Yang Gao,Xiaodong Wu,Rui Ran,Zhichun Si,Ziran Ma,Baodong Wang,Duan Weng
Monometallic (V/TiO 2 and Mo/TiO 2 ) and bimetallic (V-Mo/TiO 2 ) catalysts were prepared for selective catalytic reduction (SCR) of NO x with NH 3 at low temperatures (100–300 °C). The effect of MoO x on the dispersion of vanadia with different V 2 O 5 loadings was investigated on the basis of X-ray diffraction (XRD), inductively coupled plasma optical emission spectrometry (ICP-OES), N 2 adsorption–desorption, Raman spectroscopy, ultraviolet–visible (UV–Vis) spectroscopy, X-ray photoelectron spectroscopy (XPS), H 2 temperature-programmed reduction (H 2 -TPR) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). As the molybdenum precursor, NH 4 Mo 7 O 24 increased the solution acidity and promoted polymerization of VO x in liquid phase. At a low vanadia loading, polymerization of VO x , the adsorption rate of NH 3 and transformation of active intermediate species NH 2 were enhanced by adding MoO x , while at a high vanadia loading, the steric hindrance became dominant leading to the formation of crystalline V 2 O 5 and MoO 3 and caused decline in SCR activity.
Meng-Meng Liu,Shan-Hong Li,Dan-Dan Huang,Zhi-Wei Xu,Ya-Wei Wu,Yun Lei,Ai-Lin Liu
Diagnostic assays made of microfluidic paper-based analytical devices have become the focus of considerable attention in developing countries because of simplicity, low cost, user friendliness, and no requirement for complex equipment, which is suitable to point-of-care testing. Considering the intrinsic shortcomings of nature enzyme, synthesis of artificial peroxidase mimics possessing improved catalytic activities relative to native enzymes is of considerable interest for the development of highly sensitive and stable sensor. In this paper, water-soluble molybdenum oxide quantum dots (MoOx QDs) were developed as highly effective biomimetic catalysts which were prepared by a facile ultrasonic-assisted hydrothermal method. The resulted MoOx QDs displayed peroxidase-like activity with high sensitivity and specificity, and were constructed for efficient colorimetric quantitative detection of H 2 O 2 based on microfluidic paper-based device. As low as 0.175 μmol/L H 2 O 2 could be determined at a linear range from 1 to 20 μmol/L. Moreover, this biosensing device was successfully applied for visual detection of H 2 O 2 released from PC12 cells with the advantages of low cost, rapid response and portability, indicating that the designed sensor of H 2 O 2 has great potential in biotechnology and clinical diagnosis.
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