SrCoO3-δ and SrCo1-xTixO3-δ perovskites as electrocatalytic materials for oxygen evolution reaction in alkaline environment

Abstract

Here, we report the deposition of SrCoO3-δ perovskites thin films by chemical bath deposition, employed as electrocatalytic layers for oxygen evolution reaction (OER) in alkaline water splitting. The effect of Co excess and Ti-doping on the crystalline structure, composition and electrochemical performances was investigated. The former had effect only on electrochemical performance whilst Ti-doping, above 3 %, induced the formation of a secondary phase. Among all the investigated samples, SrCoO3-δ:Co3O4 (SCO:CB) sample showed the best electrochemical performance toward OER in 1 M KOH aqueous solution, reporting an onset overpotential, ηonset, of 284 mV and a Tafel slope of 59 mV dec−1. In contrast, Ti-doping (i.e. 3 %, SCT:CB 3 sample) drastically improved stability of the electrocatalytic layer, enabling 24 h of continuous operation, demonstrating the effectiveness of doping strategy to enhance SrCoO3-δ perovskites durability. XPS analyses revealed that degradation of electrochemical performance of thin films is related to Sr leaching, even if Ti-doping decreased leached Sr amount improving layers stability.