Study Of PdSn Catalyst For Direct Formic Ethanol Fuel Cell

The widespread utilization of fossil fuels has not only exacerbated the energy crisis,but also led to environmental pollution and global warming issues.It is significant to develop clean and stable energy.Ethanol is a renewable green energy source with high energy density,which can be produced in large scale from biomass.Direct ethanol fuel cells（DEFCs）generate power from ethanol oxidation reaction at the present of catalyst,which play important roles in electrochemical energy conversion.However,the performance of DEFCs has been heavily dependent on the electrocatalyst.Therefore,the development of low-cost electrocatalyst with superior catalytic activity and stability is of great significance for promoting the commercialization of DEFCs.Platinum（Pt）has been widely applied as anode catalyst in DEFCs attributed to the high catalytic activity.Since the empty d orbitals and unpaired d electrons of Pt,it can combine with ethanol molecules with appropriate strength（electronic effect）.However,pure Pt was not an effective anode catalyst for ethanol electro-oxidation at low temperatures,due to the poisoning inactivation after the adsorption of some surface intermediates,especially CO.The poisonous species could be removed by introducing a second metallic specie,such as Ru,Sn,Rh,and Au.The toxic intermediates can be adsorbed at lower potentials,thus minimizing surface poison and improving oxidation performance of Pt as anode catalyst.Among the alloy catalysts,Pt Ru and PtSn alloy have been currently recognized as the most effective catalysts for the ethanol oxidation.Comparing with Ru,Sn was earth-abundant metal,and PtSn alloy was also beneficial to the fracture of C-C bonds in ethanol molecules,which make Sn a favorable metal specie for Pt alloy.Morphology has been a crucial factor for influencing the performance of electro-catalysts.Many studies have reported the PtSn nanocrystals with different morphologies for ethanol oxidation reaction（EOR）.In order to reduce the cost of EOR catalyst and improve the utilization and stability of precious metal Pt,PtSn catalysts with different structures were synthesized by different synthesis methods in this paper,and the electro-catalytic performance of PtSn catalyst was explored.The main conclusions are gained as follows:（1）PtSn catalyst with a unique three-dimensional porous structure was prepared by a simple chemical reduction method.The Sn precursor was added for partial reduction to obtain the Sn skeleton,and then the Pt precursor was adde d for co-reduction to obtain PtSn alloy nanoparticles,PtSn alloy nanoparticles are anchored on the Sn skeleton to form a three-dimensional porous structure.The Sn skeleton as self-supporting enhances the structural stability and determines the final morphology of the catalyst.（2）Introducing the low-cost base metal Sn can reduce the Pt-based catalytic cost while forming an alloy with Pt,PtSn alloy nanoparticles has a good effect on promoting EOR activity.The three-dimensional porous PtSn catalyst is composed of PtSn alloy and SnO_x,and the dual-function effect can improve the anti-CO poisoning performance of the PtSn catalyst.Due to its excellent structural stability,the catalytic stability of the three-dimensional porous PtSn catalyst has also been greatly improved and the cycle life of Pt₇₃Sn₂₇and Pt₈₁Sn₁₉ catalysts is up to 5 times and 3 times that of commercial Pt/C.（3）PtSn nanoparticles with uniform size were synthesied by solvothermal.The temperature and the amount of KOH have a great influen ce on the formation of nanoparticles.The size of synthesized PtSn nanoparticles is uniform,and their composition is consistent with the theoretical value.XRD characterization shows that PtSn nanoparticles are composed of PtSn alloy and Sn O₂.PtSn nanoparticles are effective in the oxidation of ethanol,but due to the structural instability,the catalytic activity decreased very fast.Useing carbon black（CB）,graphene oxide（GO）and carbon nanotube（CNT）as the carrier to support PtSn nanoparticles respectively can be effectively enhance the catalytic activity and improve the conversion rate of ethanol to CO₂.