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Abstract

The influence of iron on nanocasting of cobalt oxide nanowires and the performance of these materials for the oxygen evolution reaction (OER) are investigated. Pristine Co₃O₄ and mixed cobalt iron oxide nanowires with a diameter of 7 nm have been synthesized via a nanocasting route by using SBA-15 silica as a template. A small amount of iron added during the synthesis results in a decrease in the nanowires’ array length and induces the formation of a bimodal pore size distribution. Raman spectroscopy, X-ray emission, and high-energy resolution X-ray absorption spectroscopies further show that Fe incorporation alters the electronic structure by increasing the average distortion around the cobalt centers and the amount of Co²⁺ in tetrahedral sites. These affect the OER activity significantly; the overpotential of pristine Co₃O₄ at 10 mA/cm² decreases from 398 to 378 mV, and the current density at 1.7 V increases from 107 to 150 mA/cm² with the addition of iron at the Co/Fe atomic ratio of 32. Furthermore, post-reaction characterization confirmed that both the morphology and electronic structure of nanowires remain intact after a long-term stability test.