Activating and optimizing MoS2 basal planes for hydrogen evolution through the formation of strained sulphur vacancies

Hong Li; Charlie Tsai; Ai Leen Koh; Lili Cai; Alex W Contryman; Alex H Fragapane; Jiheng Zhao; Hyun Soon Han; Hari C Manoharan; Frank Abild-Pedersen; Jens K Nørskov; Xiaolin Zheng

doi:10.1038/nmat4465

Activating and optimizing MoS2 basal planes for hydrogen evolution through the formation of strained sulphur vacancies

Nat Mater. 2016 Jan;15(1):48-53. doi: 10.1038/nmat4465. Epub 2015 Nov 9.

Authors

Hong Li¹, Charlie Tsai^{2

3}, Ai Leen Koh⁴, Lili Cai¹, Alex W Contryman^{5

6}, Alex H Fragapane^{5

6}, Jiheng Zhao¹, Hyun Soon Han¹, Hari C Manoharan^{5

7}, Frank Abild-Pedersen³, Jens K Nørskov^{2

3}, Xiaolin Zheng¹

Affiliations

¹ Department of Mechanical Engineering, Stanford University, Stanford, California 94305, USA.
² SUNCAT Center for Interface Science and Catalysis, Department of Chemical Engineering, Stanford University, 450 Serra Mall Stanford, California 94305, USA.
³ SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road Menlo Park, California 94025, USA.
⁴ Stanford Nanocharacterization Laboratory, Stanford University, California 94305, USA.
⁵ Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road Menlo Park, California 94025, USA.
⁶ Department of Applied Physics, Stanford University, Stanford, California 94305, USA.
⁷ Department of Physics, Stanford University, Stanford, California 94305, USA.

PMID: 26552057
DOI: 10.1038/nmat4465

Abstract

As a promising non-precious catalyst for the hydrogen evolution reaction (HER; refs ,,,,), molybdenum disulphide (MoS2) is known to contain active edge sites and an inert basal plane. Activating the MoS2 basal plane could further enhance its HER activity but is not often a strategy for doing so. Herein, we report the first activation and optimization of the basal plane of monolayer 2H-MoS2 for HER by introducing sulphur (S) vacancies and strain. Our theoretical and experimental results show that the S-vacancies are new catalytic sites in the basal plane, where gap states around the Fermi level allow hydrogen to bind directly to exposed Mo atoms. The hydrogen adsorption free energy (ΔGH) can be further manipulated by straining the surface with S-vacancies, which fine-tunes the catalytic activity. Proper combinations of S-vacancy and strain yield the optimal ΔGH = 0 eV, which allows us to achieve the highest intrinsic HER activity among molybdenum-sulphide-based catalysts.