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Surface reconstruction of NiCoP pre-catalysts for bifunctional water splitting in alkaline electrolyte
Electrochimica Acta ( IF 6.6 ) Pub Date : 2020-03-29 , DOI: 10.1016/j.electacta.2020.136114
Wenwen Zou , Congli Sun , Kangning Zhao , Jiantao Li , Xuelei Pan , Daixin Ye , Yanping Xie , Wangwang Xu , Hongbin Zhao , Lei Zhang , Jiujun Zhang

The emerging earth-abundant metal phosphides are regarded as promising bifunctional water splitting electrocatalysts. However, the real active sites in metal phosphides remain a debate. Herein, the hierarchical flower-like NiCoP microsphere is designed with the outstanding performance toward both hydrogen and oxygen evolution reaction (overpotentials of 238 and 47 mV for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) at 10 mA cm−2, respectively). The symmetrical overall water splitting devices based on NiCoP only require an ultralow voltage of 1.52 V to reach 10 mA cm−2, which is rarely reported. In-situ Raman and ex-situ TEM/XPS reveal that the surface reconstruction of designed NiCoP pre-catalysts transforms into metallic Ni(Co) for HER and Ni(Co)OOH for OER, respectively. The degradation process of HER during resting is revealed, suggesting the formation of high valence state Ni(Co)(OH)2 and blocking the active sites. We believe that the comprehensive understanding of the surface reconstruction of electrode is crucial in understanding the fundamental mechanism.



中文翻译:

碱性电解质中双功能水分解的NiCoP预催化剂的表面重建

新兴的富含地球的金属磷化物被认为是很有前途的双功能水分解电催化剂。然而,金属磷化物中的真正活性位仍然是一个争论。在此,分层花状NiCoP微球的设计具有出色的抗氢气和氧气逸出反应的性能(氧气逸出反应(OER)和氢气逸出反应(HER)在10 mA cm -2时的过电位分别为238和47 mV ,分别)。基于NiCoP的对称整体分水装置仅需要1.52 V的超低电压即可达到10 mA cm -2,这鲜有报道。原位拉曼和异位TEM / XPS结果表明,所设计的NiCoP预催化剂的表面重构分别转化为金属化的HER(金属)Ni(Co)和OER的金属Ni(Co)OOH。揭示了HER在休息过程中的降解过程,表明高价态Ni(Co)(OH)2的形成并阻断了活性位点。我们认为,全面了解电极的表面重建对于了解基本机理至关重要。

更新日期:2020-04-20
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