Ni Single Atom Decorated Porous Hollow Carbon Nanosphere-Based Electrodes for High Performance Symmetric Solid-State Supercapacitors.

Ni single atom containing hollow carbon nanospheres with nitrogen doping has been synthesized by carbonization of Ni(NO3)2/phloroglucinol-formaldehyde polymer/silica composite. The samples have been characterized by powder X-ray diffraction, nitrogen adsorption/desorption, electron microscopic, Raman and X-ray photoelectron spectroscopic studies. The microstructure and surface area vary with the amount of Ni(NO3)2 employed in the syntheses and the carbonization environment. An optimized amount of nickel and argon as the carbonization gas afford Ni-1.0@N@HCN-Ar which possesses overall superior features. The uniformly dispersed Ni single atoms within the hollow porous carbon framework fully utilize all the electroactive sites thereby improving the supercapacitive performance. The specific capacitance of Ni-1.0@N@HCN-Ar reaches 777 F g-1 at 1 A g-1 with a Coulombic efficiency of 98.4 % and excellent recyclability. The energy and power density of Ni-1.0@N@HCN-Ar are found to be high; at 1 A g-1 its energy density is 155.4 Wh kg-1 with a power density of 600.3 W kg-1. At a high current density of 10 A g-1 the material shows a high energy density of 118.4 Wh kg-1 with excellent power density of 6003.4 W kg-1. A symmetric solid-state supercapacitor assembled with this material, Ni-1.0@N@HCN-Ar//Ni-1.0@N@HCN-Ar using H2SO4/PVA gel electrolyte shows a superior energy density value of 30 Wh kg-1 at a power density of 1200 W kg-1.

A deeper insight into the evaluation of water-in-oil amicroemulsion templated samarium sulfide nanospheres: exploring its role in pickering emulsion formulation for photocatalytic dye degradation and synthesis of PANI@Sm2S3 nanocomposites.

This study examines the effectiveness of W/O microemulsion-mediated Sm2S3 nanospheres in pickering emulsion-based crystal violet (CV) dye degradation and PANI@Sm2S3 nanocomposite synthesis. The evaluation of nanospheres inside the core of reverse micelles was performed through DLS, TEM and FESEM analyses. The formation of nanospheres involve two phases: a nucleation phase (5-30 min) and growth phase (30-120 min). Through in situ hydrophobization of negatively charged (with a zeta value of -4.47 mV at neutral pH) Sm2S3 nanoparticles (0.1 wt%) with a suitable amount of a cationic CTAB surfactant, a stable O/W pickering emulsion was developed. 0.1 wt% Sm2S3in situ hydrophobized with 2.7 mM CTAB offered a stable pickering emulsion with a diameter of 23 µm after 1 day of storage. This pickering emulsion improves the local concentration of CV by efficiently encapsulating dye molecules inside the core of emulsion droplets. Therefore, dye molecules get numerous opportunities to interact with the Sm2S3 photocatalyst and efficiently degrade. The pickering emulsion stabilised by 0.1 wt% of Sm2S3 nanoparticles in situ hydrophobized with 2.7 mM of CTAB results in almost 100% degradation. Moreover, using only solid Sm2S3 (having wt% of 0.025 or 0.075) as a pickering stabiliser, new PANI@Sm2S3 spherical nanocomposites were synthesised via pickering emulsion polymerization. The formation of PANI@Sm2S3 composites was identified via UV-vis, IR, and 1H-NMR investigations. The analysis of FESEM images showed that the amount of nanoparticles used in the dispersion (for 0.025 wt%, 35 nm and 0.075 wt%, 29 nm) strongly influences the size and shape of the composites.

High dilutions of a drug of COVID-19 origin show difference in ranks

High dilutions (HDs) of drugs, used in Homeopathy, are prepared in aqueous EtOH (ethanol) through serial dilution accompanying mechanical agitation or succussion, and are called potencies. The potencies from the rank 12 onwards are too dilute to contain any original drug molecules. Do the potency ranks show any difference from each other? Do serial dilution and succussion contribute to the difference in potency ranks? This study aims to address these two questions. The throat swab of a Covid-19 patient was preserved and diluted with aqueous EtOH 90% to prepare the mother tincture (MT) and five different potencies of Covid named Covidinum. These potencies and their solvent media were analysed by electronic and vibrational spectroscopy. Charge transfer (CT) and proton transfer interactions occur during preparation of the potencies. The FT-IR spectra of all the test samples after normalization show difference from each other with respect to O-H stretching and bending (v2) bands. Serial dilution and succussion contribute to the observed difference in ranks and CT interactions.

