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Direct Observation of Structural Evolution of Metal Chalcogenide in Electrocatalytic Water Oxidation

Ke FanState Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, P. R. ChinaHaiyuan ZouState Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, P. R. ChinaYue LuInstitute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124, P. R. ChinaHong ChenSSRL, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United StatesFusheng LiState Key Lab of Fine Chemicals, DUT-KTH Joint Education and Research Center on Molecular Devices, Dalian University of Technology, Dalian 116024, P. R. ChinaJinxuan LiuState Key Lab of Fine Chemicals, DUT-KTH Joint Education and Research Center on Molecular Devices, Dalian University of Technology, Dalian 116024, P. R. ChinaLicheng SunDepartment of Chemistry, KTH Royal Institute of Technology, 10044 Stockholm, SwedenLianpeng TongSchool of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou 510006, ChinaMichael F. ToneySSRL, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United StatesManling SuiInstitute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124, P. R. ChinaJiaguo YuState Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, P. R. China

2018en

ABI

Annotatsiya

As one of the most remarkable oxygen evolution reaction (OER) electrocatalysts, metal chalcogenides have been intensively reported during the past few decades because of their high OER activities. It has been reported that electron-chemical conversion of metal chalcogenides into oxides/hydroxides would take place after the OER. However, the transition mechanism of such unstable structures, as well as the real active sites and catalytic activity during the OER for these electrocatalysts, has not been understood yet; therefore a direct observation for the electrocatalytic water oxidation process, especially at nano or even angstrom scale, is urgently needed. In this research, by employing advanced Cs-corrected transmission electron microscopy (TEM), a step by step oxidational evolution of amorphous electrocatalyst CoSx into crystallized CoOOH in the OER has been in situ captured: irreversible conversion of CoSx to crystallized CoOOH is initiated on the surface of the electrocatalysts with a morphology change via Co(OH)2 intermediate during the OER measurement, where CoOOH is confirmed as the real active species. Besides, this transition process has also been confirmed by multiple applications of X-ray photoelectron spectroscopy (XPS), in situ Fourier-transform infrared spectroscopy (FTIR), and other ex situ technologies. Moreover, on the basis of this discovery, a high-efficiency electrocatalyst of a nitrogen-doped graphene foam (NGF) coated by CoSx has been explored through a thorough structure transformation of CoOOH. We believe this in situ and in-depth observation of structural evolution in the OER measurement can provide insights into the fundamental understanding of the mechanism for the OER catalysts, thus enabling the more rational design of low-cost and high-efficient electrocatalysts for water splitting.

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Identifikatorlar

DOI: 10.1021/acsnano.8b06312

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