Negatively thermo-responsive 2D membranes,which mimic the stomatal opening/closing of plants,have drawn substantial interest for tunable molecular separation processes.However,these membranes are still restricted sign...Negatively thermo-responsive 2D membranes,which mimic the stomatal opening/closing of plants,have drawn substantial interest for tunable molecular separation processes.However,these membranes are still restricted significantly on account of low water permeability and poor dynamic tunability of 2D nanochannels under temperature stimulation.Here,we present a biomimetic negatively thermo-responsive MXene membrane by covalently grafting poly(N-isopropylacrylamide)(PNIPAm)onto MXene nanosheets.The uniformly grafted PNIPAm polymer chains can enlarge the interlayer spacings for increasing water permeability while also allowing more tunability of 2D nanochannels for enhancing the capability of gradually separating multiple molecules of different sizes.As expected,the constructed membrane exhibits ultrahigh water permeance of 95.6 L m^(-2) h^(-1) bar^(-1) at 25℃,which is eight-fold higher than the state-of-the-art negatively thermoresponsive 2D membranes.Moreover,the highly temperature-tunable 2D nanochannels enable the constructed membrane to perform excellent graded molecular sieving for dye-and antibiotic-based ternary mixtures.This strategy provides new perspectives in engineering smart 2D membrane and expands the scope of temperature-responsive membranes,showing promising applications in micro/nanofluidics and molecular separation.展开更多
Developing high-performance broadband microwave absorption material becomes an urgent concern in the field of electromagnetic protection.In this work,an ultralight magnetic composite foam was con-structed by electrost...Developing high-performance broadband microwave absorption material becomes an urgent concern in the field of electromagnetic protection.In this work,an ultralight magnetic composite foam was con-structed by electrostatic self-assembly of MXene on the surface of graphene skeletons,and subsequent hydrothermal anchoring of flower-shaped FeS clusters.Under the synergistic effect of MXene coating in-creasing conductive loss and FeS clusters improving magnetic loss,the rational construction of hierarchi-cal impedance structure in foam can effectively promote the entrance and consumption of more incident electromagnetic waves.The minimum reflection loss(RL min)reaches-47.17 dB at a thickness of 4.78 mm,and the corresponding effective absorption bandwidth(EAB)is up to 6.15 GHz.More importantly,the microwave absorption performance of composite foam can be further optimized by controlling the load-ing of MXene and thermal treatment at a low temperature.The maximum of EAB for GMF-300 can be extended to an unprecedented value of 11.20 GHz(covering 6.10-17.30 GHz).展开更多
调控催化剂表面的化学键来平衡表面水分子的吸附和分解对于碱性溶液中水分解至关重要.本研究提出一种通过原位界面工程来设计与合成表面具有丰富的Ni-W金属键的Ni2W4C-W3C Janus异质结构的简便策略.预先将金属离子均匀分散在纳米纤维中...调控催化剂表面的化学键来平衡表面水分子的吸附和分解对于碱性溶液中水分解至关重要.本研究提出一种通过原位界面工程来设计与合成表面具有丰富的Ni-W金属键的Ni2W4C-W3C Janus异质结构的简便策略.预先将金属离子均匀分散在纳米纤维中,在碳化过程中,以电纺纤维为反应器,金属盐首先被还原成Ni和W3C.在持续分解的过程中,Ni原子原位插入W3C晶体中形成新的Ni2W4C相,得到Ni2W4C-W3C Janus异质结构.这使得W3C中原本惰性的W原子成为Ni2W4C中的活性位点.Ni2W4C-W3C/碳纳米纤维可以直接作为电极材料,其在碱性电解液中析氢活性达到10 m A/cm^2的电流密度需要63 m V过电位,析氧活性达到30 m A/cm^2的电流密度需要270 m V的过电位.若同时用作阴极和阳极进行全解水性能研究,其电池电压分别需要1.55和1.87 V就达到10和100 m A/cm^2.密度泛函理论结果表明,Ni与W之间的强相互作用增强了W原子的局域电子态.Ni2W4C为H-OH键的裂解提供了活性位点,W3C促进了Hads中间体与H2分子的结合.原位电化学拉曼光谱的结果表明该材料对水分子和羟基具有很强的吸收能力,W原子是真正的反应活性位点.该方法为构建高效电解水催化材料提供了另一种思路.展开更多
The development of high-performance microwave absorption materials with strong absorption capacity and broad bandwidth is highly desirable in the field of electromagnetic pollution protection.Herein,ultralight polyimi...The development of high-performance microwave absorption materials with strong absorption capacity and broad bandwidth is highly desirable in the field of electromagnetic pollution protection.Herein,ultralight polyimide-based graphene foam with ordered lamellar structure is precisely designed and controllably constructed by bidirectional freezing process.More lamellar interfaces formed inside the foam per unit volume effectively facilitate the layer-by-layer dissipation for the vertical incident electromagnetic waves,thereby endowing the foam with efficient broadband electromagnetic absorption performance.More importantly,electromagnetic absorption performance can be controllably adjusted by optimizing impedance distribution and microstructure of skeletons.As a result,the optimized foam with an ultralow density of 9.10 mg/cm^(3)presents a minimum reflection loss value of-61.29 dB at 9.25 GHz and an effective absorption bandwidth of 5.51 GHz(7.06-12.57 GHz,covering the whole X band) when the thickness is 4.75 mm.展开更多
