[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

2.3. Evaluation of Photocatalytic Water Splitting 6507 2.3.1. Photocatalytic Activity 6507 2.3.2. Photocatalytic Stability 6507 3. UV-Active Photocatalysts for Water Splitting 6507 3.1. d0 Metal Oxide Photocatalyts 6507 3.1.1. Ti-, Zr-Based Oxides 6507 3.1.2. Nb-, Ta-Based Oxides 6514 3.1.3. W-, Mo-Based Oxides 6517 3.1.4. Other d0 Metal Oxides 6518 3.2. d10 Metal Oxide Photocatalyts 6518 3.3. f0 Metal Oxide Photocatalysts 6518 3.4. Nonoxide Photocatalysts 6518 4. Approaches to Modifying the Electronic Band Structure for Visible-Light Harvesting 6519

Semiconductor-based Photocatalytic Hydrogen Generation

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 emergence of semiconductor nanocrystals as the building blocks of nanotechnology has opened up new ways to utilize them in next generation solar cells. This paper focuses on the recent developments in the utilization of semiconductor quantum dots for light energy conversion. Three major ways to utilize semiconductor dots in solar cell include (i) metal−semiconductor or Schottky junction photovoltaic cell (ii) polymer−semiconductor hybrid solar cell, and (iii) quantum dot sensitized solar cell. Modulation of band energies through size control offers new ways to control photoresponse and photoconversion efficiency of the solar cell. Various strategies to maximize photoinduced charge separation and electron transfer processes for improving the overall efficiency of light energy conversion are discussed. Capture and transport of charge carriers within the semiconductor nanocrystal network to achieve efficient charge separation at the electrode surface remains a major challenge. Directing the future resear...

http://wiki.phy.queensu.ca/shughes/images/d/d1/Quantum_Dot_Solar_Cells._Semiconductor_Nanocrystals_as_Light_Harvesters.pdf

Quantum Dot Solar Cells. Semiconductor Nanocrystals as Light Harvesters

Transparent conductors as solar energy materials: A panoramic review

Layered Ti3C2 is attracting much attention as a promising electrode material for energy storage devices due to its excellent electrical conductivity and electrochemical properties due to its surface functional groups. Though various methods have been used to etch Ti3AlC2, the energy storage performance of Ti3C2 mainly depends on exfoliation of aluminium, surface functional groups and intercalation of potassium. Hence, the optimization of Ti3AlC2 etching process has been done by hydrothermal, stirring, and ultra-sonication methods which exhibits a different specific capacitance of 8.7 F g−1, 23.75 F g-1, and 141.45 F g−1 respectively in 3 M KOH electrolyte at 2 mA constant current galvanostatic charge/discharge (GCD) analysis even though same etching time and quantity of MAX materials used. Surprisingly, all the samples show an increased specific capacitance up to 2000th cycles and a maximum value of around 170 % is reached and this value is maintained until 5000 charge-discharge cycle at 10 mA by GCD analysis. These electrochemical differences are investigated in terms TiAl bond termination and formation of O-Ti-O bonds due to the removal by Al during etching process. It is found from XPS analysis that -OH surface termination has occurred with F desorption and the interaction of K+ ion has increased the interlayer space between the individual layers. Moreover, the material has been phase transformed from Ti3C2 to TiO2/Ti3C2 hybrid crystal structure during the cycling stability test. The high dipole moment in TiO2/Ti3C2 hybrid structure due to the decreased work function has increased the specific capacitance of MXene electrode material. To the best of the authors' knowledge, this has not been observed previously and reported. 

Anomalous increase in specific capacitance in MXene during galvanostatic cycling studies

Core-Shell nanostructures, a family of Nanomaterials have attracted increasing research interest due to their unique structural features that consist of an inner core and an external shell of different chemical compositions. Core-Shell nanostructures have exhibited improved physical and electrical, spectroscopic properties relative to their single-component counterparts. This paper describes the synthesis of TiO2 (core) / Polyaniline (shell) core-shell structured nanocomposites and characterization of the synthesized material. The morphological characterization is performed with XRD, SEM, DLS and Spectroscopic characterization is performed with FTIR, UV/Visible and ESR techniques.

