The Study Of Synergy Among Noble Metal (Au,Pt,Pd), Non-/Less-Noble Metal (Ni, Ag) And Support In Alcohol Electrooxidation

Catalyst material is one of the core components of fuel cells,and it is also the main technical barrier for the preparation of high performance,high stability and low cost fuel cells.The catalyst material consists essentially of metals and supports.In this paper,we?1?introduced non-or less-noble metals to reduce the amount of noble metals;?2?explored new support materials.The synergy between different metals or between metal and support is utilized to increase catalyst activity or stability and reduce cost.The specific research content is as follows:1.The AuPt/Ni/RGO catalysts are prepared by electrochemical deposition of a small amount of Au and Pt on the surface of Ni nanoparticles supported on reduced graphene oxide,and the electrocatalytic activity of AuPt/Ni/RGO catalysts for the oxidation of ethylene glycol in alkaline solution is investigated.By selecting a short deposition time,a low concentration of metal precursors,and a positive applied potential,only a small amount of AuPt is deposited,with its mass loadings being less than 1.0?g cm^-2.Physical and electrochemical characterizations of AuPt/Ni/RGO reveal a much lower content of Pt relative to Au.However,AuPt/Ni/RGO behaves similar to monometallic Pt/RGO rather than to Au/RGO in ethylene glycol oxidation,while Ni/RGO and Pt/Ni/RGO show no activity.The peak intensities of AuPt/Ni/RGO are higher than those of Pt/RGO and Au/RGO,although the AuPt loadings of the former are ca.2–4%of the Pt or Au loading of the latter.Another attractive feature of AuPt/Ni/RGO is low cost resulted from the low AuPt loading.The result of this study indicates that decorating the surface of non-noble metal with a small amount of two noble metals is an efficient method to fabricate highly active catalysts.2.The Au/Pt₁Ni₃/C catalysts are prepared by electrochemical deposition of Au on the surface of Pt₁Ni₃ nanoparticles supported on carbon black,and the electrocatalytic activity of Au/Pt₁Ni₃/C catalyst for the oxidation of ethylene glycol in alkaline solution is investigated.The Au/Pt₁Ni₃/C catalysts with Au/Pt atomic ratios of ca.0.02:1 and 0.08:1are obtained by depositing in a short time.Physical and electrochemical characterizations reveal that a small part of the surface of Pt₁Ni₃nanoparticles is covered by Au adatoms.In ethylene glycol oxidation,the performances of Pt₁Ni₃/C before and after the Au decoration are quite different.Au/Pt₁Ni₃/C shows remarkably high peak intensity compared to Pt₁Ni₃/C,in spite of a decrease in the surface of Pt by Au adatoms.The low Pt content and the small Au loading of Au/Pt₁Ni₃/C catalysts also suggest advantages of the Au/Pt₁Ni₃/C catalysts in cost.The result of this study reveals a significant enhancing effect of Au adatoms on the activity of Pt₁Ni₃/C for ethylene glycol oxidation.3.The PdAg/C catalysts with Pd/Ag atomic ratios of 1:1?Pd₁Ag₁/C?and 2:1?Pd₂Ag₁/C?supported on carbon black are prepared by a one-pot method,and the electrocatalytic activity of PdAg/C catalysts for the oxidation of propan-1-ol and glycerol in alkaline solution is investigated.Physical characterizations reveal a net-like structure of the PdAg alloy nanoparticles and no obvious enrichment of Pd or Ag on the nanoparticle surfaces.The PdAg/C catalysts exhibit significantly higher activity than Pd/C for the electrooxidation of propan-1-ol.This indicates a considerable improvement in the activity of Pd by combining with Ag,which is also favorable for substantially reducing the cost of catalyst.Pd₁Ag₁/C shows higher activity than Pd₂Ag₁/C.The PdAg/C catalysts are also superior to Pd/C in activity for the electrooxidation of glycerol,but are not as effective as for propan-1-ol oxidation.4.The Pd/ZSM-5?C catalysts are prepared by using ZSM-5?C composites with different ZSM-5/C mass ratios to support the Pd nanoparticles,and the electrocatalytic activity of the Pd/ZSM-5?C catalysts for the oxidation of propan-1-ol and propan-2-ol in alkaline solution is investigated.Electrochemical measurements show that the addition of ZSM-5 to carbon black improves the catalytic activities of Pd nanoparticles for the oxidation of propan-1-ol.In a wide range of ZSM-5/C mass ratios,the Pd/ZSM-5?C catalysts exhibit significantly higher activities than Pd/C and Pd/ZSM-5,indicating that the ZSM-5?C composites are superior to carbon black and ZSM-5 as supports for the Pd nanoparticles.The result reveals that efficient electrocatalysts could be fabricated using zeolites as support materials.In contrast,Pd/ZSM-5?C shows no advantages over Pd/C in the oxidation of propan-2-ol in catalytic activity,suggesting the importance of matching catalyst with reaction to obtain good results.5.Pt/4A zeolite and Pt/C catalysts with the same mass of Pt are prepared by loading the Pt nanoparticles stabilized by PEG-400 on 4A zeolite and carbon black,respectively,and the effect of 4A zeolite as a support on the electrocatalytic activity of Pt nanoparticles for the oxidation of methanol is investigated.Physical analyses reveal unevenly distributed but no large agglomerates of the Pt nanoparticles on the surface of 4A zeolite due to PEG-400 attached to the Pt nanoparticles,while the Pt nanoparticles on carbon black show a uniform distribution and a lesser degree of agglomeration.However,Pt/4A zeolite shows a much more negative onset potential and a significantly higher peak current density than Pt/C in methanol oxidation in both acidic and alkaline solutions.Pt/4A zeolite also shows high resistance to the poisoning caused by CO-like species formed in the reaction.The results indicate that 4A zeolite is superior to carbon black as a support for the Pt nanoparticles towards methanol oxidation,and further suggest that some types of zeolites could be used as efficient support materials in electrocatalysis.