Discriminatory behavior of a rhodamine 6G decorated mesoporous silica based multiple cation sensor towards Cu2+ and Hg2+vis-à-vis Al3+, Cr3+ and Fe3+: selective removal of Cu2+ and Hg2+ from aqueous media.

Selective identification of metal ions as well as their removal is possible when a sensing unit is anchored to a solid support. In this paper, functionalized mesoporous silica with a pendant rhodamine 6G moiety (R6FMS) has been obtained by successive grafting of an aldehyde derivative of bisphenol A followed by rhodamine 6G over a 3-aminopropyl anchored mesoporous silica framework. The materials have been characterized by powder X-ray diffraction, nitrogen sorption and electron microscopy studies, FT-IR and solid state MAS NMR spectral studies, and thermal analysis. In ethanol, the colorless silica material gives pink coloration in the presence of Al3+, Cr3+, Fe3+ and Cu2+ which is also clearly evident from the generation of an absorption peak at 525 nm. Upon excitation at 500 nm, the fluorescence intensity of the probe increases by 36-, 17-, 40- and 89-fold in the presence of Al3+, Cr3+, Fe3+ and Cu2+ ions, respectively. This suggests that R6FMS is a colorimetric and fluorescent chemosensor for these cations in ethanol. However, when the solvent is changed from ethanol to water, it becomes a selective chemosensor only for Cu2+ and Hg2+, by the generation of a pink color and strong fluorescence at ca. 550 nm, thereby discriminating the trivalent cations. Cations induce the opening of the spirolactam ring resulting in pink coloration and strong fluorescence. The quantum yield and lifetime of the probe have been increased considerably in the presence of these cations in ethanol as well as in aqueous media. The detection limit values for these cations range from 10-6 to 10-8 M. R6FMS has been used to remove Hg2+ and Cu2+ from their aqueous solution with a maximum adsorption capacity of 35 mg g-1 and 148 mg g-1 for Cu2+ and Hg2+, respectively.

Supercapacitor behaviour of manganese dioxide decorated mesoporous silica synthesized by a rapid sol-gel inverse micelle method.

A new type of mesoporous silica (MS) with high surface area and large pore volume has been synthesised by employing a rapid sol-gel based inverse micelle method and electrochemically active metal center, manganese, has been incorporated into it. The MnO2 decorated silica composites are obtained through the wet impregnation technique using KMnO4 followed by their reduction under neutral conditions. The structure and surface area of the samples have been characterised by powder X-ray diffraction (XRD), BET surface area and pore size analysis, transmission and scanning electron microscopy (TEM and FE-SEM), FT-IR spectroscopy and X-ray photoelectron spectroscopy (XPS). Electrochemical techniques, i.e. cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS), have been used to evaluate the electrochemical properties of the composites. The resultant composite MS/MnO2-3 with a significantly high surface area (453 m2 g-1) is found to exhibit a superior specific capacitance of 1158.50 F g-1 at a scan rate of 5 mV s-1 which is very close to the theoretical value and retains 87.8% of its capacitance up to 1000 cycles at 1 A g-1 current density. The outstanding electrochemical performance of the composite can be attributed to the high surface area and uniform pore size distribution of the novel silica host which simultaneously increases the electrochemically active centres, promotes electrolyte penetration and enhances electron transport. The simplicity of the synthesis process developed here is interesting for wide-scale production of MnO2-based electro-active materials.

The big effect of a small change: formation of CuO nanoparticles instead of covalently bound Cu(ii) over functionalized mesoporous silica and its impact on catalytic efficiency.

Two different heterogeneous catalysts, one with Cu(ii) covalently bonded to functionalized mesoporous silica (FMS-Cu(II)) and another with CuO nanoparticles immobilized over the same silica (FMS-CuO-np), have been synthesized by a common route but with a minor alteration in the sequence of addition of reagents. It is interesting to find that by merely changing the order of the addition of reagents Cu(ii) can be incorporated into the framework in two different forms. In one case Cu(ii) binds to the N and O donor centers present in the functionalized material whereas in the other case CuO nanoparticles are generated in situ. The materials have been thoroughly characterized by powder X-ray diffraction, nitrogen adsorption/desorption, transmission electron microscopy, thermal analysis, FT-IR spectroscopy, solid state MAS-NMR spectroscopy and atomic absorption spectrophotometric studies. The synthesized products have been examined for their catalytic efficiencies in the oxidation of olefins, as a model case. Styrene, α-methyl styrene, cyclohexene, trans-stilbene and cyclooctene have been used as substrates in the presence of tert-butyl hydroperoxide as the oxidant in acetonitrile medium under mild conditions. The products of the catalytic reactions have been identified and estimated by gas chromatography and gas chromatography-mass spectrometry. The rate of conversion of the substrates for both the catalysts is high and the selectivity is also good. But from comparative studies, it is found that FMS-CuO-np which contains CuO nanoparticles shows better efficiency than FMS-Cu(II). The catalysts have been recycled for five catalytic cycles without showing much decrease in their catalytic activity.

