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Electrochemically active hybrid electrodes have been obtained by non-covalent immobilization of homo-oligoribonucleotide probes on the surface of multi-walled carbon nanotubes (MWCNTs) grown vertically on a silicon substrate. Immobilization has been achieved by interaction of heterocyclic bases of oligonucleotide with MWCNT surface or through a pyrene anchor group pre-conjugated to oligonucleotide. The electrode capacitance signal measured in our model system allowed for the selective recognition of target RNA oligonucleotides. Pyrene-anchoring of oligonucleotide probes to the MWCNT surface was shown to provide the better selectivity and stability of electrochemical response of the hybrid electrode. [ABSTRACT FROM AUTHOR]

This work contributes to the understanding of single-walled carbon nanotube synthesis by an aerosol CVD method using ethylene and toluene as a hybrid carbon source. We evaluated an extensive set of synthesis conditions revealing the role of ferrocene, toluene, and ethylene. We found the fundamental role of ethylene promoting nanotube nucleation and catalyst activation degree at all the concentrations studied, and enhancing nanotube growth at low ethylene content. We observed the interplay effect of toluene and ethylene concentrations on the nanotube growth rate, accompanied by the detrimental effect of toluene on catalyst activation degree. Nevertheless, toluene apparently promotes nanotube crystallinity, increasing the film conductivity while used as an individual carbon source. Adjusting the ethylene and toluene concentrations, we produced carbon nanotube-based transparent and conductive films with an equivalent sheet resistance (at 90% transmittance at 550 nm wavelength) value of 57 Ω/□ at the synthesis yield of 0.24 cm2 L−1, which is at least two times higher than the results reported earlier. [Display omitted] • Ethylene boosts SWCNT nucleation and enhances catalyst activation degree. • Ethylene promotes growth rate but deactivates catalyst at high concentrations. • Toluene improves nanotube crystanillity and deteriorates catalyst activation degree. • Toluene and ethylene together yield in better performance unlike separate supply. • High-yield production of high-performance transparent conductive films demonstrated. [ABSTRACT FROM AUTHOR]

In this work we investigate the influence of thermal treatment of reduced graphite oxide (RGO) on its functional composition and electrochemical performance. It is found that carboxyl, carbonyl, hydroxyl and epoxy groups are present on the RGO surface, witch when subject to thermal annealing in the temperature range 230–250°C can be controllably modified. In the process of thermal annealing, we show the formation of quinoid groups due to an increase in the number of defects. Decrease of the number of layers in RGO material and the quantity of oxygen-containing functional groups (OCFG) also occurs. With increase in annealing temperature, sequential removal of OCFG occurs as follows: carboxyl (250°C–600°C), hydroxyl (600°C–800°C), carbonyl and quinoid (700°C–1000°C). Electrochemical measurements over a wide range of pH values of the buffer electrolytes is possible to correlate the peaks in the cyclic voltammogram curves with the redox reactions of oxygen-containing functional groups as a function of applied potential. Peaks correlated with specific redox reactions which are identified as two-electron. The dependence of the specific capacities of materials on the electrolyte type has been studied. Highest capacitance was detected in 1M NaOH at a scan rate 2 mVs−1 and is equal to 210 Fg−1. [ABSTRACT FROM AUTHOR]