Construction And Performance Study Of Platinum Electrocatalyst Supported On Cerium Tin Oxide And Carbon Composite Carrier

Direct methanol fuel cell?DMFC?is recognized to be a pomoising clean energy technology.However,the poor electrochemical activity and durability of the Pt anode catalysts are still the key issues hindering the commercial application of DMFC.Recently,Pt catalysts supported on the CeO₂-C hybrid support have attracted attentions from researchers.Although Pt/CeO₂-C catalysts exhibit good performance for methanol electrooxidation,there are still many urgent problems that remain to be solved.In this paper,the research is devoted to enhancing the electrocatalytic activity and stability of Pt/CeO₂-C catalysts for methanol electrooxidation.The main contents are summarized as follows:1.In order to improve the oxygen storage capacity?OSC?of CeO₂ and further enhance its co-catalytic functionality on methanol electrooxidation,Ce_1-xSn_xO_2-? solid solution,with particle size of about 10 nm,was synthesized using a simple solvothermal method.The results of Raman and XPS demonstrate that Ce_1-xSn_xO_2-? solid solution has high OSC.Pt catalysts supported on the mixture of Ce_1-xSn_xO_2-? and Vulcan XC-72 carbon black hybrid support(Ce_1-xSn_xO_2-?-C)for methanol electrooxidation were synthesized by microwave-assisted polyol process.The influences of Ce/Sn molar ratio and the percentage of Ce_xSn_1-xO_2-? in hybrid support on the performance of Pt/Ce_1-xSn_xO_2-?-C catalysts for methanol electrooxidation were also investigated in deatil.The results show that when Ce/Sn molar ratio is 0.8:0.2 and the percentage of Ce_1-xSn_xO_2-? is 30 wt.%,the prepared catalyst exhibits the best electrocatalytic activity and duriblity for methanol electrooxidation.2.In order to increase the specific surface area and electron conducity of CeO₂,thereby improving the dispersion of Pt and electron conduction during the electrochemical reaction,Ce_0.8Sn_0.2O_2-? hollow spheres?Ce8Sn2-HSs?with around 400 nm in diameter were prepared by solvothermal method.The results of N₂ adsorption-desorption and XPS demonstrate that Ce8Sn2-HSs possess higher specific surface area and better OSC.Pt/Ce8Sn2-HSs was synthesized by microwave-assisted polyol process.Then Pt/Ce8Sn2-HSs mixed with Vulcan XC-72 carbon black was used to test its performance for methanol electrooxidation.The results show that Pt/Ce8Sn2-HSs-C catalyst exhibits a higher electrocatalytic performance for methanol electrooxidation.The electrocatalytic activity of Pt/Ce8Sn2-HSs-HSs-C is 1.1 times higher than that of Pt/CeO₂-HSs-C and 1.4 times higher than that of Pt/Ce_0.8Sn_0.2O_2-?-C,respectively.The electrocatalytic stability of Pt/Ce8Sn2-HSs-C is 1.1 times higher than that of Pt/CeO₂-HSs-C and 1.3 times higher than that of Pt/Ce_0.8Sn_0.2O_2-?-C,respectively.3.In order to achieve the synergistic effect of Pt,Ce8Sn2-HSs and carbon black,Ce8Sn2-HSs coated with carbon deriving from glucose carbonization?Ce8Sn2-HSs@C_x?were synthesized.Then the Pt nanoparticles were deposited by microwave-assisted polyol process.The effects of different carbonization temperature and different carbonization time on the formation of Ce8Sn2-HSs@C_x have been explored.The results show that carbonization temperature at 160? and carbonization time of 4 h are the optimized preparation conditions.Meanwhile,the effect of different carbon content from the carbonization of carbon source on the performance of Pt/Ce8Sn2-HSs@C_x for methanol electrooxidation has also been investigated.Taking into account both the electrocatalytic activity and stability of catalyst,40 wt.%carbon from the carbonization of glucose is the optimized content.