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

Abstract

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.