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Zero-valent antimony and antimony oxide were deposited on graphene oxide by the recently introduced peroxide deposition route. The antimony@graphene oxide (GO) anode exhibits a charging capacity of 340 mAh g-1 with excellent stability at a current rate of 250 mA g-1 after 50 cycles of lithiation, which is superior to all other forms of antimony anodes that have been reported thus far. The electrode also exhibits a good rate performance, with a capacity of 230 and 180 mAh g-1 at a rate of 500 and 1000 mA g-1, respectively. We attribute the superior performance of the antimony@GO anodes to our coating protocol, which provides a thin layer of nanometric antimony coating on the graphene oxide, and to a small amount of antimony oxide that is left in the anode material after heat treatment and imparts some flexibility. The efficient charge distribution by the large surface area of reduced GO and the expansion buffering of the elastic graphene sheets also contributed to the superior stability of the anode.

A methodology for online preconcentration of analytes and their subsequent electrochemically induced delivery to an online electrospray mass spectrometer is introduced. The approach is based on electrodeposition of an active metallic layer, silver deposit in this particular case, subsequent specific accumulation of the target analyte by electrochemical or chemical means onto the active layer, and finally oxidative electrostripping of the conductive layer 'along with the supported analyte to an online mass spectrometer. We demonstrate the new concept by selective electrochemical deposition of homocysteine and other organothiols directly on the working electrode of a miniature flow cell. The same approach was extended to the conjugation of the target analyte (avidin as a test case) to a thiolated ligand (biotin in this case) that was electrode-posited on the silver coated surface. Electrostripping of the silver dissolves the target species and allows their delivery to an online ESI-MS. Furthermore, the dissolved silver ions promote ionization, and its characteristic isotopic pattern assists in the identification of the target analyte. 10.1021/ac901285m

Inorganic polysulfides have significant technological importance, and their environmental role is gradually being unraveled. But despite their importance, there is still no method for quantification of the individual members of the polysulfide family in nonsynthetic samples. The method is based on fast, single-phase derivatization with methyl trifluoromethanesulfonate followed by one of three modes of sample treatment depending on polysulfide concentration. Under the most aggressive preconcentration treatment involving liquid--liquid extraction, solvent evaporation to dryness, dissolution in n-dodecane, and finally HPLC-UV analysis of the dimethylpolysulfane distribution, the minimum detection limits of the individual polysulfides are in the range 15-70 nM. The method was demonstrated for the analysis of synthetic solutions, natural groundwater, polysulfide fortified seawater, and surface water and for time tracing of the distribution of the individual polysulfides during the oxidation of hydrogen sulfide by hydrogen peroxide. The observed speciation was evaluated by comparison with the theoretical distribution of polysulfides at equilibrium with sulfur precipitate showing that the dominant polysulfides' (i.e., tetrato hexasulfide) concentrations agree well with the predicted distribution (90% of the results fall within less than 30% deviation from the predicted values), whereas up to 3-fold deviation was observed for the less abundant trisulfide and octasulfide species.

A new matrix for electrophoresis, a low molecular weight organogel, is described. Dansylated amino acids and peptides were separated by planar and capillary electrophoresis in acetonitrile gels of trans-(1S,2S)-1,2-bis(dodecylamido)cyclohexane. The superior separation ability of the organogel over its corresponding buffer solution in capillary electrophoresis is illustrated. Organogels provide all the advantages associated with planar matrixes with 100% efficient recovery and transfer of the analytes to a mass spectrometer. We demonstrate that the planar gel can be liquefied and injected as is into an ESI-MS to identify the separands.

We describe in this paper the use of ormosil (organically modified silica) sols as additives to the run buffer for selectivity manipulations between solutes in capillary electrophoresis. CE systems that contain sol additives in the run buffer can be thought of as pseudocapillary electrochromatography. Three sols based on different types of silanes were studied. Methyltrimethoxysilane (MTMOS)-based sol was found to improve selectivities between various aromatic acids. Aminopropyltrimethoxysilane (APS) sol interacts differently with structural isomers of aromatic acids than does MTMOS. At low pH with APS sol in the run buffer, neutral solutes can be separated, as well. The separation of the neutral solutes seems to be facilitated by the formation of hydrogen bonds between the solutes and the APS sol. APS and N-[3-(trimethoxysilyl)propyl]-ethylenediamine (EDAS) affect the separation of the same compounds differently, thus indicating that even small changes of the functional groups of the sol have pronounced effect on the interactions between the sols and the solutes.

A new technique for microscopic imaging of electrochemically active surfaces is introduced. The technique combines concepts of probe microscopy and advances in mass spectrometry. The technique is based on a miniature electrochemical flow cell scanner. A liquid feed stream containing a redox component is introduced to the vicinity of the examined location through the annulus of a coaxial capillary set. The incoming reagent interacts with the target location, and the generated product stream is transferred through the inner capillary to an electrospray mass spectrometer, ESI-MS. Thus, a multicomponent, potential-dependent image of the products' distribution versus the location on the electrode is generated. The use of the technique is demonstrated by scanning the electrochemical heterogeneity of model electrodes.

Abstract: High‐charge‐capacity sodium‐ and lithium‐ion battery anodes based on tin telluride are reported for the first time. Graphene oxide/cubic β‐SnTe electrodes exhibit exceptionally high reversible volumetric charge capacities above 3000 and 1300 mAh cm−3 at 100 mA g−1 charging rate for lithium and sodium ion batteries, respectively, and they show very good rate capabilities retaining 68 and 60 % of the respective capacities even at 2000 mA g−1 charging rate. The reversible charge capacity for lithiation is approximately equal to the theoretical value of the active material. The superior electrode performance is attributed to the high conductivity of tellurium, the mechanical buffering of volume changes by the large row‐V host elements, the elasticity of the reduced graphene oxide support, and the very low specific equivalent volumes involved in sodiation and lithiation of SnTe. [ABSTRACT FROM AUTHOR]