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. The data were collected at Wetsus, European Centre of Excellence for Sustainable Water Technology, between March and September of 2023 and accompany the publication "Overlooked impact of electrolyte purity on benchmarking cathodes in alkaline water electrolysis” (DOI: 10.1021/acselectrochem.5c00326). 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).