Experimental Benchmarking for High-Reproducibility, Cross-Institutional Evaluation of Iron Redox Electrochemistry

We present a practical case study standardizing experimental protocols between collaborators with the goal of understanding ferrous iron (Fe 2+ ) chemistry and improving the iron deposition reaction for energy-efficient, electrochemical iron production. The study of iron reactions can be difficult, as aqueous iron electrolytes exhibit complex behaviors that can lead to differing interpretation of ostensibly similar experiments. The question we want to answer: are we studying the same chemistry? Our protocols address inherent challenges such as the tendency for Fe 2+ to spontaneously oxidize to ferric iron (Fe 3+ ) and the production of hydrogen at the potentials of interest. Our standardized protocol, executed by four collaborators in different labs and institutions, yields high-reproducibility results, and identified glassy carbon electrode surface quality and Fe 3+ impurities in the salt as key factors with outsized effects on cyclic voltammetry measurements. The process of developing the protocols helped to troubleshoot underlying issues that created poorer reversibility and reproducibility. This study highlights the fact that even nominally straightforward electrochemical systems can yield vastly different outcomes due to small differences in experimental preparation and serves as a useful example for creating transparent and achievable standards for the generation of reliable datasets that can be widely used and shared.