Saf ve nano-katkılı TiO2 filmlerin üretimi ve karakterizasyonu
Küçük Resim Yok
Dosyalar
Tarih
2024
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Bursa Teknik Üniversitesi, Lisansüstü Eğitim Enstitüsü
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Bir yarı iletken olan titanyum dioksit (TiO2), sadece ultraviyole (UV) ışığı ile aktive edilebilen bir fotokatalisttir. Ancak UV ışığı, elektromanyetik spektrumun sınırlı bir aralığını kapsamaktadır. Bu sınırlı aralık TiO2' nin pratik uygulamalardaki kullanımını kısıtlamaktadır. Bu kısıtlamanın önüne geçmek için atılacak rasyonel adımlardan ilki, TiO2' nin aktive olduğu elektromanyetik spektrum aralığını genişletmektir. Bu bağlamda uygulanan stratejilerin en başında katkılandırma işlemi gelmektedir. Mevcut tez çalışmasında, saf ve yapısında ağırlıkça % 32 oranında grafen bulunan çok katmanlı karbon nanotüp (ÇKKNT-ağ.%32G) katkılı TiO2 filmlerin sol-jel yöntemiyle soda-kireç-silis (SLS) cam alttaşlar üzerine kaplanması, elde edilen kompozit filmlerin kristalografik, morfolojik, fotokatalitik, optik ve yüzey özelliklerinin sistematik ve kapsamlı olarak araştırılması amaçlanmıştır. Literatüre göre TiO2' nin en üstün fotokatalitik özellikler gösterdiği anataz fazı ısıl işlem esnasında oluşurken, SLS camın yapısında bulunan sodyum, kalsiyum gibi alkaliler film kaplamaların içerisine göç ederek kristalizasyonu olumsuz yönde etkilemektedir. Bu durumun önüne geçmek için TiO2 filmler oluşturulmadan önce SLS cam yüzeyleri silisyum dioksit (SiO2) ile kaplanarak anataz fazının oluşum süreci optimize edilmiştir. Sol-jel yöntemiyle yüzey aktif madde kullanılmadan hazırlanan saf ve altı farklı konsantrasyonda (% 0.025, % 0.05, % 0.1, % 0.2, % 0.3, % 0.4) katkılandırılmış TiO2 filmler, SiO2 kaplı SLS alttaşlar üzerine daldırma yöntemiyle kaplanmış, anataz fazının oluşumu için 500oC sıcaklıkta 1 saat ısıl işlem görmüştür. Elde edilen saf ve ÇKKNT-ağ.%32G katkılı TiO2 filmlerin faz analizleri X-ışını difraksiyonu (XRD) ve Raman spektroskopi yöntemleri ile kimyasal yapı analizi X-ışını fotoelektron spektrometresi (XPS) yöntemi ile belirlenmiştir. ÇKKNT-ağ.%32G/TiO2 sollerinin kurutulmasıyla elde edilen tozların yüzey alanı ölçümünde ise Branauer-Emmett-Teller (BET) yöntemi kullanılmıştır. Morfolojik analizler ise taramalı elektron mikroskobu (SEM) ve geçirimli elektron mikroskobu (TEM) ile gerçekleştirilmiştir. Filmlerin pürüzlülüğü ve yüzey topografileri atomik kuvvet mikroskobu (AFM) ile incelenmiştir. Yine film yüzeylerinin ıslanabilirliği su temas açısı (WCA) doğrultusunda optik tensiyometre cihazı ile ölçülmüştür. Optik özellikler ultraviyole-görünür (UV-vis) ışık spektrofotometresi yardımıyla belirlenirken yasak bant aralıkları Tauc grafiği yöntemiyle hesaplanmıştır. Fotokatalitik aktivite araştırmalarında ise ISO 10678:2010 standartı kullanılarak metilen mavisinin (MB) degredasyonu üzerinden tespitlerde bulunulmuştur. XRD analizi ile saf ve ÇKKNT-ağ.