Ultrahigh-current-density niobium disulfide catalysts for hydrogen evolution.

Author(s) Yang, J.; Mohmad, A.Rahman; Wang, Y.; Fullon, R.; Song, X.; Zhao, F.; Bozkurt, I.; Augustin, M.; Santos, E.J.G.; Shin, H.Suk; Zhang, W.; Voiry, D.; Jeong, H.Young; Chhowalla, M.
Journal Nat Mater
Date Published 2019 12
Abstract

Metallic transition metal dichalcogenides (TMDs) are good catalysts for the hydrogen evolution reaction (HER). The overpotential and Tafel slope values of metallic phases and edges of two-dimensional (2D) TMDs approach those of Pt. However, the overall current density of 2D TMD catalysts remains orders of magnitude lower (~10-100 mA cm) than industrial Pt and Ir electrolysers (>1,000 mA cm). Here, we report the synthesis of the metallic 2H phase of niobium disulfide with additional niobium (2H NbS, where x is ~0.35) as a HER catalyst with current densities of >5,000 mA cm at ~420 mV versus a reversible hydrogen electrode. We find the exchange current density at 0 V for 2H NbS to be ~0.8 mA cm, corresponding to a turnover frequency of ~0.2 s. We demonstrate an electrolyser based on a 2H NbS cathode that can generate current densities of 1,000 mA cm. Our theoretical results reveal that 2H NbS with Nb-terminated surface has free energy for hydrogen adsorption that is close to thermoneutral, facilitating HER. Therefore, 2H NbS could be a viable catalyst for practical electrolysers.

DOI 10.1038/s41563-019-0463-8
ISSN 1476-1122
Citation Nat Mater. 2019;18(12):13091314.

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