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XPS investigation of F-doped MnO <sub/>2</sub> nanosystems fabricated by plasma assisted-CVD
摘要： Supported Mn(IV) oxide nanomaterials were prepared by plasma assisted-chemical vapor deposition from Ar/O2 plasmas starting from a fluorinated Mn(II) β-diketonate diamine adduct. Under the adopted conditions, the target compound served as a single-source molecular precursor for the obtainment of MnO2 nanosystems uniformly doped with fluorine. The overall F content in the target materials, composed of phase-pure β-MnO2, could be tailored as a function of the deposition temperature from 100 to 400 °C, a result of particular importance in view of photocatalytic and gas sensing applications. In the present study, attention is specifically devoted to the investigation of a representative specimen by means of x-ray photoelectron spectroscopy. Besides the wide scan spectrum, a detailed analysis of C 1s, O 1s, Mn 2p, Mn 3s, and F 1s photoelectron peaks is presented and discussed. The analyses reveal the formation of MnO2 free from other manganese oxides, with fluorine present in different chemical states, i.e., lattice F plus traces of precursor residuals at the system surface.
关键词： fluorine doping,x-ray photoelectron spectroscopy,PA-CVD,manganese oxide
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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Visible–light driven photocatalytic degradation of bisphenol-A using ultrasonically synthesized polypyrrole/K-birnessite nanohybrids: Experimental and DFT studies
摘要： Although manganese oxides are known for their semiconductor characteristics, the photocatalytic performance of conducting polymer intercalated K-Birnessite (K-Bi) has not been explored till date. With the view to design a visible light driven organic–inorganic hybrid photocatalyst for rapid degradation of Bisphenol A (BPA), the present work reports the ultrasound-assisted green synthesis of K-Bi/polypyrrole (Ppy) nanohybrids. The loading of Ppy in K-Bi was confirmed by thermogravimetric analysis while the formation of organic–inorganic hybrid was confirmed by infrared spectroscopy. K-Bi revealed a band gap of 2.8 eV while for the nanohybrids it was found to be ranging between 2.4 and 1.6 eV. X-ray diffraction studies confirmed partial intercalation of Ppy chains in the inter-layer space of K-Bi. High resolution transmission electron microscopy and scanning electron microscopy studies showed mixed morphology of K-Birnessite/Ppy nanohybrids. Rapid degradation of BPA was observed under visible irradiation in presence of K-Bi/Ppy nanohybrids and almost 90% degradation of 20 mg/L BPA solution was achieved within 120 min. The degradation was found to follow pseudo-first order kinetics and the degraded fragments were identified using liquid chromatography-mass spectrometry. Degradation pathway was proposed based on density-functional theory calculations of fukui index predicting the radical easy-attacking (f0) and (f-) sites in BPA.
关键词： DFT calculations,Degradation kinetics,Photocatalysis,Manganese oxide,Polypyrrole
更新于2025-09-04 15:30:14