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Oxygen vacancy‐rich anatase TiO2 hollow spheres via liquid nitrogen quenching process for enhanced photocatalytic hydrogen evolution
摘要： Development of novel methods to obtain highly active catalysts for photocatalytic hydrogen evolution is desired. This work reports a facile preannealing-quenching strategy to synthesize oxygen vacancy-rich anatase TiO2 hollow spheres. TiO2 hollow spheres are first synthesized via a versatile kinetics-controlled coating method and then subjected to high temperature preannealing followed by rapid quenching in liquid-nitrogen (-196 oC). The as-quenched samples appear light grey suggesting the presence of abundant surface oxygen vacancies, which are subsequently confirmed by the comprehensive analyses of XRD, XPS and EPR spectra. The oxygen vacancies induced by quenching process are proved to have promoted the light adsorption and inhibited the recombination of photo-induced charges for TiO2 hollow spheres, which obviously improve the photocatalytic performance of those samples. The results showed that the TiO2 hollow spheres quenched at 500 oC exhibited a robust stability and the most excellent photocatalytic performance for hydrogen evolution (413.5 μmol·h-1) over other quenched samples and it displayed 1.51 times higher performance than that of samples normally cooled at 500 oC (273.7 μmol · h-1). Herein, this liquid-nitrogen quenching strategy presented here provides an effective route for the synthesis of high-performance TiO2 for water splitting and have a promising prospect in the other application.
关键词： quenching,hollow spheres,photocatalytic hydrogen evolution,oxygen defects,titanium dioxide
更新于2025-09-04 15:30:14
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Effect of Ce and Mn co-doping on photocatalytic performance of sol-gel TiO2
摘要： Co-doped titanium dioxide was synthesized by doping with manganese (Mn) and cerium (Ce) through a sol-gel method for the degradation of diclofenac (DCF). The synthesized products were successfully characterized by X-ray diffraction (XRD), Raman spectroscopy, Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Nitrogen physisorption at 77 K, X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance (UV-DRS), photoluminescence spectroscopy (PL) and total organic carbon (TOC). It was shown that co-doping increased the specific surface area, improved the visible light absorption and extended the lifetime of photogenerated charge carriers. Furthermore, the results of the photocatalytic experiments show that the photodegradation rate of diclofenac can be approached by pseudo first-order kinetics and it followed the Langmuir-Hinshelwood model very well. The co-doped catalyst with 0.6 % Mn and 1 % Ce molar ratios appeared to be the most photoactive catalyst with 94 % of DCF removal and an apparent rate constant of 0.012 min-1.
关键词： Photocatalysis,co-doping,manganese and cerium,titanium dioxide,diclofenac
更新于2025-09-04 15:30:14
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Nanorods Array of SnO2 Quantum Dots Interspersed Multiphase TiO2 Heterojunctions with Highly Photocatalytic Water Splitting and Self-Rechargeable Battery-Like Applications
摘要： Facing an ever-growing demand for sustainable and renewable power sources, it has detonated the development of novel materials for photocatalytic water splitting, but how to enhance the photocatalytic efficiency remains a core problem. Herein, we reported a conceptual effective and experimental confirmed strategy in SnO2 quantum dots (QD) interspersed multiphase (Rutile, Anatase) TiO2 nanorods arrays (SnO2/RA@TiO2 NRs) to immensely enhance the carrier separation for highly efficient water splitting by merging simultaneously the QD, multiphase, and heterojunction approaches. Under this synergistic effect, a doping ratio of 25% SnO2 QD interspersed into multiphase TiO2 NRs exhibited a superior optical adsorption and excellent photocurrent density (2.45 mA/cm2 at 1.0 V), giving rise to a largely enhanced incident light to current efficiency (IPCE) in the UV region (45~50 %). More importantly, this material-based device can act as power supply with a voltage of ~2.8 V after illumination, which can automatically self-recharging by reacting with oxygen vacancy and water molecule to realize reusing. The current study provide a new paradigm about heightening the carrier separation extent of QD interspersed multiphase heterojunctions, fabricate a new solar energy converting material/device, and achieve a highly photocatalytic water splitting/self-charging battery-like application.
关键词： Photocatalytic,Water splitting,Titanium Dioxide,Heterojunction
更新于2025-09-04 15:30:14
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Optimization and modeling of UV-TiO <sub/>2</sub> mediated photocatalytic degradation of golden yellow dye through response surface methodology
摘要： In this article, heterogeneous photocatalysis of golden yellow (GY) dye by Evonik p25 titanium dioxide (PTD) and UV radiations was optimized by using central composite design of response surface methodology. The GY dye photocatalysis was expressed as the function of amount of PTD loading (X1), GY dye initial concentration (X2), and UV irradiance intensity (X3). The optimization of degradation conditions was done by measuring two different responses, that is, color removal (Y1) and chemical oxygen demand removal (Y2). The effect of X1, X2, and X3 were studied in the range 0.5–1.5 g/L, 15–35 W/m2, and 10–30 mg/L, respectively. The quadratic model was suggested for Y1 and Y2. The numerical optimization of results was done via Design Expert software. The predictive results obtained were verified by performing actual experiments. The photodegradation kinetics, total organic carbon disappearance, effect of inorganic salts, and H2O2 concentration on GY dye photodegradation were also studied.
关键词： Titanium dioxide,Heterogeneous photocatalysis,Central composite design,Optimization,Golden yellow dye,Response surface methodology
更新于2025-09-04 15:30:14
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PH SENSITIVITY DEPENDENCY ON THE ANNEALING TEMPERATURE OF SPIN-COATED TITANIUM DIOXIDE THIN FILMS
摘要： Titanium dioxide (TiO2) thin films were fabricated on indium tin oxide (ITO) glass substrates using the spin coating technique and further were implemented as sensing membranes of the extended gate field effect transistor (EGFET) based pH sensor. The as-deposited thin films were annealed at different temperatures from 200 - 600 °C in room ambient for 20 min. The effects of different annealing temperatures on electrical and crystalline properties were analyzed by I-V two point probes measurement and X-ray diffraction respectively. Meanwhile, the surface morphology of thin films was observed by field emission scanning electron microscope (FESEM). We then measured the transfer characteristics (ID-VG) of the TiO2/ITO sensing membrane using a semiconductor parametric device analyzer for sensor characterization. It was found that, TiO2/ITO sensing membrane annealed at 300 °C achieved higher sensitivity and good linearity of 51.48 mV/pH and 0.99415, respectively in the pH buffer solutions of 4, 7, 10, and 12. Thin film annealed at 300 °C gives higher conductivity thin film of 384.62 S/m. We found that the conductivity of TiO2/ITO thin films was proportional with the sensitivity of sensing membrane.
关键词： titanium dioxide,Annealing temperature,sol-gel spin coating,extended gate field effect transistor
更新于2025-09-04 15:30:14