【摘要】 本工作致力于研究核壳结构Au@Pt纳米粒子(Au@Pt NPs)在多壁碳纳米管(MWCNTs)上的组装,试图获得高的甲醇电催化氧化活性。利用光化学晶种生长法合成了Au@Pt NPs,并通过改变Au与Pt的原子比来控制壳层(Pt层)的厚度,然后将不同壳层厚度的Au@Pt NPs组装到巯基(-SH)功能化的MWCNTs上,获得了一系列Au@Pt/MWCNTs复合物。应用透射电子显微镜(TEM)和X射线光电子能谱(XPS)研究了Au@Pt NPs和Au@Pt/MWCNTs复合物的形貌结构、表面化学组成和化学价态,并结合电化学方法研究了Au@Pt NPs的Pt壳层厚度对其组装效果的影响,以及测试了Au@Pt/MWCNTs催化剂对甲醇的电催化氧化的活性。结果表明,Au@Pt NPs通过其表面的Au或Pt与MWCNTs上的-SH形成共价键,从而实现Au@Pt NPs在MWCNTs上的组装。Pt壳层厚度对Au@Pt NPs在MWCNTs上组装的影响较大:当Pt壳层没有完全包裹Au核时,Au@Pt NPs表面暴露的Au促进了Au@Pt NPs在MWCNTs上的组装;而当Pt壳层完全包裹Au核时,Au@Pt NPs表面呈氧化态的Pt(Ⅱ)则对核壳纳米粒子的组装不利。Au、Pt原子比例为1∶1时,Au@Pt NPs能均匀地组装在MWCNTs上,且Au@Pt/MWCNTs(1∶1)催化剂对甲醇的电催化氧化具有较高的活性和稳定性。更多还原

【Abstract】 It is the aim of this work to explore the assembly of Au@Pt core-shell nanoparticles(Au@Pt NPs)on multi-walled carbon nanotubes(MWCNTs)surfaces,attempting to acquire high activity for electrocatalytic methanol oxidation.We synthesized Au@Pt NPs whose shell(Pt layer)thickness can be varied by changing the molar ratio of Au/Pt,and then assembled these Au@PtNPs onto thiol(-SH)-functionalized MWCNTs surfaces to form a series of Au@Pt/MWCNTs composites.The surface chemical state,structure,and morphology of the Au@Pt NPs and Au@Pt/MWCNTs composites were characterized by transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS).The electrochemical tests including cyclic voltammetry(CV)and chronoamperometry(CA)were conducted to determine the assembly quality of Au@Pt NPs differing in shell thickness,and to characterize the activity of Au@Pt/MWCNTs catalysts.The results confirmed the successful assembly of Au@Pt NPs on MWCNTs surfaces via the covalent Pt-S/Au-S bonds formed between the monometallic Au or Pt of Au@Pt NPs and the thiol group of MWCNTs.The dispersion of Au@Pt NPs on MWCNTs highly depends on the atom ratios of Au/Pt.When the Pt envelopes outside the Au cores are incomplete,the exposed Au atoms facilitate the assembly of Au@Pt NPs.And on the contrary,if the Au cores are entirely coated by the Pt shell,the oxidation state Pt(Ⅱ)on the Au@Pt NPs surfaces will exert a negative effect.In particular,an 1∶1 atomic ratio of Au/Pt can result in the satisfactory dispersion of Au@Pt NPs on MWCNTs,also a distinctly higher activity and better stability of Au@Pt/MWCNTs(1∶1)compared with Pt/MWCNTs toward electrocatalytic methanol oxidation in alkaline media.更多还原