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Au nanoparticles supported on nanorod-like TiO2 as catalysts in the CO-PROX reaction under dark and light irradiation: Effect of acidic and alkaline synthesis conditions
摘要： Gold nanoparticles precipitated-deposited on titania nanostructures (1.0 wt% nominal loading) were studied in the preferential CO oxidation in excess of H2 at room temperature and atmospheric pressure, both in dark and under simulated solar light irradiation. Titania supports were synthesized by means of two hydrothermal methods markedly acid and basic, giving rise to rutile nanorods and anatase deformed nanorods structures, respectively. Characterization techniques such as N2 physisorption, XRD, XPS, DRUV-vis, HRTEM and XRF were performed in order to study the chemical, structural and optical properties of the catalysts. Well defined rutile nanorods structures were obtained from the acidic treatment allowing a regular distribution of gold nanoparticles and resulting quite active in the CO-PROX reaction. In particular the sample from the acidic synthetic approach calcined at 700 °C displayed the best results as it was highly selective to CO2 under both dark and simulated solar light irradiation.
关键词： Photocatalysis,CO preferential oxidation,Gold nanoparticles,Titania nanorods,Simulated solar light
更新于2025-09-23 15:22:29
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Particularities of trichloroethylene photocatalytic degradation over crystalline RbLaTa2O7 nanowire bundles grown by solid-state synthesis route
摘要： This is the first report on synthesis and photocatalytic activity for trichloroethylene (TCE) degradation under simulated solar light over RbLaTa2O7 layered perovskites with predominant nanowire or platelet morphologies. SEM images witnessed that the one step thermal treatment at 1200 °C lead to formation of RbLaTa2O7 nanowires with diameter of 80~320 nm and several microns in length associated in bundles and sharp-edged, merged platelets (minor phase). The two-step annealing at 950 °C and 1200 °C resulted in decrease of wires bundle population and increase in that of platelets merged in facetted particles. The RbLaTa2O7 nanowires are made of by well-aligned atomic rows with preferred orientation toward the c-axis, relatively free of defect. High density of hydroxyl groups on the sample calcined in mild conditions (RbLaTa_01) favors the photo mineralization of TCE. In contrast, the activity of RbLaTa_02 annealed in harsh conditions (950 and 1200 oC), poor in surface hydroxyl groups, remained modest. The weak surface basicity directed the reaction mainly to generation of intermediate chlorinated compounds. Pd and Au were supported on RbLaTa2O7 perovskites as an alternative strategy to boost the removal of chlorinated pollutants by combining photocatalytic (mineralization) and catalytic (hydrodechlorination, HDC) processes. The mineralization of TCE to Cl- was drastically hindered in presence of methanol due to quenching of ?OH radicals by alcohol. The results suggested that the density of RbLaTa2O7 surface hydroxyl groups is essential for photo mineralization of TCE whereas the surface carbonate is beneficial for the formation of intermediate chlorinated product.
关键词： solid state reaction,layered perovskites,trichloroethylene,simulated solar light,photocatalysis
更新于2025-09-23 15:21:21
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Grain-like bismuth-rich bismuth/bismuth oxychlorides intra-heterojunction: Efficacious solar-light-driven photodegradation of fluoroquinolone antibiotics and 2-level factorial approach
摘要： The grain-like BiOCl (60%)–Bi 24 O 31 Cl 10 (40%) intra-heterojunction nanophotocatalyst was fabricated by a facile one-pot combustion route using sorbitol fuel. It was characterized by the utilization of XRD, FESEM, PSD, BET–BJH and DRS, which proved its successful synthesis. The solar-light-driven photocatalytic activity of BiOCl (60%)–Bi 24 O 31 Cl 10 (40%) was appraised through the destruction of fluoroquinolone antibiotics (FQAs) such as ciprofloxacin, ofloxacin and levofloxacin as persistent and resisting emerging pollutants in an aqueous solution. Consequences obtained were implied to its prominent performance. To investigate the individual and interplay influences of the input operating parameters (catalyst loading, initial pollutant concentration, initial pH and reaction time), the modelling of the photocatalytic destruction of ofloxacin as the response was done by 2-level full factorial experimental design approach. A semi-empirical fourth-order regression model with R 2 = 0.9878 was expressed to relate between the response and independent variables. Results obtained of the mentioned approach demonstrated the high adequacy of the model. The influence of individual parameters and their interactions on the photocatalytic degradation efficiency of ofloxacin was possessed by the main effect graphs, contour and response surface plots. This study not only illustrates a hopeful application of the grain-like BiOCl–Bi 24 O 31 Cl 10 in the solar-light-driven photo-destruction of resistant pollutants such as FQAs but also shows the favourable direction to gain the high-performance.
关键词： Simulated solar light,2-level factorial approach,Rich–bismuth oxychlorides,Grain-like nanophotocatalyst,Fluoroquinolone antibiotics
更新于2025-09-10 09:29:36
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Charge separation and ROS generation on tubular sodium titanates exposed to simulated solar light
摘要： The research focuses on a few key points concerning the light-driven processes taking place on TiO2 anatase and sodium titanates with tubular morphology, such as the relationship between the morphology and activity for H2 and CO2 production, density of surface hydroxyl groups, ROS (?OH and ?O2-) production and photocatalytic activity, and charge separation at the interface of semiconducting domains and enhancement of activity. One key point discussed is whether the materials with peculiar morphologies (i.e. tubular) are superior to the conventional ones. The experimental evidences show that the main advantage of the tubular morphology of sodium titanate is given by its significantly higher surface area compared to parental anatase. FTIR and XPS progressive analyses evidence that the density of surface hydroxyl groups decreases with the development of the tubular morphology. The radical trapping experiments show that the variation of surface hydroxyl density is, generally, followed by activities for ?OH and ?O2- generation, as well as by the photocatalytic production of H2 and CO2 from water/methanol mixture. Consequently, the ROS, formed by action of photogenerated electrons and holes on adsorbed O2 and hydroxyl groups, respectively, play an important role in determining the photocatalytic activity of titania-based materials. The other major aspect revealed by this research is that the charge separation at the interfaces formed between anatase and sodium titanate crystalline phases has remarkable effect on the activity formation rates of H2 and CO2.
关键词： titanate nanotubes,reactive oxygen species,charge separation,simulated solar light,photocatalysis
更新于2025-09-09 09:28:46