Increasing the interlayer spacing of metal-organic frameworks(MOFs)through multi-metal ion doping has emerged as an effective strategy to enhance electrolyteion transport within the MOF unit cell,enabling the design o...Increasing the interlayer spacing of metal-organic frameworks(MOFs)through multi-metal ion doping has emerged as an effective strategy to enhance electrolyteion transport within the MOF unit cell,enabling the design of nickel-based MOF materials with high capacity and energy density.In this work,a series of NiCo-MOFx(x=1-5)were synthesized by incorporating Co^(2+)ions into Ni-MOF.The introduction of Co^(2+)modulated the unit cell structure and governed the stacking configuration of MOF nanosheets.At an optimal Ni/Co molar ratio of 4:1,the NiCo-MOF-2 sample demonstrates superior electrochemical performance,delivering a specific capacitance of1238.6 F g^(-1)at 0.2 A g^(-1).Subsequently,NiCo-MOF-2was grown in situ on carbonized wood(CW)to fabricate a NiCo-MOF@CW composite,which exhibits an areal capacitance of 4960 mF cm^(-2)at 0.6 mA cm^(-2).An asymmetric supercapacitor(NiCo-MOF@CW//AC)was assembled using NiCo-MOF@CW as the positive electrode and activated carbon(AC)as the negative electrode.The device achieves an areal energy density of 1.88 mWh cm^(-2)at a power density of 2.88 mW cm^(-2)(1 mA cm^(-2)),with 83.6%capacitance retention after 2000 charge-discharge cycles.Notably,two serially connected NiCoMOF@CW//AC devices successfully illuminate a red LED(operating voltage:1.6-1.75 V)for 20 min.The multimetal ion doping strategy combined with binder-free,selfsupporting electrode architecture presents a novel approach for synthesizing high-performance energy storage materials.展开更多
Recently,multifunctional materials have received widespread attention from researchers.Cellulose nanofibers(CNF)is one of biomass materials with abundant hydroxyl groups,which shows great potential in manufacturing mu...Recently,multifunctional materials have received widespread attention from researchers.Cellulose nanofibers(CNF)is one of biomass materials with abundant hydroxyl groups,which shows great potential in manufacturing multifunctional composite material.In this paper,a kind of polyaniline@CNF/polyvinyl alcohol-H_(2)SO_(4) multifunctional composite material(PANI@CNF/PVA-H_(2)SO_(4))was successfully designed by in-situ chemical polymerization of conductive polyaniline(PANI)onto CNF aerogel with high aspect ratio,and then coated with PVA-H_(2)SO_(4) gel.The composite material has a specific capacitance of 502.2 F/g at a scan rate of 5 mV/s as supercapacitor electrode.Furthermore,when the composite was assembled into a symmetrical supercapacitor,it can still provide an energy density of 11.49 W·h/kg at a high power density of 413.55 W/kg.Besides,the as-obtained PANI@CNF/PVA-H_(2)SO_(4) composite has an excellent electromagnetic shielding performance of 34.75 dB in X-band.In addition,due to the excellent flexibility of CNF and PVA,the PANI@CNF/PVA-H2SO4 composites can be further applied to stress sensors to detect pressure and human motion signals.展开更多
Accelerating the rate-limiting oxygen reduction reaction （ORR） at the cathode remains the foremost issue for the commercialization of fuel cells. Transition metal-nitrogen-carbon （M-N/C, M = Fe, Co, etc.） nanostru...Accelerating the rate-limiting oxygen reduction reaction （ORR） at the cathode remains the foremost issue for the commercialization of fuel cells. Transition metal-nitrogen-carbon （M-N/C, M = Fe, Co, etc.） nanostructures are the most promising class of non-precious metal catalysts （NPMCs） with satisfactory activities and stabilities in practical fuel cell applications. However, the long-debated nature of the active sites and the elusive structure-performance correlation impede further developments of M-N/C materials. In this review, we present recent endeavors to elucidate the actual structures of active sites by adopting a variety of physicochemical techniques that may provide a profound mechanistic understanding of M-N/C catalysts. Then, we focus on the spectacular progress in structural optimization strategies for M-N/C materials with tailored precursor architectures and modified synthetic routes for controlling the structural uniformity and maximizing the number of active sites in catalytic materials. The recognition of the right active centers and site-specific engineering of the nanostructures provides future directions for designing advantageous M-N/C catalysts.展开更多
