Carbon nanotube （CNTs）/Fe-Ni/TiO2 nanocomposite photocatalysts have been synthesized by an in situ fluidized bed chemical vapor deposition （FBCVD） method. The composite photocatalysts were characterized by XRD, Ra...Carbon nanotube （CNTs）/Fe-Ni/TiO2 nanocomposite photocatalysts have been synthesized by an in situ fluidized bed chemical vapor deposition （FBCVD） method. The composite photocatalysts were characterized by XRD, Raman spectroscopy, BET, FESEM, TEM, UV-vis spectroscopy, and XPS. The results showed that the CNTs were grown in situ on the surface of TiO2. Fe（Ⅲ） in TiO2 showed no chemical changes in the growth of CNTs. Ni（Ⅱ） was partly reduced to metal Ni in the FBCVD process, and the metal Ni acted as a catalyst for the growth of CNTs. The photocatalytic activities of CNTs/Fe-Ni/TiO2 decreased with the rise of the FBCVD reaction temperature. For the sample synthesized at low FBCVD temperature （500 ℃）, more than 90% and nearly 50% of methylene blue were removed under UV irradiation in 180 min and under visible light irradiation in 300 min, respectively. The probable mechanism of synergistic enhancement of photocatalysis on the CNTs/Fe-Ni/TiO2 nanocomposite is proposed.展开更多
Present-day all-vanadium redox flow batteries(VRFBs)generally require high purity vanadium oxide as a raw ingredient.The chlorination procedure presents distinct technical advantages with regard to preparing high puri...Present-day all-vanadium redox flow batteries(VRFBs)generally require high purity vanadium oxide as a raw ingredient.The chlorination procedure presents distinct technical advantages with regard to preparing high purity vanadium pentoxide(V2O5)using vanadium oxytrichloride(VOCl3)as a highly pure intermediate.To efficiently prepare high purity V2Os from VOCl3,a single-step fluidized bed chemical vapor deposition(FBCVD)method was explored in the present work.Based on thermodynamic analyses,the direct and complete conversion of VOCl3 to V2O5 is difficult,and may result in a small amount of residual Cl in the product.Consequently,the effects of temperature and the H2O/VOCl3 molar ratio on the quantity of residual Cl were assessed.The Cl concentration was found to decrease with increasing temperature or increasing H2O/VOCl3 molar ratios.Additionally,Cl was determined to be present only in the form of Cl-V bonds,while Cl-H and Cl-Cl bonds were not detected in a V2O5 product made at 200℃with a H2O/VOCl3 molar ratio of 18.A Cl concentration of less than 0.05 wt%was obtained under the optimal synthesis conditions,demonstrating that the FBCVD method is a viable means of preparing high purity V2O5 via the gaseous hydrolysis of VOCl3.展开更多
基金supported by the Special Projects for Nanotechnology of Shanghai(1052mm02400)the National Nature Science Foundation of China(20925621)
文摘Carbon nanotube （CNTs）/Fe-Ni/TiO2 nanocomposite photocatalysts have been synthesized by an in situ fluidized bed chemical vapor deposition （FBCVD） method. The composite photocatalysts were characterized by XRD, Raman spectroscopy, BET, FESEM, TEM, UV-vis spectroscopy, and XPS. The results showed that the CNTs were grown in situ on the surface of TiO2. Fe（Ⅲ） in TiO2 showed no chemical changes in the growth of CNTs. Ni（Ⅱ） was partly reduced to metal Ni in the FBCVD process, and the metal Ni acted as a catalyst for the growth of CNTs. The photocatalytic activities of CNTs/Fe-Ni/TiO2 decreased with the rise of the FBCVD reaction temperature. For the sample synthesized at low FBCVD temperature （500 ℃）, more than 90% and nearly 50% of methylene blue were removed under UV irradiation in 180 min and under visible light irradiation in 300 min, respectively. The probable mechanism of synergistic enhancement of photocatalysis on the CNTs/Fe-Ni/TiO2 nanocomposite is proposed.
基金This work was supported by the National Natural Science Foundation of China(Project Nos.51774262,51504231,51504232,and 21736010)the Open Project of State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization(Project No.CNMRCUKF1704).
文摘Present-day all-vanadium redox flow batteries(VRFBs)generally require high purity vanadium oxide as a raw ingredient.The chlorination procedure presents distinct technical advantages with regard to preparing high purity vanadium pentoxide(V2O5)using vanadium oxytrichloride(VOCl3)as a highly pure intermediate.To efficiently prepare high purity V2Os from VOCl3,a single-step fluidized bed chemical vapor deposition(FBCVD)method was explored in the present work.Based on thermodynamic analyses,the direct and complete conversion of VOCl3 to V2O5 is difficult,and may result in a small amount of residual Cl in the product.Consequently,the effects of temperature and the H2O/VOCl3 molar ratio on the quantity of residual Cl were assessed.The Cl concentration was found to decrease with increasing temperature or increasing H2O/VOCl3 molar ratios.Additionally,Cl was determined to be present only in the form of Cl-V bonds,while Cl-H and Cl-Cl bonds were not detected in a V2O5 product made at 200℃with a H2O/VOCl3 molar ratio of 18.A Cl concentration of less than 0.05 wt%was obtained under the optimal synthesis conditions,demonstrating that the FBCVD method is a viable means of preparing high purity V2O5 via the gaseous hydrolysis of VOCl3.
