Synthesis of hierarchical transition metal oxyhydroxides in aqueous solution at ambient temperature and their application as OER electrocatalysts
Synthesis of hierarchical transition metal oxyhydroxides in aqueous solution at ambient temperature and their application as OER electrocatalysts
复制标题
DOI：
10.1016/j.jechem.2022.02.042
复制
发表时间：
2022-08-01
影响因子：
13.1
通讯作者：
Coelfen, Helmut
中科院分区：
文献类型：
--
作者：
Chen, Zongkun;Wang, Xingkun;Coelfen, Helmut
第一排（3d）过渡金属氢氧化物由于其各种优点而引起越来越多的关注。尽管研究氧化机制和将这些材料加工成分级结构对于它们的进一步发展是非常期望的，但仍然不清楚氧化态变化是如何发生的，并且生产符合高生态和经济标准的分级羟基氧化物的努力进展缓慢。在这里，我们描述了一个简单的一步共沉淀路线，用于制备分级CoOOH，NiOOH和MnOOH，其中包括扩散的NH3源自氢氧化铵溶液到含有金属离子盐和K2 S2 O 8的水溶液中。通过扫描电子显微镜、透射电子显微镜、X射线衍射分析、X射线光电子能谱、紫外-可见光谱和原位pH测量等综合表征表明，K2 S2 O 8诱导水解开始后金属离子物种的氧化态发生变化。同时，我们发现，受益于由NH3扩散方法产生的OH-浓度梯度和K2 S2 O 8的存在提供的合适的生长环境（高成核速率和二次成核），可以在环境温度下在水溶液中实现分级羟基氧化物结构的形成，而无需使用热能和额外的结构导向剂。的分级CoOOH结构作为析氧反应在碱性介质中，表现出良好的活性与320 mV的过电位在10 mA cm-2和低塔菲尔斜率为59.6 mV dec-1，优于许多同类电催化剂的电催化剂。总体而言，我们的研究不仅提供了重要的见解，了解层次羟基氧化物的形成机制，但也开辟了新的机会，通过一个简单的，绿色和低成本的方法制备层次羟基氧化物。(c)2022科学出版社、中国科学院大连化学物理研究所。由ELSEVIER B. V.和科学出版社出版。All rights reserved.
First-row (3d) transition metal oxyhydroxides have attracted increasing attention due to their various advantages. Although investigating the oxidation mechanism and processing such materials into hierarchical architectures are greatly desired for their further development, it remains unclear how the oxidation state change occurs, and efforts to produce hierarchical oxyhydroxides in compliance with high ecological and economic standards have progressed slowly. Here, we describe a facile one-step coprecipitation route for the preparation of hierarchical CoOOH, NiOOH and MnOOH, which involves the diffusion of NH3 originating from ammonium hydroxide solution into an aqueous solution containing metal ion salts and K2S2O8. Comprehensive characterizations by scanning electron microscope, transmission electron microscopy, X-ray diffraction analysis, X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy and in situ pH measurement demonstrated that K2S2O8 induces the oxidation state change of metal ion species after the start of hydrolysis. Meanwhile, it was found that, benefiting from the OH- concentration gradient created by the NH3 diffusion method and the suitable growth environment provided by the presence of K2S2O8 (high nucleation rate and secondary nucleation), the formation of hierarchical oxyhydroxide structures can be realized in aqueous solution at ambient temperature without the use of heat energy and additional structure-directing agents. The hierarchical CoOOH structures are performed as the electrocatalysts for the oxygen evolution reaction in alkaline media, which exhibit good activity with an overpotential of 320 mV at 10 mA cm-2 and a low Tafel slope of 59.6 mV dec-1, outperforming many congeneric electrocatalysts. Overall, our study not only provides important insights to understand the formation mechanism of hierarchical oxyhydroxides, but also opens up new opportunities for the preparation of hierarchical oxyhydroxides via a facile, green and low-cost method. (c) 2022 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.