Gold nanoparticles (AuNPs) were electrodeposited on the surface of pencil graphite (PG) by fast scan cyclic voltammetry without using any additives in acidic medium. The effect of deposition time on the size of electrodeposited AuNPs was investigated in sulfuric acid as a supporting electrolyte. The deposition time was varied by varying the scan rate, number of cycles and applied potential range. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used for characterization of PG and electrodeposited AuNPs. The results confirmed that nanosized gold particles (20 ± 8 nm) were deposited on the PG substrate with almost spherical geometry.
A conductance study of the interaction between ammonium ion and 18-Crown-6 (18C6), dicyclohexano-18-crown-6 (DC18C6), ditertbutyl-dicyclohexano-18-crown-6 (t-bu) 2 DC18C6, diaza-15-crown-5 (DA15C5), dibenzo-21-crown-7 (DB21C7) and N-Phenylaza-15-crown-5 (NPA15C5) in acetonitril-dimethylsulfoxide mixture was carried out at various temperatures. The formation constants of the resultant 1:1 complexes were determined from the molar conductance-mole ratio data and found to vary in the order of DA15C5 > DC18C6 > 18C6 > (t-bu) 2 DC18C6 > DB21C7 > NPA15C5.The enthalpy and entropy of the complexation reactions were determined from the temperature dependence of the formation constants.
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