Microwave-assisted polyol synthesis of Pt-Zn electrocatalysts on carbon nanotube electrodes for methanol oxidation

摘要

Bimetallic Pt-Zn catalysts with high and stable electrochemical activity towards sulfuric acid and methanol oxidation were synthesized by microwave-assisted polyol (MP) method. A catalytic chemical vapor deposition was used to directly grow multi-layered carbon nanotubes (CNTs) on carbon paper substrate. The as-grown CNT forest serves as a support for the Pt-Zn catalysts having a mean size of 3-5 nm. The catalytic activities of the supported Pt-Zn catalysts toward acid electrolyte and methanol oxidation were examined by cyclic voltammetry test with potential cycling. Experimental results confirmed that two-stage MP synthesis enables the improvement of electrochemical activity, antipoisoning ability and long-term durability of the binary catalyst. This improvement can be attributed to the bifunctional mechanism of the binary catalysts: the Zn content serves as a promoting center for the generation of Zn-OH species, and more Pt sites are thus available for methanol oxidation. Accordingly, the Pt-Zn/CNT catalyst, prepared by the MP approach, displays a potential candidate for fuel cell application due to its easy fabrication (6 min), low cost and no additional reduction process.