No abstract

We demonstrate that graphite screen printed macroelectrodes allow the low ppb sensing of chromium(VI) in aqueous solutions over the range 100 to 1000 microg L(-1) with a limit of detection of 19 microg L(-1). The underlying electrochemical mechanism is explored indicating an indirect process involving surface oxygenated species. The drawbacks of using hydrochloric acid as a model solution to evaluate the electrochemical detection of chromium(VI) are also pointed out. The analytical protocol is shown to be applicable for the sensing of chromium(VI) in canal water samples at levels set by the World Health Organisation. The protocol is simplified over existing analytical methodologies and given its analytical performance and economical nature, holds promise for the de-centralised screening of chromium(VI).

A facile approach for the synthetic fabrication of iron oxide (Fe 3 O 4 ) particles is presented and their potential application towards energy storage (as an electrode material within a supercapacitor) is explored. The Fe 3 O 4 asymmetric supercapacitor is found to deliver a maximum specific capacitance of y120 F g 21 at a current density of 0.1 A g 21 in an aqueous electrolyte solution (3M KOH) retaining 93.70% of its initial capacity over 1000 cycles. Additionally, an iron based hydrogen superoxide [FeO(OH)] supercapacitor is readily fabricated and is found to exhibit a maximum specific capacitance of y400 F g 21 at a discharge current of 0.1 A g 21 in a 3M KOH solution.

No abstract

A facile methodology based on cyclic voltammetry is presented allowing the density of defects, viz edge plane like-sites/defects of carbon nanomaterials to be readily quantified. The approach is based on the construction of carbon nanomaterial paste electrodes which is measured using cyclic voltammetry and a standard electrochemical redox probe. This protocol allows a quantitative relationship between the heterogeneous electron-transfer rate and the density of defects to be readily determined and also provides researchers with a methodology to quantify the density of defects for comparative purposes.