Polymer electrolyte membrane fuel cells (PEMFCs) have been extensively studied as alternative power sources for transportation and mobile application. Due to the challenges in handling transportation and storage of hydrogen, small organic molecules, such as methanol and formic acid, have been directly used as fuels. Pt is the best pure metal catalyst so far for the electro-oxidation of all these fuels. However, the large-scale applicability of Pt catalyst is limited due to the high cost and low tolerance to poisoning. Electro-catalysts containing non-precious metals have thus been investigated as anodic and cathodic materials due to their low cost and enhanced performance in fuel cells. Pt-based alloys and intermetallic compounds have been reported to show good performance in the electro-oxidation of methanol or formic acid and electro-reduction of oxygen. Practically, intermetallic compounds with well-ordered structures and high stabilization against electrochemical leaching are promising electrocatalyst candidates in PEMFCs. However, the formation of intermetallic phase usually requires high-temperature annealing, where the aggregation of nanoparticles, either unprotected or capped with organic capping agents, is unavoidable. Diverse supports and inorganic coatings have been reported to prevent nanoparticle aggregations. MWNTs are regarded as ideal supports for electrocatalyst because of their high electronic conductivity, high surface area, high chemical stability and durability to oxidation under PEMFC working conditions. Silica coatings have also been demonstrated as effective protectors in Pt/mesoporous silica core-shell nanoparticles with thermal stabilities up to 750 °C. Herein, we used mSiO2 as inorganic capping to synthesize small and monodisperse PtZn iNPs supported on MWNTs (PtZn/MWNT@mSiO2), which showed superior catalytic activity and stability in catalytic electro-oxidation.

Size-controlled PtZn intermetallic nanoparticles for catalytic electro-oxidation

254th National Meeting (2017)

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