Investigation On The Supports And Promoters For PtRu Catalyst Towards Methanol Electrooxidation

Since methanol has a high specific energy density,commercially available irn large quantityand is easilytransportable as a fuel,direct methanol fuel cells（DKMFCs）exhibit great potential applicationsas portable and backup power.The most important reaction in DMFCs,i.e.methanol electro-oxidation reaction（MOR）?has a high over-potential and low reaction kinetics,which involves a 6-electron transfer process.The key is to develop MOR catalysts of high activity and durability.This is the frontier in the field.This dissertation takes PtRu/C,which is well-accepted as most active 1\MOR catalyst,as a probe.By modifying the structures and compositions of carbon supports,and optimizing the active components,we intend to further improve the activity and durability of’ current PtRu/C.Two metal oxide-carbon composite materials,SnO₂-C and WO₃-C,were synthesized via a microwave method.With as-prepared catalyst supports,PtRu/WO₃-C and PtRLu/SrnO₂-C catalysts were prepared via a liquid phase microwave synthesis method.It was found that PtRu/SnO₂-C showed good MOR activity,while its durability should be improved.The activity and methanol tolerance of PtRu/WO₃-C were improved.With the 5%WO₃-doped carbon as the support,the PtRu/WO₃-C is the most stable,which might be attributed to the hydrogen spillover and oxdiation of the intermediate product,i.e.CO.With Schiff base reaction of nitrogen-containing precursors via high temperature pyrolysis and treating XC-72R under ammonia atmosphere,nitrogen doped layered porous carbon and nitrogen doped XC-72R were prepared and worked as the supports.It was found that nitrogen in carbon support could benefit for the dispersion of PtRu nanoparticles and enhance the stability of the catalyst.The nitrogen-doped carbon supported PtRu pyrolysed of nitrogen-containing precursor at 700 ℃ shows the best MOR activity and stability.To elucidate the effect of porous structure of carbon supports on the electro-catalyst activity,three worm mesoporous carbons（WMCs）of different pore sizes were prepared,and the MOR electro-catalytic activity was investigated.It was found that the pore size of WMCs support shows strong impact on the PtRu electro-catalytic activity.It was found that the pore size of WMCs support shows strong impact on the PtRu electro-catalytic activity.When the pore size is more than twice of the PtRu particles’ diameter,the ECSA and utilization of Pt increased obviously.The MOR performance of the supported PtRu catalyst is higher than that of commercial XC-72R.Using RuCu/C as the hard template and by the displacement reaction of K₂PtCl₄ and Cu,PtRuCu/C catalysts of a hollow structure with different Pt/Ru ratios were prepared.It was found that the introduction of Cu changed the electron property of Pt in the catalyst,and thus promoted the dissociation of methanol at Pt,leading to an enhanced catalytic activity.Meanwhile,the introduction of Cu and the hollow structure change the metal crystal,resulting in weaker adsorption strength of the intermediate product i.e.,CO,at Pt surface.Pt10Ru1Cu/C showed the best MOR activity and Pt1Ru1Cu/C has the highest poison tolerance.