Tunable metal hydroxide–organic frameworks for catalysing oxygen evolution

Shuai Yuan，

Jiayu Peng，

Bin Cai，

Zhehao Huang，

Angel T． Garcia－Esparza，

Dimosthenis Sokaras，

Yirui Zhang，

Livia Giordano，

Karthik Akkiraju，

Yun Guang Zhu，

René Hübner，

Xiaodong Zou，

Yuriy Román－Leshkov＆

Yang Shao－Horn

Abstract

The oxygen evolution reaction is central to making chemicals and energy carriers using electrons． Combining the great tunability of enzymatic systems with known oxide－based catalysts can create breakthrough opportunities to achieve both high activity and stability． Here we report a series of metal hydroxide–organic frameworks （MHOFs） synthesized by transforming layered hydroxides into two－dimensional sheets crosslinked using aromatic carboxylate linkers． MHOFs act as a tunable catalytic platform for the oxygen evolution reaction， where the π–π interactions between adjacent stacked linkers dictate stability， while the nature of transition metals in the hydroxides modulates catalytic activity． Substituting Ni－based MHOFs with acidic cations or electron－withdrawing linkers enhances oxygen evolution reaction activity by over three orders of magnitude per metal site， with Fe substitution achieving a mass activity of 80 A g−1catalyst at 0．3 V overpotential for 20 h． Density functional theory calculations correlate the enhanced oxygen evolution reaction activity with the MHOF－based modulation of Ni redox and the optimized binding of oxygenated intermediates．

LDH又称层状双金属氢氧化物（Layered Double Hydroxide），是水滑石（Hydrotalcite，HT）和类水滑石化合物（Hydrotalcite－Like Compounds，HTLCs）的统称，由这些化合物插层组装的一系列超分子材料称为水滑石类插层材料（LDHs）。

这是综述和网上的介绍文字，对层状金属氢氧化物进行插层操作是个很有趣的方向。但是插层操作一般都是如上图的插入方法。插入过程是这样的。

形貌是这样的

而这文章中的层状结构，

这个不叫插层材料，金属和配体有了更复杂的相互作用。沿用了MOF Metal－Organic Frameworks的名称，叫

metal hydroxide–organic frameworks。

就像原文中说的，专业的解释

外暴露的生长的表面发生了改变，不是常规意义的金属氧化物的面，而是既有金属也有有机分子。

有机物L4是这个

为啥用L4？因为其它类型的配体容易掉出来。

掺杂了铁以后的催化剂这样

有DFT加持后的催化剂不同层之间是这样的。

对标来了

TOF是指每个活性位的催化转化能力，相比于贵金属提升了一到两个数量级。

文中有个地方没搞明白，

如果

在下图中的片状结构中e插图的电镜感觉是沿c轴拍摄（择优取向现象），但原文却说

沿a轴拍摄的Ni2（OH）2（L4）（图1f）的高分辨率透射电子显微镜（HR－TEM）图像与沿同一方向投射的原子排列（图1f插图）相匹配。

Yuriy Román

Professor Yuriy Román is from Mexico City， Mexico． He earned his B．S．E． in Chemical Engineering from the University of Pennsylvania in 2002． After working in industry for a year， Prof． Román moved to Madison， WI to pursue graduate studies．  He received his Ph．D． in Chemical and Biological Engineering from the University of Wisconsin－Madison in 2008， working under the supervision of Professor James A． Dumesic．  His thesis work involved the catalytic conversion of carbohydrates obtained from lignocellulosic biomass into chemical intermediates used for the production of biofuels and biomaterials． He then moved to the California Institute of Technology to do postdoctoral research in the synthesis and characterization of microporous and mesoporous materials in the group of Professor Mark E． Davis． There， he investigated the synthesis and implementation of  microporous Lewis and Brønsted solid acids for the isomerization of carbohydrates and production of acetic acid from methanol．