The effects of the nanoscale particle size of RuO₂ in thermally prepared RuO₂-coated Ti anodes on electrochemical kinetic parameters such as the active surface area and Tafel slope for oxygen evolution in sulfuric acid solutions were investigated. RuO₂/Ti anodes with four different average sizes of RuO₂ particles—5.6 nm, 6.8 nm, 14.6 nm, and 21.2 nm—were prepared. The double-layer charge corresponding to the active surface area for oxygen evolution of the anodes was shown to increase with decreasing average RuO₂ particle size. The polarization curves of the anodes showed that the oxygen evolution current density at a certain potential increased with decreasing average RuO₂ particle size, meaning that oxygen evolution, especially in the high-current-density region, where it mainly depends on the mass transfer rate, accelerated with decreasing RuO₂ particle size. The Tafel slope obtained for the anodes was shown to decrease with decreasing average RuO₂ particle size, indicating that the change in particle size affected the electron transfer rate for oxygen evolution. The present study reveals that changes in the nanoscale size of RuO₂ affect not only the mass transfer process but also the electron transfer process for oxygen evolution in sulfuric acid solutions.

Graphical abstract

研究了热制备的RuO ₂包覆的Ti阳极中RuO ₂的纳米级粒径对电化学动力学参数（如活性表面积和Tafel斜率）的影响，该动力学参数用于在硫酸溶液中释放氧气。制备具有四个不同平均尺寸的RuO ₂颗粒（5.6 nm，6.8 nm，14.6 nm和21.2 nm）的RuO ₂ / Ti阳极。相应于阳极上析氧的活性表面积的双层电荷显示出随着平均RuO ₂粒径的减小而增加。阳极极化曲线表明，随着平均RuO _2的降低，一定电位下的析氧电流密度增加。粒径，这意味着随着RuO ₂粒径的减小，尤其是在主要取决于传质速率的高电流密度区域中，氧的释放加快。阳极获得的Tafel斜率显示出随着RuO ₂平均粒径的减小而减小，表明粒径的变化影响了析氧的电子传递速率。本研究表明，RuO ₂纳米级尺寸的变化不仅影响质量转移过程，而且影响在硫酸溶液中析氧的电子转移过程。

图形概要