Person: PEKSÖZ, AHMET
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PEKSÖZ
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AHMET
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Publication Electrochemically characterized energy storage properties of Ni foam/poly (EGDMA-Co-VPCA)/SWCNT composite electrode produced by surface polimerization method(Elsevier, 2021-05-21) Yıldırım, Hasan; Tokgöz, Seyit Rıza; Peksöz, Ahmet; Kara, Ali; Yıldırım, Hasan; TOKGÖZ, SEYİT RIZA; PEKSÖZ, AHMET; KARA, ALİ; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü.; 0000-0001-6552-1112; 0000-0003-4050-4222; 0000-0001-9135-1508; 0000-0003-2457-6314; AHB-9353-2022; HRA-2244-2023; IXW-9711-2023; A-8113-2016Poly (EGDMA-co-VPCA)/SWCNT composite film is successfully synthesized on Ni foam substrate by surface polymerization technique. Energy storage properties of Ni foam/poly (EGDMA-co-VPCA)/ SWCNT composite electrode are investigated via cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The as-prepared Ni foam/poly (EGDMA-co-VPCA)/ SWCNT composite electrode exhibits high specific capacitance of 100 F/g at 5 A/g, high power density of 3285.0 W/kg at 8.5 Wh/kg energy density, capacitive retention of 77.7% after 5000 charge-discharge cycles and excellent chemical stability.Publication Energy storage and semiconducting properties of polyaniline/graphene oxide hybrid electrodes synthesized by one-pot electrochemical method(Elsevier, 2021-07-06) Tokgoz, Seyit Rıza; Firat, Yunus Emre; Akkurt, N.; Pat, S.; Peksoz, Ahmet; TOKGÖZ, SEYİT RIZA; Firat, Yunus Emre; PEKSÖZ, AHMET; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 0000-0003-0510-6640; 0000-0001-9135-1508; IXW-9711-2023; AAK-5283-2021; HRA-2244-2023; AAG-9772-2021Polyaniline/graphene oxide composites are produced by the one-pot electrochemical deposition method and are used as an electrode for supercapacitor energy storage. The electrochemical tests related to the energy storage performance of the PANI/GO electrodes at different mass loading of GO are successfully studied. The biggest specific capacitance for all of the electrodes is observed at a specific current of 0.3 A g(-1). Pure PANI electrode has a specific capacitance of 158.0 F g(-1), a specific energy of 18.2 W h kg(-1), and a corresponding specific power of 118.8 W kg(-1). After the loading of graphene oxide into PANI, the best specific capacitance measured at a current density of 0.3 A g(-1) is 295.9 F g(-1), and the corresponding specific energy and specific power are 34.0 Wh kg(-1) and 126.9 W kg(-1), respectively. The PANI/GO hybrid materials also exhibit a remarkably cycling stability with a capacitance retention range of 62.3%-83.7% after 5000 charge-discharge cycles. Charge transfer resistance of the PANI electrode desreases as GO loading increases. This means that electroactive surface area of the electrode increases due to the addition of GO into PANI. The enhancement in energy storage capability is supported by the increase in electroactive surface area. The high energy storage performance and easy production of PANI/GO materials make them promising electrodes for supercapacitor devices.Publication The sensitive control of semiconductor properties of non-vacuum and electrochemically synthesized cdte thin films(Springer, 2019-05-01) Demiriz, T. M.; Peksöz, Ahmet; Demiriz, T. M.; PEKSÖZ, AHMET; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü/Güneş Pili Laboratuvarı; AAG-9772-2021; CPA-7462-2022CdTe thin films are deposited on indium tin oxide (ITO) coated glass substrates by co-electrochemical deposition method. CdTe films are deposited at six different deposition potentials such as -0.4, -0.5, -0.6, -0.7, -0.8 and -0.9V versus Ag/AgCl reference electrode. Deposition time is kept constant for 2min. Deposition electrolyte includes aqueous solutions of 10mM CdCl2, 20mM Na2TeO3 as precursors, and 200mM LiCl. HCl is used for pH adjustment of the electrolyte. The effect of deposition potential on the characteristics of CdTe thin films is investigated by means of some techniques such as scanning electron microscopy (SEM), energy dispersive X-rays analysis (EDX), X-ray diffraction (XRD), Ultraviolet-Visible (UV-Vis) spectroscopy, Mott-Schottky measurements, and electrochemical impedance spectroscopy (EIS). Deposition potential dependency of the film surfaces is seen to be high from the SEM studies. EDX results show that Cd/Te ratios vary between 0.81 and 1.09. XRD analyses show that the films include hexagonal phase of CdTe and Cd1.81Te, and monoclinic phase of CdTe2O5. The