Effects of size and crystallinity of CaCu3Fe4O12 on catalytic activity for oxygen evolution reaction

Abstract

Effects of size and crystallinity of a quadruple perovskite oxide, CaCu3Fe4O12, were investigated for its catalytic activity for the oxygen evolution reaction (OER). Pristine CaCu3Fe4O12 powder sample was synthesized under high-pressure and high-temperature conditions of 8 GPa and 1000°C, and a portion was treated by ball milling for 120 min to obtain a powder sample with smaller particle size. The specific surface area significantly increased from 0.38 to 10.30 m2g11 by ball-milling, leading to increased OER activity. However, it was found that the milling did not improve the OER activity efficiency in proportion to that expected from the increase in specific surface area as determined by Brunauer-Emmett-Teller analysis of adsorption/desorption isotherms measured with nitrogen gas because the crystallinity was lowered by ball milling, which suppressed the catalytic activity. This study provides important information on how to achieve the best OER catalytic performance in terms of both size and crystallinity. [doi:10.2320/matertrans.MT-M2020147]