area of CeO₂ was143 m²/g,and the large specific surface area was beneficial to the dispersion of Pt particles on the CeO₂ surface.Can have more exposure sites.Compared with other CeO₂ supported catalysts,the content of Pt?0?,lattice oxygen and Ce³⁺in the Pt-7#CeO₂/RGO catalyst supported by flower bundle was the highest,and the content of Pt?0?,lattice oxygen and Ce³⁺in the catalyst was higher than that of the catalyst prepared at other reaction time.The results show that the oxygen mobility of Pt-7#CeO₂/RGO catalyst is high,and the catalytic sensitivity to methanol and CO is good,which is beneficial to the improvement of catalytic activity and stability.Electrochemical tests show that Pt-7#CeO₂/RGO catalyst has the best performance,and its electrochemical active surface area is 56.77m²/g,which is 3 times and 2 times as much as that of Pt/C and Pt/RGO catalysts,respectively.The peak current density of electrocatalytic oxidation of methanol is 820mA/mg,and the initial potential of CO oxidation is 0.585 V.All the electrochemical test results were the best.The results show that the composite performance of the anode catalyst can be greatly improved by the large specific surface area bouquet-like CeO₂ supported on the anode catalyst.