Strong Co–Mo Interaction behind Unexpected Physicochemical Properties in SrMo_0.9Co_0.1O_3−δ Perovskite

Abstract

A novel combined chemical procedure was employed to synthesize a homogeneous SrMo0.9Co0.1O3−δ (SMC) perovskite at lower temperatures (900 °C). The physicochemical properties of SMC were analyzed by means of in situ X-ray diffraction and X-ray absorption spectroscopy experiments under reducing and oxidizing conditions from 20 to 700 °C. The study revealed a strong interaction between Mo and Co cations in the SMC perovskite, which led to their unexpected oxidation number speciation and a critical modification of their first coordination shell. Perovskite-like unit cells containing Co in their center can drastically increase the occupation number of oxygen anions, enhancing SMC oxygen storage capability. Under reducing conditions, these loosely bonded anions were easily released from the material to chemically react with H2 in the gas phase. These findings bring novel insights into the physicochemical processes that take place in SMC materials and give rise to the catalytic and electrochemical activity that makes this material a candidate for intermediate temperature-SOFC anode application.