No abstract

MXene is a 2D transition metal carbide/nitride with excellent electrical, optical and mechanical properties. At present, most MXenes are prepared from the MAX phase by chemical etching with HF or HCl/LiF. This method is very limited in terms of large-scale production owing to the hazardous and toxic fluoride-containing reagents. There is an urgent need to explore safe and reliable synthetic methods to prepare MXene. In this short communication, we describe the mechanochemical route for preparation of the Ti3C2Tx from the Ti3AlC2. The prepared MXene has been studied by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet–visible (UV/Vis) spectrophotometry and Fourier-transform infrared spectroscopy. The results reported here have paved the way for new preparation methods for the fluorine-free MXenes.

U posljednjih desetak godina napravljen je značajan iskorak u razvoju aktivnih materijala koji se upotrebljavaju u superkondenzatorima i u dizajniranju samog superkondenzatora. Stoga je u ovom radu dan kratak pregled istraživanja aktivnih materijala za superkondenzatore te je navedena njihova osnovna podjela temeljena na mehanizmima skladištenja naboja. Iz navedenih istraživanja može se zaključiti kako je za uspješan razvoj materijala nužno razumijevanje mehanizma skladištenja naboja i povezivanje strukturnih svojstava materijala s elektrokemijskim svojstvima. Spoznaje o mehanizmu skladištenja omogućuju ciljano dizajniranje materijala te kombiniranje elektroda s različitim mehanizmima, što u konačnici utječe na svojstva ali i na primjenu superkondenzatora. Najznačajniji materijali u ovom području su materijali temeljeni na ugljiku, vodljivi polimeri i metalni oksidi.

Pseudocapacitive properties of SnO2 and Sb-doped SnO2 were determined in 0.5 mol dm-3 KCl solution. The samples were prepared by sol-gel method and analysed by X-ray powder diffraction (XRPD) and field emission scanning electron microscopy (FE SEM). Rietveld refinement of XRPD data showed the changes in unit cell parameters due to the incorporation of Sb 3+ into the host SnO2 lattice, while FE SEM pointed out the differences in morphology caused by doping. Specific capacitance values of 3.67 and 6.89 F g-1 were obtained for SnO2 and Sbdoped SnO2, respectively. Reaction mechanism of SnO2 that corresponds to the obtained mass change was proposed. It was shown that redox reactions of SnO2 and Sb-doped SnO2 are dependent on structural changes since different mass change properties were obtained in comparison to the previous reports carried out for other metal oxides.

The aim of this work was to determine the optimal synthesis conditions for the preparation of a poly(3,4-ethylenedioxythiophene) (PEDOT) layer by the electrochemical method from an electrolyte containing graphene oxide (GO) and a sodium dodecylsulfate (SDS) micellar solution. Besides an SDS anion, GO is also incorporated within the PEDOT layer as a negative counter ion. Therefore, this is a one-step electrochemical method for a PEDOT/GO composite layer preparation. The results displayed that PEDOT composites were successfully synthesised by applying a potential in the value range from 0.94 to 1.00 V, and with a synthesis duration of up to 600 s. It was concluded that the optimal concentration of EDOT monomer is 0.02 mol dm-3, and SDS 0.01 mol dm-3. The incorporation of GO into the PEDOT layer improved the polymer response in KCl solution influencing the pseudocapacitive properties, which is significant for its supercapacitor applications. The morphological and structural properties of the obtained layers were characterized by means of scanning electron microscopy and ultraviolet-visible spectrophotometry. The pseudocapacitive properties were determined in a 0.1 mol dm-3 KCl solution by using cyclic voltammetry and electrochemical impedance spectroscopy methods.