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Iridium nanohollows with porous walls for acidic water splitting
Journal of Materials Chemistry A ( IF 10.7 ) Pub Date : 2022-07-11 , DOI: 10.1039/d2ta02193e
Xiaobing Bao 1 , Sijia Li 1 , Chentao Hao 1 , Yifan Qin 1 , Yutong Gong 1 , Yong Yang 1 , Aoni Xu 2 , Mingchuan Luo 3
Affiliation  

Engineering iridium (Ir)-based electrocatalysts towards high activity and satisfactory durability for the oxygen evolution reaction (OER) in acidic media has been long pursued to commercialize proton exchange membrane-based electrolyzers. Here we report a novel class of Ir porous nanohollows (p-NHs) with tunable wall thickness, which electrocatalyze acidic OER with much enhanced performance relative to conventional Ir nanoparticles. The p-NH structure is deliberately-tailored via a facile hydrothermal approach, in which the initially-formed solid Ir spheres were in situ etched via the Kirkendall effect. At an overpotential of 300 mV, the Ir p-NH catalyst delivers a mass activity of 1.75 A mgIr−1, which is 6.25 and 3.20 times higher than those of commercial Ir/C and control Ir solid nanosphere catalysts, respectively. Ir p-NHs as an anode enable voltages of 1.50 V and 1.59 V at 10 and 100 mA cm−2, respectively, for acidic water splitting. We explore how porosity energetically promotes OER activity of Ir-based catalysts using density functional theory (DFT) calculations, which reveal that the adsorption of *OOH and thus OER activity can be described by the generalized coordination number of surface Ir sites. Our findings offer new insights into the rational design of highly-open Ir-based nanostructures for efficient OER electrocatalysis.

中文翻译:

具有多孔壁的铱纳米空心用于酸性水分解

长期以来,人们一直致力于将基于铱 (Ir) 的电催化剂设计为在酸性介质中的析氧反应 (OER) 具有高活性和令人满意的耐久性,以实现基于质子交换膜的电解槽的商业化。在这里,我们报告了一种新型的具有可调壁厚的 Ir 多孔纳米空心 (p-NHs),其电催化酸性 OER,相对于传统的 Ir 纳米粒子具有更高的性能。p-NH 结构是通过一种简便的水热方法特意定制的,其中最初形成的固体 Ir 球通过柯肯达尔效应进行原位蚀刻。在 300 mV 的过电位下,Ir p-NH 催化剂的质量活性为 1.75 A mg Ir -1,分别是商业 Ir/C 和对照 Ir 固体纳米球催化剂的 6.25 倍和 3.20 倍。Ir p-NHs 作为阳极在 10 和 100 mA cm -2下分别实现了 1.50 V 和 1.59 V 的电压,用于酸性水分解。我们使用密度泛函理论 (DFT) 计算探索孔隙率如何大力促进基于 Ir 的催化剂的 OER 活性,这表明*OOH 的吸附和 OER 活性可以通过表面 Ir 位点的广义配位数来描述。我们的研究结果为合理设计用于高效 OER 电催化的高度开放的 Ir 基纳米结构提供了新的见解。
更新日期:2022-07-11
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