Owing to abundant resource and affordable price,metal-free carbon has been extensively studied in the field of oxygen reduction reaction,while the related studies on oxygen evolution reaction(OER)are quite few.In this...Owing to abundant resource and affordable price,metal-free carbon has been extensively studied in the field of oxygen reduction reaction,while the related studies on oxygen evolution reaction(OER)are quite few.In this work,a facile and scalable knife coating coupled with annealing strategy is proposed to produce self-standing oxygen-doped graphene membranes(marked as O-GM-T,T represents the annealing temperature).Through systematic characterization and analysis,it is discovered the annealing treatment not only decreases the amount of oxygenic groups,but allows for controlled regulation of the oxygen configurations,leaving only C-OH/C-O-C and C=O.Meanwhile,theoretical calculations indicate that the OER activity trend of different oxygen configurations is as follows:-COOH>C=O≈C-OH>C-O-C.Despite the removal of highly active-COOH group through annealing treatment,the resulting O-GM-800 sample maintains good mechanical property and achieves a favorable balance on conductivity,hydrophilicity and catalytic sites.Consequently,it displays significantly improved OER performance compared to the counterparts,making it highly promising for applications in overall water splitting devices.Apparently,our work provides guidance for the rational design and controllable fabrication of self-standing carbon-based catalysts for energy-related reactions.展开更多
A self-standing dual-electric field synergistic[TiO_(2)/polyvinylidene fluoride(PVDF)]//[g-C3 N4 tube/PVDF]Janus nanofibres(named as[TP]//[CTP]JNs)S-scheme heterostructure piezoelectric photocatalyst is designed and c...A self-standing dual-electric field synergistic[TiO_(2)/polyvinylidene fluoride(PVDF)]//[g-C3 N4 tube/PVDF]Janus nanofibres(named as[TP]//[CTP]JNs)S-scheme heterostructure piezoelectric photocatalyst is designed and constructed via conjugative electrospinning.Dual-fields of built-in electric fields supplied by S-scheme heterostructure and piezoelectric field formed by PVDF jointly boost separation and transfer of photo-induced charges.As a case study,piezoelectric photocatalytic efficiency of[TP]//[CTP]JNs for tetracycline hydrochloride(TCH)under ultrasonic united with simulated sunlight illumination is 93.35%(40 min),which is 1.39 times of the photocatalytic efficiency(light illumination only)and 5.32 times of piezoelectric catalytic efficiency(applying ultrasonic only),proving the advantages of the synergistic effect of piezoelectric catalysis and photocatalysis on contaminant degradation.The dynamic behaviors of photocatalysis and photo-generated charges are deeply revealed through fs-TA and TRPL decay spectra,and the degradation pathways of antibiotics are reasonably speculated by combining LCMS spectra with Fukui index.By the degradation ability,COMSOL simulation and DFT calculation,the structural advantage of Janus nanofibers is fully verified,and S-scheme charge transfer mechanism is confirmed by combining a series of sound ample experiments with theoretical calculations.Additionally,the construction mechanism of Janus nanofibers is proposed,and corresponding construction technique is established.展开更多
Chemical vapor deposited （CVD） diamond film has broad application foreground in high-tech fields. But polycrystalline CVD self-standing diamond thick film has rough surface and non-uniform thickness that adversely a...Chemical vapor deposited （CVD） diamond film has broad application foreground in high-tech fields. But polycrystalline CVD self-standing diamond thick film has rough surface and non-uniform thickness that adversely affect its extensive applications. Laser polishing is a useful method to smooth self-standing diamond film. At present, attentions have been focused on experimental research on laser polishing, but the revealing of theoretical model and the forecast of polishing process are vacant. The paper presents a finite element model to simulate and analyze the mechanism of laser polishing diamond based on laser thermal conduction theory. The experimental investigation is also carried out on Nd：YAG pulsed laser smoothing diamond thick film. The simulation results have good accordance with the results of experimental results. The temperature and thermal stress fields are investigated at different incidence angles and parameters of Nd：YAG pulsed laser. The pyramidal-like roughness of diamond thick film leads to the non-homogeneous temperature fields. The temperature at the peak