In Situ Phase Transformation on Nickel-Based Selenides for Enhanced Hydrogen Evolution Reaction in Alkaline Medium

Lingling Zhai, Tsz Woon Benedict Lo, Zhenglong Xu, Jonathan Potter, Jiaying Mo, Xuyun Guo, Chiu Chung Tang, Shik Chi Tsang, Shu Ping Lau (Corresponding Author)

Research output: Journal article publicationJournal articleAcademic researchpeer-review

Abstract

Identification of the active species in electrocatalysts toward hydrogen evolution reaction (HER) is of great significance for the development of the catalytic industry; however, it is still the subject of considerable controversy. Herein, we applied operando synchrotron X-ray powder diffraction (SXRD) in the NiSe2 electrocatalyst system, and an in situ phase transformation from cubic NiSe2 to hexagonal NiSe was revealed. The NiSe phase showed an enhanced catalytic activity. Operando Raman spectroscopy verified the decomposition of NiSe2 during HER. Theoretical calculations suggested that the charge transfers from the Se site to Ni site during this evolution process, leading to an increased conductivity and a shifting up of d-band center, which is attributed to the enhanced activity. The generated NiSe phase acts as the “real” active species. Our work unravels the underlying phase transition of the electrocatalyst on reductive conditions in alkaline medium and highlights the significance of identifying the intrinsic active sites under realistic reaction conditions.
Original languageEnglish
Pages (from-to)2483-2491
JournalACS Energy Letters
Volume5
Issue number8
DOIs
Publication statusPublished - 14 Aug 2020

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