During water electrolysis, hydrogen bubbles form on the electrode, reducing its active surface area and impairing the efficiency of hydrogen production, while the influence of elevated pressure on their dynamics remains poorly understood. In this thesis, we experimentally determine the effect of system pressure and applied voltage on the diameter of hydrogen bubbles and their formation frequency on an untreated platinum microelectrode with a diameter of 200 µm in an aqueous H2SO4 solution. Measurements were carried out in a PEEK pressure cell using an Ossila potentiostat and a Photron FASTCAM high-speed camera at twelve voltages (2.5–6.0 V) and nine pressures (0–2.0 bar), yielding a total of 123 recorded series, which were processed using our own automated bubble-detection procedure implemented in Python. From 244,700 detections, tracking allowed us to combine 15,159 individual bubbles: the average diameter increases with voltage from approximately 6 µm at 2.5 V to 51 µm at 6.0 V, while the formation frequency simultaneously decreases from around 330 Hz to 2.5 Hz, consistent with a transition between bubble growth regimes. No consistent monotonic effect of pressure on the observed parameters was detected, as most operating points had too few repetitions to reliably separate the pressure effect from measurement scatter.
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