%32G katkılı TiO2 film kaplamalar için seçilen 500o C' nin SLS cam alttaşı deformasyona uğratmadan anataz fazını oluşturan optimum sıcaklık olduğu tespit edilmiştir. Yine XPS analizi ile numune yüzeyinde bulunan ana elementlerin titanyum, oksijen ve karbon olduğu belirlenmiş, bağlanma enerjileri ve spin yörünge yerleşimlerinden kimyasal hali tespit edilmiştir. Buna ek olarak Raman analizi ile anataz TiO2' ye ait aktif mod bantları ilgili dalga boylarında büyük bir netlikle gözlemlenirken ÇKKNT-ağ.%32G katkısına ait mod bantları katkı oranı arttıkça belirginleşmiştir. Saf ve ÇKKNT-ağ.%32G katkılı TiO2 film kaplamaların yüzeylerine ait SEM görüntüleri karşılaştırıldığında, tüm kaplamaların genel olarak homojen olduğu gözlenmiştir. ÇKKNT-ağ.%32G katkılı TiO2 tozlarına ait çeşitli büyütmelerde alınan TEM aydınlık alan görüntüleri ile TiO2 partiküllerinin ÇKKNT-ağ.%32G nano-partiküllerinin etrafında kümelendiği, ÇKKNT-ağ.%32G nano partiküllerinin ise bu küme içinde yatay düzlemde dağınık bir yerleşim gösterdiği tespit edilmiştir. (101) kristal düzlemine sahip anataz fazının varlığı ise yine TEM analizine ait hızlı Fourier dönüşümü (FFT) ve ters hızlı Fourier dönüşümü (IFFT) görüntüleri ile hesaplanmıştır. ÇKKNT-ağ.%32G/TiO2 xerojellerinin BET analizine göre, katkı oranı artıkça yüzey alanının da arttığı belirlenmiştir. Saf ve ÇKKNT-ağ.%32G katkılı TiO2 film numunelerinin AFM analizine göre ÇKKNT-ağ.%32G katkısının bir boşluk doldurucu misyonunu üstlenerek yüzeyde TiO2' nin boşluklarını doldurduğu gözlenmiştir. WCA hesaplamalarından elde edilen sonuçlara göre kaplanmış tüm yüzeyler kaplanmamış SLS cam alttaş yüzeye göre daha fazla hidrofilik davranış göstermiştir. Tüm yüzeylerin temas açısı AFM analizinden elde edilen pürüzlülük değerleriyle uyumluluk göstermiştir. Kaplamalı yüzeylere uygulanan 1 saatlik UV ışımasından sonra da yine tüm yüzeylerde temas açısı azalarak beklenen süperhidrofilik özelliğini sürdürmüştür. UV-vis ışık spektrofotometresi analizlerine göre görünür bölgede tüm katkı oranlarındaki geçirgenlik değeri saf TiO2' nin geçirgenlik değerinin üstünde kalmıştır. Absorbans değeri de hem UV bölgede hem de görünür bölgede katkı oranı arttıkça artış göstermiştir. Tauc grafikleriyle ise yasak bant aralığı enerjisinin katkı oranı arttıkça azalma gösterdiği hesaplanmıştır. Saf ve ÇKKNT-ağ.%32G katkılı TiO2 film numunelerinin fotokatalitik aktivite davranışları sulu ortamda MB degradasyonu çerçevesinde incelendiğinde saf TiO2 film kaplama ve % 0.1 - % 0.2 -% 0.3 - % 0.4 katkı oranına sahip ÇKKNT ağ.%32G/TiO2 film kaplamaların fotonik verim eşiğini geçtiği gözlenmiştir.
