Analytical Chemistry - Center for Electrochemical Sciences (CES), Ruhr-Universität Bochum, Universitätsstrasse 150, D-44780, Bochum, Germany.
Faraday Discuss. 2016 Dec 12;193:241-250. doi: 10.1039/c6fd00101g.
Silver nanoclusters are deposited on bifunctional Θ-shaped nanoelectrodes consisting of a carbon nanoelectrode combined with a hollow nanopipette. The Θ-nanoelectrodes are used as model systems to study interfacial mass transport in gas diffusion electrodes and in particular oxygen-depolarized cathodes (ODC) for the oxygen reduction reaction (ORR) in chlor-alkali electrolysers. By local delivery of O gas to the electroactive Ag nanoclusters through the adjacent nanopipette, enhanced currents for the ORR at the Ag nanoparticles are recorded which are not accountable when considering the low solubility and slow diffusion of O in highly alkaline media. Instead, local oversaturation of O leads to current enhancement at the Ag nanoclusters. Due to the intrinsic high mass transport rates at the nanometric electrodes accompanied by local delivery of reactants, the method generally allows to study electrochemical reactions at single nanoparticles beyond the limitations induced by slow diffusion and low reactant concentration. Kinetic and mechanistic information, for instance derived from Tafel slopes, can be obtained from kinetic regimes not accessible to standard techniques.
银纳米簇沉积在由碳纳米电极与中空纳米管组成的双功能 Θ 型纳米电极上。Θ 型纳米电极被用作模型系统，用于研究气体扩散电极中的界面质量传输，特别是用于氯碱电解槽中氧气还原反应 (ORR) 的氧去极化阴极 (ODC)。通过通过相邻的纳米管将 O 气体局部输送到活性 Ag 纳米簇，记录到 Ag 纳米颗粒上 ORR 的增强电流，当考虑到 O 在高碱性介质中的低溶解度和缓慢扩散时，这是无法解释的。相反，O 的局部过饱和导致 Ag 纳米簇上的电流增强。由于纳米电极固有的高传质速率以及反应物的局部输送，该方法通常允许在单个纳米颗粒上研究电化学反应，而不受缓慢扩散和反应物浓度低带来的限制。可以从动力学范围内获得动力学和机理信息，例如源自塔菲尔斜率，这些信息是标准技术无法获得的。
