Font Size: a A A

Catalytic Performance Of Pt, Pd And Pt-tb Supported On Titanium Suboxide For Formic Acid Electrooxidation

Posted on:2016-11-05Degree:MasterType:Thesis
Country:ChinaCandidate:H R ZhaoFull Text:PDF
GTID:2191330464972332Subject:Physical chemistry
Abstract/Summary:PDF Full Text Request
Recently, Pt-based, Pd-based and alloy-based catalysts are widely used in direct formic acid fuel cells. Unfortunately, the corrosion of the carbon support, which is a common support material, would cause an adverse impact on working efficiency and catalytic performance. Therefore, the non-carbon materials, especially titanium suboxides, have attracted much attention in past years. Among those titanium suboxides, Ti4O7 has been found to be a new support material, which showed superior electrical conductivity and stability and much better corrosion resistance and oxidation resistances in acid or alkaline circumstance than carbon black. In this paper, Pt, Pd and Pt-Tb bimetallic catalysts supported on titanium suboxides Ti4O7 were prepared and their electrocatalytic performances were studied. The crystalline structure, morphology and component distribution of catalysts were characterized by X-ray diffraction(XRD), Transmission electron microscopy(TEM), X-ray photoelectron spectroscopy(XPS) and so on. The electrocatalytic performance of catalysts for formic acid oxidation were conducted by cyclic voltammetry(CV), chronoamperometry(CA), linear sweep voltammetry(LSV) and CO stripping experiments.There are three main parts in this paper.In the first part, Pt/C, Pt/TiO2 and Pt/Ti4O7 catalysts were prepared by sodium borohydride reduction method in aqueous solution and their catalytic performances for formic acid electrooxidation reaction were compared. It was found that the Pt/Ti4O7 catalyst possessed better electrocatalytic activity and stability although a poor dispersion of Pt nanoparticles on the Ti4O7 support was detected. Besides a high electrical conductivity, the effect of electron transfer of Ti4O7 also contributed to the better catalytic activity according to XPS analyses.In the second part, Pd/C and Pd/Ti4O7 catalysts were prepared and their catalytic performances for formic acid electrooxidation were compared. TEM results showed Pd nanoparticles dispersed uniformly on both supports. The Pd/Ti4O7 catalyst possessed a better catalytic performance for electrocatalytic oxidation. The analysis of XPS spectra suggested that the higher content of metallic Pd caused by the Ti4O7 support contributed to the better catalytic activity of Pd/Ti4O7. To further improve the catalytic performance, Pd/PDDA-Ti4O7 catalyst was synthesized in which Ti4O7 was functionalized with PDDA. Pd nanoparticles with a good dispersion on PDDA-Ti4O7 support were found. The Pd/PDDA-Ti4O7 catalyst displayed better catalytic activity than Pd/Ti4O7 catalyst. The improvement could be attributed to an increase of metallic Pd content due to the presence of PDDA.In the third part, Pt-Tb/Ti4O7 bimetallic catalysts of different Pt-Tb ratios were prepared and their catalytic performances for formic acid electrooxidation were compared. The results of TEM display a good dispersion of Pt-Tb bimetal nanoparticles on Ti4O7 supports. Among these catalysts, Pt-2.5%Tb/Ti4O7 catalyst possessed the highest electrocatalytic activity for formic acid electrooxidation reaction. The addition of Tb facilitated the removel of the absorbed CO, and the effect could be explained by bi-functional mechanism.
Keywords/Search Tags:Titanium suboxide, support, direct formic acid fuel cells, electrooxidation, functionalization
PDF Full Text Request
Related items