Titanium dioxide (TiO2), a semiconductor, is a photocatalyst that can be activated only by ultraviolet (UV) light. However, UV light covers a limited range of the electromagnetic spectrum. This limited range restricts the use of TiO2 in practical applications. The first rational step to be taken to avoid this limitation is to expand the electromagnetic spectrum range in which TiO2 is activated. In this context, doping is the primary strategy implemented. In this study, pure and 32 weight % graphene-doped multi-walled carbon nanotubes doped TiO2 films produced by sol-gel method using soda-lime-silica (SLS) glass as substrates. Thus, it is aimed to systematically and comprehensively investigate the crystallographic, morphological, photocatalytic, optical and surface properties of the composite films obtained. According to the literature, the anatase phase, where TiO2 exhibits the most superior photocatalytic properties, is formed during heat treatment, while alkalis such as sodium and calcium in the structure of SLS glass migrate into the film coatings and negatively affects crystallization. To prevent this situation, the formation process of the anatase phase was optimized by coating SLS glass surfaces with silicon dioxide (SiO2) before coating TiO2 films. Pure and doped TiO2 films at six different concentrations (0.025 %, 0.05 %, 0.1 %, 0.2 %, 0.3 %, 0.4 %), prepared by the sol-gel method without using surfactants, were dip-coated on SiO2-coated SLS substrates for the formation of the anatase phase. It was heat treated at 500oC for 1 hour. Phase analysis of the obtained pure and MWCNTs-32wt%G doped TiO2 films were determined by X-ray diffraction (XRD) and Raman spectroscopy methods, and chemical state analysis was determined by X-ray photoelectron spectrometry (XPS) method. Branauer Emmett-Teller (BET) method was used to measure the surface area of the powders obtained by drying MWCNTs-32wt%G/TiO2 sols. Morphological analyzes were carried out using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The roughness and surface topography of the films were examined by atomic force microscopy (AFM). Again, the wettability of the film surfaces was measured with an optical tensiometer device in the direction of the water contact angle (WCA). While optical properties were determined with the help of ultraviolet-visible (UV-vis) light spectrophotometer, forbidden band gaps were calculated by the Tauc plot method. In photocatalytic activity research, determinations were made through the degradation of methylene blue (MB) using the ISO 10678:2010 standard. By XRD analysis, it was determined that 500o C, which was chosen for pure and MWCNTs-32wt%G/TiO2 film coatings, was the optimum temperature to form the anatase phase without deforming the SLS glass substrate. Again, by XPS analysis, the main elements on the sample surface were determined to be titanium, oxygen and carbon, and their chemical state was determined from their binding energies and spin orbital placements. In addition, with Raman analysis, while the active mode bands of anatase TiO2 were observed with great clarity at the relevant wavelengths, the mode bands of the MWCNTs-32wt%G dopant became more evident as the doping ratio increased. When the SEM images of the surfaces of pure and MWCNTs-32wt%G doped TiO2 film coatings were compared, it was observed that all coatings were generally homogeneous. With the TEM light field images taken at various magnifications of MWCNTs-32wt%G doped TiO2 powders, it has been determined that TiO2 particles are clustered around MWCNTs-32wt%G nanoparticles, while MWCNTs-32wt%G nanoparticles show a dispersed arrangement in the horizontal plane within the TiO2 cluster. The existence of the anatase phase with the (101) crystal plane was also calculated with the fast Fourier transform (FFT) and inverse fast Fourier transform (IFFT) images of the TEM analysis. According to the BET analysis of MWCNTs-32 wt%G/TiO2 xerogels, it was determined that the surface area increased as the doping ratio increased. AFM analysis exhibited that MWCNTs-32wt%G dopant took on a space filler mission and filled the space of the surface of TiO2. According to the results obtained from WCA calculations, all coated surfaces exhibited more hydrophilic behavior than the uncoated SLS glass substrate surface. The contact angle of all surfaces was compatible with the roughness values obtained from AFM analysis. After 1 hour of UV irradiation applied to the coated surfaces, the contact angle decreased on all surfaces and maintained its expected super hydrophilic feature. According to UV-vis light spectrophotometer analysis, the transmittance values at all dopant ratios in the visible region remained above the transmittance value of pure TiO2. Absorbance values increased both in the UV region and in the visible region as the doping ratio increased. With Tauc plots, it was calculated that the band gap energy decreases as the doping ratio increases. When the photocatalytic activity behaviors of pure and MWCNTs-32wt%G/TiO2 film samples were examined within the framework of MB degradation in aqueous environment, it was observed that pure TiO2 and MWCNTs-32wt%G/TiO2 film coatings with 0.1 % - 0.2 % - 0.3 % - 0.4 % doping ratio exceeded the photonic efficiency threshold.
