| Wed May 20th 2015 16:00 – 17:00 ZH286 | Seminar | Spontaneous chemical reactions in electrochemically generated nanobubbles Vitaly Svetovoy |
Details:Bubble formation in microsystems on a microsecond time scale is discussed. A few experimental techniques were applied to investigate bubbles produced by electrochemical water decomposition. The bubbles nucleate homogeneously in a thin highly supersaturated layer above the electrodes. Gas production by short voltage pulses of alternating polarity resulted in formation of nanobubbles containing stoichiometric mixture of hydrogen and oxygen. If the pulses were sufficiently short, the bubbles were not growing further but disappear instead releasing significant amount of energy. Different evidences indicate that the reaction between H2 and O2 is ignited spontaneously inside the bubbles, but the mechanism of the reaction is still unclear. The finding is applied to create a fast and strong microengine using internal combustion of gases as part of its cycle. A microfluidic chip containing this engine is a powerful tool for further investigation of the bubbles containing mixture of reacting gases. A few different regimes of gas termination were uncovered. Further development and possible applications of the effect are discussed briefly. | ||
