The science and technology of ultracapacitors are reviewed for a number of electrode materials, including carbon, mixed metal oxides, and conducting polymers. More work has been done using microporous carbons than with the other materials and most of the commercially available devices use carbon electrodes and an organic electrolytes. The energy density of these devices is 3¯5 Wh/kg with a power density of 300¯500 W/kg for high efficiency (90¯95%) charge/discharges. Projections of future developments using carbon indicate that energy densities of 10 Wh/kg or higher are likely with power densities of 1¯2 kW/kg. A key problem in the fabrication of these advanced devices is the bonding of the thin electrodes to a current collector such the contact resistance is less than 0.1 cm2. Special attention is given in the paper to comparing the power density characteristics of ultracapacitors and batteries. The comparisons should be made at the same charge/discharge efficiency.

Ultracapacitors: Why, How, and Where is the Technology

The current demands of sustainable green methodologies have increased the use of enzymatic technology in industrial processes. Employment of enzyme as biocatalysts offers the benefits of mild reaction conditions, biodegradability and catalytic efficiency. The harsh conditions of industrial processes, however, increase propensity of enzyme destabilization, shortening their industrial lifespan. Consequently, the technology of enzyme immobilization provides an effective means to circumvent these concerns by enhancing enzyme catalytic properties and also simplify downstream processing and improve operational stability. There are several techniques used to immobilize the enzymes onto supports which range from reversible physical adsorption and ionic linkages, to the irreversible stable covalent bonds. Such techniques produce immobilized enzymes of varying stability due to changes in the surface microenvironment and degree of multipoint attachment. Hence, it is mandatory to obtain information about the structure of the enzyme protein following interaction with the support surface as well as interactions of the enzymes with other proteins. Characterization technologies at the nanoscale level to study enzymes immobilized on surfaces are crucial to obtain valuable qualitative and quantitative information, including morphological visualization of the immobilized enzymes. These technologies are pertinent to assess efficacy of an immobilization technique and development of future enzyme immobilization strategies.

https://www.tandfonline.com/doi/pdf/10.1080/13102818.2015.1008192

An overview of technologies for immobilization of enzymes and surface analysis techniques for immobilized enzymes

Fourier transform Infrared (FTIR) spectroscopy is a versatile technique for the characterization of materials belonging to the carbon family. Based on the interaction of the IR radiation with matter this technique may be used for the identification and characterization of chemical structures. Most important features of this method are: non-destructive, real-time measurement and relatively easy to use. Carbon basis for all living systems has found numerous industrial applications from carbon coatings (i.e. amorphous and nanocrystalline carbon films: diamond-like carbon (DLC) films) to nanostructured materials (fullerenes, nanotubes, graphene) and carbon materials at nanoscale or carbon dots (CDots). In this paper, we present the FTIR vibrational spectroscopy for the characterization of diamond, amorphous carbon, graphite, graphene, carbon nanotubes (CNTs), fullerene and carbon quantum dots (CQDs), without claiming to cover entire field.

FTIR Spectroscopy for Carbon Family Study

Nanocellulose as a natural source for groundbreaking applications in materials science: Today’s state

Development of a colorimetric pH indicator based on bacterial cellulose nanofibers and red cabbage (Brassica oleraceae) extract.

Functionalization of Carbon Nanotube (CNT) plays an important role in creating CNT hybride material. In this study, integrated analysis of functional group sites on the pristine and modified Multi-Wall Carbon Nanotube (MWCNT) surface was comparably conducted to know the effect of acid solution on the surface after purification and functionalization process. Acid treatment removed rest of graphitic and residual catalytic metal particles and suffered degradation, such as nanotube shortening and additional defect generation in the graphitic network. Defects on the side wall due to functionalized group clearly shown in Transmission Electron Image (TEM) images cause a reduction in thermal stability. Functional group sited on the side wall was detected by Attenuated Total Reflectance (ATR) - Fourier Transform Infra Red (FTIR) with the relative concentration of oxygen-containing functional groups determined by Boehm titration.

/pdf/analysis-of-functional-group-sited-on-multi-wall-carbon-2piv2nemx3.pdf

Analysis of Functional Group Sited on Multi-Wall Carbon Nanotube Surface

The role of the water structure present in hydrogels from nutlets of three species of salvias,S. miltiorrhiza (SM),S. sclarea (SS) andS. viridis (SV), was analyzed by differential scanning calorimetry (DSC). The sharp endothermic peaks that appeared at 5.9 °C (SM), 2.8 °C (SS) and 1.8 °C (SV) in each 1.0% hydrogel of 10.4–15.8% were not affected by addition of 0.1 M urea and alkali-metal salts. The order-disorder portions in the network were slightly affected by the distribution of freezable and non-freezable water in the hydrogel networks. The SV hydrogel was further used to investigate the effects of additives (0.1–8.0 M urea and 0.1–5.0 M NaCl) on its melting behavior. At 0.5–4.0 M urea and 1.0–3.0 M NaCl, two endothermic peaks appeared, corresponding to unbound (high temperature) and bound (low temperature) water in the gel networks, and eventually merged into one endothermic peak at 5.0–8.0 M urea and 4.0–4.5 M NaCl. After this merger, the endothermic peak shifted to 3.7, 4.0 and 5.6 °C at 5.0, 6.0 and 8.0 M urea, respectively. In the case of NaCl, a combination of peaks that occurred at 4.0–4.5 M were accompanied by a shift to lower temperature (−14.4 and 15.3 °C) and the endothermic peak finally disappeared at 5.0 M NaCl due to the strong binding of water in the gel networks.

/pdf/dsc-analysis-on-water-state-of-salvia-hydrogels-43wgpyqio1.pdf

DSC Analysis on Water State of Salvia Hydrogels

Development of Nanocomposites from Bacterial Cellulose and Poly(vinyl Alcohol) using Casting-drying Method

Formation of nanostructured graphitic carbon from coconut waste via low-temperature catalytic graphitisation

Excellent transparent films were prepared from bacterial cellulose (BC) sheets by solubilization of its defibrillated freeze-dried specimens in a solvent of dimethylacetamide (DMAc) containing 8.0% (w/w) lithium chloride (LiCl), and their properties were compared with those of the native BC. Fibrillar structure of the native BC disappeared after dissolution, and the film formed after dissolution also loose this structure. Occurence of structural transformation from crystalline to amorphous state was also evidenced by X-ray diffraction, solid state cross polarization/magic angle spinning 13C-NMR and attenuated total reflectance–Fourier transform infrared spectroscopic analyses. In addition, excellent 3D uniform structure of the transparent BC film was further evidenced by X-ray micro computed tomography. Plastic-like characteristic was enhanced by film formation after dissolving the BC specimens in the DMAc–LiCl solution as shown by changing mechanical properties, a slight decrease in tensile strength (67.2 to 59.6 MPa) and breaking stress (67.2 to 58.4 MPa) but significant increase in elongation at break from 3.4 to 10.5%, and improvement of work of fracture from 5.8 to 21.2 kJ/m2. Copyright © 2016 John Wiley & Sons, Ltd.

Rike Yudianti

Papers

Analysis of Functional Group Sited on Multi-Wall Carbon Nanotube Surface

DSC Analysis on Water State of Salvia Hydrogels

Development of Nanocomposites from Bacterial Cellulose and Poly(vinyl Alcohol) using Casting-drying Method

Formation of nanostructured graphitic carbon from coconut waste via low-temperature catalytic graphitisation

Properties of bacterial cellulose transparent film regenerated from dimethylacetamide–LiCl solution