On the limit of proton-coupled electronic doping in a Ti(<scp>iv</scp>)-containing MOF

Mancuso, Jenna L.; Fabrizio, Kevin; Brozek, Carl K.; Hendon, Christopher H.

doi:10.1039/d1sc03019a

Cited by 7 publications

(10 citation statements)

References 72 publications

(91 reference statements)

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“…To the best of our knowledge, these experiments comprise the only measurements of MOF redox potentials without the use of electrodes, in a contactless, noninvasive technique. On the basis of these results, we hypothesize that bridging oxo units are generally necessary for Ti-MOFs to stabilize H + against the HER, as has been recently demonstrated for MIL-125 . We also expect that photodoped Ti-MOFs will serve as photocatalysts for transferring the e – –H + pairs to molecular substrates.…”

Section: Discussionsupporting

confidence: 66%

“…On the basis of these results, we hypothesize that bridging oxo units are generally necessary for Ti-MOFs to stabilize H + against the HER, as has been recently demonstrated for MIL-125. 82 We also expect that photodoped Ti-MOFs will serve as photocatalysts for transferring the e − − H + pairs to molecular substrates. Previous reports on photocatalysis with Ti-MOFs employed the Ti cluster as a photosensitizer rather than as a site for reactivity, but the availability of OMSs of MUV-10(M), demonstrated here, will allow photoredox chemistry without cocatalysts.…”

Section: ■ Discussionmentioning

confidence: 99%

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Tunable Band Gaps in MUV-10(M): A Family of Photoredox-Active MOFs with Earth-Abundant Open Metal Sites

et al. 2021

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Titanium-based metal−organic frameworks (Ti-MOFs) have attracted intense research attention because they can store charges in the form of Ti 3+ and they serve as photosensitizers to cocatalysts through heterogeneous photoredox reactions at the MOF−liquid interface. Both the charge storage and charge transfer depend on the redox potentials of the MOF and the molecular substrate, but the factors controlling these energetic aspects are not well understood. Additionally, photocatalysis involving Ti-MOFs relies on cocatalysts rather than the intrinsic Ti reactivity, in part because Ti-MOFs with open metal sites are rare. Here, we report that the class of Ti-MOFs known as MUV-10 can be synthetically modified to include a range of redox-inactive ions with flexible coordination environments that control the energies of the photoactive orbitals. Lewis acidic cations installed in the MOF cluster (Cd 2+ , Sr 2+ , and Ba 2+ ) or introduced to the pores (H + , Li + , Na + , K + ) tune the electronic structure and band gaps of the MOFs. Through the use of optical redox indicators, we report the first direct measurement of the Fermi levels (redox potentials) of photoexcited MOFs in situ. Taken together, these results explain the ability of Ti-MOFs to store charges and provide design principles for achieving heterogeneous photoredox chemistry with electrostatic control.

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Section: Discussionsupporting

confidence: 66%

Section: ■ Discussionmentioning

confidence: 99%

Tunable Band Gaps in MUV-10(M): A Family of Photoredox-Active MOFs with Earth-Abundant Open Metal Sites

et al. 2021

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“…[33][34][35] Moving from MIL-125-NH2 to MIL-125-F results in a 200 meV shift in conduction band energy. Considering a previous study from our group, 36 the energy of the conduction band is critical for deliberately disfavoring the hydrogen evolution reaction. Thus, the fluoro-functionalized MOF may be sufficiently stabilizing to turn of hydrogen evolution and increasing H • -atom loading the MOF, Figure 5b.…”

Section: Resultsmentioning

confidence: 99%

Ligand field tuning of d-orbital energies in MOF clusters

Diamond¹,

Payne²,

Hendon³

2023

Preprint

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Linker functionalization is a common route used to affect the electronic and catalytic properties of metal-organic frameworks. By either pre- or post-synthetically installing linkages with differing linker moieties the band gap, workfunction, and exciton lifetimes have been shown to be affected. One overlooked aspect of linker functionalization, however, has been the impact on the metal d-orbital energies to which they are bound. The ligand field differences should result in substantial changes in d¬-splitting. In this study we use DFT to study the energetics of d-orbital energy tuning as a function of linker chemistry. We offer a general descriptor, linker pKa, as a tool to predict the resultant d-splitting in MOFs. Our calculations reveal that simple functionalizations can affect the d-energies by up to 2 eV and illustrate the significance of this band modularity using four archetypal MOFs: UiO-66, MIL-125, ZIF-8, and MOF-5. Together, we show that linker functionalization dramatically affects d-energies in MOF clusters and highlight that linker functionalization is a useful route for fine-tuning band edges centered on the metals, rather than linkers themselves.

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“…Moving from MIL-125-NH 2 to MIL-125-F results in a 200 meV shift in conduction band energy. Considering a previous study from our group 35 , the energy of the conduction band is critical for deliberately disfavoring the hydrogen evolution reaction. Thus, the fluoro-functionalized MOF may be sufficiently stabilizing to turn off hydrogen evolution and increasing H • -atom loading the MOF, Fig.…”

Section: Resultsmentioning

confidence: 99%

Ligand field tuning of d-orbital energies in metal-organic framework clusters

2023

Self Cite

View full text Add to dashboard Cite

Linker functionalization is a common route used to affect the electronic and catalytic properties of metal-organic frameworks. By either pre- or post-synthetically installing linkages with differing linker moieties the band gap, workfunction, and exciton lifetimes have been shown to be affected. One overlooked aspect of linker functionalization, however, has been the impact on the metal d-orbital energies to which they are bound. The ligand field differences should result in substantial changes in d-splitting. In this study we use density functional theory (DFT) to study the energetics of d-orbital energy tuning as a function of linker chemistry. We offer a general descriptor, linker pKa, as a tool to predict resultant band energies in metal-organic frameworks (MOFs). Our calculations reveal that simple functionalizations can affect the band energies, of primarily metal d lineage, by up to 2 eV and illustrate the significance of this band modularity using four archetypal MOFs: UiO-66, MIL-125, ZIF-8, and MOF-5. Together, we show that linker functionalization dramatically affects d-energies in MOF clusters and highlight that linker functionalization is a useful route for fine-tuning band edges centered on the metals, rather than linkers themselves.

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On the limit of proton-coupled electronic doping in a Ti(iv)-containing MOF

Abstract: TiIV-containing metal-organic frameworks are known to accumulate electrons in their conduction bands, accompanied by protons, when irradiated in the presence of alcohols. The archetypal system, MIL-125, was recently shown to...

Cited by 7 publications

References 72 publications

Tunable Band Gaps in MUV-10(M): A Family of Photoredox-Active MOFs with Earth-Abundant Open Metal Sites

Tunable Band Gaps in MUV-10(M): A Family of Photoredox-Active MOFs with Earth-Abundant Open Metal Sites

Ligand field tuning of d-orbital energies in MOF clusters

Ligand field tuning of d-orbital energies in metal-organic framework clusters

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