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.

In this work, we have synthesized nanocomposites made up of a metal–organic framework (MOF) and conducting polymers by polymerization of specialty monomers such as pyrrole (Py) and 3,4‐ethylenedioxythiophene (EDOT) in the voids of a stable and biporous Zr‐based MOF (UiO‐66). FTIR and Raman data confirmed the presence of polypyrrole (PPy) and poly3,4‐ethylenedioxythiophene (PEDOT) in UiO‐66‐PPy and UiO‐66‐PEDOT nanocomposites, respectively, and PXRD data revealed successful retention of the structure of the MOF. HRTEM images showed successful incorporation of polymer fibers inside the voids of the framework. Owing to the intrinsic biporosity of UiO‐66, polymer chains were observed to selectively occupy only one of the voids. This resulted in a remarkable enhancement (million‐fold) of the electrical conductivity while the nanocomposites retain 60–70 % of the porosity of the original MOF. These semiconducting yet significantly porous MOF nanocomposite systems exhibited ultralow thermal conductivity. Enhanced electrical conductivity with lowered thermal conductivity could qualify such MOF nanocomposites for thermoelectric applications.

In this work, we have synthesized nanocomposites made up of a metal–organic framework (MOF) and conducting polymers by polymerization of specialty monomers such as pyrrole (Py) and 3,4‐ethylenedioxythiophene (EDOT) in the voids of a stable and biporous Zr‐based MOF (UiO‐66). FTIR and Raman data confirmed the presence of polypyrrole (PPy) and poly3,4‐ethylenedioxythiophene (PEDOT) in UiO‐66‐PPy and UiO‐66‐PEDOT nanocomposites, respectively, and PXRD data revealed successful retention of the structure of the MOF. HRTEM images showed successful incorporation of polymer fibers inside the voids of the framework. Owing to the intrinsic biporosity of UiO‐66, polymer chains were observed to selectively occupy only one of the voids. This resulted in a remarkable enhancement (million‐fold) of the electrical conductivity while the nanocomposites retain 60–70 % of the porosity of the original MOF. These semiconducting yet significantly porous MOF nanocomposite systems exhibited ultralow thermal conductivity. Enhanced electrical conductivity with lowered thermal conductivity could qualify such MOF nanocomposites for thermoelectric applications.

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S = 1/2 kagome-lattice hydroxychlorides are promising candidates for realizing the elusive quantum spin liquid (QSL) state. Herbertsmithite [Cu3Zn­(OH)6Cl2], a naturally occurring hydroxychloride mineral from the class of atacamites {[Cu4–x M x (OH)6X2] where M = Zn, Cu, Co, Ni and X = Cl, Br, I}, is one of the most appealing systems to study the QSL state because of the presence of a structurally perfect S = 1/2 kagome-lattice. It is an electrical insulator. However, realizing phase-pure herbertsmithite without imposing harsh reaction conditions remained synthetically challenging. In this work, for the first time, we have synthesized phase-pure herbertsmithite as well as its structural analogue paratacamite, [Zn x Cu4–x (OH)6Cl2; 0.33 ≤ x < 1], at ambient reaction conditions. Furthermore, taking graphene oxide (GO) as an additional precursor in the reaction mixture, we have successfully integrated phase-pure crystallites of herbertsmithite (H) and paratacamite (P) with nanosheets of semiconducting and diamagnetic reduced graphene oxide (rGO) by in situ oxidation–reduction reaction. The isolated H-rGO and P-rGO systems were found to be magnetic semiconductors inheriting strong spin frustration from H and P, and semiconductivity from rGO. The H-rGO system in particular exhibited negative Seebeck coefficient (n-type semiconductor) with a thermoelectric power factor of 0.1 μW·m–1·K–2 at 400 K. We anticipate the simple chemical principles outlined in this work to be useful for studying a variety of complex QSLs including electron doping. Also, semiconducting and rather unconventional materials of such metal oxochlorides with rGO isolated here need further exploration in view of thermoelectric applications.