Overcoming the global energy crisis due to vast economic expansion with the advent of human reliance on energy-consuming labor-saving devices necessitates the demand for next-generation technologies in the form of cleaner energy storage devices. The technology accelerates with the pace of developing energy storage devices to meet the requirements wherever an unanticipated burst of power is indeed needed in a very short time. Supercapacitors are predicted to be future power vehicles because they promise faster charging times and do not rely on rare elements such as lithium. At the same time, they are key nanoscale device elements for high-frequency noise filtering with the capability of storing and releasing energy by electrostatic interactions between the ions in the electrolyte and the charge accumulated at the active electrode during the charge/discharge process. There have been several developments to increase the functionality of electrodes or finding a new electrolyte for higher energy density, but this field is still open to witness the developments in reliable materials-based energy technologies. Nanoscale materials have emerged as promising candidates for the electrode choice, especially in 2D sheet and folded tubular network forms. Due to their unique hierarchical architecture, excellent electrical and mechanical properties, and high specific surface area, nanotubular networks have been widely investigated as efficient electrode materials in supercapacitors, while maintaining their inherent characteristics of high power and long cycling life. In this review, we briefly present the evolution, classification, functionality, and application of supercapacitors from the viewpoint of nanostructured materials to apprehend the mechanism and construction of advanced supercapacitors for next-generation storage devices.

/pdf/progress-in-supercapacitors-roles-of-two-dimensional-1845sgquka.pdf

Progress in supercapacitors: roles of two dimensional nanotubular materials

Two-dimensional graphene monolayers and bilayers exhibit fascinating electrical transport behaviors. Using infrared spectroscopy, we find that they also have strong interband transitions and that their optical transitions can be substantially modified through electrical gating, much like electrical transport in field-effect transistors. This gate dependence of interband transitions adds a valuable dimension for optically probing graphene band structure. For a graphene monolayer, it yields directly the linear band dispersion of Dirac fermions, whereas in a bilayer, it reveals a dominating van Hove singularity arising from interlayer coupling. The strong and layer-dependent optical transitions of graphene and the tunability by simple electrical gating hold promise for new applications in infrared optics and optoelectronics.

/pdf/gate-variable-optical-transitions-in-graphene-3q6kb2wuwu.pdf

Gate-Variable Optical Transitions in Graphene

A review of electrochemical energy storage behaviors based on pristine metal–organic frameworks and their composites

Recent advances in photocatalytic multivariate metal organic frameworks-based nanostructures toward renewable energy and the removal of environmental pollutants

CuI-catalyzed alkyne–azide cycloaddition provides 1,4-disubstituted 1,2,3-triazoles with such efficiency and scope that the transformation has been described as “click” chemistry. An overview of the mechanism of this remarkable reaction is presented as a means to explain the myriad of experimental results, particularly the various methods of catalyst generation, solvent and substrate effects, and choice of base or ligand. Both solution-phase and solid-phase results are comprehensively examined. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

CuI‐Catalyzed Alkyne—Azide “Click” Cycloadditions from a Mechanistic and Synthetic Perspective

A (CH3NH3)3Bi2I9 Perovskite Based on a Two-Step Deposition Method: Lead-Free, Highly Stable, and with Enhanced Photovoltaic Performance

Although traditional perovskite solar cells have made tremendous progress in terms of efficiency, the presence of toxic lead has restricted their commercialization. Herein, we report the first example of a facile synthesis and a newly designed highly stable lead free methylammonium bismuth chloride in the form of 1D-polymeric chain based perovskite. The formation of a 1D-polymeric chain with formula [(CH3NH3)3Bi2Cl9]n (1) has been authenticated by its single crystal X-ray diffraction (SCXRD) studies. The lead free 1 has been employed as an alternative to the traditional CH3NH3PbX3 perovskite with an excellent open circuit voltage of 430 mV.

