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

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

The chemistry of graphene oxide is discussed in this critical review Particular emphasis is directed toward the synthesis of graphene oxide, as well as its structure Graphene oxide as a substrate for a variety of chemical transformations, including its reduction to graphene-like materials, is also discussed This review will be of value to synthetic chemists interested in this emerging field of materials science, as well as those investigating applications of graphene who would find a more thorough treatment of the chemistry of graphene oxide useful in understanding the scope and limitations of current approaches which utilize this material (91 references)

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The chemistry of graphene oxide

Problems associated with large-scale pattern growth of graphene constitute one of the main obstacles to using this material in device applications. Recently, macroscopic-scale graphene films were prepared by two-dimensional assembly of graphene sheets chemically derived from graphite crystals and graphene oxides. However, the sheet resistance of these films was found to be much larger than theoretically expected values. Here we report the direct synthesis of large-scale graphene films using chemical vapour deposition on thin nickel layers, and present two different methods of patterning the films and transferring them to arbitrary substrates. The transferred graphene films show very low sheet resistance of approximately 280 Omega per square, with approximately 80 per cent optical transparency. At low temperatures, the monolayers transferred to silicon dioxide substrates show electron mobility greater than 3,700 cm(2) V(-1) s(-1) and exhibit the half-integer quantum Hall effect, implying that the quality of graphene grown by chemical vapour deposition is as high as mechanically cleaved graphene. Employing the outstanding mechanical properties of graphene, we also demonstrate the macroscopic use of these highly conducting and transparent electrodes in flexible, stretchable, foldable electronics.

Large-scale pattern growth of graphene films for stretchable transparent electrodes

The development of facile methods for constructing highly active, cost-effective catalysts that meet ampere-level current density and durability requirements for an oxygen evolution reaction is crucial. Herein, we posit a general topochemical transformation strategy: the M-Co9 S8 single atom catalysts (SACs) are directly converted into M-CoOOH-TT (M  =  W, Mo, Mn, V) pair sites catalysts under the role of incorporating of atomically dispersed high valence metals modulators through potential cycling. Furthermore, in situ X-ray absorption fine structure spectroscopy was used to track the dynamic topochemical transformation process at the atomic level. The W-Co9 S8 breaks through the low overpotential of 160 mV at 10 mA cm-2 . A series of pair-site catalysts exhibit a large current density approaching 1,760 mA cm-2 at 1.68 V versus RHE in alkaline water oxidation and achieve a ∼240-fold enhancement in the normalized intrinsic activity compared to that reported CoOOH, and sustainable stability of 1,000 h. Moreover, we confirmed the O-O bond formation via a two-site mechanism, supported by in situ synchrotron radiation infrared and DFT simulations, which breaks the limit of adsorption-energy scaling relationship on conventional single-site. This article is protected by copyright. All rights reserved.

Boosting Efficient and Sustainable Alkaline Water Oxidation on W-Coooh-TT Pair Sites Catalyst Synthesized via Topochemical Transformation.

Electrochemical hydrogen peroxide (H2O2) synthesis from water and air via two-electron (2e−) water oxidation or oxygen reduction reactions could provide a sustainable route for on-site H2O2 production. Unfortunately, the electrochemical H2O-to-H2O2 process usually suffers from limited selectivity under high current density. Here, we present an atomic Ni-doped TiO2 electrocatalyst that enables H2O2 production through 2e− water oxidation with high Faradaic efficiency of 70% at ∼300 mA cm−2. Furthermore, when paired with the 2e− oxygen reduction reaction using the oxidized carbon nanotube cathode, as high as 146% Faradaic efficiency for H2O2 is achieved at 240 mA in a full flow cell device. Moreover, this device could be operated for modular H2O2 synthesis with a production rate of 109.12 μmol min−1 (i.e., 3.7 mg min−1). This work demonstrates the atomically controlled metal oxide electrocatalyst for harsh anodic H2O to H2O2 and the practical applicability for the on-site H2O2 production from earth-abundant resources. 

Highly efficient paired H2O2 production through 2e− water oxidation coupled with 2e− oxygen reduction

The invention provides an aluminum nanosheet, having an equivalent diameter of 50 to 1000 nm, and a thickness of 15 to 50 nm The invention further provides a method for preparing the aluminum nanosheet and the use thereof as a two-photon light emitting material or a Raman enhanced material

Xiaoming Sun

Papers

Boosting Efficient and Sustainable Alkaline Water Oxidation on W-Coooh-TT Pair Sites Catalyst Synthesized via Topochemical Transformation.

Highly efficient paired H2O2 production through 2e− water oxidation coupled with 2e− oxygen reduction

Aluminum nanosheet, its preparing method and use thereof

Micropore-confined Ru nanoclusters catalyst for efficient pH-universal hydrogen evolution reaction