Reduced graphene oxide encapsulated perovskite-type lanthanum cobalt oxide nanoparticles for efficient electrolysis of water to oxygen reactions (OER/ORR)

Abstract

Developing high-performance non-precious electro-catalysts for water splitting reactions is important for energy conversion applications. In this study, reduced graphene oxide encapsulated perovskite-type lanthanum cobalt oxide nanoparticles (LaCoO3@rGO) have been fabricated as highly efficient electro-catalysts by ultra-sonication process for electrochemical oxygen evolution and reduction reactions (OER/ORR) in O2 – saturated alkaline medium (1.0 M KOH). The characterization techniques indicated that the targeted materials were formed with controlled support by rGO sheets to the nanoparticles. The LaCoO3@rGO nanocomposites show improved electro-catalytic performance to OER with lower over-potential (280 mV at ƞ10) and Tafel slopes (104 mV/dec) compared with pure LaCoO3 electro-catalyst. The electro-chemical ORR reactions of the prepared electrodes were monitored by the rotating disk electrode (RDE) measurements. The LaCoO3@rGO electro-catalyst shows 4e- system in ORR at all potentials (i.e. from 0.2 V to 0.5 V), while LaCoO3 electro-catalyst shows 4e- system only at low potentials (i.e. 0.2 V and 0.3 V). Moreover, the stability of the electrodes was also tested by the chronoamperometry (CA) and cyclic stability measurements for the commercial purpose. Our research will open new windows for developing the non-precious electro-catalysts in clean energy applications.