Novel electrocatalysts for generating oxygen from alkaline water electrolysis

Abstract

We have obtained spinel-type Co3O4 and La-doped Co3O4 in the form of thin film on Ni, using microwave-assisted synthesis, which dramatically exhibit very low overpotentials for the oxygen evolution reaction (OER). Investigations have shown that at the apparent current density of 100 mA cm-2 in 1 mol dm-3 KOH at 25 °C, the new electrodes, Co3O4 (oxide loading = 3.4 ± 0.3 mg cm-2) and La-doped Co3O4 (oxide loading = 2.8 ± 0.4 mg cm-2), produce overpotentials, 235 ± 7 and 224 ± 8 mV, respectively. Such low overpotentials for the OER, to our knowledge, have not been found on any mixed oxide electrode material reported in literature till today. Small La addition improved the BET surface area and porosity of the oxide catalyst powder and reduced the charge transfer resistance for the OER on the electrode made of oxide powder. © 2007 Elsevier B.V. All rights reserved.