Possible electron doping of geometrically perfect spin-1/2 kagome-lattice barlowite by reduced graphene oxide

Gupta, Kriti; Ninawe, Pranay; Jain, Anil; Dadwal, Arun; Anas, Mohd; Malik, V. K.; Yusuf, S. M.; Joy, P.A.; Ballav, Nirmalya

doi:10.1103/physrevb.104.l100418

Cited by 4 publications

(6 citation statements)

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“…In the Cu-HHTP-rGO sample, the chemical interaction would result in the doping of electrons from rGO sheets to Cu 3 (HHTP) 2 crystallites, similar to our recent report on a Cu-based coordination complex anchored onto rGO. 38 Further, as rGO sheets are more conducting than Cu 3 (HHTP) 2 crystallites, the charge-transfer pathway should majorly pass through rGO sheets, which, due to the deficit of electrons, exhibits a p-type semiconducting behavior. Such doping phenomenon must not be occurring in the Cu-HHTP/rGO or Cu-HHTP+rGO sample, as rGO is simply acting as an additive; hence, they remain n-type material, similar to pristine Cu-HHTP.…”

Section: ■ Results and Discussionsupporting

confidence: 84%

“…Remarkably, the Cu-HHTP-rGO sample was realized to be a p-type semiconductor with a positive Seebeck coefficient (Figure a), and such opposite semiconducting property in the Cu-HHTP-rGO sample suggested that, indeed, Cu-HHTP and rGO must be chemically interacting. In the Cu-HHTP-rGO sample, the chemical interaction would result in the doping of electrons from rGO sheets to Cu 3 (HHTP) 2 crystallites, similar to our recent report on a Cu-based coordination complex anchored onto rGO . Further, as rGO sheets are more conducting than Cu 3 (HHTP) 2 crystallites, the charge-transfer pathway should majorly pass through rGO sheets, which, due to the deficit of electrons, exhibits a p-type semiconducting behavior.…”

Section: Resultsmentioning

confidence: 68%

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Chemically Integrating a 2D Metal–Organic Framework with 2D Functionalized Graphene

2021

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Two-dimensional metal–organic frameworks (2D MOFs) are the next-generation 2D crystalline solids. Integrating 2D MOFs with conventional 2D materials like graphene is promising for a variety of applications, including energy or gas storage, catalysis, and sensing. However, unraveling the importance of chemical interaction over an additive effect is essential. Here, we present an unconventional chemistry to integrate a Cu-based 2D MOF, Cu-HHTP (HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene), with 2D functionalized graphene, reduced graphene oxide (rGO), by an in situ oxidation–reduction reaction. Combined Raman spectroscopy, electron spin resonance (ESR) spectroscopy, and X-ray photoelectron spectroscopy (XPS) measurements along with structural analysis evidenced the chemical interaction between Cu-HHTP and rGO, which was subsequently assigned to be the key for the manifestation of significantly modified physical properties. Of particular mention is the conversion of an n-type crystalline solid to a p-type crystalline solid upon the chemical integration of Cu-HHTP with rGO, as revealed by Seebeck coefficient. More importantly, the thermoelectric power factor exhibited an increasing trend with increasing temperature, unlike an opposite trend observed due to an additive effect. The results anticipate the ability of a redox reaction to chemically integrate other 2D MOFs with rGO and show how an in situ synthesis can trigger chemical interaction between two distinctive 2D materials.

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Section: ■ Results and Discussionsupporting

confidence: 84%

Section: Resultsmentioning

confidence: 68%

Chemically Integrating a 2D Metal–Organic Framework with 2D Functionalized Graphene

2021

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“…Out-of-plane XRD data were recorded at room temperature using a Bruker D8 Advance diffractometer using Cu Kα radiation (λ = 1.5406 Å). Rietveld refinement of the PXRD patterns were carried out by a standardized procedure using the FullProf program 53 , 54 . Raman spectra (λ exc = 632.8 nm) were recorded at Raman microscope (LabRAM HR, HoribaJobinYvon) with a 50× objective lens (spectral resolution of the system is ~1 cm −1 ).…”

Section: Methodsmentioning

confidence: 99%

Charge-transfer interface of insulating metal-organic frameworks with metallic conduction

et al. 2022

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Downsizing materials into hetero-structured thin film configurations is an important avenue to capture various interfacial phenomena. Metallic conduction at the interfaces of insulating transition metal oxides and organic molecules are notable examples, though, it remained elusive in the domain of coordination polymers including metal-organic frameworks (MOFs). MOFs are comprised of metal centers connected to organic linkers with an extended coordination geometry and potential void space. Poor orbitals overlap often makes these crystalline solids electrical insulators. Herein, we have fabricated hetero-structured thin film of a Mott and a band insulating MOFs via layer-by-layer method. Electrical transport measurements across the thin film evidenced an interfacial metallic conduction. The origin of such an unusual observation was understood by the first-principles density functional theory calculations; specifically, Bader charge analysis revealed significant accumulation and percolation of charge across the interface. We anticipate similar interfacial effects in other rationally designed hetero-structured thin films of MOFs.

