AUTHOR=Wu Tingjun , Kim Jiwon , Choa Yong-Ho , Myung Nosang V. 

TITLE=Electrodeposition of nanocrystalline FeXCo1-X thin films from choline chloride–urea deep eutectic solvents

JOURNAL=Frontiers in Chemistry

VOLUME=Volume 13 - 2025

YEAR=2025

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2025.1635084

DOI=10.3389/fchem.2025.1635084

ISSN=2296-2646

ABSTRACT=FexCo1-x thin films were electrodeposited from a choline–urea deep eutectic solvent (DES) containing Fe3+ and Co2+ ions under ambient conditions. Anomalous co-deposition was observed, with Fe preferentially depositing over Co. With higher cathodic potential, the film’s morphology shifted from smooth to nodular. X-ray diffraction (XRD) analysis showed iron oxide impurities at lower overpotential and temperatures (e.g., <−0.9 V at 70 °C), while impurity-free, nanocrystalline Co50Fe50 films had formed at higher temperatures (e.g., 130 °C). The films exhibited a body-centered cubic (BCC) structure with (110) preferred orientation and grain sizes of 30 nm–40 nm.