The key to improve the performance of heteroatom catalysts is to ensure the orderliness of catalysts and the good dispersion of heteroatoms.The alkalinity plays the indispensable role in synthetic process of V-MCM-41 ...The key to improve the performance of heteroatom catalysts is to ensure the orderliness of catalysts and the good dispersion of heteroatoms.The alkalinity plays the indispensable role in synthetic process of V-MCM-41 catalyst.The excessive alkalinity of synthetic system will make the MCM-41 difficult to crystallize,even to dissolve.It is easy to accumulate for heteroatomic species in the system of low alkalinity.Herein,the highly ordered VMCM-41 with high vanadic content in framework is synthesized in the condition of excessive NH3·H2 O in this paper.A series of characterization results prove the good dispersion of vanadium species,and most of vanadium gets into the framework of MCM-41 with the states of tetravalence and pentavalence.Furthermore,the modified MCM-41 by other transition metals is successful synthesized by the method of V-MCM-41 in this paper.The VMCM-41 shows well catalytic activity for the selective oxidation of benzyl alcohol,which up to 74.83%for the conversion of benzyl alcohol and 96.20%for selectivity of benzaldehyde when initial V/Si=0.10.The paper provides the possibility for industrial application of V-MCM-41 in the oxidation of benzyl alcohol for benzaldehyde.Besides,the work provides a significant idea for the synthesis of modified MCM-41 by well-dispersed transition metals.展开更多
Epoxidation is an important chemical process for the production of epoxides,key building blocks in chemical industry.Despite great efforts being made to facilitate this process,it remains a significant challenge to de...Epoxidation is an important chemical process for the production of epoxides,key building blocks in chemical industry.Despite great efforts being made to facilitate this process,it remains a significant challenge to develop cost-effective,environmental-friendly,and selective catalysts.Herein,we reported a highly dispersed Mn supported by g-C_(3)N_(4)(Mn/g-C_(3)N_(4))with Mn loading up to 2.56 wt%.The Mn/g-CN_(4)exhibited satisfied catalytic performance for olefin epoxidation with excellent conversion(91%),high selectivity(93%)as well as outstanding recycling stability.Further analysis revealed the importance of Mn-N structure for the generation of active oxo-containing species and subsequent oxygen atom transfer.Besides,an efficient synthesis of cyclic carbonates from styrene epoxide and CO_(2)has been achieved(88%conversion,89%selectivity)based on the polar Mn-N coordinated characteristics of Mn/g-C_(3)N_(4)catalyst.展开更多
Although considerable research efforts have been devoted to the design and development of non-noble electrocatalysts for oxygen evolution reaction(OER), substantial enhancement of OER performance with commercial-scale...Although considerable research efforts have been devoted to the design and development of non-noble electrocatalysts for oxygen evolution reaction(OER), substantial enhancement of OER performance with commercial-scale water electrolysis remains a big challenge. This could result from the difficulties in detecting the intrinsic properties and overlooking the assembly process for electrochemical OER process. Here, we employ a microjet collision method to investigate the intrinsic OER activities of individual NiZnFeO_x entities with and without a moderate magnetic field. Our results demonstrate that single NiZnFeO_x nanoparticles(NPs) show the excellent OER performance with a lowest onset potential(~1.35 V vs. RHE) and a greatest magnetic enhancement(~118%) among bulk materials, single agglomerations and NPs. Furthermore, we explore the utility of theoretical investigation by density functional theory(DFT)calculations for studying OER process on NiZnFeO_x surfaces without and with spin alignment, indicating monodispersed NiZnFeO_xNPs with totally spin alignment facilitates the OER process under the external magnetic field. It is found that the well-dispersion of NiZnFeO_x NPs would increase the electrical conductivity and the surface spin state, resulting in promoting their OER activities. This work provides a test for uncovering the essential roles of NPs assembly to a significant promotion of their magnet-assisted OER.展开更多
