P-070

Ieva Barauskienė

ieva.barauskiene@ktu.lt

Eugenijus Valatka, Kristina Bočkutė, Titas Chimičius, Giedrius Laukaitis

Department of Physical and Inorganic Chemistry, Kaunas University of Technology, Kaunas, Lithuania

Copper-doped iron oxide coatings as efficient electrocatalysts for alkaline water electrolysis

Anion-exchange membrane (AEM) electrolysis, an emerging technology, utilizes abundant and inexpensive metals as catalysts, employs safer polymer membranes and a mildly alkaline (0.1-1 M) electrolyte, alleviating rapid corrosion. However, AEM faces challenges in achieving its full potential, particularly in oxygen evolution (OER) electrocatalysts, because of their sluggish kinetics and high overpotentials [1]. Recent discoveries highlight the catalytic OER activity of transition metal oxides (TMOs) or (oxy)hydroxides (TM-(O)OH), among which Fe oxides display low overpotentials, fast kinetics, excellent long-term durability, abundance, cost-effectiveness, and environmental adaptability [2]. Fe3O4 is a cubic inverse spinel structure with tetrahedral sites occupied by Fe3+ and octahedral sites occupied by Fe2+ or Fe3+ [3]. A spinel-type Fe-based oxide where Fe ions are partially replaced by other TM ions could offer a variety of oxidation states, good electric conductivity and optimal binding energies between active sites and OER intermediates. Copper, being a low-cost transition metal with a lower environmental impact and a variety of accessible oxidation states, has exceptional electrical conductivity. Cu-doping causes deformation of the metal lattice and produces additional defects, resulting in an increase in the number of active sites [4]. The reactive magnetron sputtering technique was used to obtain compact copper-doped iron oxide coatings. Structural studies revealed that the Cu content in the coatings ranges from 8 to 32 %. XRD results disclosed that the crystalline Fe3O4 is formed at lower Cu content which becomes more amorphous at higher Cu content. Electrocatalytical measurements have disclosed that although copper as a dopant does not significantly lower reaction initial overpotential, it enhances OER kinetics at commercially applied current densities.

References:

1. Cousins, I.T., Goldenman, G., Herzke, D., Lohmann, R., Miller, M., Ng, C.A., Patton, S., Scheringer, M., Trier, X., Vierke, L., Wang, Z., DeWittl, J.C. Environ. Sci. Process. Impacts 2019, 21, 1803–1815.

2.  Yu, M., Budiyanto, E., Tuysuz, H. Angew. Chem. Int. Ed. 2022, 61, e202103824.

3.  Zhao, Q., Yan, Z., Chen, C., Chen, J. Chem. Rev. 2017, 117, 10121-10211. 

4. Al-Naggar, A.H.; Shinde, N.M.; Kim, J.S.; Mane, R.S. Coord. Chem. Rev. 2023, 474, 214864.