Promotion of carbon nanotube-supported Pt catalyst for methanol and ethanol electro-oxidation by ZrO2 in acidic media

Carbon nanotube-supported ZrO2 and Pt (Pt–ZrO2/CNT) catalysts with various Pt/ZrO2 molar ratios were prepared by sol–gel and ethylene glycol reduction methods. X-ray diffraction and transmission electron microscopy showed that ZrO2 nanocrystallites tend to grow gradually with the increase of ZrO2 ratio, whereas the size of Pt crystallites decreases and they disperse uniformly on the surface of carbon nanotube-supported ZrO2. The composite catalyst activities were examined by cyclic voltammetry, potentiostatic polarization and CO stripping voltammetry in acidic solutions. The results demonstrated that the addition of ZrO2 significantly increased the catalytic activity of Pt for methanol and ethanol oxidation. However, the promotion degree varied with the increase of ZrO2 content. The maximum catalytic activity for methanol and ethanol oxidation was observed at Pt–ZrO2/CNTs (1:1) and Pt–ZrO2/CNTs (1:3), respectively. This difference was ascribed to the dissimilar catalytic mechanism of Pt–ZrO2/CNTs for methanol and for ethanol electro-oxidation.

The electrochemical activity of ZrO2-modified Pt/CNT catalyst was studied in terms of methanol, ethanol and CO electro-oxidation. The results demonstrated that the promotion of catalytic activity was different for methanol and ethanol oxidation at the catalyst with the same Pt/ZrO2 molar ratio. A reason was proposed on the basis of the structural analysis of the catalyst nanoparticles.Figure optionsDownload as PowerPoint slide