Hierarchical Nanoassembly of MoS2/Co9S8/Ni3S2/Ni as a Highly Efficient Electrocatalyst for Overall Water Splitting in a Wide pH Range

Yan Yang; Huiqin Yao; Zihuan Yu; Saiful M Islam; Haiying He; Mengwei Yuan; Yonghai Yue; Kang Xu; Weichang Hao; Genban Sun; Huifeng Li; Shulan Ma; Peter Zapol; Mercouri G Kanatzidis

doi:10.1021/jacs.9b04492

Hierarchical Nanoassembly of MoS₂/Co₉S₈/Ni₃S₂/Ni as a Highly Efficient Electrocatalyst for Overall Water Splitting in a Wide pH Range

J Am Chem Soc. 2019 Jul 3;141(26):10417-10430. doi: 10.1021/jacs.9b04492. Epub 2019 Jun 22.

Authors

Yan Yang¹, Huiqin Yao², Zihuan Yu¹, Saiful M Islam^{3

4}, Haiying He⁵, Mengwei Yuan¹, Yonghai Yue⁶, Kang Xu⁶, Weichang Hao⁶, Genban Sun¹, Huifeng Li¹, Shulan Ma^{1

3}, Peter Zapol⁷, Mercouri G Kanatzidis^{3

7}

Affiliations

¹ Beijing Key Laboratory of Energy Conversion and Storage Materials and College of Chemistry , Beijing Normal University , Beijing 100875 , China.
² School of Basic Medical Sciences , Ningxia Medical University , Yinchuan 750004 , China.
³ Department of Chemistry , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , United States.
⁴ Department of Chemistry, Physics and Atmospheric Sciences , Jackson State University , Jackson , Mississippi 39217 , United States.
⁵ Department of Physics and Astronomy , Valparaiso University , Valparaiso , Indiana 46383 , United States.
⁶ School of Physics and School of Chemistry , Beihang University , Beijing 100191 , China.
⁷ Materials Science Division , Argonne National Laboratory , Lemont , Illinois 60439 , United States.

PMID: 31244177
DOI: 10.1021/jacs.9b04492

Abstract

The design of low-cost yet high-efficiency electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) over a wide pH range is highly challenging. We now report a hierarchical co-assembly of interacting MoS₂ and Co₉S₈ nanosheets attached on Ni₃S₂ nanorod arrays which are supported on nickel foam (NF). This tiered structure endows high performance toward HER and OER over a very broad pH range. By adjusting the molar ratio of the Co:Mo precursors, we have created CoMoNiS-NF- xy composites ( x: y means Co:Mo molar ratios ranging from 5:1 to 1:3) with controllable morphology and composition. The three-dimensional composites have an abundance of active sites capable of universal pH catalytic HER and OER activity. The CoMoNiS-NF-31 demonstrates the best electrocatalytic activity, giving ultralow overpotentials (113, 103, and 117 mV for HER and 166, 228, and 405 mV for OER) to achieve a current density of 10 mA cm^-2 in alkaline, acidic, and neutral electrolytes, respectively. It also shows a remarkable balance between electrocatalytic activity and stability. Based on the distinguished catalytic performance of CoMoNiS-NF-31 toward HER and OER, we demonstrate a two-electrode electrolyzer performing water electrolysis over a wide pH range, with low cell voltages of 1.54, 1.45, and 1.80 V at 10 mA cm^-2 in alkaline, acidic, and neutral media, respectively. First-principles calculations suggest that the high OER activity arises from electron transfer from Co₉S₈ to MoS₂ at the interface, which alters the binding energies of adsorbed species and decreases overpotentials. Our results demonstrate that hierarchical metal sulfides can serve as highly efficient all-pH (pH = 0-14) electrocatalysts for overall water splitting.