Uniformly distributed single layer of ZIF67-derived C3N4(ZIF67-C3N4)was synthesized and applied to the photocatalytic degradation of methylene blue(MB)under visible light.Results indicated that the obtained ZIF67-C3N4...Uniformly distributed single layer of ZIF67-derived C3N4(ZIF67-C3N4)was synthesized and applied to the photocatalytic degradation of methylene blue(MB)under visible light.Results indicated that the obtained ZIF67-C3N4 has a maximum specific surface area of 541.392 m^2/g,which is much larger than that of raw C3N4 of 97.291 m^2/g.The investigation of C3N4 amount involved in ZIF67-C3N4 on the photoactivity revealed that 2.57 g ZIF67 with 0.3 g C3N4,which named ZIF67-C3N4(0.3)exhibited superior photocatalytic activities.More than 90%of MB at 10 mg/L was degraded within 70 min with the addition of 0.01 g ZIF67-C3N4(0.3),while this time required for raw C3N4 was over 140 min.The effects of pH of solution,initial concentration of MB and dosage of C3N4 in ZIF67-C3N4 composites on the photocatalytic efficiency for MB degradation were also evaluated.Quenching experiments indicated that the photo-induced holes(h^+)and superoxide radicals(O2-·)were mainly responsible for MB degradation.It is anticipated that the insertion of ZIF67 nanoparticles not only increases the adsorption capacity of C3N4 but also promotes the generation and migration of the photo-induced active species.展开更多
Currently,the develop-ment of low-reflection electromagnetic interference(EMI)shielding composite materials for mitigating secondary electromagnetic wave pollution has become a major research focus.However,achieving t...Currently,the develop-ment of low-reflection electromagnetic interference(EMI)shielding composite materials for mitigating secondary electromagnetic wave pollution has become a major research focus.However,achieving thinness,high toughness,low reflectivity,and multi-functionality in flexible EMI shielding films remains a challenge.To address this issue,this study introduces a“magnetic-electric”Janus structure EMI shielding composite film composed of MXene nanosheets,carbonized ZIF-67(CZIF67)nanop-articles and aramid nanofibers(ANF),balancing thinness,high toughness,low reflectivity,and multifunctionality.As a result,the MXene/ANF-CZIF67/ANF-4(MACA-4)sample exhibits high tensile strength(110.0±7.0 MPa),large strain tolerance(21%),and superior toughness(14.9±0.9 MJ·m^(-3)),reflecting the stress dispersion effect of the three-dimensional(3D)network structure of ANF and the strengthening effect of hydrogen bonding.The sample exhibits excellent flexibility,resistance to rubbing and folding.Even with a thickness of only 80μm,the MACA-4 film exhibits a reflection performance(SER)as low as 4.3 to 4.5 dB in the 8.2 to 9.6 GHz band and the SE_(T)in the X-band reaches 44.8 dB.In addition,the superior conductivity of the MXene/ANF layer and the localized surface plasmon resonance effect give the MACA composite films excellent electrothermal conversion capabilities.Surprisingly,the sample also exhibited excellent infrared stealth and fire alarm properties.This work offers valuable guidance on the fabrication of ultra-thin flexible EMI shielding composites and provides an important scientific basis for the design and application of efficient EMI shielding materials.展开更多
Peracetic acid(PAA)-based system is becoming an emerging advanced oxidation process(AOP)for effective removal of organic contaminants from water.Various approaches have been tested to activate PAA,while no previous re...Peracetic acid(PAA)-based system is becoming an emerging advanced oxidation process(AOP)for effective removal of organic contaminants from water.Various approaches have been tested to activate PAA,while no previous researches reported the application of metal-organic frameworks(MOFs)materials for PAA activation.In this study,zeolitic imidazole framework(ZIF)-67,a representative MOFs,was facile synthesized via direct-mixing method at room temperature,and tested for PAA activation and sulfachloropyridazine(SCP)degradation.The as-synthesized ZIF-67 exhibited excellent performance for PAA activation and SCP degradation with 100%of SCP degraded within 3 min,owing to the specific MOFs structure and abundant Co^(2+) sites.The pseudo-first-order kinetic model was applied to fit the kinetic data,with rate constant k_(1) of ZIF-67 activated PAA system 34.2 and 156.5 times higher than those of conventional Co_(3)O_(4)activated PAA and direct oxidation by PAA.Radical quenching experiments and electron paramagnetic resonance(EPR)analysis indicated that CH_(3)C(O)OO^(·)played a major role in this PAA activation system.Then,the Fukui index based on density functional theory(DFT)calculation was used to predict the possible reaction sites of SCP for electrophilic attack by CH_(3)C(O)OO^(·).In addition,the degradation pathway of SCP was proposed based on Fukui index values and intermediates detection,which mainly included the S-N bond cleavage and SO_(2)extrusion and followed by further oxidation,dechlorination,and hydroxylation.Therefore,ZIF-67 activated PAA is a novel strategy and holds strong potential for the removal of emerging organic contaminants(EOCs)from water.展开更多
