The Preparation Of Noble Metal Palladium Nanomaterial Catalyst And The Study Of Its Electrochemical Properties

Low temperature fuel cell is a new generation of environmently friendly,energy saving,high efficient and safe energy storage and conversion device of high performance.In recent years,it has been the hot spot of the research problem.However,the limited resources and high cost of noble metal restrict the development prospects of the fuel cell and the commercial utilization.Hence,reducing the amount of noble metal and improving the catalytic performance are important for promoting the commercialization of fuel cells.Meanwhile,it is unclear about the relationship between the performance and the size of the noble metal nanomaterials.So the basic research is still necessary.In this article,a facile approach has been developed for the synthesis of polycrystalline palladium nanoparticles?Pd NPs?by using tannic acid?TA?as green reagent and stabilizer in a 30�C water bath.The size of Pd NPs can be tuned in a range of 10-60 nm simply by adjusting the concentration of Pd precursor.The catalytic activity and stability of the as-obtained Pd NPs toward formic acid oxidation were analyzed.It was found that these Pd NPs with different sizes exhibited size-dependent and enhanced formic acid oxidation performance compared to the commercial Pd black catalyst.It should be noted that the Pd catalysts with an average size of 24 nm demonstrate the best catalytic activity and stability among the other prepared Pd NPs,which the reason can be ascribed to its larger electrochemical surface area?ECSA?and polycrystalline structure with defects.Additionally,we have designed and prepared the Pd/Ni?OH?₂ catalyst and explored the performance of ethanol oxidation in alkaline conditions.We found that every Pd nanoparticles are evenly dispersed on the surface of Ni?OH?₂ thin films,and compared with the commercial Pd/C catalyst,the Pd/Ni?OH?₂ nanocomposite exhibited remarkable activity,excellent durability and superior CO poisoning tolerance.Because of the synergistic effects between the Pd nanoparticles and Ni?OH?₂:Pd can offer active site in ethanol oxidation;Ni?OH?₂ can provide enough OH_ads thus promote the oxidation of toxic intermediate products the like CH₃CO_ads and CO.the results suggest that Pd/Ni?OH?₂ should be considered as a good electro-catalyst material for alkaline direct ethanol fuel cells.