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

Hyunho Noh; Chung Wei Kung; Ken Ichi Otake; Aaron W. Peters; Zhanyong Li; Yijun Liao; Xinyi Gong; Omar K. Farha; Joseph T. Hupp

doi:10.1021/acscatal.8b02921

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

Hyunho Noh, Chung Wei Kung, Ken Ichi Otake, Aaron W. Peters, Zhanyong Li, Yijun Liao, Xinyi Gong, Omar K. Farha^*, Joseph T. Hupp

^*Corresponding author for this work

Chemistry

Research output: Contribution to journal › Article › peer-review

102 Scopus citations

Abstract

The Zr₆-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 (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 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.

Original language	English (US)
Pages (from-to)	9848-9858
Number of pages	11
Journal	ACS Catalysis
Volume	8
Issue number	10
DOIs	https://doi.org/10.1021/acscatal.8b02921
State	Published - Oct 5 2018

Funding

This work was supported by the ANSER Center, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award No. DE-SC0001059. H.N. gratefully acknowledges support from the Ryan Fellowship program of the Northwestern University International Institute of Nanotechnology. C.-W.K. acknowledges support from the Postdoctoral Research Abroad Program (105-2917-I-564-046) sponsored by the Ministry of Science and Technology (Taiwan). We thank Prof. Michael R. Wasielewski and his lab group for the use of a gas chromatograph. This work made use of the IMSERC, J. B. Cohen X-ray Diffraction, EPIC, and KECK II facilities of Northwestern University’s NUANCE Center, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205); the MRSEC program (NSF DMR-1720139) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; and the State of Illinois, through the IIN. Use of the Advanced Photon Source is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Materials Research Collaborative Access Team (MRCAT, Sectors 10ID) operations are supported by the U.S. Department of Energy and the MRCAT member institutions. This work was supported by the ANSER Center, an Energy Frontier Research Center funded by the U.S. Department of Energy Office of Science, Office of Basic Energy Sciences, under Award No. DE-SC0001059. H.N. gratefully acknowledges support from the Ryan Fellowship program of the Northwestern University International Institute of Nanotechnology. C.-W.K. acknowledges support from the Postdoctoral Research Abroad Program (105-2917-I-564-046) sponsored by the Ministry of Science and Technology (Taiwan). We thank Prof. Michael R. Wasielewski and his lab group for the use of a gas chromatograph. This work made use of the IMSERC, J. B. Cohen X-ray Diffraction, EPIC, and KECK II facilities of Northwestern University's NUANCE Center, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource NSF ECCS-1542205); the MRSEC program (NSF DMR-1720139) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; and the State of Illinois through the IIN. Use of the Advanced Photon Source is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Materials Research Collaborative Access Team (MRCAT, Sectors 10ID) operations are supported by the U.S. Department of Energy and the MRCAT member institutions.

ASJC Scopus subject areas

Catalysis
General Chemistry

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

Access to Document

10.1021/acscatal.8b02921

Cite this

@article{4402e2bb6e88466985e58144d7b54821,

title = "Redox-Mediator-Assisted Electrocatalytic Hydrogen Evolution from Water by a Molybdenum Sulfide-Functionalized Metal-Organic Framework",

abstract = "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.",

author = "Hyunho Noh and Kung, {Chung Wei} and Otake, {Ken Ichi} and Peters, {Aaron W.} and Zhanyong Li and Yijun Liao and Xinyi Gong and Farha, {Omar K.} and Hupp, {Joseph T.}",

note = "Publisher Copyright: {\textcopyright} 2018 American Chemical Society.",

year = "2018",

month = oct,

day = "5",

doi = "10.1021/acscatal.8b02921",

language = "English (US)",

volume = "8",

pages = "9848--9858",

journal = "ACS Catalysis",

issn = "2155-5435",

publisher = "American Chemical Society",

number = "10",

}

TY - JOUR

T1 - Redox-Mediator-Assisted Electrocatalytic Hydrogen Evolution from Water by a Molybdenum Sulfide-Functionalized Metal-Organic Framework

AU - Noh, Hyunho

AU - Kung, Chung Wei

AU - Otake, Ken Ichi

AU - Peters, Aaron W.

AU - Li, Zhanyong

AU - Liao, Yijun

AU - Gong, Xinyi

AU - Farha, Omar K.

AU - Hupp, Joseph T.

PY - 2018/10/5

Y1 - 2018/10/5

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=85054326383&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85054326383&partnerID=8YFLogxK

U2 - 10.1021/acscatal.8b02921

DO - 10.1021/acscatal.8b02921

M3 - Article

AN - SCOPUS:85054326383

SN - 2155-5435

VL - 8

SP - 9848

EP - 9858

JO - ACS Catalysis

JF - ACS Catalysis

IS - 10

ER -

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

Abstract

Funding

ASJC Scopus subject areas

UN SDGs

Access to Document

Other files and links

Fingerprint

CCDC 1817937: Experimental Crystal Structure Determination

CCDC 1817936: Experimental Crystal Structure Determination

Cite this

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

Abstract

Funding

ASJC Scopus subject areas

UN SDGs

Access to Document

Other files and links

Fingerprint

Datasets

CCDC 1817937: Experimental Crystal Structure Determination

CCDC 1817936: Experimental Crystal Structure Determination

Cite this