Supplementary Information Figures for Effect of Mass Transport on the Electrochemical Oxidation of Alcohols over Electrodeposited film and Carbon- Supported Pt electrodes

Supplementary Information Figures for Effect of Mass Transport on the Electrochemical Oxidation of Alcohols over Electrodeposited film and Carbon- Supported Pt electrodesAbstractElectrochemical oxidation of four different alcohol molecules (methanol, ethanol, n-butanol and 2-butanol) at electrodeposited Pt film and carbon-supported Pt catalyst film electrodes, as well as the effect of mass transport on the oxidation reaction, has been studied systematically using the rotating disk electrode (RDE) technique. It was shown that oxidation current decreased with an increase in the rotation rate (ω) for all alcohols studied over electrodeposited Pt film electrodes. In contrast, the oxidation current was found to increase with an increase in the ω for Pt/C in ethanol and n-butanol-containing solutions. The decrease was found to be nearly reversible for ethanol and n-butanol at the electrodeposited Pt film electrode ruling out the possibility of intermediate COads poisoning being the sole cause of the decrease and was attributed to the formation of soluble intermediate species which diffuse away from the electrode at higher ω. In contrast, an increase in the current with an increase in ω for the carbon supported catalyst may suggest that the increase in residence time of the soluble species within the catalyst layer, results in further oxidation of these species. Furthermore, the reversibility of the peak current on decreasing the ω could indicate that the surface state has not significantly changed due to the sluggish reaction kinetics of ethanol and n-butanol.

补充信息图：研究电极沉积膜和碳载Pt催化剂膜电极上醇类物质的电化学氧化及质量传输对氧化反应的影响摘要：本研究采用旋转圆盘电极（RDE）技术，系统性地研究了四种不同醇分子（甲醇、乙醇、正丁醇和2-丁醇）在电极沉积Pt膜和碳载Pt催化剂膜电极上的电化学氧化过程，以及质量传输对氧化反应的影响。研究结果表明，在电极沉积Pt膜电极上，所有研究醇的氧化电流均随旋转速率（ω）的增加而降低。然而，在乙醇和正丁醇含有的溶液中，Pt/C的氧化电流却随ω的增加而增加。对于乙醇和正丁醇在电极沉积Pt膜电极上的降低，发现其几乎可逆，从而排除了中间COads中毒是降低的唯一原因，并归因于在较高ω下形成的可溶性中间物种从电极扩散出去。相反，碳载催化剂电流随ω增加而增加可能表明，可溶性物种在催化剂层中的停留时间增加，导致这些物种的进一步氧化。此外，降低ω时峰值电流的可逆性可能表明，由于乙醇和正丁醇的反应动力学缓慢，表面状态并未发生显著变化。