The rational design and preparation of promising cathode electrocatalysts with excellent activity and strong stability for metal-air batteries is a huge challenge.In this work,we innovate an approach of combining solv...The rational design and preparation of promising cathode electrocatalysts with excellent activity and strong stability for metal-air batteries is a huge challenge.In this work,we innovate an approach of combining solvothermal with high-temperature pyrolysis utilizing zeolitic imidazolate framework(ZIF)-8 and ZIF-67 as the template to synthesize a novel hybrid material of hierarchical porous yolk-shell Co-N-C polyhedron nanocatalysts engaged in graphene nanopocket(yolk-shell Co-N-C@GNP).The obtained catalyst exhibits prominent bifunctional electrocatalytic performance for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)in the alkaline condition,in which the half-wave potential is 0.86 V for ORR,and the over-potential for OER is 0.42 V at 10 mA·cm^(-2).The rechargeable aqueous Zn-air battery fabricated with yolk-shell Co-N-C@GNP cathode deliveries an open circuit voltage(OCV)of 1.60 V,a peak power density of 236.2 mW·cm^(-2),and excellent cycling stability over 94 h at 5 mA·cm^(-2).The quasi-solid-state Zn-air battery(ZAB)using yolk-shell Co-N-C@GNP displays a high OCV of 1.40 V and a small voltage gap of 0.88 V in continuous cycling tests at 2 mA·cm^(-2).This work provides a valuable thought to focus attention on the design of high-efficient bifunctional catalysts with hierarchical porous yolk-shell framework and high-density metal active sites for metal-air battery technologies.展开更多
文摘Uniformly distributed single layer of ZIF67-derived C3N4(ZIF67-C3N4)was synthesized and applied to the photocatalytic degradation of methylene blue(MB)under visible light.Results indicated that the obtained ZIF67-C3N4 has a maximum specific surface area of 541.392 m^2/g,which is much larger than that of raw C3N4 of 97.291 m^2/g.The investigation of C3N4 amount involved in ZIF67-C3N4 on the photoactivity revealed that 2.57 g ZIF67 with 0.3 g C3N4,which named ZIF67-C3N4(0.3)exhibited superior photocatalytic activities.More than 90%of MB at 10 mg/L was degraded within 70 min with the addition of 0.01 g ZIF67-C3N4(0.3),while this time required for raw C3N4 was over 140 min.The effects of pH of solution,initial concentration of MB and dosage of C3N4 in ZIF67-C3N4 composites on the photocatalytic efficiency for MB degradation were also evaluated.Quenching experiments indicated that the photo-induced holes(h^+)and superoxide radicals(O2-·)were mainly responsible for MB degradation.It is anticipated that the insertion of ZIF67 nanoparticles not only increases the adsorption capacity of C3N4 but also promotes the generation and migration of the photo-induced active species.
基金supported by the Talent Fund of Beijing Jiaotong University(No.2023XKRC015)the National Natural Science Foundation of China(No.52172081)+2 种基金the Key R&D and Promotion Special Projects(Science and Technology)of Henan Province(No.232102240068)the Henan Provincial Department of Education(No.22B150010)Henan Province Key Research and Development Project(No.251111321500).
文摘Currently,the develop-ment of low-reflection electromagnetic interference(EMI)shielding composite materials for mitigating secondary electromagnetic wave pollution has become a major research focus.However,achieving thinness,high toughness,low reflectivity,and multi-functionality in flexible EMI shielding films remains a challenge.To address this issue,this study introduces a“magnetic-electric”Janus structure EMI shielding composite film composed of MXene nanosheets,carbonized ZIF-67(CZIF67)nanop-articles and aramid nanofibers(ANF),balancing thinness,high toughness,low reflectivity,and multifunctionality.As a result,the MXene/ANF-CZIF67/ANF-4(MACA-4)sample exhibits high tensile strength(110.0±7.0 MPa),large strain tolerance(21%),and superior toughness(14.9±0.9 MJ·m^(-3)),reflecting the stress dispersion effect of the three-dimensional(3D)network structure of ANF and the strengthening effect of hydrogen bonding.The sample exhibits excellent flexibility,resistance to rubbing and folding.Even with a thickness of only 80μm,the MACA-4 film exhibits a reflection performance(SER)as low as 4.3 to 4.5 dB in the 8.2 to 9.6 GHz band and the SE_(T)in the X-band reaches 44.8 dB.In addition,the superior conductivity of the MXene/ANF layer and the localized surface plasmon resonance effect give the MACA composite films excellent electrothermal conversion capabilities.Surprisingly,the sample also exhibited excellent infrared stealth and fire alarm properties.This work offers valuable guidance on the fabrication of ultra-thin flexible EMI shielding composites and provides an important scientific basis for the design and application of efficient EMI shielding materials.
