This communication demonstrates that the SiC coated glassy carbon electrode resolved the overlapping voltammetric responses of ascorbic acid (AA), dopamine (DA), and uric acid (UA), which could be used for selective determination of DA in the presence of AA and UA.

The surfaces of acid- and amine-functionalized carbon nanotubes (C-CNT and N-CNT) were decorated with MnO₂ nanoflakes as supercapacitors by a spontaneous redox reaction. C-CNT was found to have a lower edge plane structure and fewer defect sites than N-CNT. MnO₂/C-CNT with a highly developed surface area exhibited favorable electrochemical performance. To determine the atomic/electronic structures of the MnO₂/functionalized CNTs (MnO₂/C-CNT and MnO/N-CNT) during the charge/discharge process, in situ X-ray absorption spectroscopy (XAS) measurements were made at the Mn K-edge. Both C-CNT and N-CNT are highly conductive. The effect of the scan rate on the capacitance behavior was also examined, revealing that the π* state of CNT and the size of the tunnels in pseudo-capacitor materials (which facilitate conduction and the transport of electrolyte ions) are critical for the capacitive performance, and their role depends on the scan rate. In the slow charge/discharge process, MnO₂/N-CNT has a more symmetrical rectangular cyclic voltammetry (CV) curve. In the fast charge/discharge process, MnO₂/C-CNT with a highly developed surface provides fast electronic and ionic channels that support a reversible faradaic redox reaction between MnO₂ nanoflakes and the electrolyte, significantly enhancing its capacitive performance over that of MnO₂/N-CNT. The MnO₂/C-CNT architecture has great potential for supercapacitor applications. The information that was obtained herein helps to elucidate CNT surface modification and the design of the MnO₂/functionalized CNT interface with a view for the further development of supercapacitors. This work, and especially the combination of CV with in situ XAS measurements, will be of value to readers with an interest in nanomaterial, nanotechnology and their applications in energy storage.

Microwave activation of electrochemical processes is possible by self-focussing of intense microwave radiation at the electrode|solution (electrolyte) interface of an electrode immersed in a solution and placed in a microwave cavity. Considerable changes in voltammetric current responses are observed experimentally for the one-electron reduction of Ru(NH3)63+ in aqueous 0.1 M KCl and for the stepwise two-electron reduction of the methylviologen dication (MV2+) in aqueous 0.1 M NaCl. The formation and interconversion of two distinct forms of solid deposits, MVam0 and MVcryst0, on a mercury electrode surface is investigated, both in the presence of microwave activation and with conventional heating. It is shown that microwave activation achieves (i) high temperatures in the vicinity of the electrode, (ii) thermal desorption of deposits from the electrode surface and (iii) limiting currents an order of magnitude higher compared to those induced by conventional isothermal heating to the same electrode temperature.A simple physical model based on Joule heating of the aqueous solution phase is employed in a finite element simulation (FIDAPTM) procedure to explain the differences observed experimentally between conventional heating and microwave activation. Based on the comparison of simulation and experimental data, a considerable thermal gradient and ‘hot spot ’ region in the diffusion layer of the electrode, together with convective mass transport are proposed.

An in situ XAS investigation reveals charge–discharge mechanisms of MnO ₂ /carbon-based materials.