Highly energetic phenomena in water electrolysis

• Published in: Scientific reports 2016-12, Vol.6 (1), p.39381-39381, Article 39381
• Main Authors: Postnikov, A. V., Uvarov, I. V., Lokhanin, M. V., Svetovoy, V. B.
• Format: Article
• Language: English
• Subjects: 132/124; 639/301/357; 639/638/675; 639/766/25; Bubbles; Combustion; Electrodes; Electrolysis; Energy; Gases; Humanities and Social Sciences; Hydrogen; Internal combustion engines; multidisciplinary; Polarity; Science; Silicon; Sound; Temperature effects
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep39381

Water electrolysis performed in microsystems with a fast change of voltage polarity produces optically invisible nanobubbles containing H 2 and O 2 gases. In this form the gases are able to the reverse reaction of water formation. Here we report extreme phenomena observed in a millimeter-sized open system. Under a frequency of driving pulses above 100 kHz the process is accompanied by clicking sounds repeated every 50 ms or so. Fast video reveals that synchronously with the click a bubble is growing between the electrodes which reaches a size of 300  μ m in 50  μ s. Detailed dynamics of the system is monitored by means of a vibrometer by observing a piece of silicon floating above the electrodes. The energy of a single event is estimated as 0.3  μ J and a significant part of this energy is transformed into mechanical work moving the piece. The observations are explained by the combustion of hydrogen and oxygen mixture in the initial bubble with a diameter of about 40  μ m. Unusual combustion mechanism supporting spontaneous ignition at room temperature is responsible for the process. The observed effect demonstrates a principal possibility to build a microscopic internal combustion engine.