of diamond film is much higher than that in the valley, which leads to the smoothing of diamond thick film. The effect of laser parameters on the surface roughness and thickness of graphite transition layer is also carried out. The results show that high power density laser makes the diamond surface rapid heating, evaporation and sublimation after its graphitization. It is also found that the good polish quality of diamond thick film can be obtained by a combination of large incident angle, moderate laser pulsed energy, large repetition rate and moderate laser pulse width. The results obtained here provide the theoretical basis for laser polishing diamond film with high efficiency and high quality.展开更多
Supercapacitors（SCs） have attracted much attention as one of the alternative energy devices due to their high power performance,long cycle life,and low maintenance cost.Graphene is considered as an innovative and pr...Supercapacitors（SCs） have attracted much attention as one of the alternative energy devices due to their high power performance,long cycle life,and low maintenance cost.Graphene is considered as an innovative and promising material due to its large theoretical specific surface area,high electrical conductivity,good mechanical properties and chemical stability.Herein,we report an effective strategy for elaborately constructing rationally functionalized self-standing graphene（SG） obtained from giant graphene oxide（GGO） paper followed by an ultrarapid thermal-processing.This treatment results in both the exfoliation of graphene sheets and the reduction of GGO by elimination of oxygencontaining groups.The as-prepared SG electrode materials without additive and conducting agent provide an excellent combination of the electrical double layer capacitor（EDLC） and pseudocapacitor（PC） functions and exhibit superior electrochemical performance,including high specific capacitance,good rate capability and excellent cycling stability when investigated in three-electrode electrochemical cells.展开更多
Lithium-sulfur(Li-S) batteries have attracted considerable attention due to their high energy density(2600 Wh kg-1). However, its commercialization is hindered seriously by the low loading and utilization rate of sulf...Lithium-sulfur(Li-S) batteries have attracted considerable attention due to their high energy density(2600 Wh kg-1). However, its commercialization is hindered seriously by the low loading and utilization rate of sulfur cathodes. Herein, we designed the cellulose-based graphene carbon composite aerogel(CCA) self-standing electrode to enhance the performance of Li-S batteries. The CCA contributes to the mass loading and utilization efficiency of sulfur, because of its unique physical structure: low density(0.018 g cm-3), large specific surface area(657.85 m2 g-1), high porosity(96%), and remarkable electrolyte adsorption(42.25 times). Compared to Al(about 49%), the CCA displayed excellent sulfur use efficiency(86%) and could reach to high area capacity of 8.60 mAh cm-2 with 9.11 mgS loading. Meanwhile,the CCA exhibits the excellent potential for pulse sensing applications due to its flexibility and superior sensitivity to electrical response signals.展开更多
Restraining the aggregation and polysulfide dissolution of edge-enriched metal sulfides is of significance for their applications as anode materials of lithium-ion batteries(LIBs)with high capacity and long cycle-life...Restraining the aggregation and polysulfide dissolution of edge-enriched metal sulfides is of significance for their applications as anode materials of lithium-ion batteries(LIBs)with high capacity and long cycle-life.In this work,we have reported the incorporation of MoS2 nanocrystals into amorphous carbon on the surface of reduced graphene oxide(rGO)by balancing the decomposition rates of phenolic resin(PF)-impregnated ammonium thiomolybdate(ATM),which subsequently forms the MoS2@C/rGO film through redispersion and vacuum filtration.Such structural design effectively avoids the aggregation of MoS2 nanocrystals and Li2S loss,and meanwhile ion enrichment in amorphous carbon and diffusion reinforcement can greatly accelerate the electrochemical reaction kinetics.When applied as the selfstanding anode,the MoS2@C/rGO film possesses high reversible capacities of 1164 mA h g^-1 at the current density of 0.2 A g^-1 and 810 mA h g^-1 at 6.4 A g^-1.It also exhibits quite a high capacity retention after 1000 cycles at 3.2 A g^-1.This work develops the formation theory of incorporation structures and promotes their applications in energy storage devices.展开更多
