Hollow Pt Nanocrystals Supported On MoO_x?modified Carbon And Carbon-supported Pt₅P₂ Nanoparticles Used As A High-performance Electrocatalyst For Methanol Oxidation Reaction

Direct methanol fuel cell?DMFC?is considered as one of the most promising energy conversion equipment for portable electronic devices due to its portable device,environmentally friendly and high energy density.However,the high cost,low catalytic activity,weak resistance towards CO poisoning and poor stability limit the commercialization of DMFCs.In this dissertation,the research is devoted to enhancing the electrocatalytic activity,stability and producing cost of DMFC anode electrocatalysts.Pt nanocrystals?NCs?with hollow structure immobilized on MoO_x-modified carbon black?h-Pt/MoO_x-C?was developed for methanol oxidation reaction?MOR?.The MoO_xC is fabricated by phosphomolybdic acid self-assembly on carbon black.The h-Pt/MoO_xC evolved from Ag@Pt core-shell NCs deposited on MoO_x-C in saturated Na Cl aqueous solution containing NH₄ OH.Because of the presence of MoO_x,the electrocatalyst of solid Pt NCs anchored on MoO_x-C?Pt/MoO_x-C?for methanol oxidation exhibits about 3.4 times higher electrocatalytic activity than solid Pt NCs anchored on carbon black?Pt/C-H?.The mass activity of h-Pt/MoO_x-C is 2.4 times greater than that of Pt/MoO_xC,ascribing to the unique hollow structure.Furthermore,the h-Pt/MoO_x-C also exhibits better tolerance to poisoning species and is more stable under electro-oxidation conditions.A simple one-pot wet-chemical approach that incorporation of phosphorus?P?into Pt to form supported Pt₅P₂ alloy phase was developed to enhance the catalytic property of Pt catalysts toward MOR,including both the activity and durability.The simultaneous use of NaH₂PO₂ and Na₂HPO₄ is the most crucial for the formation of Pt₅P₂ phase,and the introduction of P results in smaller size,better dispersion,and the electronic structure change of Pt.The Pt₅P₂/C catalyst achieves a factor of 11.0 and 9.1 enhancement in mass activity?3.603 A mg Pt-1?and specific activity(63.43 A m^-2)for methanol oxidation reaction?MOR?relative to Pt/C,respectively.Moreover,the Pt₅P₂/C also exhibits better tolerance to poisoning species and is more stable under electro-oxidation conditions.