Mesoporous silica based recyclable probe for colorimetric detection and separation of ppb level Hg2+ from aqueous medium.

Functional mesoporous silica probes, MCM-TFM and SBA-TFM, have been synthesized with varying pore sizes and having S-donor sites judiciously selected to bind soft metal centers. The soft S-donor centers are contributed by the thiol functional groups that are introduced into the silica matrices by functionalization with tris(4-formylphenyl)amine followed by 2-aminothiophenol. The materials rapidly and selectively detect Hg2+ colorimetrically and the change in color profile can be perceived through bare eyes. The probes can decontaminate the pollutant heavy metal from aqueous medium at ppb level and the materials are recyclable and reusable for several separation cycles.

In situ synthesis of CuO nanoparticles over functionalized mesoporous silica and their application in catalytic syntheses of symmetrical diselenides.

A versatile and novel catalyst, CuO nanoparticles immobilized over functionalized mesoporous silica (nCuO-FMS), has been synthesized over an organically modified mesoporous silica framework following a facile synthetic route. The surface of the silica support (SBA-15) is first grafted with the 3-aminopropyl silane group and then further functionalized with tris(4-formylphenyl)amine. The reaction is performed in such a way that a few -CHO groups remain free for further functionalization. Finally, the CuO nanoparticles immobilized on mesoporous silica are obtained by a one pot reaction between the functionalized silica, 2-aminophenol and CuCl2. The product obtained has been used as a catalyst for the syntheses of symmetrical diselenides in the presence of KOH as the base and dimethyl sulphoxide (DMSO) as the solvent. The materials have been characterized thoroughly by X-ray powder diffraction, nitrogen adsorption-desorption studies, transmission electron microscopy, thermal analysis and different spectroscopic techniques. The Cu content of the sample has been determined by atomic absorption spectrophotometry (AAS). The products of the catalytic studies have been identified and estimated by NMR spectroscopy. Almost 78% isolated yield could be achieved at 363 K within 3 hours of the reaction and the catalyst, nCuO-FMS, can be recycled at least up to five catalytic cycles.

One Step Synthesis of a Gold/Ordered Mesoporous Carbon Composite Using a Hard Template Method for Electrocatalytic Oxidation of Methanol and Colorimetric Determination of Glutathione.

Ordered mesoporous carbon-supported gold nanoparticles (Au/OMC) have been fabricated in one step through a hard template method using gold nanoparticle-intercalated mesoporous silica (GMS) to explore two different catalytic properties, for example, electrocatalytic oxidation of methanol and colorimetric determination of glutathione (GSH). The catalytically inert but conducting nature of mesoporous carbon (OMC) and promising catalytic activity of gold nanoparticles (AuNPs) has inspired us to synthesize Au/OMC. The as-prepared Au/OMC catalyst was characterized by powder X-ray diffraction, N2 adsorption-desorption, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray analysis-elemental mapping, and X-ray photoelectron spectroscopy. The characterization results indicate that AuNPs are uniformly distributed on the surface of OMC. The conducting-OMC framework with a high surface area of Au/OMC provides superior transport of electrons through the porous surface of carbon matrix and resulted in its high efficiency and stability as an electrocatalyst for the oxidation of methanol in comparison to CMK-3, SBA-15, and GMS in alkaline medium. The efficiency of Au/OMC toward methanol oxidation in alkaline medium is much higher in comparison to that in acidic medium. The lower value of I f/I b in the acidic medium in comparison to that in the alkaline medium clearly indicates that the oxidation process with Au/OMC as a catalyst is much more superior in alkaline medium with better tolerance toward the accumulation of intermediate CO species on the active surface area. Furthermore, the Au/OMC catalyst is successfully utilized for the detection and quantification of GSH spectrophotometrically with a limit of detection value of 0.604 nM.

Activated carbon monoliths derived from bacterial cellulose/polyacrylonitrile composite as new generation electrode materials in EDLC.