Ultrasmall y-Fe203 nanodots （- 3.4 nm） were homogeneously encapsulated in interlinked porous N-doped carbon nanofibers （labeled as Fe2O3@C） at a considerable loading （-51 wt.%） via an electrospinning technique. ...Ultrasmall y-Fe203 nanodots （- 3.4 nm） were homogeneously encapsulated in interlinked porous N-doped carbon nanofibers （labeled as Fe2O3@C） at a considerable loading （-51 wt.%） via an electrospinning technique. Moreover, the size and content of Fe2O3 could be controlled by adjusting the synthesis conditions. The obtained Fe203@C that functioned as a self-standing membrane was used directly as a binder- and current collector-free anode for sodium-ion batteries, displaying fascinating electrochemical performance in terms of the exceptional rate capability （529 mA.h.gq at 100 mA-g-1 compared with 215 mA-h-g-1 at 10,000 mA.g-1） and unprecedented cyclic stability （98.3% capacity retention over 1,000 cycles）. Furthermore, the Na-ion full cell constructed with the Fe2O3C anode and a P2-Na2/3Ni1/3Mn2/302 cathode also exhibited notable durability with 97.2% capacity retention after 300 cycles. This outstanding performance is attributed to the distinctive three-dimensional network structure of the very-fine Fe203 nanoparticles uniformly embedded in the interconnected porous N-doped carbon nanofibers that effectively facilitated electronic/ionic transport and prevented active materials pulverization/aggregation caused by volume change upon prolonged cycling. The simple and scalable preparation route, as well as the excellent electrochemical performance, endows the Fe2O3@C nanofibers with great prospects as high-rate and long-life Na-storage anode materials.展开更多
Rechargeable lithium-iodine (Li-I2) battery is a promising energy storage system because of the high energy and power density. However, the shuttle effects of iodine species and the unstable features of l2 block the p...Rechargeable lithium-iodine (Li-I2) battery is a promising energy storage system because of the high energy and power density. However, the shuttle effects of iodine species and the unstable features of l2 block the practical applications of Li-I2 batteries. Herein, a dual heteroatom doped porous carbon cloth is fabricated as the host material for lithium iodide (Lil). Specifically, the self-standing nitrogen, phosphorus co-doped carb on cloth with high Lil loading exhibits a large specific capacity (221 mAh·g^-1 at 1 C), excelle nt rate capability (95.8% capacity rete ntion at 5 C) and superior I ong cycli ng stability (2,000 cycles with a capacity rete ntion of 96%). Electrochemical kin etic an alysis con firms the domi nant contribution of capacitive effects at high sean rates, which is responsible for the good high-rate performance. The improved electrochemical performance mainly stems from two unique features of nitrogen, phosphorus co-doped porous carbon cloth. Heteroatom doping provides extra active sites for strong adsorption of iodine species while the highly porous structure with large surface area favors the capacitive effects at high rates. This work provides a facile yet efficient approach to regulating both redox reaction and capacitive effects via adjusting surface composition and pore structure of carbon materials for en hanced battery performance.展开更多
Developing high-performance noble metal-free and free-standing catalytic electrodes are crucial for overall water splitting. Here, nickel sulfide（NiS） and nickel selenide（Ni Se） are synthesized on nickel foam（NF...Developing high-performance noble metal-free and free-standing catalytic electrodes are crucial for overall water splitting. Here, nickel sulfide（NiS） and nickel selenide（Ni Se） are synthesized on nickel foam（NF） with a one-pot solvothermal method and directly used as free-standing electrodes for efficiently catalyzing hydrogen evolution reaction（HER） and oxygen evolution reaction（OER） in alkaline solution.In virtue of abundant active sites, the NiS/NF and the NiS e/NF electrodes can deliver a current density of 10 m A cmat only 123 m V, 137 m V for HER and 222 m V, 271 m V for OER. Both of the hierarchical NiS/NF and Ni Se/NF electrodes can serve as anodes and cathodes in electrocatalytic overall watersplitting and can achieve a current density of 10 m A cmwith an applied voltage of.59 V and 1.69 V,respectively. The performance of as-obtained NiS/NF||NiS/NF is even close to that of the noble metalbased Pt/C/NF||IrO/NF system.展开更多
