Optimal cobalt-based catalyst containing high-ratio of oxygen vacancy synthesized from metal-organic-framework (MOF) for oxygen evolution reaction (OER) enhancement
Taeoh Kang, Jooheon Kim
Abstract
Oxygen evolution reaction (OER) is a significant reaction in metal-air battery and water splitting. Commonly, noble metals, which are expensive and less stable, have been used as catalysts for OER due to their high catalytic activity. To replace the noble metal catalyst, 3d transition metal-based materials, which are relatively inexpensive and have adequate catalytic activity, have been widely studied as promising candidates for OER catalysts. However, their moderate OER performance presents an obstacle for practical application. The introduction of oxygen vacancies is an effective way to tune the various properties of catalysts, which, in turn, can enhance the catalytic activity. Here, we manufacture cobalt-based catalysts with high ratios of oxygen vacancy from metal-organic framework (MOF) materials. Depending on the amount of treated-hexamethylenetetramine (HMT), the cobalt-based catalysts exhibit various morphologies, compositions, and ratios of oxygen vacancy. The optimal cobalt-based catalyst (300-h/Co/CC) shows significantly enhanced OER performance with a low overpotential of 280 mV at current density of 10 mA cm−2. This work presents a new approach to synthesize catalysts with high ratios of oxygen vacancy from MOF.