作为一种具有广泛应用前景的高效电合成技术,耦合电溶解的铪醇盐合成(EHS)基于铪溶解/乙醇脱氢的同时非均相反应以及溶液中Hf4+阳离子和烷氧阴离子的自发结合反应。为了阐明EHS过程的机制和动力学,通过电化学测试、扫描电镜、气相色谱...作为一种具有广泛应用前景的高效电合成技术,耦合电溶解的铪醇盐合成(EHS)基于铪溶解/乙醇脱氢的同时非均相反应以及溶液中Hf4+阳离子和烷氧阴离子的自发结合反应。为了阐明EHS过程的机制和动力学,通过电化学测试、扫描电镜、气相色谱和微观动力学模拟等手段,探究阳极铪溶解和阴极乙醇脱氢的电化学行为。结果表明,优选的支持电解质四乙基氯化铵(Et4NCl)展现了钝化膜击穿与铪溶解协同的剧烈点蚀机制以及两段脱氢机制。为量化钝化膜击穿和铪点蚀的动力学参数,提取与钝化速率、钝化膜击穿敏感性和点蚀速率相关的3个指标,并通过建立微观动力学模型评估基于Et4NCl体系的EHS工艺,其电能消耗为1.53~1.83 k W·h/kg Hf(OC_(2)H_(5))_(4)。展开更多
Nanocrystalline TiO 2 has been studied extensively in recent years as photocatalysts to deal with environmental pollutions, such as water purification, wastewater treatment and air purification. Here a novel sonochemi...Nanocrystalline TiO 2 has been studied extensively in recent years as photocatalysts to deal with environmental pollutions, such as water purification, wastewater treatment and air purification. Here a novel sonochemical method for directly preparing anatase nanocrystalline TiO 2 has been established. Nanocrystalline TiO 2 were synthesized by the hydrolysis of titanium tetrabutyl in the presence of water and ethanol under a high intensity ultrasonic irradiation(20 kHz, 100 W/cm 2) at 363 K for 3 h. The structure and particle sizes of the product were dependent upon the reaction temperature, the acidity of the medium and the reaction time. Characterization was accomplished by using various different techniques, such as powder X ray diffraction(XRD), transmission electron microscopy(TEM), thermogravimetry differential thermal analysis(TG DTA) and Fourier transform infrared(FTIR) spectroscopy. The TEM images showed that the particles of TiO 2 were columnar in shape and the average sizes were ca. 3 nm×7 nm . The formation mechanism of nanocrystalline TiO 2 under a high intensity ultrasonic irradiation was also investigated. The hydrolytic species of titanium tetrabutyl in water condensed to form a large number of tiny gel nuclei which aggregated to form larger clusters. Ultrasound irradiation generated a lot of local hot spots within the gel and the crystal structural unit was formed near the hot spots with the decrease of the gel nuclei, which lead to form nanocrystal particles.展开更多
The direct electrochemical synthesis of metal alkoxides [Ti（OEt）4, Ti（OPr-i）4, Ti（OBu）4, Ti（OEt）2（acac）, Cu（OEt）2, Cu（OBu）2, Mg（OEt）2 and Ni（OEt）2] were studied by anode dissolution of metals in abso...The direct electrochemical synthesis of metal alkoxides [Ti（OEt）4, Ti（OPr-i）4, Ti（OBu）4, Ti（OEt）2（acac）, Cu（OEt）2, Cu（OBu）2, Mg（OEt）2 and Ni（OEt）2] were studied by anode dissolution of metals in absolute ethanol in the presence of a conductive additives. The anodic behaviour of Ti electrode in ethanol was investigated by using cyclic voltammetry（CV）. These metal alkoxides were characterized by FTIR spectra. The results show that direct electrochemical synthesis of metal alkoxides have a high current efficiency and electrolysis yield. These alkoxides have a high purity and can be directly used as the precursor of nanosize oxides prepared by sol-gel procedure. The anodic behaviour of Ti electrode in alcohol is markedly the feature of the pitting corrosion. The passivation of Ti anode would occur in the presence of trace water.展开更多
The preparation of yttria-stabilised zirconia (YSZ) sol and the mechanismsof sol formation and sol-gel transition have been studied. The YSZ sol was prepared viacontrolled hydration of propanol zirconia alkoxide doped...The preparation of yttria-stabilised zirconia (YSZ) sol and the mechanismsof sol formation and sol-gel transition have been studied. The YSZ sol was prepared viacontrolled hydration of propanol zirconia alkoxide doped with yttrium nitrite. The sol formation process and gelling time are affected by many parameters such as water content,acetic acid content and the amount of propanol. The stability of the sol can be greatlyimproved by adding appropriate polymer.展开更多
