The state-of-the-art approaches for adjusting the structural characteristics of porous carbons are the aftertreatments, which are complicated and time consuming. In this work, a facile approach was developed, i.e., co...The state-of-the-art approaches for adjusting the structural characteristics of porous carbons are the aftertreatments, which are complicated and time consuming. In this work, a facile approach was developed, i.e., controlling the initial oxygen concentration in-situ during the direct carbonization of zeolitic imidazole framework-8(ZIF-8), to adjust the pore structure and prepare hierarchically porous carbons. The introduction of oxygen can significantly affect the crystalline and pore structures of porous carbons, and promote the pore widening and the formation of mesopores. An appropriate initial oxygen concentration can notably enhance the surface area and mesopore volume of porous carbon, and then improve the adsorption capacity toward methylene blue(MB) dye from water by 3.4 times. The developed approach is more efficient at lower carbonization temperature.Moreover, the introduction of oxygen can increase the ratio of HO\\C_O groups on the carbon surface, leading to enhanced interaction with MB molecules and higher adsorption capacity toward MB. The as-prepared porous carbons exhibit superior adsorption capacities toward MB dye as compared to the reported ZIF-8 derived carbons. These findings would aid the development of porous carbon materials with high performance.展开更多
The conversion of CO_(2) electrocatalytic hydrogenation into energy-rich fuel is considered to be the most effective way to carbon recycle.Nitrogen-doping carbonized ZIF-8 is proposed as carrier of the earth-rich Sn c...The conversion of CO_(2) electrocatalytic hydrogenation into energy-rich fuel is considered to be the most effective way to carbon recycle.Nitrogen-doping carbonized ZIF-8 is proposed as carrier of the earth-rich Sn catalyst to overcome the limit of electron transfer and CO_(2) adsorption capacity of Sn.Hierarchically porous structure of Sn doped carbonized ZIF-8 is controlled by hydrothermal and carbonization conditions,which induces much higher specific surface area than that of the commercial Sn nanoparticle(1003.174 vs.7.410 m^(2)·g^(-1)).The shift of nitrogen peaks in X-ray Photoelectron Spectroscopy spectra indicates interaction between ZIF-8 and Sn,which induces the shift of electron cloud from Sn to the chemical nitrogen to enhance conductivity and regulate electron transfer from catalyst to CO_(2).Lower mass transfer resistance and Warburg resistance are investigated through EIS,which significantly improves the catalytic activity for CO_(2) reduction reaction(CO_(2)RR).Onset potential of the reaction is reduced from-0.74 V to less than-0.54 V vs.RHE.The total Faraday efficiency of HCOOH and CO reaches 68.9%at-1.14 V vs.RHE,which is much higher than that of the commercial Sn(45.0%)and some other Sn-based catalyst reported in the literature.展开更多
Ring-opening polymerization of trimethylene carbonate (TMC) with a rare earth calixarene compound as catalyst has been studied for the first time. The effect of TMC/Nd (molar ratio) and polymerization conditions were ...Ring-opening polymerization of trimethylene carbonate (TMC) with a rare earth calixarene compound as catalyst has been studied for the first time. The effect of TMC/Nd (molar ratio) and polymerization conditions were investigated in detail. It was found that calix[8]arene-neodymium is a highly effective catalyst for the bulk polymerization of TMC and gives high molecular weight (M-v = 60,000) polymer. The optimum conditions of TMC polymerization were found to be as follows:TMC/Nd (molar ratio) = 2,000, 80 degrees C, 16 h. The polymers were characterized by NMR, GPC and DSC. Studying the mechanism by NMR showed that the polymerization of TMC catalyzed by calix[8]arene-neodymium proceeds via a cationic mechanism.展开更多
