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Reversible Structural Evolution of NiCoOxHy during the Oxygen Evolution Reaction and Identification of the Catalytically Active Phase
ACS Catalysis ( IF 11.3 ) Pub Date : 2018-01-17 00:00:00 , DOI: 10.1021/acscatal.7b03191 Zhu Chen 1 , Li Cai 2 , Xiaofang Yang 1 , Coleman Kronawitter 3 , Liejin Guo 2 , Shaohua Shen 2 , Bruce E. Koel 1
ACS Catalysis ( IF 11.3 ) Pub Date : 2018-01-17 00:00:00 , DOI: 10.1021/acscatal.7b03191 Zhu Chen 1 , Li Cai 2 , Xiaofang Yang 1 , Coleman Kronawitter 3 , Liejin Guo 2 , Shaohua Shen 2 , Bruce E. Koel 1
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Operando Raman spectroscopy and electrochemical techniques were used during the oxygen evolution reaction to identify the composition and local structure of electrodeposited CoOxHy and NiCoOxHy catalyst films. Before evaluation, the electrodeposited samples were subjected to a variety of thermal and electrochemical conditioning procedures, which generated unique initial catalyst structures and crystallinities. During oxygen evolution, Ni-modified CoOxHy films having lower initial crystallinity underwent substantial structural evolution that began with an irreversible transformation of a spinel local structure to an amorphous CoO structure at low anodic potentials (0.2 V vs Ag/AgCl). Increasing anodic polarization to greater than 0.3 V vs Ag/AgCl facilitated additional structural conversion from the amorphous CoO structure to a complex phase best described as an amalgamation of NiOOH and layered CoO2 motifs (NiOOH-h-CoO2) under elevated oxygen evolution rates. The formation of this NiOOH-h-CoO2 active structure was correlated with improved OER activity, which at 0.35 V overpotential is 100% greater than that of the catalyst where Ni was coordinated in a spinel structure. Independent of the initial cobalt oxide structure, the same NiOOH-h-CoO2 structure was formed during oxygen evolution, which suggests the active phase identified herein could be the universally active structure for NiCoOxHy materials.
中文翻译：
氧气析出反应过程中NiCoO x H y的可逆结构演变以及催化活性相的鉴定
在氧气逸出反应中使用Operando拉曼光谱和电化学技术来鉴定电沉积CoO x H y和NiCoO x H y催化剂膜的组成和局部结构。在评估之前，对电沉积的样品进行各种热和电化学调节程序，从而产生独特的初始催化剂结构和结晶度。在氧气逸出期间，Ni改性的CoO x H y具有较低初始结晶度的薄膜经历了显着的结构演化，该过程从尖晶石局部结构在低阳极电势（0.2 V对Ag / AgCl）的不可逆转变开始。与Ag / AgCl相比，将阳极极化增加至大于0.3 V有助于从非晶态CoO结构到复杂相的额外结构转换，这种相变最好描述为在较高的氧气逸出速率下NiOOH和层状CoO 2基序（NiOOH-h-CoO 2）的合并。NiOOH-h-CoO 2的形成活性结构与提高的OER活性相关，OER活性在0.35 V时比在尖晶石结构中配位Ni的催化剂大100％。与最初的氧化钴结构无关，在氧气析出过程中形成了相同的NiOOH-h-CoO 2结构，这表明本文确定的活性相可能是NiCoO x H y材料的通用活性结构。
更新日期：2018-01-17
中文翻译：
氧气析出反应过程中NiCoO x H y的可逆结构演变以及催化活性相的鉴定
在氧气逸出反应中使用Operando拉曼光谱和电化学技术来鉴定电沉积CoO x H y和NiCoO x H y催化剂膜的组成和局部结构。在评估之前，对电沉积的样品进行各种热和电化学调节程序，从而产生独特的初始催化剂结构和结晶度。在氧气逸出期间，Ni改性的CoO x H y具有较低初始结晶度的薄膜经历了显着的结构演化，该过程从尖晶石局部结构在低阳极电势（0.2 V对Ag / AgCl）的不可逆转变开始。与Ag / AgCl相比，将阳极极化增加至大于0.3 V有助于从非晶态CoO结构到复杂相的额外结构转换，这种相变最好描述为在较高的氧气逸出速率下NiOOH和层状CoO 2基序（NiOOH-h-CoO 2）的合并。NiOOH-h-CoO 2的形成活性结构与提高的OER活性相关，OER活性在0.35 V时比在尖晶石结构中配位Ni的催化剂大100％。与最初的氧化钴结构无关，在氧气析出过程中形成了相同的NiOOH-h-CoO 2结构，这表明本文确定的活性相可能是NiCoO x H y材料的通用活性结构。
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