Reduced graphene oxide(rGO)-based fibers with high electrochemical performance have recently showed great potential in the field of flexible energy storage devices.However,they still suffer from low capacitance due to...Reduced graphene oxide(rGO)-based fibers with high electrochemical performance have recently showed great potential in the field of flexible energy storage devices.However,they still suffer from low capacitance due to the severe stacking of graphene sheets.Hybrids with nanofillers are an efficient way to improve the electrochemical performance of rGO fibers.Nevertheless,controlling the distribution of nanoparticles in the matrix is still an enormous challenge due to the strong attraction among these nanoparticles which results into agglomeration.Here,we continually prepared rGO hybrid fibers via nonliquid-crystal spinning,accompanied by chemical reduction.Manganic oxide(Mn OX)nanoparticles remained well-dispersed in GO dispersion during the continuous spinning of rGO/Mn OXhybrid fibers.Results showed that rGO/Mn OX-20 hybrid fibers possessed the best capacitance of 123.3 F g^(-1)(87.6 F cm^(-3))and 97.1 F g^(-1)(68.9 F cm^(-3))at the current density of 0.2 A g^(-1),and 0.5 A g^(-1)respectively.Furthermore,a fiber-shaped all-solid-state supercapacitor assembly from the optimized hybrid fibers demonstrated an energy density of 2.67 m Wh cm^(-3)(3.76 m Wh g^(-1))at the power density of 24.76 m Wh cm^(-3)(34.89 m Wh g^(-1)).These fiber-based devices show great potential for application in the fields of wearable electronics and energy storage devices.展开更多
Ti O2 nanowire(NW) is one of the potential scattering layer materials in dye-sensitized solar cells(DSSCs) owing to its fast electron conductivity and excellent light scattering property resulting from its one-dimensi...Ti O2 nanowire(NW) is one of the potential scattering layer materials in dye-sensitized solar cells(DSSCs) owing to its fast electron conductivity and excellent light scattering property resulting from its one-dimensional(1D) morphology. However, Ti O2 NWs used as scattering layers in previous work were either aggregated or shortened into shuttles that cannot use their unique 1D properties. In this paper, we present the preparation of a well-dispersed long NW paste(exceeding 1 ?m) by a mild method and used as a scattering layer in DSSC. The paste achieved a photoconversion efficiency of 5.73% and an efficiency enhancement of 12% compared with commercial scattering layer(P200 paste). Compared with the DSSC without a scattering layer, an efficiency enhancement of 54.9% was achieved. Also, the largest efficiency of 6.89% was obtained after optimization of photoanode thickness. The photoanodes were investigated through dye desorbed experiments and transmission spectra, which suggested that P25 nanoparticles with the as-prepared NW scattering layer loaded more dye than those with P200 paste. These results indicate that well-dispersed long NW paste has a potential application in scattering layers.展开更多
基金partially supported by the National Natural Science Foundation of China(Grant Nos.21601026,21771030)Fundamental Research Funds for the Central Universities(DUT16RC(4)10,DUT18RC(6)008)。
文摘The key to improve the performance of heteroatom catalysts is to ensure the orderliness of catalysts and the good dispersion of heteroatoms.The alkalinity plays the indispensable role in synthetic process of V-MCM-41 catalyst.The excessive alkalinity of synthetic system will make the MCM-41 difficult to crystallize,even to dissolve.It is easy to accumulate for heteroatomic species in the system of low alkalinity.Herein,the highly ordered VMCM-41 with high vanadic content in framework is synthesized in the condition of excessive NH3·H2 O in this paper.A series of characterization results prove the good dispersion of vanadium species,and most of vanadium gets into the framework of MCM-41 with the states of tetravalence and pentavalence.Furthermore,the modified MCM-41 by other transition metals is successful synthesized by the method of V-MCM-41 in this paper.The VMCM-41 shows well catalytic activity for the selective oxidation of benzyl alcohol,which up to 74.83%for the conversion of benzyl alcohol and 96.20%for selectivity of benzaldehyde when initial V/Si=0.10.The paper provides the possibility for industrial application of V-MCM-41 in the oxidation of benzyl alcohol for benzaldehyde.Besides,the work provides a significant idea for the synthesis of modified MCM-41 by well-dispersed transition metals.
基金financial supports from the National Natural Science Foundation of China(Nos.216330133and 22102197)Jiangsu Province Natural Science Foundation(No.BK20211096)the Science Fund of Shandong Laboratory of Advanced Materials and Green Manufacturing(Yantai,No.AMGM2021F07).
文摘Epoxidation is an important chemical process for the production of epoxides,key building blocks in chemical industry.Despite great efforts being made to facilitate this process,it remains a significant challenge to develop cost-effective,environmental-friendly,and selective catalysts.Herein,we reported a highly dispersed Mn supported by g-C_(3)N_(4)(Mn/g-C_(3)N_(4))with Mn loading up to 2.56 wt%.The Mn/g-CN_(4)exhibited satisfied catalytic performance for olefin epoxidation with excellent conversion(91%),high selectivity(93%)as well as outstanding recycling stability.Further analysis revealed the importance of Mn-N structure for the generation of active oxo-containing species and subsequent oxygen atom transfer.Besides,an efficient synthesis of cyclic carbonates from styrene epoxide and CO_(2)has been achieved(88%conversion,89%selectivity)based on the polar Mn-N coordinated characteristics of Mn/g-C_(3)N_(4)catalyst.
