在自然界中,甲壳素一般以有序的结晶纳米纤维形式存在,赋予了生物体优异的力学性能。本研究分别采用“常温温和”(常温,Mild condition)和“高温加热”(高温,High temperature condition)两种方法从废弃蟹壳中提取α-甲壳素并制得常温α...在自然界中,甲壳素一般以有序的结晶纳米纤维形式存在,赋予了生物体优异的力学性能。本研究分别采用“常温温和”(常温,Mild condition)和“高温加热”(高温,High temperature condition)两种方法从废弃蟹壳中提取α-甲壳素并制得常温α-甲壳素纳米纤维膜(常温膜)和高温α-甲壳素纳米纤维膜(高温膜),分别对所得两种α-甲壳素纳米纤维样品从微观结构、力学性能、结晶构造、表面特性以及光学性能等方面进行表征,分析对比两种不同提取方法对甲壳素纤维结构及性能的影响,并进一步探究提取制备过程中甲壳素的纤维形态及均匀性对其薄膜力学性能、光学透明性的影响。结果表明,与“高温”提取条件相比,经“常温”条件提取所得α-甲壳素纳米纤维具有较高的长径比且尺寸分布均匀,较好地保留了甲壳素原有的天然结构。其中,常温膜的拉伸强度可达(152±2.56) MPa,断裂伸长率约为10.0%,是高温膜的2.50倍左右,具有较好的柔韧性。同时,常温膜还具备优异的光学及热稳定性能,透光率高达91.0%,雾度低至3.19%,在200℃高温条件下仍能保持性状稳定。综上,“常温”条件下提取的甲壳素纳米纤维由于较好地保留了其天然结构优势,使得制备所得膜材料具备优异的力学强度及透光性等。本工作的研究成果为制备全生物质高强度、低雾度柔性透明膜材料提供了理论依据和技术支持,有望作为柔性透明基材应用于柔性电子元件、电子皮肤、智能标签及柔性传感等研究领域。展开更多
C MAS NMR has been performed in situ to investigate the activation of 13C labeled propane under a mild condition over Ga-modified H-ZSM-5 catalysts prepared via different methods. The results indicate that the ion-exc...C MAS NMR has been performed in situ to investigate the activation of 13C labeled propane under a mild condition over Ga-modified H-ZSM-5 catalysts prepared via different methods. The results indicate that the ion-exchanged and/or its related Ga species are the highly active catalytic components, while impregnated Ga species is not the active species for propane activation at 573 K.展开更多
半导体光催化剂是一种极具前景的绿色催化剂,广泛用于污染物降解、水解制氢和有机合成等领域,有望利用太阳能来解决能源和环境问题,是当前的研究前沿和热点.然而,单组分半导体光催化剂的光生电子和空穴容易复合,导致量子效率差和光催化...半导体光催化剂是一种极具前景的绿色催化剂,广泛用于污染物降解、水解制氢和有机合成等领域,有望利用太阳能来解决能源和环境问题,是当前的研究前沿和热点.然而,单组分半导体光催化剂的光生电子和空穴容易复合,导致量子效率差和光催化效率低.近年人们发现,将两种或多种催化材料结合,构建异质结光催化体系可有效促进光生电子-空穴分离.但传统的异质结体系中光生电子的还原性和光生空穴的氧化性通常在电荷转移后变弱,因此,很难同时具备高电荷转移效率和强氧化还原能力.研究发现,构建Z型异质结光催化体系不仅可以减少本体电子-空穴的复合,使其在不同半导体材料上实现空间分离,具有光谱响应宽、电荷分离效率高和稳定性高等优势,而且能保持良好的氧化还原能力.在半导体材料领域,石墨相氮化碳(g-C_(3)N_(4))作为一种无金属聚合物半导体,具有良好的热化学稳定性、电学和光学特性,但存在量子效率低和适用范围窄等局限性.而五氧化二钒(V_(2)O_(5))是一种重要的过渡金属氧化物半导体,由于具有良好的电学和光学性能被广泛用于锂离子电池、气敏传感器和光电器件.V_(2)O_(5)能带间隙(~2.19 e V)窄,具有合适的能量频带边缘(ECB=0.81 e V,EVB=3.0 e V),可以与g-C_(3)N_(4)(ECB=1.14 e V,EVB=1.59 e V)很好地匹配,形成稳定状态的Z型光催化体系,并提高光催化有机合成反应的效率.本文以三聚氰胺和偏钒酸铵为原料,采用热处理法分别制备g-C_(3)N_(4)和V_(2)O_(5),采用水热法制备Z型V_(2)O_(5)/g-C_(3)N_(4)二元复合材料.X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)和紫外-可见光吸收光谱(UV-Vis)等结果表明,成功制备了Z型V_(2)O_(5)/g-C_(3)N_(4).UV-Vis结果表明,V_(2)O_(5)/g-C_(3)N_(4)具有较宽的光吸收范围,从而提高了复合半导体材料的光学性能.展开更多
Separation of products from ionic liquid(IL) solvents is one of the main challenges that hinder their utilizations. In this study, the production of γ-valerolactone(GVL) by selective hydrogenation of α-angelica lact...Separation of products from ionic liquid(IL) solvents is one of the main challenges that hinder their utilizations. In this study, the production of γ-valerolactone(GVL) by selective hydrogenation of α-angelica lactone(AL) and separation of the products from the IL solvent were carried out by using subcritical CO_2 as a "switch" at room temperature. After the mixture was separated into two phases by subcritical CO_2, AL and nano Pd/C catalyst were only found in the lower IL-rich phase, GVL was produced with quantitative yield and enriched in the upper methanolrich phase. Pure GVL can be obtained by depressurizing to release CO_2 and evaporation to remove methanol of the upper phase, the lower phase containing IL, catalyst and methanol can be recycled for the next reaction. The strategy may provide a new approach to produce and separate products from IL solvents at mild conditions.展开更多