Titanium dioxide (TiO2), a semiconductor, is a photocatalyst that can be activated only by ultraviolet (UV) light. However, UV light covers a limited range of the electromagnetic spectrum. This limited range restricts the use of TiO2 in practical applications. The first rational step to be taken to avoid this limitation is to expand the electromagnetic spectrum range in which TiO2 is activated. In this context, doping is the primary strategy implemented. In this study, pure and 32 weight % graphene-doped multi-walled carbon nanotubes doped TiO2 films produced by sol-gel method using soda-lime-silica (SLS) glass as substrates. Thus, it is aimed to systematically and comprehensively investigate the crystallographic, morphological, photocatalytic, optical and surface properties of the composite films obtained. According to the literature, the anatase phase, where TiO2 exhibits the most superior photocatalytic properties, is formed during heat treatment, while alkalis such as sodium and calcium in the structure of SLS glass migrate into the film coatings and negatively affects crystallization. To prevent this situation, the formation process of the anatase phase was optimized by coating SLS glass surfaces with silicon dioxide (SiO2) before coating TiO2 films. Pure and doped TiO2 films at six different concentrations (0.025 %, 0.05 %, 0.1 %, 0.2 %, 0.3 %, 0.4 %), prepared by the sol-gel method without using surfactants, were dip-coated on SiO2-coated SLS substrates for the formation of the anatase phase. It was heat treated at 500oC for 1 hour. Phase analysis of the obtained pure and MWCNTs-32wt%G doped TiO2 films were determined by X-ray diffraction (XRD) and Raman spectroscopy methods, and chemical state analysis was determined by X-ray photoelectron spectrometry (XPS) method. Branauer Emmett-Teller (BET) method was used to measure the surface area of the powders obtained by drying MWCNTs-32wt%G/TiO2 sols. Morphological analyzes were carried out using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The roughness and surface topography of the films were examined by atomic force microscopy (AFM). Again, the wettability of the film surfaces was measured with an optical tensiometer device in the direction of the water contact angle (WCA). While optical properties were determined with the help of ultraviolet-visible (UV-vis) light spectrophotometer, forbidden band gaps were calculated by the Tauc plot method. In photocatalytic activity research, determinations were made through the degradation of methylene blue (MB) using the ISO 10678:2010 standard. By XRD analysis, it was determined that 500o C, which was chosen for pure and MWCNTs-32wt%G/TiO2 film coatings, was the optimum temperature to form the anatase phase without deforming the SLS glass substrate. Again, by XPS analysis, the main elements on the sample surface were determined to be titanium, oxygen and carbon, and their chemical state was determined from their binding energies and spin orbital placements. In addition, with Raman analysis, while the active mode bands of anatase TiO2 were observed with great clarity at the relevant wavelengths, the mode bands of the MWCNTs-32wt%G dopant became more evident as the doping ratio increased. When the SEM images of the surfaces of pure and MWCNTs-32wt%G doped TiO2 film coatings were compared, it was observed that all coatings were generally homogeneous. With the TEM light field images taken at various magnifications of MWCNTs-32wt%G doped TiO2 powders, it has been determined that TiO2 particles are clustered around MWCNTs-32wt%G nanoparticles, while MWCNTs-32wt%G nanoparticles show a dispersed arrangement in the horizontal plane within the TiO2 cluster. The existence of the anatase phase with the (101) crystal plane was also calculated with the fast Fourier transform (FFT) and inverse fast Fourier transform (IFFT) images of the TEM analysis. According to the BET analysis of MWCNTs-32 wt%G/TiO2 xerogels, it was determined that the surface area increased as the doping ratio increased. AFM analysis exhibited that MWCNTs-32wt%G dopant took on a space filler mission and filled the space of the surface of TiO2. According to the results obtained from WCA calculations, all coated surfaces exhibited more hydrophilic behavior than the uncoated SLS glass substrate surface. The contact angle of all surfaces was compatible with the roughness values obtained from AFM analysis. After 1 hour of UV irradiation applied to the coated surfaces, the contact angle decreased on all surfaces and maintained its expected super hydrophilic feature. According to UV-vis light spectrophotometer analysis, the transmittance values at all dopant ratios in the visible region remained above the transmittance value of pure TiO2. Absorbance values increased both in the UV region and in the visible region as the doping ratio increased. With Tauc plots, it was calculated that the band gap energy decreases as the doping ratio increases. When the photocatalytic activity behaviors of pure and MWCNTs-32wt%G/TiO2 film samples were examined within the framework of MB degradation in aqueous environment, it was observed that pure TiO2 and MWCNTs-32wt%G/TiO2 film coatings with 0.1 % - 0.2 % - 0.3 % - 0.4 % doping ratio exceeded the photonic efficiency threshold.
Açıklama
Anahtar Kelimeler
Metallurgical Engineering, Mühendislik Bilimleri, Metalurji Mühendisliği, Engineering Sciences
