Porous lanthanum cobaltite (LaCoO3) was prepared by hydrothermal reaction and converted into hollow nanospheres through heat treatment. These hollow spheres were examined as electrocatalysts toward oxygen evolution reaction (OER) using the rotating disk electrode technique in an alkaline solution. The obtained mass-specific OER activity was 7.51 A/g for porous LaCoO3 particles and 12.58 A/g for hollow LaCoO3 nanospheres at 1.60 V. These values were more than 4–6 times higher than that of bulk LaCoO3 compound (1.87 A/g). The OER performance of these perovskite-type LaCoO3 compounds was characterized using the Tafel equation, which showed the hollow nanospheres had the fastest kinetics among the three morphologies. The amorphous surface of these porous structures could contribute to the enhanced OER performance. The electrocatalytic and structural analysis results show the porous nanostructures with amorphous surface layers are important to achieve high activity toward OER for water splitting.

Sluggish kinetic of oxygen redox reactions, namely, oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is often a main reason for the low efficiency of oxygen electrocatalysts. It hinders the wide-spread applications of renewable energy conversion devices. For those electrocatalysts that are made of transition metal oxides, poor electrical conductivity further compounds the problem. In this study, we show a strategy, in which low level of dopants is used to increase the electrical conductivity of both perovskite CaMnO3 and reduced, oxygen-deficient perovskite CaMnO2.5 electrocatalysts. Introduction of tungsten cation to replace B-site manganese up to 3% in CaMn1-xWxOy (x = <0.03; y = 2.5 and 3) results in enhanced ORR and OER performance, due to the increase of electrical conductivity of these oxide catalysts via double-exchange mechanism. The concept of using low-level dopants to increase the electrical conductivity, thus the activity, should be a quite useful strategy for designing the transition metal oxide electrocatalysts for enhanced performance in OER and ORR.