A novel electrochemical procedure for the synthesis of ethyl carbanilate from aniline and carbon dioxide was developed via the selective cathodic reduction of carbon dioxide in CO2-saturated DMF solution containing 0....A novel electrochemical procedure for the synthesis of ethyl carbanilate from aniline and carbon dioxide was developed via the selective cathodic reduction of carbon dioxide in CO2-saturated DMF solution containing 0. 1 mol/L TEABr at room temperature, followed by the addition of Eft as an alkylating agent. The synthesis was carried outun der mild[p（CO2） = 1.0×10^5 Pa, t =20 ℃ ] and safe conditions. Influences of the nature of the electrodes, the current densities, the passed charges during electrolysis, temperatures, and supporting electrolytes on the yield of ethyl carbanilate were studied to optimize the electrolytic conditions. The selectivity of ethyl carbanilate is 100%.展开更多
A new method for the synthesis of 3-thioazaspiro[4,5]trienones was developed using Pd nanoparticle catalysts,which are highly efficient,environmentally friendly and recyclable.Alkynes and thiophene phenols are effecti...A new method for the synthesis of 3-thioazaspiro[4,5]trienones was developed using Pd nanoparticle catalysts,which are highly efficient,environmentally friendly and recyclable.Alkynes and thiophene phenols are effectively cyclized by Pd/ZrO2 catalyst under visible light irradiation.The present protocol simply utilizes visible light as the safe and ecofriendly energy source,and the Pd/ZrO2 nanocomposite as photocatalyst provides a simple and practical approach to various 3-thioazaspiro[4,5]trienones in moderate conditions to high yields.展开更多
A simple, mild and green approach has been developed for the synthesis of asymmetrical heterobiaryls under the irradiation of visible light without any oxidants and promoting reagents through using Pd/Ce O2 nanocompos...A simple, mild and green approach has been developed for the synthesis of asymmetrical heterobiaryls under the irradiation of visible light without any oxidants and promoting reagents through using Pd/Ce O2 nanocomposite photocatalyst. This method can tolerate considerable functional groups such as electrondonating groups and electron-withdrawing groups through CààC cross-coupling. Moreover, we obtain the products with moderate yields in an efficient way. Finally, a plausible mechanism is proposed.展开更多
文摘在自然界中,甲壳素一般以有序的结晶纳米纤维形式存在,赋予了生物体优异的力学性能。本研究分别采用“常温温和”(常温,Mild condition)和“高温加热”(高温,High temperature condition)两种方法从废弃蟹壳中提取α-甲壳素并制得常温α-甲壳素纳米纤维膜(常温膜)和高温α-甲壳素纳米纤维膜(高温膜),分别对所得两种α-甲壳素纳米纤维样品从微观结构、力学性能、结晶构造、表面特性以及光学性能等方面进行表征,分析对比两种不同提取方法对甲壳素纤维结构及性能的影响,并进一步探究提取制备过程中甲壳素的纤维形态及均匀性对其薄膜力学性能、光学透明性的影响。结果表明,与“高温”提取条件相比,经“常温”条件提取所得α-甲壳素纳米纤维具有较高的长径比且尺寸分布均匀,较好地保留了甲壳素原有的天然结构。其中,常温膜的拉伸强度可达(152±2.56) MPa,断裂伸长率约为10.0%,是高温膜的2.50倍左右,具有较好的柔韧性。同时,常温膜还具备优异的光学及热稳定性能,透光率高达91.0%,雾度低至3.19%,在200℃高温条件下仍能保持性状稳定。综上,“常温”条件下提取的甲壳素纳米纤维由于较好地保留了其天然结构优势,使得制备所得膜材料具备优异的力学强度及透光性等。本工作的研究成果为制备全生物质高强度、低雾度柔性透明膜材料提供了理论依据和技术支持,有望作为柔性透明基材应用于柔性电子元件、电子皮肤、智能标签及柔性传感等研究领域。
文摘C MAS NMR has been performed in situ to investigate the activation of 13C labeled propane under a mild condition over Ga-modified H-ZSM-5 catalysts prepared via different methods. The results indicate that the ion-exchanged and/or its related Ga species are the highly active catalytic components, while impregnated Ga species is not the active species for propane activation at 573 K.
