Juan C. Noveron

Metallomesogens: Supramolecular Design via Alkane-rich Metal Complexes

Molecules that use non-covalent interactions to self-organize into supramolecular structures have the potential to generate functional materials with a broad range of applications. This review article focuses on the design and synthesis of molecules that use transition metal ions and long alkyl chains to direct the formation of ordered supramolecular phases. This unique combination of coordination bonds and alkyl interdigitation provide exceptional control over intermolecular interactions and can generate nanoscale molecular order as liquid crystalline states, Langmuir-Blodgett films on surfaces, highly ordered lyotropic phases such as metallo-micelles in water and reverse metallo-micelles in organic media. The synthetic strategy for alkane-rich ligands and the coordination- and lipid-directed self-assembly of these molecules are de- scribed.

Green synthesis of gold nanoparticles reduced and stabilized by squaric acid and supported on cellulose fibers for the catalytic reduction of 4-nitrophenol in water

We report a simple, fast, and green method to produce gold nanoparticles (AuNPs) that are reduced and stabilized by sodium squarate in water and easily attach to cellulose fibers. The AuNPs and its nanocomposites with cellulose fibers exhibited excellent catalytic activity for the reduction of 4-nitrophenol (4-NP) with NaBH4. A glass column was packed with the nanocomposites and used for the continuous catalytic reduction of 4-NP with NaBH4 and demonstrated to be used multiple times (20×) without loss of catalytic activity.

Microwave exfoliated graphene oxide/TiO2 nanowire hybrid for high performance lithium ion battery

Lithium ion battery (LIB) is a key solution to the demand of ever-improving, high energy density, clean-alternative energy systems. In LIB, graphite is the most commonly used anode material; however, lithium-ion intercalation in graphite is limited, hindering the battery charge rate and capacity. To date, one of the approaches in LIB performance improvement is by using porous carbon (PC) to replace graphite as anode material. PCs pore structure facilitates ion transport and has been proven to be an excellent anode material candidate in high power density LIBs. In addition, to overcome the limited lithium-ion intercalation obstacle, nanostructured anode assembly has been extensively studied to increase the lithium-ion diffusion rate. Among these approaches, high specific surface area metal oxide nanowires connecting nanostructured carbon materials accumulation have shown promising results for enhanced lithium-ion intercalation. Herein, we demonstrate a hydrothermal approach of growing TiO2 nanowires (TON) on microwave exfoliated graphene oxide (MEGO) to further improve LIB performance over PC. This MEGO-TON hybrid not only uses the high surface area of MEGO but also increases the specific surface area for electrode–electrolyte interaction. Therefore, this new nanowire/MEGO hybrid anode material enhances both the specific capacity and charge–discharge rate. Scanning electron microscopy and X-ray diffraction were used for materials characterization. Battery analyzer was used for measuring the electrical performance of the battery. The testing results have shown that MEGO-TON hybrid provides up to 80% increment of specific capacity compared to PC anode.

Fullerene stabilized gold nanoparticles

We report a simple and one-step method of generating gold nanoparticles stabilized directly with fullerenes C60 and [6,6]-phenyl-C61-butyric acid (PCBA) that led to C60-AuNPs (1) and PCBA-AuNPs (2), respectively. The C60-AuNPs (1) and PCBA-AuNPs (2) were characterized with UV-vis, FTIR, DLS, zeta potential, XRD, TEM, and AFM.

High-performance porous carbon/CeO2 nanoparticles hybrid super-capacitors for energy storage

Increasing demand for energy storage devices has propelled researchers for developing efficient super-capacitors (SC) with long cycle life and ultrahigh energy density. Carbon-based materials are commonly used as electrode materials for SC. Herein we report a new approach to improve the SC performance utilizing porous carbon /Cerium oxide nanoparticle (PC-CON) hybrid as electrode material synthesized via low temperature hydrothermal method and tetraethyl ammonium tetrafluroborate in acetonitrile as organic electrolyte. Through this approach, charges can be stored not only via electrochemical double layer capacitance (EDLC) from PC but also through pseudo-capacitive effect from CeO2 NPs. The excellent electrode-electrolyte interaction due to the electrochemical properties of the ionic electrolyte provides a better voltage window for the SC. Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-Ray Diffraction (XRD) measurements were used for the initial characterization of this PC/CeO2 NPs hybrid material system. Electrochemical measurements of SCs was performed using a potentio-galvanostat. It is found that the specific capacitance was improved by 30% using PC-CON system compared with pristine PC system.

Green synthesis of gold, silver, platinum, and palladium nanoparticles reduced and stabilized by sodium rhodizonate and their catalytic reduction of 4-nitrophenol and methyl orange

Sodium rhodizonate was used as a bifunctional reducing as well as stabilizing agent for the single step synthesis of gold (Au), silver (Ag), platinum (Pt), and palladium (Pd) nanoparticles (NPs) in water. Transmission electron microscopy analysis revealed that Pt, Au, Ag, and PdNPs have average core diameters of about 2, 8, 26, and 39 nm, respectively. The ability of these nanoparticles towards the catalytic reduction of 4-nitrophenol (4-NP) with sodium borohydride (NaBH4) and the dual-catalytic oxidation of formic acid followed by the reduction of methyl orange (MO) was studied. The apparent rate constants (kapp) of the catalytic reduction of 4-NP in the presence of Ag, Au, Pt, and PdNPs were calculated to be 2.1482, 1.1167, 1.088 × 10−1, and 1.65 × 10−2 min−1, respectively. However, for the dual-catalytic oxidation of formic acid followed by the reduction of MO, the kapp values were calculated to be 4.145, 1.25 × 10−2, 6.7 × 10−3, and 9.0 × 10−5 for the Pt, Pd, Au, and AgNPs, respectively.

