Title: Molybdenum Sulfide within a Metal–Organic Framework for Photocatalytic Hydrogen Evolution from Water

Abstract

A representative metal–organic framework, NU-1000, was functionalized with MoS_x. The previously determined crystal structure of the material, named MoS_x-SIM, consists of monometallic Mo(IV) ions with two sulfhydryl ligands. The metal ions are anchored to the framework by displacing protons presented by the –OH/–OH₂ groups on the Zr₆ node. As shown previously, the MOF-supported complexes are electrocatalytic for hydrogen evolution from acidified water. The earlier electrocatalysis results, together with the nearly ideal formal potential of the Mo(IV/II) couple (i.e., nearly coincident with that of the hydrogen couple), and the physical proximity of UV-absorbing MOF linkers to the complexes, suggested to us that the linkers might behave photosensitizers for catalyst reduction, and subsequently, for H₂ evolution from water. To our surprise, MoS_x-SIM, when UV-illuminated in an aqueous buffer at near-neutral pH, displays a biphasic photocatalytic response: an initially slow rate of reaction, i.e. 0.56 mmol g^-1 h^-1, followed by an increase to 4 mmol g^-1 h^-1. Ex-situ catalyst examination revealed that nanoparticulate MoSx suspended within the reaction mixture is the actual catalyst. Thus, photo-assisted restructuring and detachment of the catalyst or pre-catalyst from the MOF node appears to be necessary for the catalyst to reduce water at neutral pH.

Authors:

Noh, Hyunho ;

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Yang, Ying; Ahn, Sol; Peters, Aaron W.; Farha, Omar K.; Hupp, Joseph T.

• Search DOE PAGES for author "Hupp, Joseph T."
• Search DOE PAGES for ORCID "0000-0003-3982-9812"
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Publication Date:

2019-01-24

Research Org.:

Energy Frontier Research Centers (EFRC) (United States). Center for Light Energy Activated Redox Processes (LEAP); Northwestern Univ., Evanston, IL (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1491951

Alternate Identifier(s):

OSTI ID: 1566728

Grant/Contract Number:  

SC0001059

Resource Type:

Published Article

Journal Name:

Journal of the Electrochemical Society

Additional Journal Information:

Journal Name: Journal of the Electrochemical Society Journal Volume: 166 Journal Issue: 5; Journal ID: ISSN 0013-4651

Publisher:

The Electrochemical Society

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Energy Conversion; Hydrogen Evolution; Molybdenum Sulfide; Photocatalysis