Experimental data: Overlooked impact of electrolyte purity on benchmarking cathodes in alkaline water electrolysis

This dataset contains the recorded current and voltage data during electrolysis tests with nickel electrodes in high-purity and laboratory-grade potassium hydroxide.<br>The data were collected at Wetsus, European Centre of Excellence for Sustainable Water Technology, between March and September of 2023 and accompany the publication "<em>Overlooked impact of electrolyte purity on benchmarking cathodes in alkaline water electrolysis</em>” (DOI: 10.1021/acselectrochem.5c00326).<br>Version history:v1 (12 September 2024)Dataset first online.v2 (30 January 2026)Dataset linked to the published article; dataset title updated to align with the article and README.txt updated to include article title and DOI.v3 (20 February 2026)README.txt updated to explicitly state experimental conditions, including temperature (25°C) and pressure (atmospheric).