The Electrochemical Performance of Co3O4 Electrodes with Platinum Nanoparticles for Chlorine Evolution

Different morphologies of cobalt oxide (Co3O4) electrodes were prepared through the electrochemical deposition technique with various electrodeposition times from 10 min to 50 min. Platinum (Pt) nanoparticles were deposited on the Co3O4 electrodes through sputter coating. The crystallographic, microstructural, surface functional, textural–structural, and electric properties of the Co3O4 electrodes were investigated. X-ray diffraction analysis identified a pure cubic Co3O4 crystal structure in the samples. In the electrodeposition process, the microstructure of the electrodes varied from hierarchical 3D flower-like to 2D hexagonal porous nanoplates due to an increase in oxygen vacancies. The carrier densities of all samples were between 5.77 × 1014 cm−3 and 8.77 × 1014 cm−3. The flat band potentials of all samples were between −5.91 V and −6.21 V vs. an absolute electron potential, and the potential values for electrodes became more positive as the oxygen vacancy concentration in the film structure increased. The 2D hexagonal porous nanoplate Pt/Co3O4 electrodes offered the highest oxygen vacancies and thus the maximum current density of 102.66 mA/cm2, with an external potential set at 1.5 V vs. an Ag/AgCl reference electrode.