LAUSR

The development of low-cost, highly efficient and stable electrocatalysts for the oxygen evolution reaction (OER) is of great significance for many promising energy storage and conversion applications, including metal-air batteries and water splitting technology. Here we report a layer-structured Ca0.5CoO2 nanofibers composed of interconnected ultrathin nanoplates, synthesized using an electrospinning process. The OER activity of Ca0.5CoO2 can be dramatically improved by iron doping, and the overpotential of Ca0.5Co1-xFexO2 (x = 0.25) is only 346 mV at a current density of 10 mA cm-2. The mass activity and intrinsic activity of Ca0.5Co0.75Fe0.25O2 at 1.6 V are, respectively, ∼18.7 and ∼11.4 times higher than those of Ca0.5CoO2. Iron doping modifies the electronic structure of Ca0.5CoO2, resulting in partial oxidation of the surface cobalt and increased amount of highly oxidative species (O22-/O2). Consequently, Ca0.5Co0.75Fe0.25O2 nanofibers with tuned electronic states have shown great potential as cost-effective and efficient electrocatalysts for OER.