Comparison of bubble parameters between boiling and hydrogen evolving systems

•Bubble parameters of the boiling and hydrogen evolving systems (HES) were investigated.•Bubble nucleation site density, departure diameter and bubble frequency were compared.•HES showed higher site density, smaller bubble diameter and similar frequency.•Bubble parameters upon increasing current showed similar trends with water boiling system.•Experimental evidences were provided supporting the analogy between two systems. Bubble behavior in a hydrogen evolving system was compared to that under boiling conditions. Hydrogen was generated electrochemically in an aqueous solution of 1.5 M sulfuric acid (H2SO4). Hydrogen bubble parameters such as active nucleation site density, bubble departure diameter, and bubble frequency, were measured and compared to those observed during boiling. The hydrogen evolving system exhibited higher active nucleation site density that increased, and smaller departure diameters that gradually decreased, with increasing current density. Bubble growth time, which is related to bubble frequency, was shorter in the hydrogen evolving system due to smaller departure diameters. This study provides experimental evidence supporting the analogous relationship between bubble formation in boiling and that in hydrogen evolving systems.