Two-dimensional MXene has recently captured widespread research attention in energy storage and conversion fields due to its high conductivity,large specific surface area,and remarkable electro-activity.However,its pe...Two-dimensional MXene has recently captured widespread research attention in energy storage and conversion fields due to its high conductivity,large specific surface area,and remarkable electro-activity.However,its performance is still hindered by severe self-restacking of MXene flakes.Herein,conductive Ti_(3)C_(2)T_(x)/carbon nanofiber(CNF)composite aerogel with typical“layer-strut”bracing 3D microscopic architecture has been fabricated via synergistic assembly and freeze-drying process.In virtu of the strong interfacial interaction between polymeric precursor nanofibers and MXene mono-layers,gelation capability and 3D formability of Ti_(3)C_(2)T_(x) is greatly reinforced,as resulted Ti_(3)C_(2)T_(x)/CNF aerogels possess a highly ordered microporous structure with interlayered CNF penetrating between large size MXene lamellae.This special configuration guarantees the stability and pliability of the composite aerogels.Furthermore,the 3D form interconnected conductive network and the parallell alignment of the pores allow free electrical carriers motion and ion migration.As a result,the prepared Ti_(3)C_(2)T_(x)/CNF aerogel-based electrode exhibits an exceptional gravimetric specific capacitance of 268 F g^(−1) at a current density of 0.5 A g^(−1) and an excellent cycling stability of 8000 cylcles,and the assembled symmetric supercapacitor,delivers a high energy density of 3.425 W h kg^(−1) at 6000 W kg^(−1).This work offers a new route for the rational construction of 3D MXene assembly for advanced energy storage materials.展开更多
基金supported by the National Nature Science Foundation of China(No.22278179,U23A20688)the National Key Research and Development Program of China(2021YFB3802600)+3 种基金the Fundamental Research Funds for the Central Universities(JUSRP622035)National First-Class Discipline Program of Light Industry Technology and Engineering(LIFE2018-19)MOE&SAFEA for the 111 Project(B13025)Natural Science Foundation of Xinjiang Uygur Autonomous Region(2022D01D030).
文摘Negatively thermo-responsive 2D membranes,which mimic the stomatal opening/closing of plants,have drawn substantial interest for tunable molecular separation processes.However,these membranes are still restricted significantly on account of low water permeability and poor dynamic tunability of 2D nanochannels under temperature stimulation.Here,we present a biomimetic negatively thermo-responsive MXene membrane by covalently grafting poly(N-isopropylacrylamide)(PNIPAm)onto MXene nanosheets.The uniformly grafted PNIPAm polymer chains can enlarge the interlayer spacings for increasing water permeability while also allowing more tunability of 2D nanochannels for enhancing the capability of gradually separating multiple molecules of different sizes.As expected,the constructed membrane exhibits ultrahigh water permeance of 95.6 L m^(-2) h^(-1) bar^(-1) at 25℃,which is eight-fold higher than the state-of-the-art negatively thermoresponsive 2D membranes.Moreover,the highly temperature-tunable 2D nanochannels enable the constructed membrane to perform excellent graded molecular sieving for dye-and antibiotic-based ternary mixtures.This strategy provides new perspectives in engineering smart 2D membrane and expands the scope of temperature-responsive membranes,showing promising applications in micro/nanofluidics and molecular separation.
基金supported by the National Natu-ral Science Foundation of China(Nos.52003106,21674019)the Fundamental Research Funds for the Central Universities(Nos.JUSRP12032,2232019A3-03)+1 种基金the China Postdoctoral Science Foun-dation(No.2021M691265),the Ministry of Education of the Peo-ple’s Republic of China(No.6141A0202202)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(Nos.KYCX22_2319,SJCX22_1110).
文摘Developing high-performance broadband microwave absorption material becomes an urgent concern in the field of electromagnetic protection.In this work,an ultralight magnetic composite foam was con-structed by electrostatic self-assembly of MXene on the surface of graphene skeletons,and subsequent hydrothermal anchoring of flower-shaped FeS clusters.Under the synergistic effect of MXene coating in-creasing conductive loss and FeS clusters improving magnetic loss,the rational construction of hierarchi-cal impedance structure in foam can effectively promote the entrance and consumption of more incident electromagnetic waves.The minimum reflection loss(RL min)reaches-47.17 dB at a thickness of 4.78 mm,and the corresponding effective absorption bandwidth(EAB)is up to 6.15 GHz.More importantly,the microwave absorption performance of composite foam can be further optimized by controlling the load-ing of MXene and thermal treatment at a low temperature.The maximum of EAB for GMF-300 can be extended to an unprecedented value of 11.20 GHz(covering 6.10-17.30 GHz).