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“…Such a site doping approach could lead to the loss of spin frustration with the dopant occupying the Kagome plane instead of the interlayer sites in the Herbertsmithite‐like systems [14] . To overcome this problem, in our previous reports, we have adopted an unconventional approach of anchoring various atacamite family‐based minerals with S=

{{ 1/2 }}

Section: Introductionmentioning

confidence: 93%

“…To overcome this problem, in our previous reports, we have adopted an unconventional approach of anchoring various atacamite family‐based minerals with S=

{{ 1/2 }}

Kagome lattices onto reduced graphene oxide (rGO), [6d,7c,15] which resulted in the enhanced electrical transport properties with the retention of characteristic magnetic signatures of the pristine material [6d,7c] . Especially, in the Barlowite system, we demonstrated the elusive electron doping phenomenon which resulted in the insulator‐to‐semiconductor transition [7c] . However, Barlowite is a non‐QSL material, while 2D‐MOFs are promising QSL materials, which are even realized to be stable with the presence of site‐dopants [9a] .…”

Section: Introductionmentioning

confidence: 93%

Robust Spin Liquidity in 2D Metal‐Organic Framework Cu₃ (HHTP)₂ with S=¹/₂ Kagome Lattice

Ninawe,

Jain,

Sangole

et al. 2023

Chemistry A European J

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On the one hand electron or hole doping of quantum spin liquid (QSL) may unlock high‐temperature superconductivity and on the other hand it can disrupt the spin liquidity giving rise to a magnetically ordered ground state. Recently, a 2D MOF, Cu3(HHTP)2 (HHTP ‐ 2,3,6,7,10,11‐hexahydroxytriphenylene), containing Cu(II) S = ½ frustrated spins in the Kagome lattice is emerging as a promising QSL candidate. Herein, we present an elegant in situ redox‐chemistry strategy of anchoring Cu3(HHTP)2 crystallites onto diamagnetic reduced graphene oxide (rGO) sheets, resulting in the formation of electron‐doped Cu3(HHTP)2‐rGO composite which exhibited semiconducting behavior (5 K to 300 K) with high electrical conductivity of 70 S∙m‐1 and a carrier density of ~1.1 × 1018 cm‐3 at 300 K. Remarkably, no magnetic transition in the Cu3(HHTP)2‐rGO composite was observed down to 1.5 K endorsing the robust spin liquidity of the 2D MOF Cu3(HHTP)2. Specific heat capacity measurements led to the estimation of the residual entropy values of 28% and 34% of the theoretically expected value for the pristine Cu3(HHTP)2 and Cu3(HHTP)2‐rGO composite, establishing the presence of strong quantum fluctuations down to 1.5 K (two times smaller than the value of the exchange interaction J).

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Possible electron doping of geometrically perfect spin-1/2 kagome-lattice barlowite by reduced graphene oxide

Cited by 4 publications

References 44 publications

Chemically Integrating a 2D Metal–Organic Framework with 2D Functionalized Graphene

Chemically Integrating a 2D Metal–Organic Framework with 2D Functionalized Graphene

Charge-transfer interface of insulating metal-organic frameworks with metallic conduction

Robust Spin Liquidity in 2D Metal‐Organic Framework Cu₃ (HHTP)₂ with S=¹/₂ Kagome Lattice

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Possible electron doping of geometrically perfect spin-1/2 kagome-lattice barlowite by reduced graphene oxide

Cited by 4 publications

References 44 publications

Chemically Integrating a 2D Metal–Organic Framework with 2D Functionalized Graphene

Chemically Integrating a 2D Metal–Organic Framework with 2D Functionalized Graphene

Charge-transfer interface of insulating metal-organic frameworks with metallic conduction

Robust Spin Liquidity in 2D Metal‐Organic Framework Cu3 (HHTP)2 with S=1/2 Kagome Lattice

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Robust Spin Liquidity in 2D Metal‐Organic Framework Cu₃ (HHTP)₂ with S=¹/₂ Kagome Lattice