Hollandite Structure Kx≈0.25IrO2 Catalyst with Highly Efficient Oxygen Evolution Reaction

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• 作者：Wei Sun ; Ya Song ; Xue-Qing Gong ; Li-mei Cao ; Ji Yang
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：January 13, 2016
• 年：2016
• 卷：8
• 期：1
• 页码：820-826
• 全文大小：615K
• ISSN：1944-8252

文摘

Oxygen evolution reaction (OER) catalysts with high activity are of particular importance for renewable energy production and storage. Here, we prepare K_x≈0.25IrO₂ catalyst that exhibits an excellent OER activity compared to IrO₂, which is univerally acknoweledged as a state-of-the-art OER catalyst. The prepared catalyst reflects a small overpotential 0.35 V at a current density of 10 mA cm^–2 and a lower Tafel slope (65 mV dec^–1) compared to that for IrO₂ (74 mV dec^–1). The performed X-ray photoelectron spectroscopy (XPS) and X-ray adsorption (XAS) experiments indicate that the Ir-site of K_x≈0.25IrO₂ has a lower valence and more Ir-5d occupied states, suggesting more electrons on the Ir site. The extra electrons located on the Ir site and distorted IrO₆ octahedral symmetry have a significant effect on the 5d orbital energy distribution which is verified by our DOS calculation. The performed DFT calculations state that the K_x≈0.25IrO₂ essentially obtains good OER performance because it has a lower theoretical overpotential (0.50 V) compared to IrO₂ (0.61 V).