Synthesis and characterization of nanosize conducting polyaniline, titania and their composite

Graphene is a well-known two-dimensional material with a large surface area and is used for numerous applications in a variety of fields. Metal-free carbon materials such as graphene-based materials are widely used as an electrocatalyst for oxygen reduction reactions (ORRs). Recently, more attention has been paid to developing metal-free graphenes doped with heteroatoms such as N, S, and P as efficient electrocatalysts for ORR. In contrast, we found our prepared graphene from graphene oxide (GO) by the pyrolysis method under a nitrogen atmosphere at 900 °C has shown better ORR activity in aqueous 0.1 M potassium hydroxide solution electrolyte as compared with the electrocatalytic activity of pristine GO. At first, we prepared various graphene by pyrolysis of 50 mg and 100 mg of GO in one to three alumina boats and pyrolyzed the samples under a N2 atmosphere at 900 °C. The prepared samples are named G50-1B to 3B and G100-1B and G100-2B. The prepared GO and graphenes were also analyzed under various characterization techniques to confirm their morphology and structural integrity. The obtained results suggest that the ORR electrocatalytic activity of graphene may differ based on the pyrolysis conditions. We found that G100-1B (Eonset, E1/2, JL, and n values of 0.843, 0.774, 4.558, and 3.76) and G100-2B (Eonset, E1/2, and JL values of 0.837, 0.737, 4.544, and 3.41) displayed better electrocatalytic ORR activity, as did Pt/C electrode (Eonset, E1/2, and JL values of 0.965, 0.864, 5.222, and 3.71, respectively). These results display the wide use of the prepared graphene for ORR and also can be used for fuel cell and metal–air battery applications.

/pdf/electrocatalytic-oxygen-reduction-reaction-of-graphene-oxide-3qsg0snt.pdf

Electrocatalytic Oxygen Reduction Reaction of Graphene Oxide and Metal-Free Graphene in an Alkaline Medium

Rutile TiO2 nanocrystals having rectangular faces were directly deposited on fluorine-doped tin oxide coated glass substrates. Using polyethylene glycol-400 as the surfactant, we succeeded in growing a porous rutile layer having maximum thickness of 4.8 μm and containing nanocrystals with lateral dimensions of at least 30 nm. We observed that polyethylene glycol not only controlled the sizes of the nanocrystals but also enhanced the rate of deposition. The nanocrystals had rutile structure and the film was strongly textured with preferential orientation along {002} direction. The dye adsorption properties of the nanocrystalline films depended on their microscopic surface areas which were determined by the sizes of the nanocrystals. A dye-sensitized solar cell, fabricated with a 4.8 μm thick nanocrystalline rutile thin film photoanode, exhibited a light-to-electricity conversion efficiency of 5.02 % under 1.0 sun illumination. The internal resistance, interface capacitance and electron lifetime of dye sensitized solar cell were estimated by electrochemical impedance spectroscopy and an electron lifetime of 0.19 s was recorded.

Polyethylene glycol assisted direct deposition of rutile TiO 2 nanocrystals on transparent conducting oxide substrate for dye-sensitized solar cell applications

Cephalosporin antibiotics are the most widelyused as life saving drugs. The drug is subjected to bacterial endotoxins test before releasing into market but due to interfering factors in most of the cases there is a probability of getting false positive results. Hence, noninterfering dilution (NID) to be selected before validating the product. Single product from 1 st to 4 th generation cephalosporins were selected in this study and the NID factor among those Cephalosporin antibiotics is found between ± two fold.

Kandasamy Prabakar

Papers

Anomalous increase in specific capacitance in MXene during galvanostatic cycling studies

Synthesis and characterization of nanosize conducting polyaniline, titania and their composite

Electrocatalytic Oxygen Reduction Reaction of Graphene Oxide and Metal-Free Graphene in an Alkaline Medium

Polyethylene glycol assisted direct deposition of rutile TiO 2 nanocrystals on transparent conducting oxide substrate for dye-sensitized solar cell applications

Determination of NID Factor in cephalosporin Antibiotics