Perovskite-like oxide La2-xSrxCuO4 (x = 0, 1) single crystallites with microrod-like morphologies and tetragonal crystal structures were prepared hydrothermally at 240°C with poly(ethylene glycol) (PEG) or hexadecyltrimethyl ammonium bromide (CTAB) as a surfactant and after calcination at 850°C. The physicochemical properties of the materials were characterized by means of XRD, BET, SEM, TEM/SAED (selected-area electron diffraction), XPS and H2-TPR techniques. It is found that doping Sr2+ to La2CuO4 lattice enhanced the catalytic activity for methane combustion and the LaSrCuO4 catalyst derived from PEG is the best among the tested ones. It is concluded that factors, such as adsorbed oxygen species concentration, reducibility and surface area, determined the catalytic performance of such single-crystalline materials.
Monoclinic BiVO4 with multiple morphologies and/or porous structures were fabricated using the hydrothermal strategy. The materials were characterized by means of the XRD, Raman, TGA/DSC, SEM, XPS, and UV-Vis techniques. The photocatalytic activities of the BiVO4 materials were evaluated for the degradation of Methyl Orange under visible-light irradiation. It is observed that pH value and surfactant exerted a great effect on the morphology and pore structure of the BiVO4 product. Spherical BiVO4 with porous structures, flower-cluster-like BiVO4, and flower-bundle-like BiVO4 were generated hydrothermally at 100°C with poly(vinyl pyrrolidone) (PVP) and urea (pH = 2) and at 160°C with NaHCO3 (pH = 7 and 8), respectively. The PVP-derived BiVO4 showed much higher surface areas (5.0-8.4 m2/g) and narrower bandgap energies (2.45-2.49 eV). The best photocatalytic performance of the spherical BiVO4 material with a surface area of 8.4 m2/g was associated with its higher surface area, narrower bandgap energy, higher surface oxygen vacancy density, and unique porous architecture.
Haiyan JiangHongxing DaiXue MengLei ZhangJiguang DengYuxi LiuChak Tong Au
Zeolite P was synthesized for the first time via a novel water-bathing route at 90 C using scrubbed diatomite,sodium hydroxide,and aluminum hydroxide as precursor,with SiO 2/Al 2 O 3,SiO 2/Na 2 O,and H 2 O/Na 2 O molar ratios of 7.43,3.81,and 80.00,respectively.The as-fabricated samples were characterized by means of scanning electron microscopy,X-ray diffraction,and nitrogen adsorption measurements.This study showed that (i) treating the diatomite raw material with sodium hexametaphosphate could open the pores in the diatomite via removal of the clay clogged in its pores;(ii) tetragonal mesoporous zeolite P samples with a surface area of 56-60 m 2/g could be generated after 6-24 h of water-bathing reaction at 90 C;(iii) extension of water-bathing reaction time could improve the mesoporous structure of zeolite P;and (iv) Ca 2+ adsorption capacity of the zeolite P sample was about 300 cmol/kg.Such high-surface-area porous zeolite P could be used as an effective adsorbent for the treatment of water containing calcium and magnesium ions.
