Logar Anja, Kozlica Dževad K, Vodeb Ožbej, Gaberšček Miran, Hodnik Nejc, Strmčnik Dušan
National Institute of Chemistry, Department of Materials Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia.
University of Nova Gorica, Graduate School, Vipavska 13, 5000 Nova Gorica, Slovenia.
ACS Catal. 2025 Apr 4;15(8):6380-6385. doi: 10.1021/acscatal.5c00144. eCollection 2025 Apr 18.
The accumulation of electrochemically produced bubbles is inevitable in gas-evolving reactions and can induce potential losses by theoretically increasing activation, concentration, and ohmic overpotentials. These effects are often either overstated or completely neglected in the literature, which complicates the accurate analysis of experimental results for gas evolution reactions. This study systematically identifies and quantifies the overpotential losses induced by bubbles by combining experimental results for hydrogen (HER) and oxygen evolution reactions (OER), obtained using the rotating disk electrode (RDE) technique, with simulations based on a two-dimensional transmission line model. Our results show that ohmic overpotential is the primary cause of apparent activity loss due to bubbles in RDE. This effect leads to catalyst activity misestimates exceeding 2 orders of magnitude, and Tafel slope errors of 100% at higher currents if left uncorrected. By identifying these effects, this work provides a robust framework for mitigating inaccuracies and improving the characterization of electrocatalysts for gas evolution reactions.
在析气反应中，电化学生成的气泡积累是不可避免的，并且理论上会通过增加活化过电位、浓度过电位和欧姆过电位而导致电位损失。这些影响在文献中常常被夸大或完全忽略，这使得对析气反应实验结果的准确分析变得复杂。本研究通过结合使用旋转圆盘电极（RDE）技术获得的氢析出反应（HER）和氧析出反应（OER）的实验结果，以及基于二维传输线模型的模拟，系统地识别并量化了气泡引起的过电位损失。我们的结果表明，欧姆过电位是RDE中气泡导致表观活性损失的主要原因。如果不加以校正，这种影响会导致催化剂活性估计误差超过2个数量级，并且在较高电流下塔菲尔斜率误差达到100%。通过识别这些影响，这项工作为减少不准确因素和改进析气反应电催化剂的表征提供了一个可靠的框架。
