LaNi1-xCoxO3 perovskites for application in electrochemical reactions involving molecular oxygen

LaNi1-xCoxO3 perovskite materials were synthesized by a sol-gel method for use in electrochemical reactions which involve molecular oxygen. The metal oxides were characterized by different physicochemical techniques and it was observed that the incorporation of Co induces some changes in the surface of the materials that affect the electrocatalytic activity. The different perovskite metal oxides were mixed with carbon black (Vulcan) to improve their electrocatalytic performance. The results from TPR and TPD techniques supported the XPS interpretation suggesting that a stronger interaction between carbon material and metal oxides can be obtained by physically mixing the two materials. This interaction improves the electron transfer and enhances the catalytic activity. Among the as-prepared materials, it was observed that the electrocatalytic performance of LaNi1-xCoxO3 perovskite/Vulcan materials is higher than that of LaNiO3/Vulcan for ORR, but similar towards OER. It is claimed that Co3+ is more catalytic for ORR, while Ni3+ favors the OER. Moreover, the presence of Co stimulates the formation of chemisorbed oxygen species, which also favor the electron transfer. Metal oxides containing both cations show higher stability, being this effect more notorious for OER. LaNi0.5Co0.5O3/Vulcan seems a suitable bifunctional catalyst for both electrochemical reactions.