| Summary: | 碩士 === 國立臺灣師範大學 === 化學系 === 98 === In this work, an ultralow or ultrathin Pt films fabricated on the nanostructure of the gold dendrites (GD) were investigated to act as novel electrodes for methanol electro-oxidation. The GD-Pt-type materials were characterized by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and cyclovoltammetry (CV).
A small amount of Pt was deposited in a quasi-two-dimensional form onto the GD substrate through a simple immersion-electrodeposition (IE) method, forming nanostructured bimetallic GD-Pt catalysts. The ultrathin Pt film was also fabricated on GD through a simple way, in which only glucose and low concentration of H2PtCl4 were used. Such Pt-Au nanostructures have much higher structural stability than the bare GD. Compared with bare GD and high Pt loaded GD, the performances of methanol electro-oxidation on the low-Pt-content bimetallic film were greatly improved.
The ultrathin Pt films from one to several atomic layers were also successfully decorated onto GD by utilizing under potential deposition (UPD) of Cu onto the Au or Pt surfaces, followed by in situ redox replacement reaction (RRR) of UPD Cu by Pt. The thickness of Pt layers could be controlled precisely by repeating the Cu-UPD-RRR cycles. The electrocatalytic activity of GD-Pt exhibited an interesting dependence of surface structure in electrooxidation reactions of methanol.
Our results showed the relationship between nanosturcture and electrocatalytic performance towards methanol oxidation and provided a method to control the distribution of Pt nanoparticles. The resulting Au/Pt bimetallic nanocatalysts exhibited the excellent electrocatalytic activity and enhanced poison tolerance. Thus, the success in the fabrication of GD-Pt-type materials provides a new method to prepare electrocatalysts with ultralow Pt loading and high utilization, which are of great significance in energy-related applications, such as the direct methanol fuel cells (DMFCs).
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