The shuttling diffusion of polysulfides is a bottleneck that seriously limits the performance of Li-S batteries.Purposeful construction of sulfur cathodes with reliable trapping ability of polysulfides is the key to o...The shuttling diffusion of polysulfides is a bottleneck that seriously limits the performance of Li-S batteries.Purposeful construction of sulfur cathodes with reliable trapping ability of polysulfides is the key to overcome such limitation.Herein,a hierarchical porous architecture,i.e.,Co(OH)_(2)sheets bonded Ti_3C_(2)T_x MXene aerogel(Co(OH)_(2)/MXA),is constructed via a facile selfassembled approach and used as an efficient free-standing polysulfides reservoir.The interconnected three-dimensional(3D)porous network with void space and strong interfacial interaction not only enables high sulfur loading but facilitates fast ion and electron transport.Experimental and theoretical results confirm the hetero-framework exhibits outstanding immobilization and conversion ability for polysulfides due to its polar surface and bifunctional catalytic activities toward both formation and decomposition of Li2S.The optimized Co(OH)_(2)/MXA cathode delivers excellent rate capability(407 mAh·g^(-1)at 5C)with a sulfur loading of 2.7 mg·cm^(-2),and ultra-stable cycling performance as an extremely small capacity decay of~0.005%per cycle within 1700 cycles at 1C is achieved with a high sulfur loading of 6.7 mg·cm^(-2).More significantly,our design structural/componential methodology here promises the MXene-based aerogel electrodes for LiS batteries and beyond.展开更多
The development of low-cost,robust and efficient non-noble metal electrocatalysts is still a pursuit for the hydrogen evolution reaction(HER).Herein,a self-standing electrocatalyst,Ni_(2)P/CoP nanosheet,was fabricated...The development of low-cost,robust and efficient non-noble metal electrocatalysts is still a pursuit for the hydrogen evolution reaction(HER).Herein,a self-standing electrocatalyst,Ni_(2)P/CoP nanosheet,was fabricated directly on three-dimensional Ni foams by two facile steps,which illustrated both high activity and stability for HER in different electrolytes.Benefiting from the porous structures of nanosheets with large specific surface area and the hybrid Ni_(2)P/CoP,the as-prepared electrocatalyst presented remarkable HER with overpotentials of 65.2 and 87.8 mV to reach a current density of-10 mA cm^(-2)in neutral and alkaline media,respectively.Density function theory calculations revealed a lower activation energy of water dissociation and efficient HER steps of hybrid Ni_(2)P/CoP nanosheets compared with mono CoP.The self-standing electrocatalyst maintained excellent chemical stability.Additionally,the HER process in domestic wastewater was realized with more impressive performance by using Ni_(2)P/CoP nanosheets compared with commercial Pt/C.Hydrogen was continuously generated for 20 h in mildly alkaline dishwashing wastewater.This work provides a feasible way to fabricate non-noble metal and self-standing hybrid bimetallic phosphides for HER in neutral and alkaline media,showing great potential for efficient hydrogen production by re-utilizing wastewater resources.展开更多
The structure of sulfur host materials plays a key role in alleviating the shuttle effect,volume expansion and sluggish redox reaction of lithium–sulfur batteries(LSBs).In this work,the well-designed multichannel car...The structure of sulfur host materials plays a key role in alleviating the shuttle effect,volume expansion and sluggish redox reaction of lithium–sulfur batteries(LSBs).In this work,the well-designed multichannel carbon fibers decorated by carbon nanotubes(CNTs)and CoS nanoparticles(MCF/CoS/CNT)are synthesized and serve as the flexible sulfur host.The in situ grown CNTs network and embedded CoS enhance the overall conductivity of electrode and facilitate the redox reaction of sulfur-related electrochemistry.Benefitting from these merits,the MCF/CoS/CNT-based cathode exhibits a high reversible capacity of 927 mAh g^(−1) after 180 cycles with a low decay of 0.034%per cycle at 1.0 C.A superb areal capacity of 5.2 mAh cm^(−2) could be obtained under a high sulfur loading of 6.3 mg cm^(−2) and an ultralow electrolyte/sulfur ratio of 6.5μL mg^(−1) after 100 cycles.This work offers a promising approach to the reasonable design of flexible sulfur host for LSBs toward high energy density.展开更多
