OER catalyst fabricated with ZIF-67 derived carbon and selectively exsolvated perovskite oxide

Abstract

Perovskite oxide (ABO3) is a potential oxygen evolution reaction (OER) electrocatalyst, and its B-site is generally regarded as the active center. However, perovskite oxides suffer from poor conductivity and insufficient active sites due to severe calcination during high-temperature synthesis. To address these issues, we started from a well-demonstrated OER catalyst Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) and developed an approach to load abundant active sites with the exsolution of CoFe nanoparticles from parent phase BSCF. During this process, ZIF-67 has been used as the carbon source to generate highly conductive network of cobalt-doped carbon and further fabricated as BSCF/ZIF(67)-650 composite. Such hybrid catalyst exhibits an overpotential of 285 mV at current density of 10 mA cm−2 and a minor Tafel slope of 40 mV dec−1 in 1 M KOH alkaline solution. The remarkably enhanced activity is attributed to the increment of active sites, oxygen vacancies and excellent conductivity. Importantly, such OER performance shows excellent stability for 200 h operation.