Abstract
Computational calculations and experimental studies reveal that the CoOOH phase and the intermediate-spin (IS) state are the key factors for realizing efficient Co-based electrocatalysts for the oxygen evolution reaction (OER). However, according to thermodynamics, general cobalt oxide converts to the CoO2 phase under OER condition, retarding the OER kinetics. Herein, we demonstrate a simple and scalable strategy to fabricate electrodes with maintaining Fe-CoOOH phase and an IS state under the OER. The changes of phase and spin states were uncovered by combining in-situ/operando X-ray based absorption spectroscopy and Raman spectroscopy. Electrochemical reconstruction of chalcogenide treated Co foam affords a highly enlarged active surface that conferred excellent catalytic activity and stability in a large-scale water electrolyzer. Our findings are meaningful in that the calculated results were experimentally verified through the operando analyses. It also proposes a new strategy for electrode fabrication and confirms the importance of real active phases and spin states under a particular reaction condition.
Highlights
Computational calculations and experimental studies reveal that the CoOOH phase and the intermediate-spin (IS) state are the key factors for realizing efficient Co-based electrocatalysts for the oxygen evolution reaction (OER)
X-ray photoelectron spectroscopy (XPS) spectrum suggested that Co and S were present at an atomic ratio of 1:1.74
After the S and Fe treatment, electrochemical reconstruction was performed under OER conditions to produce CFFeSO
Summary
Computational calculations and experimental studies reveal that the CoOOH phase and the intermediate-spin (IS) state are the key factors for realizing efficient Co-based electrocatalysts for the oxygen evolution reaction (OER). We proposed a simple and scalable strategy to convert a cobalt foam (CF) electrode into a highly active catalyst for the OER through sulfur and iron treatment with the goal of maintaining the CoOOH phase and IS state of the Co-based electrode under OER conditions. The Fe-CoOOH electrode for the OER was fabricated by the surface reconstruction strategy under alkaline OER conditions by treating the raw CF with iron and sulfur (Fig. 1a).
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