Nanoparticle Size Effects on Methanol Electrochemical Oxidation on Carbon Supported Platinum Catalysts

Abstract

The particle size effect observed on the performance of Pt/C electrocatalysts toward the methanol oxidation reaction (MOR) has been investigated with differential electrochemical mass spectrometry (DEMS). The investigation has been conducted under both potentiodynamic and potentiostatic conditions as research on methanol electrochemical oxidation is closely related to interest in direct methanol fuel cells. The particle size effect observed on the MOR is commonly regarded as a reflection of different Pt-CO and Pt-OH bond strengths for different particle sizes. This work focuses mainly on the mechanism of methanol dehydrogenation on platinum which is central to the problem of the optimization of the efficiency of methanol electro-oxidation by favoring the CO(2) formation pathway. It was found that the partitioning of the methanol precursor among the end products on supported platinum nanoparticles is strongly dependent on particle size distribution. Also, it is postulated that the coupling among particles of different sizes via soluble products must be considered in order to understand the particle size effects on the observed trends of product formation. An optimum particle size range for efficiently electro-oxidizing methanol to CO(2) was found between 3 and 10 nm, and loss in efficiency is mostly related to the partial oxidation of methanol to formaldehyde on either too small or too large particles. The possible reasons for these observations are also discussed.

Recent Advances in the Liquid‐Phase Synthesis of Metal Nanostructures with Controlled Shape and Size for Catalysis

“…Nanoparticle size effects on methanol electrochemical oxidation on Pt/C catalysts was studied using differential electrochemical mass spectrometry under both potentiodynamic and potentiostatic conditions (165). While the particle size effect in this reaction is usually regarded as a reflection of different Pt-CO and Pt-OH bond strengths for different particle sizes, the authors (165) focused mainly on the mechanism of methanol dehydrogenation on platinum which is crucial for the optimization of the methanol electrooxidation efficiency by favouring the CO 2 formation pathway.…”

Research Progress on Pt-Based Anode Catalysts in the Direct Methanol Fuel Cell

“…催化剂比表面积受催化剂粒度控制, 催化剂尺寸越 小, 其比表面积越大, 有关粒度对其催化剂性能的影响 已有相关研究 [106,107] . Frelink 等 Bergamaski 等 [111] 采用微分电化学质谱技术研究了 不同粒径的粒子催化活性的不同, 从定量的角度更为直 观地揭示了粒径对催化活性的影响.…”

“…Frelink 等 Bergamaski 等 [111] 采用微分电化学质谱技术研究了 不同粒径的粒子催化活性的不同, 从定量的角度更为直 观地揭示了粒径对催化活性的影响. 研究发现, 粒径在 3～10 nm 之间的催化剂催化性能最佳, 粒径过小, Pt 表 面连续的活性位点浓度下降, 而粒径过大, 甲醛的解吸 效应加重.…”

“…以 P 掺杂的 MCNTs 作为 Pt 的催化剂载体, 不仅能够降低催化剂粒子的粒径, 提高 催化剂利用率, 还可以改变 Pt 的电子云密度, 减弱反应 中间体的不可逆吸附, 从而使得 Pt/P-MCNTs 复合催化 剂对甲醇氧化具有更高的催化活性和稳定性 [69] . (110)＞Pt (100)＞Pt (111). 甲醇的氧化主要 包括两种途径: (1)甲醇直接被氧化为 CO 2 而没有经过中 间体过程; (2)间接氧化, CO 作为主要中间体 [75] .…”

Monitoring of the Transfer of Tetrachloroaurate(III) Ions by Thin-layer Electrochemistry and Electrochemical Deposition of Metallic Gold over a Graphite Electrode

“…[5][6][7] The size effects of nanoparticles have also been reported, indicating that the surface morphologies are important in elctrocatalytic oxidations of compounds such as carbon monoxide, methanol, and formic acid. [8][9][10][11] Hence, systematic studies are required to produce suitable surface morphologies, such as micro-or nano-structures, and obtain an understanding of their correlated effects on catalytic electrode reactions.…”