Beyond bubbles: Unraveling the interfacial pH effects on bubble size distribution

Interfacial pH changes and bubble dynamics play pivotal roles in water electrolysis, significantly impacting cell overvoltage and energy consumption. The quantification of these changes has proven challenging, given the traditional focus on bulk solution pH fluctuations. In contrast to previous studies on individual bubble growth, this research adopts a distinctive approach, analyzing over than 8,000 bubbles in each experiment through advanced image processing computational procedures for edge detection. This methodology provides extensive data for comprehensive statistical analysis. Furthermore, the study delves into the generation of H2 and O2 bubbles during water electrolysis in both acidic and alkaline media, employing a platinum strip electrode. Crucial experimental variables, such as electrolyte pH, gas type, and current density, are systematically explored for their influence on bubble size and distribution using a 23 factorial design. In addition to this work, finite element simulations were conducted to model interfacial pH under the same experimental conditions. These simulations substantiate our experimental findings, confirming the occurrence of interfacial pH transitions in some instances. This transition, in turn, influences the bubble size distribution and consequently impacts cell voltage. These experimental and simulated datasets and potential curves allow for comparing interfacial pH changes with bubble size and the cell voltage relationship. With broad implications for various applications, such as energy production and material development, where interfacial pH changes and bubble formation are essential, this novel approach allows the optimization of boundary conditions for more effective electrochemical processes.