Bacterial cellulose (BC) gel is synthesized by static culture process at the interface between air and medium. The solvent-exchanged BC gel is incorporated into polyacrylonitrile (PAN) copolymer solution under heating at 90 °C and subsequent cooling gives bacterial cellulose-polyacrylonitrile composite (BC-PAN) monolith. The BC-PAN monolith is carbonized at 1000 °C with physical activation in the presence of CO2 to obtain the activated carbon monolith, BC-PAN-AC, with large surface area and high microporosity. Unique morphologies are observed for BC gel which is propagated to the BC-PAN monolith and restored in BC-PAN-AC. The BC nanofibers remain entwined throughout the porous skeleton of the PAN backbone and the entangled structure helps in retaining the continuity of the matrix of BC-PAN-AC and reduce the grain boundary impedance for electrical conduction. Cyclic voltammetry shows that these activated carbons are good electrode materials in electric double layer capacitors (EDLC) with capability of high-speed charging and discharging.

2-Hydroxy-naphthyl functionalized mesoporous silica for fluorescence sensing and removal of aluminum ions.

Mesoporous silica functionalized with a 2-hydroxy-naphthyl moiety has been synthesized and characterized by standard techniques like powder X-ray diffraction, N2 adsorption/desorption studies, transmission electron microscopy and spectral studies like FT-IR, UV-visible, fluorescence and 13C and 29Si solid state NMR. The functionalized silica material showed significant enhancement in its emission intensity in the presence of Al3+ ions whereas other metal ions could not bring about any increase in its emission intensity. They either quench the emission or do not alter the intensity significantly making the functionalized material a fluorescence chemosensor for Al3+. The sensitivity of the probe towards Al3+ has been determined to be high with a low limit of detection value. As functionalized silica is not soluble in common solvents, it has been effectively used to bind and remove Al3+ from a solution. Theoretical calculations on a model system have been performed to investigate the electronic spectral transitions.

Exceptional CO2 adsorbing materials under different conditions.

In this article we discuss those materials that have recorded the highest adsorption capacities for the greenhouse gas CO2 under ambient conditions as well as at different temperatures and pressures. For convenience, the materials have been categorized under four categories, viz., porous carbon, metal-organic, zeolite and mesoporous silica, and porous organic frameworks. It has been found that the gas adsorption property significantly relies on several factors such as high surface area and pore volume and the presence of N-, O- and S-containing moieties. The presence of a microporous structure and strong interaction between the CO2 molecules with the framework through H-bonding or dipole-quadrupole interactions facilitates adsorption of the gas.

Synthesis of mesoporous hollow silica nanospheres using polymeric micelles as template and their application as a drug-delivery carrier.

Mesoporous hollow silica nanospheres with uniform particle sizes of 31-33 nm have been successfully synthesized by cocondensation of tetramethoxysilane (TMOS) and alkyltrimethoxysilanes [RSi(OR)3], where the latter also acts as a porogen. ABC triblock copolymer micelles of poly(styrene-b-2-vinyl pyridine-b-ethylene oxide) (PS-PVP-PEO) with a core-shell-corona architecture have been employed as a soft template at pH 4. The cationic shell block with 2-vinyl pyridine groups facilitates the condensation of silica precursors under the sol-gel reaction conditions. Phenyltrimethoxysilane, octyltriethoxysilane, and octadecyltriethoxysilanes were used as porogens for generating mesopores in the shell matrix of hollow silica and the octadecyl precursor produced the largest mesopore among the different porogens, of dimension ca. 4.1 nm. The mesoporous hollow particles were thoroughly characterized by small-angle X-ray diffraction (SXRD), thermal (TG/DTA) and nitrogen sorption analyses, infra-red (FTIR) and nuclear magnetic resonance ((13)C-CP MAS NMR and (29)Si MAS NMR) spectroscopies, and transmission electron microscopy (TEM). The mesoporous hollow silica nanospheres have been investigated for drug-delivery application by an in vitro method using ibuprofen as a model drug. The hollow silica nanospheres exhibited higher storage capacity than the well-known mesoporous silica MCM-41. Propylamine functionalized hollow particles show a more sustained release pattern than their unfunctionalized counterparts, suggesting a huge potential of hollow silica nanospheres in the controlled delivery of small drug molecules.

Unprecedented CO2 uptake over highly porous N-doped activated carbon monoliths prepared by physical activation.

