Peptide-regulated Fabrication Of One Dimensional Pt Nanostructures And Their Electrocatalytic Properties

The fabrication of one dimensional（1-D）Pt nanostructures through assembly has inspired many researchers’ interests in the field of fuel cell due to their high catalytic activity and conductive ability.Among the various methods to prepare 1-D noble metal nanotructures,template method is an effective method and has received much more attentions.Owing to the merits of diverse compositions,adjustable sequences,simple synthetic method,plenty of active groups,environment-friendship,as well as its unique property of self-assembly ability and specific adsorption on inorganic surface,peptides can be used as soft templates and templating agents for 1-D Pt nanostructure fabrication.In this thesis,peptides were used in the synthesis of 1-D Pt nanostructures,and the effects on 1-D Pt nanostructures of peptide template concentration,peptide template type,as well as the concentration of modulators peptide P7A,BP7A,S7,and T7 were studied.The application of 1-D Pt nanostructures with different detail characteristic were studied as fuel cell electrocatalyst.Methods of fabricating 1-D Pt nanostructures were reviewed,including polyalcohol reduction,electrochemical deposition,template regulation.And the fabrication of 1-D Pt nanostructures through soft template direction method including in situ reduction and post reduction were also reviewed.In this thesis,the study was focused on in situ method to make 1-D Pt nanostructures with different structures.With ultroshort peptide I₃K as a template,we have obtained 1-D continuous Pt nanofibers of different diameters from 10 to 50 nm through changing the concentration ratio of template peptide and Pt precursor salt.The Pt nanofiber diameter changed with the concentration of I₃K;and at the concentration ratio 1:10（peptide to platinum salt）,the nanofiber has the biggest diameter.The electrocatalytic results indicated that the 1-D continuous Pt nanofibers has the largest specific ECSA and it is bigger than commercial Pt / C catalyst at the concentration ratio of 1:10.The results of anodic methanol oxidation reaction showed that 1-D Pt nanofibers had higher If/Ib,indicating higher resistance to CO and other intermediate product poisoning.In addition,the accelerated durability test showed that 1-D Pt nanofibers had higher stability than the commercial Pt/C catalyst after 1000 cyclic voltammetry（CV）measurements.At the concentration ratio of 1:10（peptide to platinum salt）,we choosed I₄K₂,I₃ CGK,I₃H as templates to prepare 1-D Pt nanofibers and compared with I₃K template.TEM results indicated that 1-D continuous nanofibers could be assembled with I₄K₂ as template,while with I₃ H,I₃CGK,1-D Pt nanostructures assembled were ordered arrays of Pt nanoparticles.These 1-D Pt nanostructures from I₄K₂ exhibited much higher electrocatalytic activity,stability and resistance to CO poisoning than those from I₃H and I₃ CGK.Although the activity of 1-D Pt nanostructures from I₃ CGK and I₃H was lower than the commercial Pt/C catalyst,these 1-D Pt nanostructures electrocatalysts had higher resistance to CO and other intermediate product poisoning.Modulator peptides,such as P7A,BP7A,S7 and T7,were adopted to modulate the 1-D nanostructures of platinum during reduction of Pt precursor with I₃K and 1-D Pt nanostructures.with different structure details were fabricated.For P7A,1-D Pt nanostructures with poor continuity at low P7A concentration and 1-D Pt nanostructures assembled with regularly interparticle-distanced Pt nanoparticles at high P7A concentration were observed through TEM.For BP7A,we obtained 1-D continuous Pt nanowires with smooth surface at low BP7A concentration and intermittent 1-D Pt nanowires at high BP7A concentration.For S7 and T7,which can specifically adsorb Pt（111）and the Pt（100）surface respectively,we also achieved 1-D Pt nanowires exhibited different continuity.Although the electrocatalytic activity was slightly decreased with modulator peptides,the resisitance to poisoning was increased.