CuxCo3−xO4 (0 ≤x < 1) nanoparticles for oxygen evolution in high performance alkaline exchange membrane water electrolysers

Cu incorporated Co3O4 (CuxCo3−xO4, 0 ≤ x < 1) nanoparticles were prepared using a thermal decomposition method. Properties of the CuxCo3−xO4, such as morphology, particle sizes, crystallite structure and cation distribution, were characterized with SEM, TEM, XRD and EDX. The CuxCo3−xO4 particles, with various x values, were found to be cubic spinel nanoparticles, with average size of 20–30 nm. Incorporation of Cu in the spinel lattice of Co3O4 shifted the Co3+/Co4+ redox peak as well as the onset point for OER to more negative potentials, which may be related to inversion of Cu2+ into the octahedral sites. Amongst all samples studied, Cu0.7Co2.3O4 was the most active for OER. The CuxCo3−xO4 electrodes exhibited satisfying stability during repetitive cyclic voltammetry. A membrane electrode assembly, using 3 mg cm−2 Cu0.7Co2.3O4 on the anode, demonstrated, in an alkaline membrane water electrolyser, a high current density performance of 1 A cm−2 at a voltage of 1.8 V in 1 mol dm−3 KOH at 25 °C.