Electrodeposited CoFeCuMoW multi-element coatings on 3D copper foam: Influence of deposition current density on HER and OER activity

Electrocatalytic materials are being investigated to reduce activation barriers for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), improving water-splitting efficiency. Electrodeposited multi-element coatings are promising, cost-effective alternatives to noble-metal electrocatalysts. In this work, CoFeCuMoW coatings were synthesized via electrodeposition on copper foam and characterized by SEM/EDS, XRD, Raman, and XPS. Increasing the current density from 70 to 170 mA/cm 2 produced a fine-grained coating. It also changed the composition: the Cu content decreased, the Fe, Mo, and W contents progressively increased, and the Co content peaked at 100 mA/cm 2 . The coated sample prepared at 140 mA/cm 2 exhibited the best performance, with overpotentials of 89 and 264 mV at 10 mA/cm 2 and Tafel slopes of 50 and 53 mV/dec for HER and OER, respectively. Long-term tests confirmed durability, and overall water splitting required only 1.59 V to reach 10 mA/cm 2 , underscoring its potential for scalable green hydrogen production.