Investigation of electrochemical hydrogen evolution under microgravity condition

We investigated the electrochemical evolution of hydrogen gas under microgravity conditions in a dropshaft over a potential range of 2-5 V vs a silver electrode using a three-electrode system. The formation of hydrogen gas bubbles on a platinum electrode in an aqueous solution of sulfuric acid was observed under high magnification. Under microgravity conditions, bubbles remained on the electrode, covering the electrode surface, and their diameter increased tenfold. The current density became lower than that under terrestrial conditions. The use of an acceleration level of good quality eliminated the bubble motion caused by residual acceleration and allowed precise measurement of bubble behavior. The bubbles did not coalesce to form a single large bubble but detached from the surface of the electrode due to the inertia of coalescence. The effect of microgravity on the current density became appreciable when the potential exceeded about 2.5 V. (C) 1997 Elsevier Science Ltd.