Papers by Keyword: Photocatalyst

Abstract: Titanium dioxide (TiO₂) was utilized in photocatalysis applications due to their non- toxic, cheap and high photocatalytic activity. However, its photocatalytic reaction is limited by low surface area as well as the rapid recombination of photogenerated electron-hole pairs and only has ability to absorb a small fraction (<5%) of indoor light. In this study, copper oxide coupled titanium dioxide (CuO/TiO₂) nanocomposite photocatalyst was synthesized using hydrothermal method. The synthesised photocatalyst was characterized by using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), Scanning electron microscopy(SEM), Brunauer, Emmett, teller (BET) and UV- Visible Spectroscopy. Spectra obtained from FTIR have proved that there are existence of O-H stretching, O-H vibration and metal-O bond that correlates to the functional groups of the samples. As affirmed by XRD analysis, highly crystalline rutile TiO₂ phase was obtained for pure TiO₂ samples. Rutile TiO₂ phase is remained and additional peaks belong to copper oxide was observed for CuO/TiO₂ nanocomposite photocatalyst sample. This finding suggesting that copper oxide was successfully loaded onto TiO₂. Morphological study from SEM shows the presence of short rod-like particles of copper oxide and agglomerated TiO₂ bulk particles. BET surface area for CuO, TiO₂ and CuO/TiO₂ nanocomposite photocatalysts were 20.50 m²/g, 15.26 m²/g and 17.13 m²/g, respectively. The photocatalytic degradation of methyl orange (MO) was found to be 85.0% using CuO/TiO₂ nanocomposite photocatalyst, which is better than pure TiO₂ and pure CuO after 3 hours reaction.

Abstract: Photocatalyst is a material that can not only generate clean energy for the environment but can also be used in various applications such as antibacterial and antifouling properties. In this study, we compared the photocatalytic performance of titanium dioxide under indoor conditions by adjusting the amount of tin oxide attached to it. The amount of tin oxide deposited can be varied by adjusting the hydrothermal synthesis time. Appropriate tin oxide deposition recorded higher performance than excessive tin oxide deposition in both the yeast antimicrobial test and the water-splitting power generation test.

Abstract: The application of a photocatalyst with effective adsorption capacity and higher photocatalytic activity under direct sunlight for the treatment of industrial effluent contaminated with dyes has received increased attention. In this work, mesoporous TiO₂-NiO nanosheets were synthesized by a modified auto-combustion technique followed by thermal post-treatment at 400°C. The XRD pattern for modified auto-combusted resulting TiO₂ (sc) and TiO₂-NiO (sc) [5wt%NiO] nanosheets comprised of mixed-phase anatase and rutile for TiO₂ and cubic for NiO. The result of SEM demonstrated that the morphology of TiO₂ is a sheet and TiO₂-NiO is a rod-like structure. UV-vis spectroscopy results imply that the bandgap of TiO2 and TiO₂-NiO mixed phase is 3.1eV and 2.7eV. N₂ sorption (BET) showed a mesoporous structure and interpret specific surface areas of 19.528m²/g and 63.215 m²/g. Adsorption of the dye on the solid catalyst is inexpensive and efficient but disposing of the adsorbed dye is challenging. Among various dye removal techniques, photocatalytic degradation under direct sunlight is significant, cost-effective, and sustainable. Photocatalytic experiments using alizarin yellow as a model pollutant showed that the degradation percentage of AY was 93.54% in 120min for 100mg of TiO₂(sc) and 97% in 90min for 60mg of TiO₂-NiO(sc). Degradation of AY using TiO₂(sc) and TiO₂-NiO(sc) follows a pseudo-first-order reaction, whereas adsorption of AY on TiO₂-NiO(sc) follows the second-order kinetics, fits well in the Freundlich Isotherm model. Therefore, nanosized mesoporous TiO₂-NiO(sc) nanosheets with a p-n junction are considered efficient photocatalysts under direct sunlight due to narrowing down in bandgap, larger surface, and mixed-phase.

Abstract: ZnO nanorods and ZnO nanowires were obtained using solutions of zinc chloride and zinc acetate dihydrate, respectively, as precursors. The thin films were deposited by ultrasonic spray pyrolysis onto glass substrates at 350 °C and their morphological, structural, and optical properties were investigated. ZnO nanostructures morphologies were observed by SEM and images showed that a large amount of ZnO nanorods and nanowires were deposited onto the full substrates surfaces. The films have polycrystalline nature and hexagonal wurtzite structure with (002) and (101) preferential orientations for ZnO nanorods and nanowires, respectively. The crystallite size was found to be in the range of 30 nm. The films exhibit an optical transparency in the visible region of about 60 % for ZnO nanowires and 30 % for ZnO nanorods. The different ZnO films were used as photocatalysts to study the photodegradation of methyl green dye induced by UV light. ZnO nanorods exhibited higher photodegradation efficiency and a larger rate constant than ZnO nanowires leading to an improvement from 60 % to 80 % of the degradability of the dye.