optical band gaps (E-g) of all the films are derived from Tauc's relation using absorbance data. E-g values change between 1.54 and 1.92eV depending on the deposition voltage. Donor density of the n-type CdTe thin films deposited in the potential range between -0.4 and -0.8V changes between 10(17) and 10(19)cm(-3), while acceptor density is 10(20)cm(-3) for only one p-type CdTe thin film with a deposition potential of -0.9V. Electronic energy band structure of the synthesized CdTe thin films are also studied in detail. From the equivalent electronic circuit fitted to the EIS data, electronic charge transfer in the CdTe/electrolyte system is determined to be the biggest for the CdTe film deposited at -0.5V.Publication Electrodeposition of In:CdSe precursor thin films in aqueous electrolytes including different selenous acid concentrations as Se source(Elsevier, 2019-08-01) Degdaş, G.; Peksöz, A.; Degdaş, G.; PEKSÖZ, AHMET; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; AAG-9772-2021; ERW-8810-2022In:CdSe precursor thin films were electrochemically grown on indium fin oxide (ITO) coated glass substrates at a constant potential of -0.95 V vs. Ag/AgCl reference electrode. Deposition solutions were composed of 10 mM CdCl2, 10 mM InCl3, 5-10 mM H2SeO3 as precursors, and 200 mM LiCl. The concentration of Se source (H2SeO3) was increased from 5 mM to 35 mM by a step of 5 mM. HCl was used for pH adjustment of the electrolytes. The uniform thin films are characterized by SEM-EDX, XRD, UV-VIS and Hall-Effect measurements. SEM studies show that the surface formations of In:CdSe deposits change depending on the Se content. For all deposits, XRD analyses confirm the formation of CdIn2S4 with a tetragonal crystalline phase. Energy band gap of the films is calculated from Tauc equation using UV-VIS absorbance spectra. Energy band gaps are found to be between 1.98 eV and 2.23 eV. Hall-Effect measurements show all deposits exhibit n-type semiconductor character. The donor density changes between -1.3 x 10(17) cm(-3) and -4.1 x 10(18)cm(-3). The conductivity of the In:CdSe thin films decreases from 73.2 (Omega cm)(-1) to 24.2 (Omega cm)(-1) as the Se atomic percentage in the film increases. The mobility of the films increases with the increasing of Se atomic percentage.The reason of the increasing in mobility is most probably due to the decreasing in the donor concentration depending on Se percentage.Publication Electrochemically growth and characterization of CuInTe₂ chalcopyrite thin films(Springer, 2020-07-28) Keser, Gökhan; Peksöz, Ahmet; Keser, Gökhan; PEKSÖZ, AHMET; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü/Güneş Pili Laboratuvarı.; 0000-0003-2382-6027; AAG-9772-2021; FZX-9393-2022Copper indium tellurite (CIT) chalcopyrite compounds were electrochemically grown from an aqueous electrolyte including water-soluble Cu, In, and Te molecular sources onto indium thin oxide-coated glass substrates. CuSO4 center dot 5H(2)O, InCl3, and Na2TeO3 were used as copper, indium, and tellurium sources, respectively. Deposition mechanisms of the CIT thin films are explained by cyclic voltammetry (CV) studies. It is also noted that the effect of deposition potential on the electrical, optical, and structural facilities of the electrodeposited CIT thin films. Energy bandgap of the electrodeposited CIT films is in the range of 0.97-1.83 eV. Stoichiometry of the CIT films deposited at - 0.5, - 0.6, - 0.7, and - 0.8 V is near to CuInTe2. We report that the produced CIT films is polycrystalline nature, and CuInTe(2)is a major chalcopyrite phase corresponding to (1 1 2), (2 0 4), and (1 1 6) directions at 2 theta similar to 25 degrees, 41 degrees, and 49 degrees, respectively. Hall-effect measurements show that the produced CIT thin films have p-type semiconducting conductivity with the acceptor concentration range of 2.8 x 10(17) and 2.8 x 10(18) cm(-3). The variation of the mobility within 20.4-60.2 cm(2)/V s can be explained by the variation of Cu/In ratio within 2.19-0.59. The resistivity of the films is found to vary within 0.011-0.036 Omega cm, which is in good agreement with the literature data.Publication Fast electrochromic response and high coloration efficiency of al-doped WO3 thin films for smart window applications(Elsevier, 2021-10-18) Arslan, Mürüvvet; Firat, Y. E.; Tokgöz, Seyit Rıza; Peksöz, A.; Arslan, Mürüvvet; TOKGÖZ, SEYİT RIZA; PEKSÖZ, AHMET; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü; 0000-0002-3136-315X; 0000-0001-9135-1508; AAG-9772-2021; HRA-2244-2023; GYU-7137-2022; IXW-9711-2023Herein, vertically