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Title: Redox-Mediator-Assisted Electrocatalytic Hydrogen Evolution from Water by a Molybdenum Sulfide-Functionalized Metal–Organic Framework

Abstract

The Zr 6-based metal–organic framework NU-1000 was successfully functionalized with candidate catalysts—MoS x units—via SIM (solvothermal deposition in MOFs) of molybdenum(VI), followed by reaction with H2S gas. The structure of the material, named MoS x-SIM, was characterized spectroscopically and through a single-crystal X-ray diffraction measurement. These measurements and others established that the catalyst is monometallic, with mixed oxygen and sulfur coordination, and that it forms from a MOF-node-supported molybdenum-based cluster featuring only oxy ligands. Notably, the formal potential for the MOF-grafted complex, like that for the metal–sulfur active site of hydrogenase, is nearly coincident with the formal potential for the hydrogen couple. Its effective concentration within the mesoporous MOF is several hundred millimolar, and its porous-framework-based immobilization/heterogenization obviates the need for aqueous solubility as a condition for use as a well-defined catalyst. MoS x-SIM was evaluated as an electrocatalyst for evolution of molecular hydrogen from aqueous acid. Although the MoS x-functionalized framework exhibits catalytic behavior, the highly insulating nature of the support inhibits high electrocatalytic performance. Introduction of an archetypal redox mediator (RM), methyl viologen (MV 2+), resulted in more than 20-fold enhancement in its catalytic performance on a turnover frequency basis, implying efficient RM-assisted electron transfer to otherwise electrochemicallymore » non-addressable MoS x moieties. Electrochemical kinetic studies with additional viologens as mediators reveal an unexpected square-root dependence of overall reaction rate on mediator concentration, as well as sensitivity to the strength of RM •+ as a reductant. These observations, together with observations of potential-dependent H/D isotope effects and potential-dependent pH effects, provide useful insights into the catalysis mechanism and help to explain how the MOF-affixed monometallic catalyst can effectively catalyze a two-electron reduction reaction, i.e., hydrogen evolution from acidified water.« less

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1];  [1];  [1]; ORCiD logo [3]; ORCiD logo [1]
  1. Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry
  2. Northwestern Univ., Evanston, IL (United States). Dept. of Chemical and Biomolecular Engineering
  3. Northwestern Univ., Evanston, IL (United States). Dept. of Chemical and Biomolecular Engineering, and Dept. of Chemistry; King Abdulaziz Univ., Jeddah (Saudi Arabia). Dept. of Chemistry
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Center for Light Energy Activated Redox Processes (LEAP); Argonne National Lab. (ANL), Argonne, IL (United States); Northwestern Univ., Evanston, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1566564
Grant/Contract Number:  
AC02-06CH11357; SC0001059
Resource Type:
Accepted Manuscript
Journal Name:
ACS Catalysis
Additional Journal Information:
Journal Volume: 8; Journal Issue: 10; Journal ID: ISSN 2155-5435
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; catalysis (homogeneous); catalysis (heterogeneous); solar (photovoltaic); solar (fuels); optics; phonons; photosynthesis (natural and artificial); bio-inspired; hydrogen and fuel cells; charge transport; magnetism and spin physics; materials and chemistry by design; mesostructured materials; synthesis (novel materials); synthesis (self-assembly); synthesis (scalable processing)

Citation Formats

Noh, Hyunho, Kung, Chung-Wei, Otake, Ken-ichi, Peters, Aaron W., Li, Zhanyong, Liao, Yijun, Gong, Xinyi, Farha, Omar K., and Hupp, Joseph T. Redox-Mediator-Assisted Electrocatalytic Hydrogen Evolution from Water by a Molybdenum Sulfide-Functionalized Metal–Organic Framework. United States: N. p., 2018. Web. doi:10.1021/acscatal.8b02921.
Noh, Hyunho, Kung, Chung-Wei, Otake, Ken-ichi, Peters, Aaron W., Li, Zhanyong, Liao, Yijun, Gong, Xinyi, Farha, Omar K., & Hupp, Joseph T. Redox-Mediator-Assisted Electrocatalytic Hydrogen Evolution from Water by a Molybdenum Sulfide-Functionalized Metal–Organic Framework. United States. doi:10.1021/acscatal.8b02921.
Noh, Hyunho, Kung, Chung-Wei, Otake, Ken-ichi, Peters, Aaron W., Li, Zhanyong, Liao, Yijun, Gong, Xinyi, Farha, Omar K., and Hupp, Joseph T. Wed . "Redox-Mediator-Assisted Electrocatalytic Hydrogen Evolution from Water by a Molybdenum Sulfide-Functionalized Metal–Organic Framework". United States. doi:10.1021/acscatal.8b02921. https://www.osti.gov/servlets/purl/1566564.
@article{osti_1566564,
title = {Redox-Mediator-Assisted Electrocatalytic Hydrogen Evolution from Water by a Molybdenum Sulfide-Functionalized Metal–Organic Framework},
author = {Noh, Hyunho and Kung, Chung-Wei and Otake, Ken-ichi and Peters, Aaron W. and Li, Zhanyong and Liao, Yijun and Gong, Xinyi and Farha, Omar K. and Hupp, Joseph T.},
abstractNote = {The Zr6-based metal–organic framework NU-1000 was successfully functionalized with candidate catalysts—MoSx units—via SIM (solvothermal deposition in MOFs) of molybdenum(VI), followed by reaction with H2S gas. The structure of the material, named MoSx-SIM, was characterized spectroscopically and through a single-crystal X-ray diffraction measurement. These measurements and others established that the catalyst is monometallic, with mixed oxygen and sulfur coordination, and that it forms from a MOF-node-supported molybdenum-based cluster featuring only oxy ligands. Notably, the formal potential for the MOF-grafted complex, like that for the metal–sulfur active site of hydrogenase, is nearly coincident with the formal potential for the hydrogen couple. Its effective concentration within the mesoporous MOF is several hundred millimolar, and its porous-framework-based immobilization/heterogenization obviates the need for aqueous solubility as a condition for use as a well-defined catalyst. MoSx-SIM was evaluated as an electrocatalyst for evolution of molecular hydrogen from aqueous acid. Although the MoSx-functionalized framework exhibits catalytic behavior, the highly insulating nature of the support inhibits high electrocatalytic performance. Introduction of an archetypal redox mediator (RM), methyl viologen (MV2+), resulted in more than 20-fold enhancement in its catalytic performance on a turnover frequency basis, implying efficient RM-assisted electron transfer to otherwise electrochemically non-addressable MoSx moieties. Electrochemical kinetic studies with additional viologens as mediators reveal an unexpected square-root dependence of overall reaction rate on mediator concentration, as well as sensitivity to the strength of RM•+ as a reductant. These observations, together with observations of potential-dependent H/D isotope effects and potential-dependent pH effects, provide useful insights into the catalysis mechanism and help to explain how the MOF-affixed monometallic catalyst can effectively catalyze a two-electron reduction reaction, i.e., hydrogen evolution from acidified water.},
doi = {10.1021/acscatal.8b02921},
journal = {ACS Catalysis},
number = 10,
volume = 8,
place = {United States},
year = {2018},
month = {9}
}

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Works referencing / citing this record:

Metal–Organic Frameworks Toward Electrocatalytic Applications
journal, June 2019

  • Li, Jun-Hong; Wang, Yi-Sen; Chen, Yu-Chuan
  • Applied Sciences, Vol. 9, Issue 12
  • DOI: 10.3390/app9122427