Developing effective electrodes with commercial-level active mass-loading(>10 mg cm^(−2))is vital for the practical application of supercapacitors.However,high active mass-loading usually requires thick active mass...Developing effective electrodes with commercial-level active mass-loading(>10 mg cm^(−2))is vital for the practical application of supercapacitors.However,high active mass-loading usually requires thick active mass layer,which severely hinders the ion/electron transport and results in poor capacitive performance.Herein,a self-standing biochar electrode with active mass-loading of ca.40 mg cm^(−2) and thickness of 800μm has been developed from basswood.The basswood was treated with formamide to incorporate N/O in the carbon structure,followed by mild KOH activation to ameliorate the pore size and introduce more O species in the carbon matrix.The as-prepared carbon monoliths possess well conductive carbon skeleton,abundant N/O dopant and 3D porous structure,which are favorable for the ion/electron transport and promoting capacitance performance.The self-standing carbon electrode not only exhibits the maximum areal/mass/volumetric specific capacitance of 5037.5 mF cm^(−2)/172.5 F g^(−1)/63.0 F cm^(−3) at 2 mA cm^(−2)(0.05 A g^(−1)),but also displays excellent rate performance with 76%capacitance retention at 500 mA cm^(−2)(12.5 A g^(−1))in a symmetric supercapacitor,surpassing the state-of-art biomass-based thick carbon electrode.The assembled model can power typical electron devices including a fan,a digital watch and a logo made up of 34 light-emitting diodes for a proper period,revealing its practical application potential.This study not only puts forward a commercial-level high active mass-loading electrode from biomass for supercapacitor,but also bridges the gap between the experimental research and practical application.展开更多
Soft molecule-based ferroelectrics with unique structural flexibility hold apromise for versatile applications of non-volatile memory, imaging and photovoltaicdevices. Except for few polymers (e.g., polyvinylidene flu...Soft molecule-based ferroelectrics with unique structural flexibility hold apromise for versatile applications of non-volatile memory, imaging and photovoltaicdevices. Except for few polymers (e.g., polyvinylidene fluoride, PVDF),it is challenging to exploit soft ferroelectric crystals toward free-standing flexiblephotoactive devices. We here report a multiaxial soft molecule-based ferroelectric,(n-PA)_(2)PbCl_(4) (1, where n-PA^(+)is n-pentylammonium), of whichspontaneous polarization can be reversibly switched in both crystal and powderforms. Strikingly, single crystals of 1 have unusual structural flexibility andbendability, achieving the self-standing bending with a bending radius of0.22 mm. Besides, the pyroelectric activities are also preserved for these singlecrystals after several bending cycles. Further, the bendable crystal-basedphotodetector of 1 allows broadband photoactivities via the photo-pyroelectriceffect, covering a wide range from 405 to 940 nm spectral region, breakingthrough the limit of optical absorption bandgap. As the first study of bendablefree-standing photo-pyroelectric detectors in ferroelectric crystals, our worksheds light on the assembly of flexible smart photoelectric devices.展开更多
基金supported by Science&Technology Talents Lifting Project of Hunan Province(No.2022TJ-N16)Natural Science Foundation of Hunan province,China(Nos.2024JJ4022,2023JJ30277,and 2023JJ30280)+2 种基金the Science and Technology Innovation Program of Hunan Province(No.2022RC3037)China Postdoctoral Fellowship Program(No.GZC20233205)Innovation and Entrepreneurship Training Program for College Students(No.50).
文摘Owing to abundant resource and affordable price,metal-free carbon has been extensively studied in the field of oxygen reduction reaction,while the related studies on oxygen evolution reaction(OER)are quite few.In this work,a facile and scalable knife coating coupled with annealing strategy is proposed to produce self-standing oxygen-doped graphene membranes(marked as O-GM-T,T represents the annealing temperature).Through systematic characterization and analysis,it is discovered the annealing treatment not only decreases the amount of oxygenic groups,but allows for controlled regulation of the oxygen configurations,leaving only C-OH/C-O-C and C=O.Meanwhile,theoretical calculations indicate that the OER activity trend of different oxygen configurations is as follows:-COOH>C=O≈C-OH>C-O-C.Despite the removal of highly active-COOH group through annealing treatment,the resulting O-GM-800 sample maintains good mechanical property and achieves a favorable balance on conductivity,hydrophilicity and catalytic sites.Consequently,it displays significantly improved OER performance compared to the counterparts,making it highly promising for applications in overall water splitting devices.Apparently,our work provides guidance for the rational design and controllable fabrication of self-standing carbon-based catalysts for energy-related reactions.
