Vibrational spectroscopy at electrolyte/electrode interfaces with graphene gratings.

Microscopic understanding of physical and electrochemical processes at electrolyte/electrode interfaces is critical for applications ranging from batteries, fuel cells to electrocatalysis. However, probing such buried interfacial processes is experimentally challenging. Infrared spectroscopy is sensitive to molecule vibrational signatures, yet to approach the interface three stringent requirements have to be met: interface specificity, sub-monolayer molecular detection sensitivity, and electrochemically stable and infrared transparent electrodes. Here we show that transparent graphene gratings electrode provide an attractive platform for vibrational spectroscopy at the electrolyte/electrode interfaces: infrared diffraction from graphene gratings offers enhanced detection sensitivity and interface specificity. We demonstrate the vibrational spectroscopy of methylene group of adsorbed sub-monolayer cetrimonium bromide molecules and reveal a reversible field-induced electrochemical deposition of cetrimonium bromide on the electrode controlled by the bias voltage. Such vibrational spectroscopy with graphene gratings is promising for real time and in situ monitoring of different chemical species at the electrolyte/electrode interfaces

Effects of Polypyrrole/Graphene Oxide Composites with Different Reaction Times on Electrochemical Performance

Graphene oxide (GO) was prepared using the modified Hummers method and used as a template for polypyrrole. Polypyrrole was polymerized in situ on the surface of GO to finally obtain the polypyrrole/graphene oxide composite material. The effects of different reaction times on the electrochemical performance of polypyrrole/graphene oxide in the second step were studied. It was obtained that the composite material had optimal properties when the reaction time was 24 h

Synthesis and Characterization of 4,4′-Dibromoazobenzene

Abstract: Azobenzene molecules show excellent application potential in many fields due to their photoisomerization properties. Azobenzene molecules will gradually change from trans-structure to cis-structure under the irradiation of UV. In this paper, we have synthesized 4,4'-dibromoazobenzene molecules and characterized their photoisomerization properties. We found that with the extension of UV time, the trans absorption peak at 343 nm decreased significantly, while the cis absorption peak at 435 nm showed an upward trend. Furthermore, photoisomerization of azobenzene is not a first-order reaction

Overwintering physiology of the rice stem borer larvae, Chilo suppressalis Walker (Lepidoptera: Pyralidae): Roles of glycerol, amino acids, low-molecular weight carbohydrates and antioxidant enzymes

The rice stem borer, Chilo suppressalis (Walker), is a major rice pest around the world. A strong ability of the rice stem borer to adapt/resist cold temperature (cold hardiness) contributes to its survival through winter. However, the physiological mechanism of its cold hardiness is poorly understood. In this study, we determined the supercooling points (SCPs), the contents of amino acids and low-molecular weight carbohydrates of overwintering rice stem borer larvae. We also assessed the levels of their superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) antioxidative enzymes in the overwintering larvae. Our results revealed an intimate relationship of larval SCP with environmental temperature; SCP change reflected proportionally to change of environmental temperature. Analysis of low molecular weight carbohydrates established that the concentrations of glycerol and trehalose change in a manner that is inversely proportional to that of the environmental temperatures. Changes or significant changes of some amino acids and antioxidative enzymes were also observed in overwintering larvae. Our data suggest that decrease of the SCP in overwintering larvae is due primarily to the increase of cryoprotective glycerol and trehalose and also to the increase of several amino acids to an extent. The decreased SCP in-turn enabled rice stem borer larvae to withstand low temperature. Our study therefore provides an overall picture regarding seasonal changes of the cryoprotective substances in relation to the ability of the rice stem borer to survive cold environmental conditions.Keywords: Chilo suppressalis (Walker), cold hardiness, supercooling points (SCPs), amino acids, low-molecular weight carbohydrates, antioxidant enzyme