aligned Al:WO3 nanoplate arrays were directly grown on ITO glass by a facile electrodeposition method and annealed in an argon atmosphere at 450 degrees C for 2h. Besides, this study reports the influence of Al doping on the electrochromic properties of WO3 film in detail. Electrochromic properties such as cyclic voltammetry, chronoamperometry and optical transmittance were analyzed by protonic insertion/extraction in the 1 M LiClO4/propylene carbonate as an electrolyte. The noticeable reversible color changing from transparent to the blue can be realized under the potential bias of +/- 1.0 V. XRD studies show that the produces films have highly crystalline structure. The EDS results clearly confirm the incorporation of Al element into the WO3 network. From the optical absorption measurement, direct band gap energies are calculated as 3.62 and 3.34 eV for the WO3 and the Al:WO3, respectively. Compared to the as-prepared WO3, the Al:WO3 film exhibits outstanding electrochromic performance, including wide optical modulation (55.9%), high coloration efficiency (148.1 cm(2)C(-1)), quick reaction kinetics (1.23 s and 1.01 s for colored and bleaching times, respectively), good rate capability and cycle durability at a wavelength of 632.8 nm. EIS measurements based on a charge-transfer resistance reveal that the dramatic improvement in the electrochemically active surface is achieved in the Al:WO3 film. The increase of active surface facilitates transport kinetics for electron and ion intercalation/deintercalation within the porous metal oxide to enhance coloration efficiency. Comparatively energy levels of the WO3 and the Al:WO3 electrochromic films are also represented. From the Mott-Schottky studies, it is estimated that the donor concentration of the films is of the order of 1020 cm(-3). Taken together, these results not only provide important insight into a promising electrode for electrochromic displays applications, but also offer an economic and effective strategy for manufacturing of other doped metal oxide films.Publication Intermolecular magnetic spin-spin interactions in solution state at 1.53 mT(Taylor, 2015-01-01) Yıldız, Fevkani; Şahin, Özkan; Peksöz, Ahmet; Yıldız, Fevkani; ŞAHİN, ÖZKAN; PEKSÖZ, AHMET; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü; KQV-0698-2024; AAH-6445-2021; AAG-9772-2021; I-9715-2017Overhauser dynamic nuclear polarization (DNP) technique can provide a dramatic increase in the signal obtained from nuclear magnetic resonance experiments owing to the magnetic spin-spin interactions between H-1 nuclei of the solvent and electrons delocalized on the asphaltene in crude petroleum or asphalt. Studies on H-1 Overhauser DNP enhancements at 1.53 mT are reported for benzene solvent medium with three different radical sources: Iran crude petroleum, MC30 liquid asphalt, and MC800 liquid asphalt for a range of radical concentrations. The results show that protons of benzene are good detectors for dipolar coupling.Publication Electrochemically fabrication of a composite electrode based on tungsten oxide and cobalt on 3d ni foam for high and stable electrochemical energy storage(Elsevier, 2022-08-30) Killi, Halime; Tokgöz, Seyit Rıza; Çarpan, Mürüvvet Arslan; PEKSÖZ, AHMET; TOKGÖZ, SEYİT RIZA; Bursa Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Fizik Bölümü.; GYU-7137-2022; IXW-9711-2023; HRA-2244-2023The present work reports new findings on the electrical energy storage capabilities of WO3/Ni and Co@WO3/Ni electrodes produced via galvanostatic electrochemical deposition. The paper also describes a novel process for cleaning Ni foam, which has significant effect on the electrode's charge accumulation properties. Electro-chemical measurements in an aqueous solution are performed to compare the supercapacitive behavior of the WO3/Ni foam and Co@WO3/Ni foam. The specific capacitance of the former electrode increases from 492.8 to 977.4 F g-1 because of Co adding into tungsten oxide. Furthermore, the former has 42.5% capacitance retention after 7000 charge-discharge cycles, while the latter has 83.7% owing to the Co loading. The specific energies are respectively calculated to be 64.27 Wh kg-1 and 64.44 Wh kg- 1 for the pure WO3/Ni and Co@WO3/Ni elec-trodes. The specific powers are 3761.49 W kg- 1 and 3303.90 W kg- 1 for the former and latter electrodes. Ac-cording to the findings, adding Co to the pure WO3/Ni electrode increases its electrochemical and supercapacitor capabilities, allowing it to be used in energy storage devices.