Combination Of rGO Research Articles

Reduced graphene oxide/α-Fe2O3 composite nanofibers for application in gas sensors

Pure α-Fe2O3 nanobelts (NBs) and 0.5, 1.0, 3.0wt% reduced graphene oxide (rGO)/α-Fe2O3 composite nanofibers (NFs) have been successfully synthesized by a homotaxial electrospinning method. Various techniques were employed for the characterization of the nanostructures and morphologies of the as-obtained nanofibers. The results indicate that pure α-Fe2O3 NBs have uniform widths more than 200nm and series of rGO/α-Fe2O3 NFs have diameters approximately 100nm. In addition, the gas sensing properties of the obtained nanofibers were investigated. It is found that 1wt% rGO/α-Fe2O3 shows high response, excellent repeatability and long-term stability to 100ppm acetone at the operating temperature of 375°C. The response of 1wt% rGO/α-Fe2O3 nanofibers to 100ppm acetone is about 8.9, which is about 4.5 times higher than pure α-Fe2O3 NBs.Furthermore, the combination of rGO with α-Fe2O3 can also improve the response/recovery properties. The response and recovery times of the sensor were about 3 and 9s, respectively, which were superior to pure α-Fe2O3 NBs. Finally, we have proposed that the creation of ohmic contact, defects on the rGO nanosheets surface play significant roles in raising the sensitivity of rGO/α-Fe2O3 NFs.

New Insights into the Analysis of the Electrode Kinetics of Flavin Adenine Dinucleotide Redox Center of Glucose Oxidase Immobilized on Carbon Electrodes

New insights into electrochemical kinetics of the flavin adenine dinucleotide (FAD) redox center of glucose-oxidase (GlcOx) immobilized on reduced graphene oxide (rGO), single- and multiwalled carbon nanotubes (SW and MWCNT), and combinations of rGO and CNTs have been gained by application of Fourier transformed AC voltammetry (FTACV) and simulations based on a range of models. A satisfactory level of agreement between experiment and theory, and hence establishment of the best model to describe the redox chemistry of FAD, was achieved with the aid of automated e-science tools. Although still not perfect, use of Marcus theory with a very low reorganization energy (≤0.3 eV) best mimics the experimental FTACV data, which suggests that the process is gated as also deduced from analysis of FTACV data obtained at different frequencies. Failure of the simplest models to fully describe the electrode kinetics of the redox center of GlcOx, including those based on the widely employed Laviron theory is demonstrated, as is substantial kinetic heterogeneity of FAD species. Use of a SWCNT support amplifies the kinetic heterogeneity, while a combination of rGO and MWCNT provides a more favorable environment for fast communication between FAD and the electrode.