基金financially Supported by the fund of National Natural Science Foundation of China(Nos.22078184 and 22378249)Key R&D Plan of Shaanxi Province(No.2024GX-YBXM-335)Natural science advance research foundation of Shaanxi University of Science and Technology(No.2018QNBJ03)
文摘Increasing the interlayer spacing of metal-organic frameworks(MOFs)through multi-metal ion doping has emerged as an effective strategy to enhance electrolyteion transport within the MOF unit cell,enabling the design of nickel-based MOF materials with high capacity and energy density.In this work,a series of NiCo-MOFx(x=1-5)were synthesized by incorporating Co^(2+)ions into Ni-MOF.The introduction of Co^(2+)modulated the unit cell structure and governed the stacking configuration of MOF nanosheets.At an optimal Ni/Co molar ratio of 4:1,the NiCo-MOF-2 sample demonstrates superior electrochemical performance,delivering a specific capacitance of1238.6 F g^(-1)at 0.2 A g^(-1).Subsequently,NiCo-MOF-2was grown in situ on carbonized wood(CW)to fabricate a NiCo-MOF@CW composite,which exhibits an areal capacitance of 4960 mF cm^(-2)at 0.6 mA cm^(-2).An asymmetric supercapacitor(NiCo-MOF@CW//AC)was assembled using NiCo-MOF@CW as the positive electrode and activated carbon(AC)as the negative electrode.The device achieves an areal energy density of 1.88 mWh cm^(-2)at a power density of 2.88 mW cm^(-2)(1 mA cm^(-2)),with 83.6%capacitance retention after 2000 charge-discharge cycles.Notably,two serially connected NiCoMOF@CW//AC devices successfully illuminate a red LED(operating voltage:1.6-1.75 V)for 20 min.The multimetal ion doping strategy combined with binder-free,selfsupporting electrode architecture presents a novel approach for synthesizing high-performance energy storage materials.
基金supported by the fund of National Natural Science Foundation of China(22078184,22378249 and 22178208)Key R&D Plan of Shaanxi Province(2024GX-YBXM-335)+1 种基金China Postdoctoral Science Foundation(2019M653853XB)Natural science advance research foundation of Shaanxi University of Science and Technology(2018QNBJ-03).
文摘Recently,multifunctional materials have received widespread attention from researchers.Cellulose nanofibers(CNF)is one of biomass materials with abundant hydroxyl groups,which shows great potential in manufacturing multifunctional composite material.In this paper,a kind of polyaniline@CNF/polyvinyl alcohol-H_(2)SO_(4) multifunctional composite material(PANI@CNF/PVA-H_(2)SO_(4))was successfully designed by in-situ chemical polymerization of conductive polyaniline(PANI)onto CNF aerogel with high aspect ratio,and then coated with PVA-H_(2)SO_(4) gel.The composite material has a specific capacitance of 502.2 F/g at a scan rate of 5 mV/s as supercapacitor electrode.Furthermore,when the composite was assembled into a symmetrical supercapacitor,it can still provide an energy density of 11.49 W·h/kg at a high power density of 413.55 W/kg.Besides,the as-obtained PANI@CNF/PVA-H_(2)SO_(4) composite has an excellent electromagnetic shielding performance of 34.75 dB in X-band.In addition,due to the excellent flexibility of CNF and PVA,the PANI@CNF/PVA-H2SO4 composites can be further applied to stress sensors to detect pressure and human motion signals.
文摘Accelerating the rate-limiting oxygen reduction reaction （ORR） at the cathode remains the foremost issue for the commercialization of fuel cells. Transition metal-nitrogen-carbon （M-N/C, M = Fe, Co, etc.） nanostructures are the most promising class of non-precious metal catalysts （NPMCs） with satisfactory activities and stabilities in practical fuel cell applications. However, the long-debated nature of the active sites and the elusive structure-performance correlation impede further developments of M-N/C materials. In this review, we present recent endeavors to elucidate the actual structures of active sites by adopting a variety of physicochemical techniques that may provide a profound mechanistic understanding of M-N/C catalysts. Then, we focus on the spectacular progress in structural optimization strategies for M-N/C materials with tailored precursor architectures and modified synthetic routes for controlling the structural uniformity and maximizing the number of active sites in catalytic materials. The recognition of the right active centers and site-specific engineering of the nanostructures provides future directions for designing advantageous M-N/C catalysts.
