Enhancement of oxygen evolution reaction activity and durability of Ba0.5Sr0.5Co0.8Fe0.2O3-δ by CO2 thermal treatment

• 来源期刊: 材料科学技术（英文版）
• 年，卷（期）: 2019,（6）
• 页码范围: 1184-1191
• 页数: 8页
• 语种: 英文

摘要

This work demonstrates that in situ formation of carbonate layer on the surface of Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) obtained by exposure to CO2 during heating between 500 ℃ and 700 ℃ can provide enhanced oxygen evolution reaction (OER) performance and durability in an alkaline solution relative to the original BSCE Three temperatures,i.e.,500℃,600℃,and 700℃ were chosen to perform the CO2 thermal treatment,resulting into BSCF-500,BSCF-600,and BSCT-700 samples.The OER was enhanced in the order of BSCF-500 ＜ BSCF-700 ＜ BSCF-600.BSCF-600 showed the best OER performance,i.e.,a low overpotential of 0.36 V required to attain 10 mA cm-2 current density as well as a mass activity of 74.14 Ag-1cat and a specific activity of 5.04 mA cm-2cat at an overpotential of 0.4 V.The OER performance durability of BSCF-600 was highlighted by its ability to maintain a stable potential of around 1.61 V vs.RHE (RHE:reversible hydrogen electrode) when charged at a constant current density of 10 mA cm-2 throughout the 800 min continuous chronopotentiometry test.The enhanced OER performance for BSCF-600 relative to the original BSCF is attributed to three factors:(i) higher electrochemically active surface area;(ii) faster charge transfer rate and higher electrical conductivity;and (iii) modified oxidation state of cobalt ions.The formation of thin carbonate layer in BSCF-600 appears to suppress the durability issue observed in BSCF.