基金supported by the National Natural Science Foundation of China(No.52173155)the Natural Science Foundation of Jilin Province(Nos.YDZJ202101ZYTS130,YDZJ202101ZYTS059)the Natural Science Foundation of Chongqing(Nos.cstc2021jcyj-msxmX1076,cstc2021jcyj-msxmX0798).
文摘A self-standing dual-electric field synergistic[TiO_(2)/polyvinylidene fluoride(PVDF)]//[g-C3 N4 tube/PVDF]Janus nanofibres(named as[TP]//[CTP]JNs)S-scheme heterostructure piezoelectric photocatalyst is designed and constructed via conjugative electrospinning.Dual-fields of built-in electric fields supplied by S-scheme heterostructure and piezoelectric field formed by PVDF jointly boost separation and transfer of photo-induced charges.As a case study,piezoelectric photocatalytic efficiency of[TP]//[CTP]JNs for tetracycline hydrochloride(TCH)under ultrasonic united with simulated sunlight illumination is 93.35%(40 min),which is 1.39 times of the photocatalytic efficiency(light illumination only)and 5.32 times of piezoelectric catalytic efficiency(applying ultrasonic only),proving the advantages of the synergistic effect of piezoelectric catalysis and photocatalysis on contaminant degradation.The dynamic behaviors of photocatalysis and photo-generated charges are deeply revealed through fs-TA and TRPL decay spectra,and the degradation pathways of antibiotics are reasonably speculated by combining LCMS spectra with Fukui index.By the degradation ability,COMSOL simulation and DFT calculation,the structural advantage of Janus nanofibers is fully verified,and S-scheme charge transfer mechanism is confirmed by combining a series of sound ample experiments with theoretical calculations.Additionally,the construction mechanism of Janus nanofibers is proposed,and corresponding construction technique is established.
基金supported by National Natural Science Foundation of China (Grant No. 51005117)Graduate Innovation Fund of Nanjing University of Aeronautics and Astronautics,China (Grant No.KFJJ20110223)Priority Academic Program Development of Jiangsu Higher Education Institutions of China (PAPD)
文摘Chemical vapor deposited （CVD） diamond film has broad application foreground in high-tech fields. But polycrystalline CVD self-standing diamond thick film has rough surface and non-uniform thickness that adversely affect its extensive applications. Laser polishing is a useful method to smooth self-standing diamond film. At present, attentions have been focused on experimental research on laser polishing, but the revealing of theoretical model and the forecast of polishing process are vacant. The paper presents a finite element model to simulate and analyze the mechanism of laser polishing diamond based on laser thermal conduction theory. The experimental investigation is also carried out on Nd：YAG pulsed laser smoothing diamond thick film. The simulation results have good accordance with the results of experimental results. The temperature and thermal stress fields are investigated at different incidence angles and parameters of Nd：YAG pulsed laser. The pyramidal-like roughness of diamond thick film leads to the non-homogeneous temperature fields. The temperature at the peak of diamond film is much higher than that in the valley, which leads to the smoothing of diamond thick film. The effect of laser parameters on the surface roughness and thickness of graphite transition layer is also carried out. The results show that high power density laser makes the diamond surface rapid heating, evaporation and sublimation after its graphitization. It is also found that the good polish quality of diamond thick film can be obtained by a combination of large incident angle, moderate laser pulsed energy, large repetition rate and moderate laser pulse width. The results obtained here provide the theoretical basis for laser polishing diamond film with high efficiency and high quality.
基金supported by 100 Talents Programme of the Chinese Academy of SciencesNational Program on Key Basic Research Project of China(973 Program,Grant No.2012CB215500)+1 种基金Foundation for Innovative Research Groups of the National Natural Science Foundation of China(Grant No.20921002 and No.21101147)the Science and Technology Development Program of Jilin Province(Grant No.20100102 and 20116008)
文摘Supercapacitors（SCs） have attracted much attention as one of the alternative energy devices due to their high power performance,long cycle life,and low maintenance cost.Graphene is considered as an innovative and promising material due to its large theoretical specific surface area,high electrical conductivity,good mechanical properties and chemical stability.Herein,we report an effective strategy for elaborately constructing rationally functionalized self-standing graphene（SG） obtained from giant graphene oxide（GGO） paper followed by an ultrarapid thermal-processing.This treatment results in both the exfoliation of graphene sheets and the reduction of GGO by elimination of oxygencontaining groups.The as-prepared SG electrode materials without additive and conducting agent provide an excellent combination of the electrical double layer capacitor（EDLC） and pseudocapacitor（PC） functions and exhibit superior electrochemical performance,including high specific capacitance,good rate capability and excellent cycling stability when investigated in three-electrode electrochemical cells.