基金the National Natural Science Foundation of China(Nos.21906001 and 52100069)the National Key Research and Development Program of China(No.2021YFA1202500)+2 种基金Beijing Nova Program(No.Z191100001119054)the Fundamental Research Funds for the Central Universities(No.BFUKF202118)China Postdoctoral Science Foundation(No.2021M690208)。
文摘Peracetic acid(PAA)-based system is becoming an emerging advanced oxidation process(AOP)for effective removal of organic contaminants from water.Various approaches have been tested to activate PAA,while no previous researches reported the application of metal-organic frameworks(MOFs)materials for PAA activation.In this study,zeolitic imidazole framework(ZIF)-67,a representative MOFs,was facile synthesized via direct-mixing method at room temperature,and tested for PAA activation and sulfachloropyridazine(SCP)degradation.The as-synthesized ZIF-67 exhibited excellent performance for PAA activation and SCP degradation with 100%of SCP degraded within 3 min,owing to the specific MOFs structure and abundant Co^(2+) sites.The pseudo-first-order kinetic model was applied to fit the kinetic data,with rate constant k_(1) of ZIF-67 activated PAA system 34.2 and 156.5 times higher than those of conventional Co_(3)O_(4)activated PAA and direct oxidation by PAA.Radical quenching experiments and electron paramagnetic resonance(EPR)analysis indicated that CH_(3)C(O)OO^(·)played a major role in this PAA activation system.Then,the Fukui index based on density functional theory(DFT)calculation was used to predict the possible reaction sites of SCP for electrophilic attack by CH_(3)C(O)OO^(·).In addition,the degradation pathway of SCP was proposed based on Fukui index values and intermediates detection,which mainly included the S-N bond cleavage and SO_(2)extrusion and followed by further oxidation,dechlorination,and hydroxylation.Therefore,ZIF-67 activated PAA is a novel strategy and holds strong potential for the removal of emerging organic contaminants(EOCs)from water.
基金This study was supported by the National Natural Science Foundation of China(Nos.22008058 and 52074119)the Joint Funds of National Natural Science Foundation of China(No.U20A20280)+3 种基金the program for Innovative Teams of Outstanding Young and Middle-aged Researchers in the Higher Education Institutions of Hubei Province(No.T2021010)the Joint supported by Hubei Provincial Natural Science Foundation and Huangshi of China(No.2022CFD039)the Postgraduate Innovative Research Project of Hubei Normal University(Nos.20220512 and 20220552)College Students innovation and entrepreneurship training program of Hubei Province(No.S202210513055).
文摘The rational design and preparation of promising cathode electrocatalysts with excellent activity and strong stability for metal-air batteries is a huge challenge.In this work,we innovate an approach of combining solvothermal with high-temperature pyrolysis utilizing zeolitic imidazolate framework(ZIF)-8 and ZIF-67 as the template to synthesize a novel hybrid material of hierarchical porous yolk-shell Co-N-C polyhedron nanocatalysts engaged in graphene nanopocket(yolk-shell Co-N-C@GNP).The obtained catalyst exhibits prominent bifunctional electrocatalytic performance for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)in the alkaline condition,in which the half-wave potential is 0.86 V for ORR,and the over-potential for OER is 0.42 V at 10 mA·cm^(-2).The rechargeable aqueous Zn-air battery fabricated with yolk-shell Co-N-C@GNP cathode deliveries an open circuit voltage(OCV)of 1.60 V,a peak power density of 236.2 mW·cm^(-2),and excellent cycling stability over 94 h at 5 mA·cm^(-2).The quasi-solid-state Zn-air battery(ZAB)using yolk-shell Co-N-C@GNP displays a high OCV of 1.40 V and a small voltage gap of 0.88 V in continuous cycling tests at 2 mA·cm^(-2).This work provides a valuable thought to focus attention on the design of high-efficient bifunctional catalysts with hierarchical porous yolk-shell framework and high-density metal active sites for metal-air battery technologies.
