Residual stress field effect induced on cathodic electrodes for alkaline electrolysis

<h2>Abstract</h2> Electrodes are a crucial component of alkaline electrolysers, as they enable the electrochemical reaction that separates water into hydrogen and oxygen gas. Electrodes with superior performance can lead to reduced power demand in the alkaline electrolysis process. This work analyses two types of electrodes: a heat-treated stainless-steel cathode (CHT) and a heat-treated stainless-steel cathode with shot peening treatment (CRS). The induction of the residual stress field with the shot peening treatment was evaluated using X-ray diffraction. The CRS electrode demonstrated a 420 % increase in active surface area compared to the CHT electrode. To assess the performance of the electrodes, two tests were carried. The first involves identifying the hydrogen evolution reaction through linear voltammetry and obtaining the Tafel slope. The second test focused on obtaining voltage-current curves to assess the performance of the electrolyser. The results of both tests showed that the CRS electrode exhibited the best performance towards Hydrogen Evolution Reaction, HER. Three elements are responsible for this improvement: first, the increase in the active area; second, an increased number of peaks in surface roughness, which minimises bubble retention during hydrogen generation; and third, the presence of induced residual stresses, which enhance HER kinetics. Implementing this process on an industrial scale offers several advantages over conventional electrochemical surface coating processes, primarily due to the more straightforward surface preparation requirements of shot peening techniques compared to chemical treatments. A key indicator of this efficiency is the lower Tafel slope, where the CHT electrode exhibited a slope of 125 mV dec⁻¹, and the CRS electrode was 113 mV dec⁻¹. This relatively low difference demonstrates improved efficiency for hydrogen generation. These findings highlight the potential to further enhance the performance and durability of alkaline electrolysis through innovative designs tailored for industrial applications.