Yesilbag, Yasar Ozkan; Salih, Ahmed Jalal Salih

The integration of one-dimensional (1D) and two-dimensional (2D) materials into three-dimensional (3D) structures shows great potential for improving energy storage. This study investigates the optimization of interlayer spacing in MXene structures by incorporating conductive materials. Free-standing Ti3C2Tx MXene and carbon nanotube (CNT) composite electrodes were fabricated via vacuum filtration, with CNT weight ratios of 10 %, 20 %, and 30 %. The MXene/CNT10 (MX1) composite exhibited superior electrochemical performance, with a specific capacitance of 254 F g⁻1 and remarkable durability, retaining 101.2 % of its initial capacitance after 10,000 cycles. A symmetric supercapacitor (SSC) using the MX1 electrode achieved a stable voltage window of 0–1.2 V, a specific capacitance of 70.1 F g⁻¹, and retained 85 % of its capacitance after 5000 cycles. With an energy density of 14.1 Wh kg⁻1 and a power density of 13.9 kW kg⁻1, MXene/CNT composites demonstrate significant potential for advanced energy storage applications.

Ammar, Ameen Uddin; Bakan-Misirlioglu, Feray; Aleinawi, Mohamad Hasan; Franzo, Giorgia; Condorelli, Guglielmo Guido; Yesilbag, Fatma Nur Tuzluca; Yesilbag, Yasar Ozkan; Mirabella, Salvo; Erdem, Emre

Here, we report the development of high-performance supercapacitor devices using manganese-doped zinc oxide nanowires (Mn-doped ZnO NWs) and copper-doped zinc oxide nanoparticles (Cu-doped ZnO NPs) as a positive electrode with MXene as a negative electrode. Both transition metal (TM)-based electrodes were used separately with MXene, and the performance was tested. When used in combination with MXene as a second electrode, TM-ZnO samples displayed a major increase in the supercapacitors’ performance. The highest-performance supercapacitor recorded values of 151 F/g specific capacitance along with 84 Wh/kg energy density and a power density of 75 kW/kg. Electron paramagnetic resonance and photoluminescence spectroscopy of Mn/Cu-doped ZnO reveals intrinsic and extrinsic defect signals, which were discussed and attributed to the enhancement of the capacitive performance. The presence of the aforementioned defects optimizes the intrinsic properties and boosts the reaction kinetics, thus providing increased electrochemical activity and superior supercapacitor device performance.

Bozkurt Çırak, Burcu; Caglar, Bulent; Kılınç, Tuba; Morkoç Karadeniz, Sibel; Erdoğan, Yaşar; Kılıç, Selçuk; Kahveci, Enver; Ercan Ekinci, Ali; Çırak, Çağrı

In present study, we report on the synthesis of TiO2/ZnO nanocomposite (TZN) films for potential applications as photocatalyst in heterogeneous photo-degradation of Rhodamine B under UVA irradiations. ZnO nano-rice decorated TiO2 nanotubes were successfully synthesized via a facile and effective two-step route. Firstly, TiO2 nanotube arrays were grown by anodic oxidation. Afterwards, ZnO rice shaped nanostructures were decorated by successive chemical bath deposition cycles of 2, 4, 6 and 8. The XRD, FESEM, XPS and μ-XRF results showed that the rice-shaped wurtzite ZnO nanoparticles with dimensions of ca. 1μm × 100 nm were homogeneously distributed on the anatase TiO2 nanotube arrays with highly uniform in the presence of in zinc nitrate hexahydrate and hexamethylenetetramine precursors with 1:4 M ratios. The photodegradation results showed that the photocatalytic activity of TZN films were gradually increased in parallel with the number of ZnO deposition cycles and the best performance was found for TNZ8 film. The RhB photodegradation efficiency was determined to be 65% for bare TiO2 whereas 95% degradation of Rhodamine B was occurred for TNZ8 film which follow pseudo-first-order kinetic. In addition, TZN films exhibited good photostability after four reuses. Also, photocatalytic activity of TZN were tested under UVC, UVB, UVA and visible region irradiations for comparative purposes.

Topcu, Cihan; Caglar, Bulent; Onder, Ahmet; Coldur, Fatih; Caglar, Sema; Guner, Eda Keles; Cubuk, Osman; Tabak, Ahmet

Chitosan-smectite biocomposite was prepared by intercalation of protonated chitosan molecules into the interlayer space of smectite in monolayer arrangement through cation exchange mechanism and the obtained biocomposite was successfully used as an electroactive component in the structure of a PVC membrane potentiometric sensor for the direct and highly selective determination of monohydrogen phosphate ions. The comparative elemental, structural, thermal and morphological analysis of starting-smectite, neat chitosan and chitosan-smectite were investigated by utilizing EDX, XRD, ATR-FTIR, TG/DTG/DTA, SEM and surface area measurement techniques. The optimum membrane composition, detection limit, response time, pH working range and repeatability of the proposed electrode were determined.

Akaltun, Yunus; Yildirim, M. Ali; Ateş, Aytunç; Yildirim, Muhammet

Cd 1-xZn xSe thin films with different compositions (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) were deposited on glass substrates using successive ionic layer adsorption and reaction (SILAR) method at room temperature and ambient pressure. The zinc concentration (x) effect on the structural, morphological, optical and electrical properties of Cd 1-xZn xSe thin films were investigated. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies showed that all the films exhibited polycrystalline nature and were covered well on glass substrates. The energy dispersive X-ray (EDAX) analysis confirmed nearly stoichiometric deposition of the films. The energy bandgap values were changed from 1.99 to 2.82 eV depending on the zinc concentration. Bowing parameter was calculated as 0.08 eV. The electron effective mass (m e*/m o), refractive index (n), optical static and high frequency dielectric constants (ε o, ε ∞) values were calculated by using the energy bandgap values as a function of the zinc concentration. The resistivity values of the films changed between 10 5 and 10 7 Ω cm with increasing zinc concentration at room temperature.