基金supported by the National Natural Science Foundation of China(51803077,51872204)the National Key Research and Development Program of China(2017YFA0204600)+4 种基金the Natural Science Foundation of Jiangsu Province(BK20180627)Postdoctoral Science Foundation of China(2018M630517,2019T120389)the Ministry of Education(MOE)and the State Administration for Foreign Expert Affairs(SAFEA),111 Project(B13025)the National First-Class Discipline Program of Light Industry Technology and Engineering(LITE2018-19)the Fundamental Research Funds for the Central Universities。
文摘调控催化剂表面的化学键来平衡表面水分子的吸附和分解对于碱性溶液中水分解至关重要.本研究提出一种通过原位界面工程来设计与合成表面具有丰富的Ni-W金属键的Ni2W4C-W3C Janus异质结构的简便策略.预先将金属离子均匀分散在纳米纤维中,在碳化过程中,以电纺纤维为反应器,金属盐首先被还原成Ni和W3C.在持续分解的过程中,Ni原子原位插入W3C晶体中形成新的Ni2W4C相,得到Ni2W4C-W3C Janus异质结构.这使得W3C中原本惰性的W原子成为Ni2W4C中的活性位点.Ni2W4C-W3C/碳纳米纤维可以直接作为电极材料,其在碱性电解液中析氢活性达到10 m A/cm^2的电流密度需要63 m V过电位,析氧活性达到30 m A/cm^2的电流密度需要270 m V的过电位.若同时用作阴极和阳极进行全解水性能研究,其电池电压分别需要1.55和1.87 V就达到10和100 m A/cm^2.密度泛函理论结果表明,Ni与W之间的强相互作用增强了W原子的局域电子态.Ni2W4C为H-OH键的裂解提供了活性位点,W3C促进了Hads中间体与H2分子的结合.原位电化学拉曼光谱的结果表明该材料对水分子和羟基具有很强的吸收能力,W原子是真正的反应活性位点.该方法为构建高效电解水催化材料提供了另一种思路.
基金financially supported by the National Natural Science Foundation of China (Nos. 21674019, 21704014, 52003106, 22008086, and 52003107)China Postdoctoral Science Foundation (Nos. 2020M671332, 2021M691265, and 2021M691266)+2 种基金Fundamental Research Funds for the Central Universities (Nos. 2232019A3-03 and JUSRP12032)Ministry of Education of the People’s Republic of China (No. 6141A0202202)Shanghai Scientific and Technological Innovation Project (No. 18JC1410600)。
文摘The development of high-performance microwave absorption materials with strong absorption capacity and broad bandwidth is highly desirable in the field of electromagnetic pollution protection.Herein,ultralight polyimide-based graphene foam with ordered lamellar structure is precisely designed and controllably constructed by bidirectional freezing process.More lamellar interfaces formed inside the foam per unit volume effectively facilitate the layer-by-layer dissipation for the vertical incident electromagnetic waves,thereby endowing the foam with efficient broadband electromagnetic absorption performance.More importantly,electromagnetic absorption performance can be controllably adjusted by optimizing impedance distribution and microstructure of skeletons.As a result,the optimized foam with an ultralow density of 9.10 mg/cm^(3)presents a minimum reflection loss value of-61.29 dB at 9.25 GHz and an effective absorption bandwidth of 5.51 GHz(7.06-12.57 GHz,covering the whole X band) when the thickness is 4.75 mm.
基金This work is financially supported by the National Natural Science Foundation of China(No.21875033)the Shanghai Scientific and Technological Innovation Project(No.18JC1410600)+1 种基金the Program of the Shanghai Academic Research Leader(No.17XD1400100)the State Key Laboratory for Modification of Chemical Fibers and Polymer Materials(Donghua University).
文摘Two-dimensional MXene has recently captured widespread research attention in energy storage and conversion fields due to its high conductivity,large specific surface area,and remarkable electro-activity.However,its performance is still hindered by severe self-restacking of MXene flakes.Herein,conductive Ti_(3)C_(2)T_(x)/carbon nanofiber(CNF)composite aerogel with typical“layer-strut”bracing 3D microscopic architecture has been fabricated via synergistic assembly and freeze-drying process.In virtu of the strong interfacial interaction between polymeric precursor nanofibers and MXene mono-layers,gelation capability and 3D formability of Ti_(3)C_(2)T_(x) is greatly reinforced,as resulted Ti_(3)C_(2)T_(x)/CNF aerogels possess a highly ordered microporous structure with interlayered CNF penetrating between large size MXene lamellae.This special configuration guarantees the stability and pliability of the composite aerogels.Furthermore,the 3D form interconnected conductive network and the parallell alignment of the pores allow free electrical carriers motion and ion migration.As a result,the prepared Ti_(3)C_(2)T_(x)/CNF aerogel-based electrode exhibits an exceptional gravimetric specific capacitance of 268 F g^(−1) at a current density of 0.5 A g^(−1) and an excellent cycling stability of 8000 cylcles,and the assembled symmetric supercapacitor,delivers a high energy density of 3.425 W h kg^(−1) at 6000 W kg^(−1).This work offers a new route for the rational construction of 3D MXene assembly for advanced energy storage materials.