A facile strategy to construct CoO_x in situ embedded nanoflowers as an efficient electrocatalyst for oxygen evolution reaction

With a growing demand for clean and renewable energy associated with water splitting, regenerative fuel cells, metal-air batteries, etc., exploring an efficient and cost-effective electrocatalyst with superior durability for oxygen evolution reaction (OER) is of great significance. In this study, a unique CoO_x embedded nanoflower microstructure (Co_0.6-PyNa) has been synthesized via an extremely facile one-step, highly scalable aqueous method under mild conditions, by using Co(COOH)₂ as the precursor and pyrrole as the structure-directing agent. The Co_0.6-PyNa exhibits the excellent electrocatalytic activity toward OER in 1 M KOH solution with an overpotential of as low as 299 mV and a small Tafel slope of 67 mV dec⁻¹, which is comparable to the commercial RuO₂, along with superior operational stability to RuO₂. The high OER catalytic performance of Co_0.6-PyNa has been reasoned to originate from the exposure of abundant CoO_x active species uniformly dispersed on the nanoflakes due to its high specific surface area and the intrinsic extraordinarily high activity of CoO_x active species. This work provides a promising strategy to fabricate efficient, stable and low-cost OER electrocatalyst, which is expected to promote the development of OER-related energy storage and conversion technologies.