基金supported by the Major Research Project (No.92061108)the National Natural Science Foundation of China (No.22272052)+2 种基金Shanghai Municipal Science and Technology Major Project (No.2018SHZDZX03)Xiamen University Opening Project of PCOSS (No.201901)Yongjiang Talent Introduction Programme(No.2021A-115-G)。
文摘Although considerable research efforts have been devoted to the design and development of non-noble electrocatalysts for oxygen evolution reaction(OER), substantial enhancement of OER performance with commercial-scale water electrolysis remains a big challenge. This could result from the difficulties in detecting the intrinsic properties and overlooking the assembly process for electrochemical OER process. Here, we employ a microjet collision method to investigate the intrinsic OER activities of individual NiZnFeO_x entities with and without a moderate magnetic field. Our results demonstrate that single NiZnFeO_x nanoparticles(NPs) show the excellent OER performance with a lowest onset potential(~1.35 V vs. RHE) and a greatest magnetic enhancement(~118%) among bulk materials, single agglomerations and NPs. Furthermore, we explore the utility of theoretical investigation by density functional theory(DFT)calculations for studying OER process on NiZnFeO_x surfaces without and with spin alignment, indicating monodispersed NiZnFeO_xNPs with totally spin alignment facilitates the OER process under the external magnetic field. It is found that the well-dispersion of NiZnFeO_x NPs would increase the electrical conductivity and the surface spin state, resulting in promoting their OER activities. This work provides a test for uncovering the essential roles of NPs assembly to a significant promotion of their magnet-assisted OER.
基金supported by the Fundamental Research Funds for the Central Universities(2232021D-05)the National Natural Science Foundation of China(Nos.51733002,51803022,51673038)+6 种基金the Science and Technology Commission of Shanghai Municipality(20JC1414900,20JC1414901)National Key Research and Development Program of China(2016YFA0201702/2016YFA0201700)Program for Changjiang Scholars and Innovative Research Team in University(IRT16R13)Science and Technology Commission of Shanghai Municipality(16JC1400700)Innovation Program of Shanghai Municipal Education Commission(2017–01–07–00–03E00055)supported by the Fundamental Research Funds for the Central UniversitiesGraduate Student Innovation Fund of Donghua University(CUSF-DH-D-2020038)。
文摘Reduced graphene oxide(rGO)-based fibers with high electrochemical performance have recently showed great potential in the field of flexible energy storage devices.However,they still suffer from low capacitance due to the severe stacking of graphene sheets.Hybrids with nanofillers are an efficient way to improve the electrochemical performance of rGO fibers.Nevertheless,controlling the distribution of nanoparticles in the matrix is still an enormous challenge due to the strong attraction among these nanoparticles which results into agglomeration.Here,we continually prepared rGO hybrid fibers via nonliquid-crystal spinning,accompanied by chemical reduction.Manganic oxide(Mn OX)nanoparticles remained well-dispersed in GO dispersion during the continuous spinning of rGO/Mn OXhybrid fibers.Results showed that rGO/Mn OX-20 hybrid fibers possessed the best capacitance of 123.3 F g^(-1)(87.6 F cm^(-3))and 97.1 F g^(-1)(68.9 F cm^(-3))at the current density of 0.2 A g^(-1),and 0.5 A g^(-1)respectively.Furthermore,a fiber-shaped all-solid-state supercapacitor assembly from the optimized hybrid fibers demonstrated an energy density of 2.67 m Wh cm^(-3)(3.76 m Wh g^(-1))at the power density of 24.76 m Wh cm^(-3)(34.89 m Wh g^(-1)).These fiber-based devices show great potential for application in the fields of wearable electronics and energy storage devices.
基金supported by the National Basic Research Program of China(2011CB933002,2012CB932702)the National Natural Science Foundation of China(61306079,60871002)
文摘Ti O2 nanowire(NW) is one of the potential scattering layer materials in dye-sensitized solar cells(DSSCs) owing to its fast electron conductivity and excellent light scattering property resulting from its one-dimensional(1D) morphology. However, Ti O2 NWs used as scattering layers in previous work were either aggregated or shortened into shuttles that cannot use their unique 1D properties. In this paper, we present the preparation of a well-dispersed long NW paste(exceeding 1 ?m) by a mild method and used as a scattering layer in DSSC. The paste achieved a photoconversion efficiency of 5.73% and an efficiency enhancement of 12% compared with commercial scattering layer(P200 paste). Compared with the DSSC without a scattering layer, an efficiency enhancement of 54.9% was achieved. Also, the largest efficiency of 6.89% was obtained after optimization of photoanode thickness. The photoanodes were investigated through dye desorbed experiments and transmission spectra, which suggested that P25 nanoparticles with the as-prepared NW scattering layer loaded more dye than those with P200 paste. These results indicate that well-dispersed long NW paste has a potential application in scattering layers.
