Commercial supercapacitors, mainly made of activated carbon, offers insufficient capacitance at high cost. Recently, graphene-based materials are emerging as smart alternatives. Reduction of graphene oxide (GO) is an elegant and important approach to produce reduced graphene oxide (rGO), because it holds the promise to closely resemble its physicochemical properties with pristine graphene. The conventional reducing agents such as sodium borohydride and hydrazine are strong reducing agents, and cannot be recycled. The fast reaction kinetics bring an imbalance in the desirable properties of rGO. Here, we present onepot chemical reduction of GO in aqueous medium by an unconventional mild reducing agent (FeCl2/HCl) where pure rGO is isolated and the reducing agent is recycled upon simple treatment of the filtrate with HCl. The fabricated all-solid-state supercapacitor of assynthesized rGO exhibited significantly higher specific capacitance (171 F/g at 1.1 A/g), remarkable cycling stability (>80% retention of capacitance beyond 100,000 continued cycles), and flexibility (>500 bending cycles), which is comparatively better than those of rGO derived from conventional reducing agents. Use of commercially available organic electrolyte further boosted the supercapacitor performance (282 F/g at 1.8 A/g) of rGO. 1

(MOFs) in common organic solvents which heavily limits thin-film processing on various support substrates for fabrication of devices. SURMOFs are in principle possible to achieve virtually on any support including flexible plastic and cloth substrates with molecular-level control of the dimensionality as well as functionality. [2] Subsequent loading of guest molecules opens-up an immense opportunity of SURMOFs for applications in storage and separation of gas and liquid, making highly specific sensors, performing unconventional catalysis, and overall, for the development of stimuli responsive electronic and magnetic thin-film devices. [3] As for the electronic applications of metal-organics, the experimental challenges are, in general, i) patterning feasibility as thin-films by employing standard lithographic techniques, ii) controllable thickness and orientation, iii) film homogeneity, iv) reasonable porosity, v) desirable electrical conductivity, vi) tuning electrical conductivity of thin-films by physical and chemical stimuli, and finally, vii) stability of the thin-films at ambient conditions, specifically against moisture and heat. At a glance, SURMOFs appear suitable platforms to overcome all these challenges to a considerable extent except the facts that MOFs are i) intrinsically poor conductors of electricity (due to insulating nature of the organic ligands and an energy mismatch in the overlap between ligand's p orbitals and metal ion's d orbitals); and ii) usually nonhydrophobic and sensitive to moisture. [4] Such important issues bring to the origin of this work: How to fabricate SURMOF thin-film devices hydrophobic as well electrically conductive?In order to achieve reasonably good electrical conductivity, so far, HKUST-1-based (a porous metal-organic coordination polymer comprised of Cu ion and 1,3,5-benzene tricarboxylic acid (BTC) ligand (benzene tricarboxylic acid) SURMOF thinfilm device was infiltrated with organic electrophile guest tetracyanoquinodimethane (TCNQ) and the subsequent redoxreaction between Cu 2+ ions and TCNQ molecules resulted in a significant increase in the conductivity value within the semiconducting span. [5] However, HKUST-1-based SURMOF thin-films are not really hydrophobic. Another disadvantage

Metal−organic coordination polymers (CPs) downsized to thin films with controllable electrical conductivity are promising for electronic device applications. Here we demonstrate, for the first time, thermally driven resistive switching in thin films of semiconducting CPs consisting of silver ion and tetracyanoquinodimethane ligand (AgTCNQ). High-quality and highly hydrophobic thin films of Ag-TCNQ were fabricated through a layer-by-layer approach upon sacrificing a pre-deposited layer of Cu-TCNQ on a thiolated Au substrate. Reversible switching between the high-resistance state (HRS) at 300 K and the low-resistance state (LRS) at 400 K with an enhancement factor of as high as ∼10 6 in the electrical resistance was realized. The phenomenon is attributed to the alternation of the Schottky barrier at the metal−semiconductor interface by thermal energy and not due to the formation of a conductive filament. Our discovery of thermally driven resistive switching as well as sacrificial growth of CP thin films on an organically modified substrate holds promise for the development of solution-processable non-volatile memory devices.

In this work we report fabrication of high-quality AB- and BA-type heterostructured thin films of cubic Cu­(II) (A-type) and tetragonal Cu­(I) (B-type) coordination polymers (CPs) on the functionalized Au substrate by the layer-by-layer method. Successful growth of Cu­(I)-CP on top of Cu­(II)-CP was assigned to be due to the interfacial reduction reaction (IRR). Notably, electrical transport measurements across AB- and BA-type heterostructured thin films revealed rectification of current in opposite directions. We have attributed such an interestingly new observation to the formation of a well-defined interface of Cu­(II)-CP and Cu­(I)-CP resembling a p–n junctiona hitherto unreported phenomenon that is anticipated to open enormous opportunities for the heterostructured thin films of CPs, likewise celebrated interfaces of oxide heterostructures.

Oxidation and reduction reactions are of central importance in chemistry as well as vital to the basic functions of life and such chemical processes are generally brought about by oxidizing and reducing agents, respectively. Herein, we report the discovery of an interfacial reduction reaction (IRR) − without the use of any external reducing agent. In course of metal−ligand coordination, spontaneous reduction of Cu(II) to Cu(I) at a solid−liquid interface was observed−unlike in a liquid-phase reaction where no reduction of Cu(II) to Cu(I) was occurred. High-quality thin films of a new coordination network compound bearing a Fe(II)−CN−Cu(I) link were fabricated by IRR and employed for efficient electro-catalysis in the form of oxygen reduction reaction. Also, thermally activated reversible structural phase transition modulated the electron transport property in thin film. This work unveils the importance of chemical reactions at solid−liquid interfaces that can lead to the development of new functional thin film materials.