Solid-phase organic synthesis of 2-tridecanyl-1,4-naphthoquinone and 2-tridecanyl-1,4-naphthodiol that form redox-active micelles and vesicles

The solid-phase synthesis of new amphiphilic compounds is reported. It is based on a newly designed 1,4-naphthoquinone derivative that contains polar and nonpolar groups and self-assembles into micelles or vesicles in water depending on the concentration. They also display redox-active properties.

Adsorption of methylene blue and tetracycline onto biomass-based material prepared by sulfuric acid reflux

The adsorptive removal of environmental pollutants is an effective method for the treatment of contaminated water. Thus, the preparation of adsorbents from low-cost, readily available, and renewable resources has garnered immense attention in recent years. In this study, a facile one-step method for the preparation of a high-capacity adsorbent is demonstrated by refluxing pine cones in concentrated sulfuric acid. With sulfuric acid reflux, the pine cones undergone carbonization as well as functionalization with sulfonic acid groups. The adsorbent demonstrated high adsorption capacity for two emerging organic pollutants, methylene blue (MB) and tetracycline (TC). Different variables such as pH, temperature, contact time, and initial concentration of the pollutants were analyzed and showed that the adsorption capacity for MB increased in a basic pH and vice versa for TC. Also, the elevated temperature favored the adsorption for both MB and TC. The maximum adsorption capacity was found to be 1666.66, and 357.14 mg g−1 for MB and TC, respectively. In comparison to the pristine pine cone, the sulfuric acid treated pine cone demonstrated an extraordinary improvement in the adsorption capacity. The adsorption of MB and TC was performed from the tap water matrix and similar adsorption capacities were found. A packed glass column was also prepared to demonstrate the adsorption of MB from tap water under flow conditions.

Mesomorphic Behavior in Silver(I) N-(4-Pyridyl) Benzamide with Aromatic π–π Stacking Counterions

Organic semiconductor materials composed of π–π stacking aromatic compounds have been under intense investigation for their potential uses in flexible electronics and other advanced technologies. Herein we report a new family of seven π–π stacking compounds of silver(I) bis-N-(4-pyridyl) benzamide with varying counterions, namely [Ag(NPBA)2]X, where NPBA is N-(4-pyridyl) benzamine, X = NO3− (1), ClO4− (2), CF3SO3− (3), PF6− (4), BF4− (5), CH3PhSO3− (6), and PhSO3− (7), which form extended π−π stacking networks in one-dimensional (1D), 2D and 3D directions in the crystalline solid-state via the phenyl moiety, with average inter-ring distances of 3.823 Å. Interestingly, the counterions that contain π–π stacking-capable groups, such as in 6 and 7, can induce the formation of mesomorphic phases at 130 °C in dimethylformamide (DMF), and can generate highly branched networks at the mesoscale. Atomic force microscopy studies showed that 2D interconnected fibers form right after nucleation, and they extend from ~30 nm in diameter grow to reach the micron scale, which suggests that it may be possible to stop the process in order to obtain nanofibers. Differential scanning calorimetry studies showed no remarkable thermal behavior in the complexes in the solid state, which suggests that the mesomorphic phases originate from the mechanisms that occur in the DMF solution at high temperatures. An all-electron level simulation of the band gaps using NRLMOL (Naval Research Laboratory Molecular Research Library) on the crystals gave 3.25 eV for (1), 3.68 eV for (2), 1.48 eV for (3), 5.08 eV for (4), 1.53 eV for (5), and 3.55 eV for (6). Mesomorphic behavior in materials containing π–π stacking aromatic interactions that also exhibit low-band gap properties may pave the way to a new generation of highly branched organic semiconductors.

Bimetallic CoMoS Composite Anchored to Biocarbon Fibers as a High-Capacity Anode for Li-Ion Batteries

Our work reports the hydrothermal synthesis of a bimetallic composite CoMoS, followed by the addition of cellulose fibers and its subsequent carbonization under Ar atmosphere (CoMoS@C). For comparison, CoMoS was heat-treated under the same conditions and referred as bare-CoMoS. X-ray diffraction analysis indicates that CoMoS@C composite matches with the CoMoS4 phase with additional peaks corresponding to MoO3 and CoMoO4 phases, which probably arise from air exposure during the carbonization process. Scanning electron microscopy images of CoMoS@C exhibit how the CoMoS material is anchored to the surface of carbonized cellulose fibers. As anode material, CoMoS@C shows a superior performance than bare-CoMoS. The CoMoS@C composite presents an initial high discharge capacity of ∼1164 mA h/g and retains a high specific discharge capacity of ∼715 mA h/g after 200 cycles at a current density of 500 mA/g compared to that of bare-CoMoS of 102 mA h/g. The high specific capacity and good cycling stability could be attributed to the synergistic effects of CoMoS and carbonized cellulose fibers. The use of biomass in the anode material represents a very easy and cost-effective way to improve the electrochemical Li-ion battery performance.