Bis(8-quinolinolato)zirconium dichloride (Ox)2ZrCl2 (Ox- = 8-quinolinolato) was found active for ethylene oligomerization with a high selectivity of 84~94% to C4~C10 olefins at 70~100C under the pressure of 1.8 MPa us...Bis(8-quinolinolato)zirconium dichloride (Ox)2ZrCl2 (Ox- = 8-quinolinolato) was found active for ethylene oligomerization with a high selectivity of 84~94% to C4~C10 olefins at 70~100C under the pressure of 1.8 MPa using Et2AlCl as a co-catalyst (Al/Zr = 60).展开更多
得益于较高的理论能量密度、环境友好性和丰富的海水储量,海水基锌-空气电池(S-ZABs)被认为是一种极具应用前景的储能和能源转换装置,是解决能源短缺和环境污染问题的能源装置之一。然而对于S-ZABs而言,构筑在海水中具有高耐氯离子腐蚀...得益于较高的理论能量密度、环境友好性和丰富的海水储量,海水基锌-空气电池(S-ZABs)被认为是一种极具应用前景的储能和能源转换装置,是解决能源短缺和环境污染问题的能源装置之一。然而对于S-ZABs而言,构筑在海水中具有高耐氯离子腐蚀性与高性能的阴极氧还原反应电催化剂仍然具有挑战性。因此,我们通过高温硒化策略,在氮掺杂介孔碳材料上设计了超薄碳铠甲层封装的Co_(9)Se_(8)纳米颗粒高效ORR电催化剂(命名为NMC-Co_(9)Se_(8))。外部的超薄碳铠甲层不仅可以改善催化过程中的电子转移过程,抑制纳米颗粒的团聚,而且可以作为盔甲保护内部活性位点免受Cl^(-)吸附和腐蚀。得益于这种独特的结构,NMC-Co_(9)Se_(8)在0.1 mol·L^(-1)KOH海水电解质中表现出优异的ORR性能,其起始电位为0.904V,半波电位为0.860 V。更重要的是,基于NMC-Co_(9)Se_(8)催化剂的S-ZABs可提供172.4 m W·cm^(-2)的功率密度和超过150h的优异长期放电稳定性,均高于基于Pt/C的S-ZABs性能。这项工作为开发用于海水基锌-空气电池和其他能源转换技术具有耐氯离子腐蚀且高效的ORR催化剂提供了新思路。展开更多
基金Supported by the National Key R&D Program of China(2016YFB0301503)the National Natural Science Foundation of China(91534110,21776127)+1 种基金the Jiangsu Province Natural Science Foundation for Distinguished Young Scholars(BK20150044)the Jiangsu Province Natural Science Foundation(BK20160978)
文摘The state-of-the-art approaches for adjusting the structural characteristics of porous carbons are the aftertreatments, which are complicated and time consuming. In this work, a facile approach was developed, i.e., controlling the initial oxygen concentration in-situ during the direct carbonization of zeolitic imidazole framework-8(ZIF-8), to adjust the pore structure and prepare hierarchically porous carbons. The introduction of oxygen can significantly affect the crystalline and pore structures of porous carbons, and promote the pore widening and the formation of mesopores. An appropriate initial oxygen concentration can notably enhance the surface area and mesopore volume of porous carbon, and then improve the adsorption capacity toward methylene blue(MB) dye from water by 3.4 times. The developed approach is more efficient at lower carbonization temperature.Moreover, the introduction of oxygen can increase the ratio of HO\\C_O groups on the carbon surface, leading to enhanced interaction with MB molecules and higher adsorption capacity toward MB. The as-prepared porous carbons exhibit superior adsorption capacities toward MB dye as compared to the reported ZIF-8 derived carbons. These findings would aid the development of porous carbon materials with high performance.
基金the National Natural Science Foundation of China(Joint Fund U1663223 and 21776034)Science Fund for Creative Research Groups of the National Natural Science Foundation of China(22021005)+3 种基金the National Key Research and Development Program of China(2016YFB0101203)Educational Department of Liaoning Province of China(LT2015007)Fundamental Research Funds for the Central Universities(DUT16TD19)the Changjiang Scholar Program(T2012049).