基金Science and Technology Innovation Program of Hunan Province,China(No.2021RC2002)Yangfan Plan,China(No.2017YT05C107)。
文摘作为一种具有广泛应用前景的高效电合成技术,耦合电溶解的铪醇盐合成(EHS)基于铪溶解/乙醇脱氢的同时非均相反应以及溶液中Hf4+阳离子和烷氧阴离子的自发结合反应。为了阐明EHS过程的机制和动力学,通过电化学测试、扫描电镜、气相色谱和微观动力学模拟等手段,探究阳极铪溶解和阴极乙醇脱氢的电化学行为。结果表明,优选的支持电解质四乙基氯化铵(Et4NCl)展现了钝化膜击穿与铪溶解协同的剧烈点蚀机制以及两段脱氢机制。为量化钝化膜击穿和铪点蚀的动力学参数,提取与钝化速率、钝化膜击穿敏感性和点蚀速率相关的3个指标,并通过建立微观动力学模型评估基于Et4NCl体系的EHS工艺,其电能消耗为1.53~1.83 k W·h/kg Hf(OC_(2)H_(5))_(4)。
文摘Nanocrystalline TiO 2 has been studied extensively in recent years as photocatalysts to deal with environmental pollutions, such as water purification, wastewater treatment and air purification. Here a novel sonochemical method for directly preparing anatase nanocrystalline TiO 2 has been established. Nanocrystalline TiO 2 were synthesized by the hydrolysis of titanium tetrabutyl in the presence of water and ethanol under a high intensity ultrasonic irradiation(20 kHz, 100 W/cm 2) at 363 K for 3 h. The structure and particle sizes of the product were dependent upon the reaction temperature, the acidity of the medium and the reaction time. Characterization was accomplished by using various different techniques, such as powder X ray diffraction(XRD), transmission electron microscopy(TEM), thermogravimetry differential thermal analysis(TG DTA) and Fourier transform infrared(FTIR) spectroscopy. The TEM images showed that the particles of TiO 2 were columnar in shape and the average sizes were ca. 3 nm×7 nm . The formation mechanism of nanocrystalline TiO 2 under a high intensity ultrasonic irradiation was also investigated. The hydrolytic species of titanium tetrabutyl in water condensed to form a large number of tiny gel nuclei which aggregated to form larger clusters. Ultrasound irradiation generated a lot of local hot spots within the gel and the crystal structural unit was formed near the hot spots with the decrease of the gel nuclei, which lead to form nanocrystal particles.
文摘The direct electrochemical synthesis of metal alkoxides [Ti（OEt）4, Ti（OPr-i）4, Ti（OBu）4, Ti（OEt）2（acac）, Cu（OEt）2, Cu（OBu）2, Mg（OEt）2 and Ni（OEt）2] were studied by anode dissolution of metals in absolute ethanol in the presence of a conductive additives. The anodic behaviour of Ti electrode in ethanol was investigated by using cyclic voltammetry（CV）. These metal alkoxides were characterized by FTIR spectra. The results show that direct electrochemical synthesis of metal alkoxides have a high current efficiency and electrolysis yield. These alkoxides have a high purity and can be directly used as the precursor of nanosize oxides prepared by sol-gel procedure. The anodic behaviour of Ti electrode in alcohol is markedly the feature of the pitting corrosion. The passivation of Ti anode would occur in the presence of trace water.
文摘The preparation of yttria-stabilised zirconia (YSZ) sol and the mechanismsof sol formation and sol-gel transition have been studied. The YSZ sol was prepared viacontrolled hydration of propanol zirconia alkoxide doped with yttrium nitrite. The sol formation process and gelling time are affected by many parameters such as water content,acetic acid content and the amount of propanol. The stability of the sol can be greatlyimproved by adding appropriate polymer.
