Studies On Anode Pt-based Electrocatalysts For Direct Methanol Fuel Cell

Direct methanol fuel cell?DMFC?is considered as one of the most promising energy conversion equipment for portable electronic devices due to its high energy density,environmentally friendly and portable device.Nevertheless,challenging issues of anode catalysts such as high cost,low catalytic activity,weak resistance towards CO poisoning and poor stability are the main obstacles to the commercialization of DMFCs.In this dissertation,the research is devoted to enhancing the electrocatalytic activity,stability and producing cost of DMFC anode electrocatalysts.A series of high loading Pt nanoparticles with a small particle size uniformly dispersed on graphite nanoplatelets?Pt/I-IL?x?/GNPs?were synthesized in the presence of[EMIM][BF₄].This[EMIM][BF₄]assisted synthesis method facilitates a narrow size profile,which is centered at approximately 2-3 nm,and an even spatial distribution on the GNPs surface for the Pt nanoparticles.The resultant Pt/I-IL?x?/GNPs catalysts all exhibit noticeably higher activity and durability toward methanol oxidation reaction?MOR?than the commercial Pt/C-JM,with the Pt/I-IL?10?/GNP catalyst topping all Pt/I-IL?x?/GNP catalysts compared.Moreover,the Pt/I-IL?10?/GNP catalyst is about2.75 times as active as the Pt/C-JM catalyst.A solvothermal method was employed to prepare Mo-doped CeO₂(Ce_1-xMo_xO_2-?)with different Ce/Mo ratios.The synthesized Ce_1-xMo_xO_2-?is employed as a co-catalyst for Pt catalysts(Pt/Ce_1-xMo_xO_2-?-C)for MOR.Among all Pt/Ce_1-xMo_x O_2-?-C catalysts,the catalyst with a Ce/Mo atomic ratio of 7/3 and an oxide/C mass ratio of 25/75(Pt/Ce_0.7Mo_0.3O_2-?-C)exhibits the highest activity,up to 1888.4 mA mg _Pt^-1,which is one of the best results reported so far.A simple and facile strategy was developed for prepare highly uniform Pd-Pt alloy nanoparticles with different Pt/Pd molar ratios supported on1-pyrenecarboxylic acid?PCA?-functionalized GNPs?Pd-Pt/GNPs?.Pd-Pt nanoparticles on PCA-functionalized GNPs show much better distribution with no aggregation as compared to that on bare GNPs supported Pd-Pt nanoparticles?Pd-Pt/b-GNPs?.The catalytic activity for MOR varies with the relative content of Pd and Pt with the Pd₁Pt₃/GNPs catalyst topping all Pd-Pt/GNPs catalysts studied.The activity of Pd₁Pt₃/GNPs is about 1.9 and 2.3-fold as large as those of Pd₁Pt₃/b-GNPs and Pt/C-JM,respectively.A simple and efficient strategy to porous Pt-Cu alloy nanocrystals with different Pt/Cu molar ratios supported on 1-aminopyrene functionalized GNPs?p-Pt-Cu/AP-GNPs?has been developed.The formation mechanism of the porous structure has been explored.The as-prepared p-Pt-Cu/AP-GNPs catalysts exhibit superior electrocatalytic activities and stabilities for MOR compared to p-Pt/AP-GNPs and Pt/C-JM,with the Pt₁Cu₁/AP-GNPs catalyst topping all p-Pt-Cu/AP-GNPs catalysts compared.For the first time,we present an efficient strategy for synthesis of Pt₃Cu₁ nanocrystals deposited on GNPs with systematic nanostructure evolution from dendritic?D-Pt₃Cu₁/GNPs?to wire-like?W-Pt₃Cu₁/GNPs?and spherical?Pt₃Cu₁/GNPs?by only varying the pH of reaction solution.Gratifyingly,the as-prepared three Pt₃Cu₁ catalysts exhibited superior electrocatalytic properties for MOR compared to Pt/GNPs and Pt/C-JM,with the activity,durability and anti-poisonous ability following the order Pt₃Cu₁/GNPs<W-Pt₃Cu₁/GNPs<D-Pt₃Cu₁/GNPs.Highly dispersed PtP_x/C catalysts were prepared via the EG-NaH₂PO₂ self-decomposition reduction method.The addition of NaH₂PO₂ produces an ultrahigh small nanoparticles with uniform dispersion and good size distribution.The incorporation of P into Pt can markedly enhance the electrocatalytic performance of Pt for MOR,and the PtP_1.0/C catalyst exhibits a highest activity,which is about 6.6 times as activity as home-made Pt/C.