Design and Synthesis of 1D-Polymeric Chain Based [(CH3NH3)3Bi2Cl9]n Perovskite: A New Light Absorber Material for Lead Free Perovskite Solar Cells

The structural diversity of Co(II) metal centers is known to influence their physicochemical properties. A novel two-dimensional (2D) Co(II)-MOF {[Co5(HL)4(dpp)2(H2O)2(μ-OH)2]·21H2O} n has been designed and synthesized by adopting a mixed-ligand strategy, using 1,3-di(4-pyridyl)propane (dpp) colinker with a flexible spacer H3L (H3L: 5-(2 carboxybenzyloxy)isophthalic acid). Co(II)-MOF features a 2D network, which is further interpenetrated among the equivalent sets and therefore results in a 3D supramolecular network. Topologically, the entire network can be viewed as a (3,4,8)-connected three-nodal net with the extended point symbol of {4.5.7}4{412.52.710.94}{52.8.92.10}2, duly assigned to the novel topological type smm2. The functional utility of Co(II)-MOF is demonstrated by employing it toward oxygen evolution reaction (OER) in a photoelectrochemical cell, exhibiting appreciable photocurrents of up to 5.89 mA/cm2 when used as an anode in a photoelectrochemical cell, while also displaying encouraging electrocatalytic currents of 9.32 mA/cm2 (at 2.01 V vs RHE) for the OER. Moreover, detailed electrochemical impedance spectroscopy studies confirm enhanced charge-transfer kinetics and improved conductivity under illumination with minimal effect of interfacial phenomena. This work provides a reference for the expanding field of research into applications of MOF materials and establishes MOF materials as favorable candidates for sustainable and efficient design of electrodes for water splitting.

Mixed-Ligand-Architected 2D Co(II)-MOF Expressing a Novel Topology for an Efficient Photoanode for Water Oxidation Using Visible Light.

Mixed-metal metal–organic frameworks (M-MOFs) consist of at least two different metal ions as nodes in the same framework. The incorporation of a second or more metal ions provides structural/compositional diversity, multi-functionality and stability to the framework. Moreover, the periodical array of different metal ions in the framework may alter the physical/chemical properties of M-MOFs and result in fascinating applications. M-MOFs with exciting structural features offer superior supercapacitor performances compared to single metal MOFs due to the synergic effect of different metal ions. In this review, we summarize several synthetic methods to construct M-MOFs by employing various organic ligands or metalloligands. Further, we discuss the electrochemical performance of several M-MOFs and their derived composite materials for supercapacitor applications.

Recent highlights and future prospects on mixed-metal MOFs as emerging supercapacitor candidates.

A porous, Cu(II)-metal organic framework (Cu-MOF) constituted of a rigid lactam functionalized ditopic ligand (H2L) was synthesized at room temperature under slow evaporation conditions {H2L = (5-(1-oxo-2,3-dihydro-1H-inden-2-yl)isophthalic acid)}. The single crystal X-ray structure revealed the formation of a 3D framework of Cu-MOF with one-dimensional (1D) channels decorated with lactam groups and exposed metal centers in the crystallographic c-axis. Interestingly, Cu(II) coordinated DMF molecules were eliminated from the Cu(II) metal center on activation of Cu-MOF at a temperature of 150 °C under high vacuum to generate a solvent free framework with pores lined with unsaturated Lewis acidic Cu(II) ions, i.e., Cu-MOF'. The lactam functionalized channels inclined toward the CO2, which interact with the Cu(II) metal sites lined in the channels of Cu-MOF' and exhibit fascinating solvent-free heterogeneous catalytic conversion of CO2 to cyclic carbonates at atmospheric pressure of CO2, under mild conditions. Furthermore, the Cu-MOF' catalyst was easily recycled and reused for several cycles without a significant loss in catalytic activity.

Shagufi Naz Ansari

Papers

A (CH3NH3)3Bi2I9 Perovskite Based on a Two-Step Deposition Method: Lead-Free, Highly Stable, and with Enhanced Photovoltaic Performance

Design and Synthesis of 1D-Polymeric Chain Based [(CH3NH3)3Bi2Cl9]n Perovskite: A New Light Absorber Material for Lead Free Perovskite Solar Cells

Mixed-Ligand-Architected 2D Co(II)-MOF Expressing a Novel Topology for an Efficient Photoanode for Water Oxidation Using Visible Light.

Recent highlights and future prospects on mixed-metal MOFs as emerging supercapacitor candidates.

Catalytic CO2 Fixation over a Robust Lactam-Functionalized Cu(II) Metal Organic Framework.