Preparation and Electrocatalytic Performance of Highly Oriented Pt Nanowire Arrays Electrodes
|School||Wuhan University of Technology|
|Keywords||Proton exchange membrane fuel cells AAO templates platinum nanowires oxygen reduction methanol oxidation|
In the electrode of PEMFC, Pt/C catalyst is most commonly used. For the lack of Pt material and its high cost in the world, commercial application of PEMFC faces barriers. Because of the carbon corrosion, the catalyst would lead to deactivation. And also, large-size carbon support increases the thickness of the catalyst layer, thus affecting the rate of mass transfer and electrode reaction speed. In order to improve the catalyst performance, it is necessary to optimize the structure of catalyst. In this paper, platinum nanowire arrays were fabricated by electrodepositing, utilizing nanochannel alumina templates, then used it as the catalyst of PEMFC. First we prepared different size aluminum templates by anodic oxidation, then electrodeposited Pt as catalyst. X-ray photoelectron spectroscopy(XPS), scanning electron microscope(SEM), transmission electron microscopy(TEM), inductively coupled plasma-atomic emission spectrometry(ICP-AES) and electrochemical measurement were used to characterize these catalysts. The results indicated that:(1) After dissolving AAO template, as-prepared Pt NWs are relatively regular cylindrical shape, and they are good replicas of the uniform pores of AAO templates. As Pt NWs are upright in good condition, their self-supporting structure will facilitate the electrochemical measurements.(2) According to the cyclic voltammetry curves of hydrogen adsorption and CO stripping for Pt NWs catalysts, it is seen that electrochemical surface area(ECSA) of Pt NWs was far greater than the geometric area.(3) The half wave potential in ORR curves of Pt NWs is more positive than Pt/C in RDE measurements. This shows that the oxygen reduction reaction carries out more easily for Pt NWs. Moreover, compared with the conventional Pt/C catalyst, Pt NWs catalysts present higher limiting diffusion current. It is because highly ordered Pt NWs provides a good set of mass transfer channel and serves as an excellent current collector.(4) The peak current in methanol oxidation curves of Pt NWs is greater than Pt/C, indicating better methanol electrooxidation of Pt NWs. The peak potential in methanol oxidation of three kinds of Pt NWs peak potential showed a positive shift compared with that of Pt/C. The peak potential of 25nmPt NWs is most closed to that of Pt/C, which shows that the smaller size of Pt NWs, the better the catalytic of methanol oxidation.