Güney, Harun; İskenderoğlu, Demet; Güldüren, Muhammed Emin; Demir, Kübra Çinar; Karadeniz, Sibel Morkoç

Here, ultrasonic spray pyrolysis method (USP) was utilized to produce pure and silver doped copper oxide nanostructures on glass substrates. Thereafter, several characterization techniques were conducted on the grown samples to delve into their morphological, structural, electrochemical, and optical aspects. The mentioned analyses were carried out by performing x-ray photoelectron spectroscopy, scanning electron microscope, X-ray diffraction, electrochemical impedance spectroscopy, galvostatic charge-discharge, cyclic voltammetry, and UV–visible spectroscopy measurements. Thus, the impact of silver impurity doping on the relevant aspects of host material were recorded as well as the features of unspoiled copper oxide films. Accordingly, the samples, as indicated by X-ray diffraction results, possessed (002) preferential plane orientation of copper oxide material along with the crystallite sizes ranging from 52.52 nm to 75.02 nm due to the imperfections caused by the silver doping. The scanning electron microscope images exhibited that the silver doping did not form significant modifications in the host material morphology where nanowire-like structures observed. The presence of the suggested materials in the films was verified by the x-ray photoelectron spectroscopy. Also, the UV–visible spectroscopy measurements detected that optical absorbance edge and bandgap energy values red shifted as a result of the impurity doping. The electrochemical supercapacitors performances of the silver doped copper oxide nanostructured thin films were inspected by using the GCD, EIS, and CV. The silver doped copper oxide films demonstrated a specific capacitance value of 66 F/g at a current density of 1 A/g in 1 M KOH electrolyte. From Nyquist plot, Rs, Rcor, Rpo, Ccor and Cc were obtained as 2.327 × 103 Ω.cm2, 43.63 × 103 Ω.cm2, 4.580 × 103 Ω.cm2, 111.5 × 10-6 S*s^a. cm-2 and 101.1 × 10-6 S*s^a. cm-2, respectively. The results indicated that the electrochemically synthesized the silver doped copper oxide electrodes can be obtained and developed as an alternative electrode material for supercapacitors (SCs).

Yilmaz, Mehmet; Cirak, Cagri; Canpolat, Nurtac; Aydogan, Sakir

In this study, ZnO micro/nanorods were grown on both glass and p-Si substrates by a simple and applicable homemade chemical spray pyrolysis method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to analyze the structural and morphological features of the produced ZnO layers, revealing the presence of ZnO micro/nanorods with high crystallinity of various orientations and diameters. The interface performance of these ZnO micro/nanorod arrays in the Co/p-Si device was also investigated and the rectification ratio of the fabricated Co/ZnO micro-nanorods/p-Si device at ± 1 V was calculated in the order of 103. In addition, some photodiode parameters, such as responsivity, sensitivity, and specific detectivity, were investigated depending on the increased light power intensity from 150 to 300 mW/cm2. Finally, the performance of ZnO micro/nanorod arrays during degradation of Rhodamine B dyestuff under UVA light was investigated and it was concluded that they could have good photocatalytic activity in advanced oxidation processes. All results supported that ZnO micro/nanorod arrays obtained by a simple homemade chemical spray pyrolysis method in this study have the potential for optical applications.

Karabatak, Aysun; Danışman-Kalındemirtaş, Ferdane; Tan, Ezgi; Erdem-Kuruca, Serap; Karakuş, Selcan

The development of green multifunctional nanoformulation has been given great attention with unique anticancer activity and ultra-sensitive sensing properties in biomedical applications. This study investigated the smartphone-integrated colorimetric dopamine sensing platform and the anticancer activity of Kappa Carrageenan/PEG-CuO nanoparticles (κCA/PEG-CuO NPs). The characterization of the prepared κCA/PEG-CuO NPs was conducted using scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction analysis (XRD), zeta-potential, Fourier transform infrared spectroscopy (FTIR), and ultraviolet–visible (UV–Vis) techniques. The surface characterization revealed that the obtained NPs had a spherical surface in the particle-size range of 5–10 nm. With a high coefficient of correlation (R2 = 0.982), the digital colorimetric κCA/PEG-CuO NPs-based biosensor detected dopamine in a wide concentration range of 0.1–100 µM and a low limit of detection (LOD) of 504 nM in 0.1 M phosphate buffer solution (PBS) (pH 7.4). In addition, the cytotoxicity of the prepared κCA/PEG-CuO NPs in living cells (HepG2 hepatocellular carcinoma), MIA PaCa-2 pancreatic cancer cells, and HUVEC (human umbilical vein endothelial cells) was investigated, which proved that κCA/PEG-CuO NPs exhibited high anticancer activity against MIA PaCa-2 pancreatic cancer cells. In conclusion, experimental results showed that multifunctional κCA/PEG-CuO NPs are both a promising biosensor for dopamine detection and an effective nanocarrier for pancreatic cancer therapy.

Karaduman Er, Irmak; Yıldırım, Memet Ali; Örkçü, H. Hasan; Ateş, Aytunç; Acar, Selim

This paper presents the preparation of Zn1−xSnxO thin films by Successive Ionic Layer Adsorption and Reaction (SILAR) method and a systematic investigation of their low-level NO gas detection properties. By changing Sn dopant ratio “x” from 0 to 1 with 0.25 increment steps, a wide range analysis from pure ZnO to pure SnO2 was carried out. X-ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive X-ray analysis (EDAX) and optical absorption measurements were used in the characterization of the synthesized films. Characterization data showed that the films have polycrystalline nature with hexagonal wurtzite (pure ZnO) and tetragonal (pure SnO2) structure and that the increase in the concentration of Sn dopant leads to an increase in the optical bandgap and a decrease in the average crystallite size. The 25% Sn doping value gave the smallest dislocation density, and the film with this doping value showed the best crystalline structure among all others. From SEM images, different doping ratios appeared to affect the distribution of surface particles. And by gas sensing analysis, the individual responses of the synthesized sensors to 100 ppb NO gas were examined, among which Zn0.75Sn0.25O recorded the highest responsivity of 37% at 55 °C as well as the highest selectivity towards NO gas as compared with other control group gases, and the latter was also proved through principal component analysis (PCA). Doping- and temperature-dependent gas sensing analysis can provide quite efficient information on the sensing mechanism of metal oxide semiconductor (MOS) materials. It was concluded from the measurements that Sn doping has a significant effect on gas sensing properties with 25% doping value regarded as the optimal doping value within the investigated series.

Kaçuş, Hatice; Çırak, Çağrı; Aydoğan, Şakir

In this study, Congo Red (CR) organic dye interlayer was covered by sping coating on p-Si semiconductor wafer and Co/CR/p-Si/Al photodiode was fabricated. The surface morphology of CR film was characterized by SEM measurement. Current–voltage (I–V) characteristics of the photodiode were obtained under different illumination intensities. The electrical, sensitivity, and photoresponsivity properties of Co/CR/p-Si/Al photodiode were investigated using the current–voltage and capacitance–voltage measurements. While the calculated barrier height (Φb) and ideality factor (n) were 0.58 eV and 1.52 under the dark, these values were 0.55 eV and 1.62 under the 400 mW cm−2, respectively. The exponent of photocurrent was found to be 1.10. This value indicates that the photodiode exhibited a linear photocurrent variation with power of the light. It was found that the interface-state intensity of the photodiode decreased from 1.64 × 1015 to 8 × 1012 eV−1 cm−2 under the 400 mW cm−2 light intensity. The rectification rate of photodiode (RR) of the photodiode was found under the dark and illumination. All experimental results indicate that the photodiode exhibits a photoconducting characteristic.