文摘The conversion of CO_(2) electrocatalytic hydrogenation into energy-rich fuel is considered to be the most effective way to carbon recycle.Nitrogen-doping carbonized ZIF-8 is proposed as carrier of the earth-rich Sn catalyst to overcome the limit of electron transfer and CO_(2) adsorption capacity of Sn.Hierarchically porous structure of Sn doped carbonized ZIF-8 is controlled by hydrothermal and carbonization conditions,which induces much higher specific surface area than that of the commercial Sn nanoparticle(1003.174 vs.7.410 m^(2)·g^(-1)).The shift of nitrogen peaks in X-ray Photoelectron Spectroscopy spectra indicates interaction between ZIF-8 and Sn,which induces the shift of electron cloud from Sn to the chemical nitrogen to enhance conductivity and regulate electron transfer from catalyst to CO_(2).Lower mass transfer resistance and Warburg resistance are investigated through EIS,which significantly improves the catalytic activity for CO_(2) reduction reaction(CO_(2)RR).Onset potential of the reaction is reduced from-0.74 V to less than-0.54 V vs.RHE.The total Faraday efficiency of HCOOH and CO reaches 68.9%at-1.14 V vs.RHE,which is much higher than that of the commercial Sn(45.0%)and some other Sn-based catalyst reported in the literature.
基金This work was supported by the National Natural Science Foundation of China (No. 29674027, No. 29844002), the Ministry of National Education (G98402) and Organometallic Laboratory of Institute of Organic Chemistry of Chinese Academy of Sciences.
文摘Ring-opening polymerization of trimethylene carbonate (TMC) with a rare earth calixarene compound as catalyst has been studied for the first time. The effect of TMC/Nd (molar ratio) and polymerization conditions were investigated in detail. It was found that calix[8]arene-neodymium is a highly effective catalyst for the bulk polymerization of TMC and gives high molecular weight (M-v = 60,000) polymer. The optimum conditions of TMC polymerization were found to be as follows:TMC/Nd (molar ratio) = 2,000, 80 degrees C, 16 h. The polymers were characterized by NMR, GPC and DSC. Studying the mechanism by NMR showed that the polymerization of TMC catalyzed by calix[8]arene-neodymium proceeds via a cationic mechanism.
基金We are gratefully acknowledge the National Natural Science Foundation of China(Grant no.20173006)for financial support of this research
文摘Bis(8-quinolinolato)zirconium dichloride (Ox)2ZrCl2 (Ox- = 8-quinolinolato) was found active for ethylene oligomerization with a high selectivity of 84~94% to C4~C10 olefins at 70~100C under the pressure of 1.8 MPa using Et2AlCl as a co-catalyst (Al/Zr = 60).
文摘得益于较高的理论能量密度、环境友好性和丰富的海水储量,海水基锌-空气电池(S-ZABs)被认为是一种极具应用前景的储能和能源转换装置,是解决能源短缺和环境污染问题的能源装置之一。然而对于S-ZABs而言,构筑在海水中具有高耐氯离子腐蚀性与高性能的阴极氧还原反应电催化剂仍然具有挑战性。因此,我们通过高温硒化策略,在氮掺杂介孔碳材料上设计了超薄碳铠甲层封装的Co_(9)Se_(8)纳米颗粒高效ORR电催化剂(命名为NMC-Co_(9)Se_(8))。外部的超薄碳铠甲层不仅可以改善催化过程中的电子转移过程,抑制纳米颗粒的团聚,而且可以作为盔甲保护内部活性位点免受Cl^(-)吸附和腐蚀。得益于这种独特的结构,NMC-Co_(9)Se_(8)在0.1 mol·L^(-1)KOH海水电解质中表现出优异的ORR性能,其起始电位为0.904V,半波电位为0.860 V。更重要的是,基于NMC-Co_(9)Se_(8)催化剂的S-ZABs可提供172.4 m W·cm^(-2)的功率密度和超过150h的优异长期放电稳定性,均高于基于Pt/C的S-ZABs性能。这项工作为开发用于海水基锌-空气电池和其他能源转换技术具有耐氯离子腐蚀且高效的ORR催化剂提供了新思路。
