No abstract

A facile method has been developed to synthesize a high-quality platinum nanoparticle (PtNP) decorated graphene via one-step g-ray induced reduction of graphite oxide (GO) and chloroplatinic acid at room temperature. GO and Pt(IV) precursor salt could be co-reduced by the electrons generated from the radiolysis of ethylene glycol under g-ray irradiation. The synchronous reduction of the metal precursor and regulation of pH greatly increased the ratio of C/O in the reduced GO (RGO). PtNPs with an average diameter of 1.8 nm were uniformly dispersed on the surface of RGO sheets. The as-prepared PtNP-RGO composites as supercapacitor electrodes displayed a specific capacitance of 154 F g À1 at a current density of 0.1 A g À1 and the value retained as high as 72.3% at 20 A g À1 which was significantly enhanced compared to 16.2% capacity retention of RGO prepared by the same method. The investigation of electrochemical performances suggests that PtNPs play an important role in enhancing supercapacitor performance with high rate capability by accelerating the electron transfer and increasing the electrochemical active surface area of RGO.

Using hexadecyl trimethyl ammonium bromide (CTAB) as the template, mesoporous VN nanocrystalline was synthesized by NH3 reduction of precursor V2O5. The structure and surface morphology of mesoporous VN were characterized by XRD and TEM. Specific area and pore size distribution were studied by N2 absorption. The XRD result indicated that VN nanocrystalline belonged to the cubic crystal system. VN nanoparticles were in dimension of about 10 nm. N2 absorption result indicated that the surface area of VN sample was 88 m²/g, and most pores were distributed in the range of 2–6 nm. The supercapacitive behavior of VN electrode in 1 mol/L KOH electrolyte was studied by cyclic voltammetry (CV) and constant current charge-discharge measurements. The results showed that mesoporous VN electrode had both electrical double-layer capacitive properties and redox pseudocapacitive properties. The specific capacitance was of VN electrode 517 F/g at 1 mV/s scan rate, when the scan rate was up to 10 mV/s, its specific capacitance maintained 275 F/g