Highly porous N-doped activated carbon monoliths (ACMs) are fabricated by carbonization and physical activation of mesoporous polyacrylonitrile (PAN) monoliths in the presence of CO(2). The monoliths exhibit exceptionally high CO(2) uptake; 5.14 mmol g(-1) at ambient pressure and temperature and 11.51 mmol g(-1) at ambient pressure and 273 K.

3D hexagonal mesoporous silica and its organic functionalization for high CO2 uptake.

Highly ordered 3D-hexagonal mesoporous silica HMS-3 and its vinyl- and 3-chloropropyl-functionalized analogues HMS-4 and -5, respectively, are synthesized under strongly alkaline conditions at 277 K. Tetraethyl orthosilicate, vinyltrimethoxysilane, and 3-chloropropyltrimethoxysilane are used as silica sources, and cetyltrimethylammonium bromide as the structure-directing agent. The 3D-hexagonal pore structures of HMS-3, 4-, and -5 were confirmed by powder XRD and high-resolution TEM studies. Brunauer-Emmett-Teller surface areas of these materials are 1353, 1211, and 603 m(2) g(-1) for HMS-3, -4, and -5, respectively. Among these materials, vinyl-functionalized mesoporous material HMS-4 adsorbs the highest CO(2) (5.5 mmol g(-1) , 24.3 wt%) under 3 bar pressure at 273 K. The 3D-hexagonal pore openings, very high surface area, and cagelike mesopores as well as organic functionalization could be responsible for very high CO(2) uptakes of these materials compared to other related mesoporous silica-based materials.

Hybrid porous tin(IV) phosphonate: an efficient catalyst for adipic acid synthesis and a very good adsorbent for CO2 uptake.

A new porous organic-inorganic hybrid tin phosphonate material has been synthesized hydrothermally, which shows a Brunauer-Emmett-Teller surface area of 723 m(2) g(-1) and it adsorbs 4.8 mmol g(-1) CO(2) at 273 K and 5 bar pressure. The material also shows remarkable catalytic activity in one-pot liquid phase oxidation of cyclohexanone to adipic acid under eco-friendly conditions.

Porphyrin based porous organic polymers: novel synthetic strategy and exceptionally high CO2 adsorption capacity.

Iron containing porous organic polymers (Fe-POPs) have been synthesized by a facile one-pot bottom-up approach to porphyrin chemistry by an extended aromatic substitution reaction between pyrrole and aromatic dialdehydes in the presence of small amount of Fe(III). The Fe-POPs possess very high BET surface area, large micropores and showed excellent CO(2) capture (~19 wt%) at 273 K/1 bar.

Functionalized mesoporous silica supported copper(II) and nickel(II) catalysts for liquid phase oxidation of olefins.

Highly ordered 2D-hexagonal mesoporous silica has been functionalized with 3-aminopropyltriethoxysilane (3-APTES). This is followed by its condensation with a dialdehyde, 4-methyl-2,6-diformylphenol to produce an immobilized Schiff-base ligand (I). This material is separately treated with methanolic solution of copper(II) chloride and nickel(II) chloride to obtain copper and nickel anchored mesoporous materials, designated as Cu-AMM and Ni-AMM, respectively. The materials have been characterized by Fourier transform infrared (FT-IR) and UV-vis diffuse reflectance (DRS) spectroscopy, powder X-ray diffraction (XRD), transmission electron microscopy (TEM), N(2) adsorption-desorption studies and (13)C CP MAS NMR spectroscopy. The metal-grafted mesoporous materials have been used as catalysts for the efficient and selective epoxidation of alkenes, viz. cyclohexene, trans-stilbene, styrene, α-methyl styrene, cyclooctene and norbornene to their corresponding epoxides in the presence of tert-butyl hydroperoxide (TBHP) as the oxidant under mild liquid phase conditions.

Fabrication of mesoporous polymer monolith: a template-free approach.

Mesoporous polyacrylonitrile (PAN) monolith has been fabricated by a template-free approach using the unique affinity of PAN towards a water/dimethyl sulfoxide (DMSO) mixture. A newly developed Thermally Induced Phase Separation Technique (TIPS) has been used to obtain the polymer monoliths and their microstructures have been controlled by optimizing the concentration and cooling temperature.

Highly ordered acid functionalized SBA-15: a novel organocatalyst for the preparation of xanthenes.

Post-synthesis modification of SBA-15 has been carried out to design highly ordered acid functionalized hybrid mesoporous organosilica, AFS-1. This material has been used as an efficient heterogeneous organocatalyst for the syntheses of xanthenes under mild conditions in the absence of any other metal co-catalyst.