Abstract: The synthesis of zinc oxide and nano-composite ZnO/TiO₂ was successfully prepared using lignin extracted from an oil palm empty fruit bunch. The synthesized materials i.e. zinc oxide and nano-composite ZnO/TiO₂ were characterized by UV–Vis spectrophotometry (UV-Vis), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The crystalline nature of ZnO and ZnO/TiO₂ nanocomposite is indicated by XRD analysis and SEM images. The result of UV–vis spectrophotometry shows the red shift occurred in the case of ZnO/TiO₂ composite. The nano range of the particles was demonstrated by the TEM images. The photocatalytic activity of the synthesized nanocomposite ZnO/TiO₂ was tested and compared to ZnO for the decolorization of rhodamine B. The decolorization results indicate that ZnO/TiO₂ nanocomposite showed better photocatalytic activity under visible light than ZnO as well as TiO₂.

Abstract: The development of Ag₃PO₄ photocatalyst for dye waste treatment is necessary because of its superiority compared to other materials. In this research, Ag₃PO₄ was synthesized with AgNO₃ and HAp from milkfish bones. Syntesis was done by simple ion-exchange method. In this research, composition of AgNO₃:HAp are 1:0.1; 1:0.3; and 1:0.5 to determine the optimum composition. Based on XRD results, it shows that ion-exchange process between phosphate ions from HAp milkfish bones and Ag+ from AgNO₃ was imperfect. It was shown from the presence of HAp peaks in synthesis results. Furthermore, the diffraction pattern showed that AgNO₃:HAp 1:0.1 composition has the best cristalinity. Based on SEM characterization, it shows that all compositions have majority shape as spherical and small part at AgNO₃/HAp 1:0.5 composition has nanorod morphology. It was also known that material with composition of AgNO₃:HAp 1:0.1; 1:0.3 and 1:0.5 have average size are 100.76 nm, 92.31 nm and 107.51. From UV-Vis spectroscopy data processing, it represent the value of direct band gap of material is 3.83 eV and the value of indirect band gap is 3.6 eV. It also shows the degradation value of methylene blue with the best value was shown in AgNO₃:HAp 1:0.3 composition with 47.4%.

Abstract: In present study, a simple chemical method for the synthesis of silver-reduced graphene oxide (AG/RGO) nanocomposite was reported. The objective is to evaluate the performance of AG/RGO in photocatalytic degradation activity of methyl orange (MO) under artificial visible light source. The synthesized catalyst was then characterized using field emissions scanning electron microscope with energy dispersive X-Ray spectroscope (FESEM-EDX), photoluminescence spectroscopy (PL) and UV-visible spectroscope (UV-VIS) to determine the morphology, physical and chemical composition of the photocatalyst. The characterization results show the synthesized catalyst possess nanometre dimension silver nanoparticles (AgNPs) were deposited on reduced graphene oxide sheets. The photocatalytic activity of 0.3 g AG/RGO obtained through the degradation of 5 mg/l MO is 93.74% with a degradation rate of 3.1 × 10^-2 min^-1.

Abstract: A comparative study of the Carbon Quantum Dots (CQDs) based composites photocatalyst for water purification was carried out. New finding of CQDs and TiO₂ have demonstrated significant advantage since it provides environmentally friendly for photocatalytic degradation of methyl orange (MO) dye. CQDS and TiO₂ were prepared by using hydrothermal method. The CQDs and CQDS/TiO₂ were fully characterized by using transmission electron microscope (TEM) to identify the size range and shape that involve in the adsorption process. The synthesized CQDs and CQDs/TiO₂ had small semi spherical morphology with 5 nm in size. The result of photocatalytic activity revealed that there is photocatalytic degradation of MO in the presence of only pure CQDs and CQDs/TiO₂ composites which the value of concentration decreased against time. CQDs/TiO₂ exhibited higher photocatalytic activity, which indicated that both CQDs and TiO₂ played important roles for the high photocatalytic activity under visible light irradiation.

Abstract: Nb₂O₅ has recently been considered as one of the oxides thin films that attracts a noticeable attraction by scientific prospective aspects. Its usefulness in a wide practical applications range such as in optoelectronic devices, optical coatings, catalysis, gas sensors, photocell, electrochromics, photoelectrodes, Ec devices, microelectronics and in the medical field paid researchers attention to synthesize it by various methods like sol.gel, electrodeposition, chemical vapor deposition etc. Among those, Pulsed laser deposition technique has achieved an effective improvements. In this paper, we aim to revise increasing significance of Nb₂O₅ supported by previous applications and a further possible future outlook.

Abstract: A hydrothermal process was proposed to prepare BiVO₄/ diatomite composite photocatalysts, where BiVO₄ was grown from a precursor solution containing diatomite, and EDTA used as a chelating agent to prevent the precipitation of precursor solution compositions on diatomite before hydrothermal treatment. The effect of some processing parameters like diatomite percentage and Ag-loaded amount on their photocatalytic performance were also investigated in detail by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), BET, and UV‐Vis spectroscopy. The results show that BiVO₄/ diatomite composite photocatalysts can be successfully prepared at 160 °C for the duration of 3h by the hydrothermal process. The diatomite has two significant impacts on their photocatalytic performance: (1) enhancing the dispersion of BiVO₄ crystallites due to its high porosity and specific surface area to favor their photocatalytic performance, and (2) having a light screening effect to incident visible light to decrease their photocatalytic activity. Appropriately incorporating diatomite could improve their photocatalytic performance, but the overuse of diatomite would reduce that. Similarly, depositing Ag could effectively improve their photocatalytic activity because of its good light absorption and photosensitive characteristics, but excessive addition would result in their decrease since the overuse of Ag would also promote the electron-hole recombination.