Dedicating to the exploration of efficient electromagnetic(EM)absorption and electromagnetic interference(EMI)shielding materials is the main strategy to solve the EM radiation issues.The development of multifunction ...Dedicating to the exploration of efficient electromagnetic(EM)absorption and electromagnetic interference(EMI)shielding materials is the main strategy to solve the EM radiation issues.The development of multifunction EM attenuation materials that are compatible together EM absorption and EMI shielding properties is deserved our exploration and study.Here,the graphenewrapped multiloculated NiFe_(2)O_(4) composites are reported as multifunction EM absorbing and EMI shielding materials.The conductive networks configurated by the overlapping flexible graphene promote the riched polarization genes,as well as electron transmission paths,and thus optimize the dielectric constant of the composites.Meanwhile,the introduction of magnetic NiFe_(2)O_(4) further establishes the magnetic-dielectric synergy effect.The abundant non-homogeneous interfaces not only generate effective interfacial polarization,also the deliberate multiloculated structure of NiFe_(2)O_(4) strengthens multi-scattering and multi-reflection sites to expand the transmission path of EM waves.As it turns out,the best impedance matching is matched at a lower filled concentration to achieve the strongest reflection loss value of−48.1 dB.Simultaneously,green EMI shielding based on a predominantly EM absorption and dissipation is achieved by an enlargement of the filled concentration,which is helpful to reduce the secondary EM wave reflection pollution to the environment.In addition,the electrocatalytic properties are further examined.The graphene-wrapped multiloculated NiFe_(2)O_(4) shows the well electrocatalytic activity as electrocatalysts for hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),which is mainly attributed to the interconnected structures formed by graphene and NiFe_(2)O_(4) connection.The structural advantages of multiloculated NiFe_(2)O_(4) expose more active sites,which plays an important role in optimizing catalytic reactions.This work provides an excellent jumping-off point for the development of multifunction EM absorbing materials,eco-friendliness EMI shielding materials and electrocatalysts.展开更多
Environment and energy are the eternal hot topics in the world,multiloculated microscale materials have attracted great attention in the field of electromagnetic interference(EMI)shielding and lithium ions storage.Her...Environment and energy are the eternal hot topics in the world,multiloculated microscale materials have attracted great attention in the field of electromagnetic interference(EMI)shielding and lithium ions storage.Herein,a novel flower-like NiFe_(2)O_(4)/graphene composite with adjustable structure was fabricated as EMI shielding material and anode material of lithium-ion batteries.NiFe_(2)O_(4)/graphene composite is a potential green EMI shielding material.The EMI shielding effectiveness(SE)increases with the increase of graphene content in NiFe_(2)O_(4)/graphene composite,and the total EMI SE of NiFe_(2)O_(4)/graphene with 73.6 wt.%graphene increases from 26.5 to 40.6 d B with the increase of frequency in 2–18 GHz.Furthermore,it exhibits long-life and large capacity lithium storage performance at high current density.The capacity reaches 732.79 m Ah g^(-1)after 100 cycles at 0.1 A g^(-1),recovering to more than 139%from the minimum capacity value.After 300 cycles at 0.5 A g^(-1),the capacity increases to 688.5 mAh g^(-1).The initial capacities at 2 and 5 A g^(-1)are 704.9 and 717.8 mAh g^(-1),and remain 297.9 and 203.2 m Ah g^(-1)after 1000 cycles.The distinguished EMI shielding performance and electrochemical performance are mainly ascribed to the structure regulation of NiFe_(2)O_(4)/graphene composite,as well as the synergistic effect of graphene and NiFe_(2)O_(4).This research opens up infinite opportunities for the application of multifunctional and interdisciplinary materials.展开更多
We have developed a practical and mild electrochemical protocol for cyanation and cyanomethylation of trimethylammonium salts through a pathway involving C–N bond cleavage without the need for an exter-nal stoichiome...We have developed a practical and mild electrochemical protocol for cyanation and cyanomethylation of trimethylammonium salts through a pathway involving C–N bond cleavage without the need for an exter-nal stoichiometric reducing agent or a sacrificial anode.The reaction employs tosyl cyanide(TsCN)or azido allyl alcohol as the cyanation or cyanomethylation reagent,respectively.It shows high functional group compatibility and can be applied for the cyanation of natural product derivatives.Preliminary mechanistic studies indicate the involvement of a radical addition pathway.展开更多
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.52177014,51977009,11774027,51372282 and 51132002).
