The synthesis of carbon nanotubes （CNTs） via chemical vapour deposition of methane on NiO/γ-Al2O3 catalyst has been investigated.The reduction behavior of NiO/γ-Al2O3 by methane was studied using thermogravimetric...The synthesis of carbon nanotubes （CNTs） via chemical vapour deposition of methane on NiO/γ-Al2O3 catalyst has been investigated.The reduction behavior of NiO/γ-Al2O3 by methane was studied using thermogravimetric （TG） and X-ray diffraction （XRD） techniques.It was found that the NiO supported on γ-Al2O3,was reduced to Ni0 in methane atmosphere in the temperature range of 710-770℃.The catalytic activity of NiO/γ-Al2O3 for CNTs synthesis by in situ chemical vapour deposition of methane during the reduction was also investigated.Scanning electron microscopy （SEM） and transmission electron microscopy （TEM） were used to observe the CNTs produced at various reduction temperatures.The results indicated that the reduction temperature exhibits obvious influence on the morphology and the yield of CNTs.CNTs with the diameter of about 20 nm were obtained at reduction temperature of 750℃,and higher reduction temperature （such as 800 and 850℃） led to an increase in CNTs diameter and a decrease in CNTs yield.展开更多
A series of NiO/SiO2 aerogel catalysts were prepared by sol gel method. The effects of the nickel content on the structure and existing forms of NiO/SiO2 aerogel catalysts were investigated by using XRD, TPR and FT IR...A series of NiO/SiO2 aerogel catalysts were prepared by sol gel method. The effects of the nickel content on the structure and existing forms of NiO/SiO2 aerogel catalysts were investigated by using XRD, TPR and FT IR. The results showed that there were interactions between NiO and SiO2. But as nickel content increased, the interaction decreased. The nickel oxide in the catalysts appeared in different forms as nickel content was changed. When the content was less than 13%, Ni? entered into the SiO2 structure completely and it became clusters after calcining. If the content altered from 20% to 50%, NiO existed as both microcrystal and clusters, the later spices was dominating. However, when the content increased to 70%, microcrystal became the primary components.展开更多
基金supported by the Key Project of Chinese Ministry of Education(No. 208076)Foundation for Outstanding Young Scientist in Shandong Province(BS2009CL004)the Open Foundation of Chemical Engineering Subject of Qingdao University of Science & Technology(No. 20100102)
文摘The synthesis of carbon nanotubes （CNTs） via chemical vapour deposition of methane on NiO/γ-Al2O3 catalyst has been investigated.The reduction behavior of NiO/γ-Al2O3 by methane was studied using thermogravimetric （TG） and X-ray diffraction （XRD） techniques.It was found that the NiO supported on γ-Al2O3,was reduced to Ni0 in methane atmosphere in the temperature range of 710-770℃.The catalytic activity of NiO/γ-Al2O3 for CNTs synthesis by in situ chemical vapour deposition of methane during the reduction was also investigated.Scanning electron microscopy （SEM） and transmission electron microscopy （TEM） were used to observe the CNTs produced at various reduction temperatures.The results indicated that the reduction temperature exhibits obvious influence on the morphology and the yield of CNTs.CNTs with the diameter of about 20 nm were obtained at reduction temperature of 750℃,and higher reduction temperature （such as 800 and 850℃） led to an increase in CNTs diameter and a decrease in CNTs yield.
文摘设计低廉、高效且长稳定的析氢反应(HER)催化剂对于水分解技术的工业实施至关重要。本研究采用溶胶凝胶法结合后续热分解的方式制备出了异质纳米结构NiO KNbO_(3)催化剂,通过X射线衍射(XRD)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和电化学工作站(CHI660E)对NiO KNbO_(3)催化剂的晶型结构、元素价态、微观形貌和HER催化性能进行了系统分析。结果表明,NiO KNbO_(3)催化剂在1 mol L KOH电解液中表现出优异的HER催化性能,-10 mA cm 2电流密度下的析氢反应过电位仅为-217 mV,对应Tafel斜率为77.4 mV dec,在24 h恒电位析氢反应稳定性测试中,表现出良好的催化稳定性和耐腐蚀性。NiO KNbO_(3)催化剂优异的HER性能归因于NiO和KNbO_(3)的协同作用以及独特的异质纳米复合结构增大了活性位点暴露和改善了离子传输路径。
文摘A series of NiO/SiO2 aerogel catalysts were prepared by sol gel method. The effects of the nickel content on the structure and existing forms of NiO/SiO2 aerogel catalysts were investigated by using XRD, TPR and FT IR. The results showed that there were interactions between NiO and SiO2. But as nickel content increased, the interaction decreased. The nickel oxide in the catalysts appeared in different forms as nickel content was changed. When the content was less than 13%, Ni? entered into the SiO2 structure completely and it became clusters after calcining. If the content altered from 20% to 50%, NiO existed as both microcrystal and clusters, the later spices was dominating. However, when the content increased to 70%, microcrystal became the primary components.
