Evrim Hür

Controlled growth of c-axis oriented ZnO nanorod array films by electrodeposition method and characterization.

ZnO nanorod array films were deposited from aqueous solution containing different concentrations (1×10(-2) M and 5×10(-3) M) Zn(NO3)2⋅6H2O and C6H12N4 and at different electrodeposition times (i.e., 15 min, 30 min, 60 min, 120 min and 180 min) using chronoamperometry method on p-Si substrate. Surface morphology and crystal structural properties of ZnO films were investigated by XRD and FESEM to select ZnO films which have optimum properties. The highest TC(hkl) value was observed in (002) plane for the film, which is deposited at 1×10(-2) M and 120 min. It is also observed that the highly oriented nanorods in this film are denser. Additionally, the conductivity type was determined by using Mott-Schottky which is electrochemical impedance spectroscopy method (EIS). On the other hand, to investigate the utility of obtained ZnO on p-Si (p-Si/n-ZnO) as supercapacitor electrode active material, the electrochemical storage properties of p-Si/ZnO was studied by electrochemical impedance spectroscopy and repeating chronopotentiometry methods. It is suggested from electrochemical tests results that p-Si/ZnO is a promising electrode materials for supercapacitor applications that required low voltage (<10 V). Rectifiying behavior was observed from the I-V characteristic of nanorod array n-ZnO/p-Si heterojunction diode. The n value, Io and the ϕb were found to be 5.48, 1.93×10(-8) A and 0.75 eV, respectively.

Electrochemical storage properties of polyaniline-, poly(N-methylaniline)-, and poly(N-ethylaniline)-coated pencil graphite electrodes

Three types of conducting polymers, polyaniline (PANI), poly(N-methylaniline) (PNMA), poly(N-ethylaniline) (PNEA) were electrochemically deposited on pencil graphite electrode (PGE) surfaces characterized as electrode active materials for supercapacitor applications. The obtained films were electrochemically characterized using different electrochemical methods. Redox parameters, electro-active characteristics, and electrostability of the polymer films were investigated via cyclic voltammetry (CV). Doping types of the polymer films were determined by the Mott-Schottky method. Electrochemical capacitance properties of the polymer film coating PGE (PGE/PANI, PGE/PNMA, and PGE/PNEA) were investigated by the CV and potentiostatic electrochemical impedance spectroscopy (EIS) methods in a 0.1 M H2SO4 aqueous solution. Thus, capacitance values of the electrodes were calculated. Results show that PGE/PANI, PGE/PNMA, and PGE/PNEA exhibit maximum specific capacitances of 131.78 F g−1 (≈ 436.50 mF cm−2), 38.00 F g−1 (≈ 130.70 mF cm−2), and 16.50 F g−1 (≈ 57.83 mF cm−2), respectively. Moreover, charge-discharge capacities of the electrodes are reported and the specific power (SP) and specific energy (SE) values of the electrodes as supercapacitor materials were calculated using repeating chronopotentiometry.

Electrochemical Characterisation of Poly(aniline-co-N-methylaniline) and Poly(aniline-co-N-ethylaniline) Films on Pencil Graphite Electrode for Supercapacitor Applications

In this work, poly(aniline-co-N-methylaniline) (co-PNMA) and poly(aniline-co-N-ethylaniline) (co-PNEA) have been electrochemically synthesised on pencil graphite electrode (PGE) surface to use as an electrode material for supercapacitors. The films have been formed from aqueous solution of monomers and sulfuric acid as electrolyte. The copolymer films have been characterised by cyclic voltammetry (CV), Mott-Schottky (MS) analysis, and scanning electron microscopy (SEM). The electrochemical storage properties of uncoated electrode and copolymer coated electrodes (PGE/co-PNMA and PGE/co-PNEA) have been investigated via CV, electrochemical impedance spectroscopy (EIS), and repeating chronopotentiometry (RCP) methods in 0.100 M H2SO4 solution. Experimental results indicate that PGE/co-PNMA exhibits higher specific capacitance than PGE/co-PNEA. Highest specific capacitance values of the PGE/co-PNMA and PGE/co-PNEA have been obtained as 213.85 mF g–1 (17.7 mF cm–2) and 48.60 mF g–1 (4.36 mF cm–2) at 50 mV s–1, respectively when compared with that of uncoated PGE which is 1.63 mF g–1 (0.14 mF cm–2). Charge-discharge characteristics of the electrodes have shown that both of the electrodes can be used as supercapacitor electrode active materials for low voltage (<10 V) applications.

Cobalt ion-doped polyaniline, poly( N -methylaniline), and poly( N -ethylaniline): electrosynthesis and characterisation using electrochemical methods in acidic solutions

Cobalt ion (Co2+)-doped polyaniline (PANI-Co), poly(N-methylaniline) (PNMA-Co), and poly(N-ethylaniline) (PNEA-Co) films were synthesised electrochemically on a pencil graphite electrode (PGE) and their electrochemical properties were investigated for supercapacitor applications. The polymer film-coated electrodes (PGE/PANI-Co, PGE/PNMA-Co, and PGE/PNEA-Co) thus obtained were characterised by scanning electron microscopy (SEM) and different electrochemical methods. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements were employed in 0.1 M H2SO4 solution to calculate the specific capacitance (CS) values of the electrodes. The maximum CS of 192.94 F g−1, 139.83 F g−1, and 47.12 F g−1 were achieved for PGE/PANI-Co, PGE/PNMA-Co, and PGE/PNEA-Co at 1 mV s−1, respectively. On the other hand, the charge/discharge stability of the electrodes was analysed using the repeating chronopotentiometry (RCP) method. The RCP measurements indicate that the electrodes could be used as an electrode active material for low voltage supercapacitor applications.