文摘半导体光催化剂是一种极具前景的绿色催化剂,广泛用于污染物降解、水解制氢和有机合成等领域,有望利用太阳能来解决能源和环境问题,是当前的研究前沿和热点.然而,单组分半导体光催化剂的光生电子和空穴容易复合,导致量子效率差和光催化效率低.近年人们发现,将两种或多种催化材料结合,构建异质结光催化体系可有效促进光生电子-空穴分离.但传统的异质结体系中光生电子的还原性和光生空穴的氧化性通常在电荷转移后变弱,因此,很难同时具备高电荷转移效率和强氧化还原能力.研究发现,构建Z型异质结光催化体系不仅可以减少本体电子-空穴的复合,使其在不同半导体材料上实现空间分离,具有光谱响应宽、电荷分离效率高和稳定性高等优势,而且能保持良好的氧化还原能力.在半导体材料领域,石墨相氮化碳(g-C_(3)N_(4))作为一种无金属聚合物半导体,具有良好的热化学稳定性、电学和光学特性,但存在量子效率低和适用范围窄等局限性.而五氧化二钒(V_(2)O_(5))是一种重要的过渡金属氧化物半导体,由于具有良好的电学和光学性能被广泛用于锂离子电池、气敏传感器和光电器件.V_(2)O_(5)能带间隙(~2.19 e V)窄,具有合适的能量频带边缘(ECB=0.81 e V,EVB=3.0 e V),可以与g-C_(3)N_(4)(ECB=1.14 e V,EVB=1.59 e V)很好地匹配,形成稳定状态的Z型光催化体系,并提高光催化有机合成反应的效率.本文以三聚氰胺和偏钒酸铵为原料,采用热处理法分别制备g-C_(3)N_(4)和V_(2)O_(5),采用水热法制备Z型V_(2)O_(5)/g-C_(3)N_(4)二元复合材料.X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)和紫外-可见光吸收光谱(UV-Vis)等结果表明,成功制备了Z型V_(2)O_(5)/g-C_(3)N_(4).UV-Vis结果表明,V_(2)O_(5)/g-C_(3)N_(4)具有较宽的光吸收范围,从而提高了复合半导体材料的光学性能.
基金supported by International S&T Cooperation Program of China(2014DFA61670)External Cooperation Program of BIC,Chinese Academy of Sciences(GJHZ201306)National Natural Science Foundation of China(No.21276260,21576269,21476245,21406230)
文摘Separation of products from ionic liquid(IL) solvents is one of the main challenges that hinder their utilizations. In this study, the production of γ-valerolactone(GVL) by selective hydrogenation of α-angelica lactone(AL) and separation of the products from the IL solvent were carried out by using subcritical CO_2 as a "switch" at room temperature. After the mixture was separated into two phases by subcritical CO_2, AL and nano Pd/C catalyst were only found in the lower IL-rich phase, GVL was produced with quantitative yield and enriched in the upper methanolrich phase. Pure GVL can be obtained by depressurizing to release CO_2 and evaporation to remove methanol of the upper phase, the lower phase containing IL, catalyst and methanol can be recycled for the next reaction. The strategy may provide a new approach to produce and separate products from IL solvents at mild conditions.
基金Supported by the National Natural Science Foundation of China(No.20573037)the Natural Science Foundation of Shang-hai,China(No.05JC1470).
文摘A novel electrochemical procedure for the synthesis of ethyl carbanilate from aniline and carbon dioxide was developed via the selective cathodic reduction of carbon dioxide in CO2-saturated DMF solution containing 0. 1 mol/L TEABr at room temperature, followed by the addition of Eft as an alkylating agent. The synthesis was carried outun der mild[p（CO2） = 1.0×10^5 Pa, t =20 ℃ ] and safe conditions. Influences of the nature of the electrodes, the current densities, the passed charges during electrolysis, temperatures, and supporting electrolytes on the yield of ethyl carbanilate were studied to optimize the electrolytic conditions. The selectivity of ethyl carbanilate is 100%.
基金financial support from Jiangsu Planned Projects for Postdoctoral Research Funds(No.2018K293C)。
文摘A new method for the synthesis of 3-thioazaspiro[4,5]trienones was developed using Pd nanoparticle catalysts,which are highly efficient,environmentally friendly and recyclable.Alkynes and thiophene phenols are effectively cyclized by Pd/ZrO2 catalyst under visible light irradiation.The present protocol simply utilizes visible light as the safe and ecofriendly energy source,and the Pd/ZrO2 nanocomposite as photocatalyst provides a simple and practical approach to various 3-thioazaspiro[4,5]trienones in moderate conditions to high yields.
文摘A simple, mild and green approach has been developed for the synthesis of asymmetrical heterobiaryls under the irradiation of visible light without any oxidants and promoting reagents through using Pd/Ce O2 nanocomposite photocatalyst. This method can tolerate considerable functional groups such as electrondonating groups and electron-withdrawing groups through CààC cross-coupling. Moreover, we obtain the products with moderate yields in an efficient way. Finally, a plausible mechanism is proposed.
