There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Redox‐Based Resistive Switching Memories – Nanoionic Mechanisms, Prospects, and Challenges

Electrochemical energy storage technology is based on devices capable of exhibiting high energy density (batteries) or high power density (electrochemical capacitors). There is a growing need, for current and near-future applications, where both high energy and high power densities are required in the same material. Pseudocapacitance, a faradaic process involving surface or near surface redox reactions, offers a means of achieving high energy density at high charge–discharge rates. Here, we focus on the pseudocapacitive properties of transition metal oxides. First, we introduce pseudocapacitance and describe its electrochemical features. Then, we review the most relevant pseudocapacitive materials in aqueous and non-aqueous electrolytes. The major challenges for pseudocapacitive materials along with a future outlook are detailed at the end.

https://hal.archives-ouvertes.fr/hal-01171774/document

Pseudocapacitive oxide materials for high-rate electrochemical energy storage

Approaches, Derivatives and Applications Vasilios Georgakilas,† Michal Otyepka,‡ Athanasios B. Bourlinos,‡ Vimlesh Chandra, Namdong Kim, K. Christian Kemp, Pavel Hobza,‡,§,⊥ Radek Zboril,*,‡ and Kwang S. Kim* †Institute of Materials Science, NCSR “Demokritos”, Ag. Paraskevi Attikis, 15310 Athens, Greece ‡Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacky University Olomouc, 17. listopadu 12, 771 46 Olomouc, Czech Republic Center for Superfunctional Materials, Department of Chemistry, Pohang University of Science and Technology, San 31, Hyojadong, Namgu, Pohang 790-784, Korea Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo naḿ. 2, 166 10 Prague 6, Czech Republic

Functionalization of Graphene: Covalent and Non-Covalent Approaches, Derivatives and Applications

A facile, green strategy is explored to synthesize mesoporous Au/Li4Ti5O12 spheres based on in situ conversion of titanium glycolate in LiOH aqueous solution. Compared with TiO2 precursors, titanium glycolate possesses some strengths: (i) fast and easy preparation; (ii) direct reaction with LiOH without introduce of TiO2 impurity. In the synthesis, the produced chemical waste is only the mixed solvent of acetone and ethylene glycol (EG). Furthermore, acetone and EG in chemical waste can be easily separated by distillation and reused in the next synthesis process due to the great difference between their boiling points. In particular, the as-prepared mesoporous Au/Li4Ti5O12 spheres combines the advantages of large specific surface area (166 m2/g) and good electronic conduction enhanced by Au nanoparticles when used as an anode electrode material. The electrochemical tests show that the mesoporous Au/Li4Ti5O12 spheres display excellent high rate capability and cycling performance.

A facile titanium glycolate precursor route to mesoporous Au/Li4Ti5O12 spheres for high-rate lithium-ion batteries.

Si–Al thin film anode material with superior cycle performance and rate capability for lithium ion batteries

Synthesis of mesoporous SnO2 spheres via self-assembly and superior lithium storage properties

CeO2 is a good humidity sensitive material, which has been widely investigated by using direct current (d.c.) analysis method. In this paper, we used the complex impedance analysis method to analyze CeO2 nanoparticles (NPs). It was found that the impedance as a function of humidity exhibited the best linearity and smallest hysteresis at 1 KHz than the capacitance or resistance did. The complex impedance modulus (|Z|) varied by four orders of magnitude from 3.8 × 107 Ω to 4.3 × 103 Ω in the humidity range of 11–98% RH. The value of the linearity fit correlation (R2) was 0.997. The sensor exhibits a rapid and reversible response characterized by a very small hysteresis (∼2% RH). The response time and recovery time were 10 s and 3 s, respectively. These results further demonstrated promising application of CeO2 as humidity sensor.

High performance humidity sensors based on CeO2 nanoparticles

New, highly sensitive room temperature (RT) hydrogen gas sensors were fabricated by coating Pt-decorated-cube-like-In 2 O 3 on Au electrodes. In 2 O 3 , with diameters between 200 and 300 nm, was obtained by a hydrothermal method and coated with Pt by a simple solution based on chemical technique. The morphological and elemental studies of the material were carried out using SEM, TEM and EDAX analysis. The loading of the Pt nanoparticles (NPs) enhanced the catalytic dissociation of oxygen molecules, adsorbed a substantial quantity of hydrogen, and the sensor exhibited a dramatic decrease in working temperatures to 25 °C. Responding to 1.5 vol% hydrogen, the sensor achieved response and recovery times of approximately 33 s and 66 s, respectively. The sensor also achieved excellent stability and high sensitivity to hydrogen at RT. In addition, it also showed a slow response to CO. The gas response to 1.5 vol% CO was 10 times lower than that to hydrogen. For other organic compounds in the gaseous state, such as ethanol, acetone and isopropanol, the response could be neglected. Such a large discrepancy reveals the sensor's outstanding selectivity to H 2 . Grain boundary theory and spillover theory are applied to explain the gas sensing effect of the Pt-coated In 2 O 3 nanocubes sensor.

Taihong Wang

Papers

A facile titanium glycolate precursor route to mesoporous Au/Li4Ti5O12 spheres for high-rate lithium-ion batteries.

Si–Al thin film anode material with superior cycle performance and rate capability for lithium ion batteries

Synthesis of mesoporous SnO2 spheres via self-assembly and superior lithium storage properties

High performance humidity sensors based on CeO2 nanoparticles

Room-temperature hydrogen sensor based on grain-boundary controlled Pt decorated In2O3 nanocubes