文摘Dedicating to the exploration of efficient electromagnetic(EM)absorption and electromagnetic interference(EMI)shielding materials is the main strategy to solve the EM radiation issues.The development of multifunction EM attenuation materials that are compatible together EM absorption and EMI shielding properties is deserved our exploration and study.Here,the graphenewrapped multiloculated NiFe_(2)O_(4) composites are reported as multifunction EM absorbing and EMI shielding materials.The conductive networks configurated by the overlapping flexible graphene promote the riched polarization genes,as well as electron transmission paths,and thus optimize the dielectric constant of the composites.Meanwhile,the introduction of magnetic NiFe_(2)O_(4) further establishes the magnetic-dielectric synergy effect.The abundant non-homogeneous interfaces not only generate effective interfacial polarization,also the deliberate multiloculated structure of NiFe_(2)O_(4) strengthens multi-scattering and multi-reflection sites to expand the transmission path of EM waves.As it turns out,the best impedance matching is matched at a lower filled concentration to achieve the strongest reflection loss value of−48.1 dB.Simultaneously,green EMI shielding based on a predominantly EM absorption and dissipation is achieved by an enlargement of the filled concentration,which is helpful to reduce the secondary EM wave reflection pollution to the environment.In addition,the electrocatalytic properties are further examined.The graphene-wrapped multiloculated NiFe_(2)O_(4) shows the well electrocatalytic activity as electrocatalysts for hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),which is mainly attributed to the interconnected structures formed by graphene and NiFe_(2)O_(4) connection.The structural advantages of multiloculated NiFe_(2)O_(4) expose more active sites,which plays an important role in optimizing catalytic reactions.This work provides an excellent jumping-off point for the development of multifunction EM absorbing materials,eco-friendliness EMI shielding materials and electrocatalysts.
基金National Natural Science Foundation of China(Nos.52177014,51977009,11774027,51132002,51372282,52071192 and 51804191)Basic Research Project of Shanxi Province(No.202103021223342)。
文摘Environment and energy are the eternal hot topics in the world,multiloculated microscale materials have attracted great attention in the field of electromagnetic interference(EMI)shielding and lithium ions storage.Herein,a novel flower-like NiFe_(2)O_(4)/graphene composite with adjustable structure was fabricated as EMI shielding material and anode material of lithium-ion batteries.NiFe_(2)O_(4)/graphene composite is a potential green EMI shielding material.The EMI shielding effectiveness(SE)increases with the increase of graphene content in NiFe_(2)O_(4)/graphene composite,and the total EMI SE of NiFe_(2)O_(4)/graphene with 73.6 wt.%graphene increases from 26.5 to 40.6 d B with the increase of frequency in 2–18 GHz.Furthermore,it exhibits long-life and large capacity lithium storage performance at high current density.The capacity reaches 732.79 m Ah g^(-1)after 100 cycles at 0.1 A g^(-1),recovering to more than 139%from the minimum capacity value.After 300 cycles at 0.5 A g^(-1),the capacity increases to 688.5 mAh g^(-1).The initial capacities at 2 and 5 A g^(-1)are 704.9 and 717.8 mAh g^(-1),and remain 297.9 and 203.2 m Ah g^(-1)after 1000 cycles.The distinguished EMI shielding performance and electrochemical performance are mainly ascribed to the structure regulation of NiFe_(2)O_(4)/graphene composite,as well as the synergistic effect of graphene and NiFe_(2)O_(4).This research opens up infinite opportunities for the application of multifunctional and interdisciplinary materials.
基金This work was supported by the National Natural Science Foundation of China(22102012)the Changzhou Science and Technology Plan Applied Basic Research Project(CJ20210159 and CJ20210129)Henan University.
文摘We have developed a practical and mild electrochemical protocol for cyanation and cyanomethylation of trimethylammonium salts through a pathway involving C–N bond cleavage without the need for an exter-nal stoichiometric reducing agent or a sacrificial anode.The reaction employs tosyl cyanide(TsCN)or azido allyl alcohol as the cyanation or cyanomethylation reagent,respectively.It shows high functional group compatibility and can be applied for the cyanation of natural product derivatives.Preliminary mechanistic studies indicate the involvement of a radical addition pathway.