基金This work was financially supported by the National Natural Science Foundation of China(51773165,51973171)Innovation Capability Support Program of Shaanxi(2018PT-28,2019PT-05).
文摘Lithium-sulfur(Li-S) batteries have attracted considerable attention due to their high energy density(2600 Wh kg-1). However, its commercialization is hindered seriously by the low loading and utilization rate of sulfur cathodes. Herein, we designed the cellulose-based graphene carbon composite aerogel(CCA) self-standing electrode to enhance the performance of Li-S batteries. The CCA contributes to the mass loading and utilization efficiency of sulfur, because of its unique physical structure: low density(0.018 g cm-3), large specific surface area(657.85 m2 g-1), high porosity(96%), and remarkable electrolyte adsorption(42.25 times). Compared to Al(about 49%), the CCA displayed excellent sulfur use efficiency(86%) and could reach to high area capacity of 8.60 mAh cm-2 with 9.11 mgS loading. Meanwhile,the CCA exhibits the excellent potential for pulse sensing applications due to its flexibility and superior sensitivity to electrical response signals.
基金supported by the National Natural Science Foundation of China(21975074 and 21838003)the Basic Research Program of Shanghai(17JC1402300)+1 种基金Shanghai Scientific and Technological Innovation Project(18JC1410500)the Fundamental Research Funds for the Central Universities(222201718002)。
文摘Restraining the aggregation and polysulfide dissolution of edge-enriched metal sulfides is of significance for their applications as anode materials of lithium-ion batteries(LIBs)with high capacity and long cycle-life.In this work,we have reported the incorporation of MoS2 nanocrystals into amorphous carbon on the surface of reduced graphene oxide(rGO)by balancing the decomposition rates of phenolic resin(PF)-impregnated ammonium thiomolybdate(ATM),which subsequently forms the MoS2@C/rGO film through redispersion and vacuum filtration.Such structural design effectively avoids the aggregation of MoS2 nanocrystals and Li2S loss,and meanwhile ion enrichment in amorphous carbon and diffusion reinforcement can greatly accelerate the electrochemical reaction kinetics.When applied as the selfstanding anode,the MoS2@C/rGO film possesses high reversible capacities of 1164 mA h g^-1 at the current density of 0.2 A g^-1 and 810 mA h g^-1 at 6.4 A g^-1.It also exhibits quite a high capacity retention after 1000 cycles at 3.2 A g^-1.This work develops the formation theory of incorporation structures and promotes their applications in energy storage devices.
文摘Ultrasmall y-Fe203 nanodots （- 3.4 nm） were homogeneously encapsulated in interlinked porous N-doped carbon nanofibers （labeled as Fe2O3@C） at a considerable loading （-51 wt.%） via an electrospinning technique. Moreover, the size and content of Fe2O3 could be controlled by adjusting the synthesis conditions. The obtained Fe203@C that functioned as a self-standing membrane was used directly as a binder- and current collector-free anode for sodium-ion batteries, displaying fascinating electrochemical performance in terms of the exceptional rate capability （529 mA.h.gq at 100 mA-g-1 compared with 215 mA-h-g-1 at 10,000 mA.g-1） and unprecedented cyclic stability （98.3% capacity retention over 1,000 cycles）. Furthermore, the Na-ion full cell constructed with the Fe2O3C anode and a P2-Na2/3Ni1/3Mn2/302 cathode also exhibited notable durability with 97.2% capacity retention after 300 cycles. This outstanding performance is attributed to the distinctive three-dimensional network structure of the very-fine Fe203 nanoparticles uniformly embedded in the interconnected porous N-doped carbon nanofibers that effectively facilitated electronic/ionic transport and prevented active materials pulverization/aggregation caused by volume change upon prolonged cycling. The simple and scalable preparation route, as well as the excellent electrochemical performance, endows the Fe2O3@C nanofibers with great prospects as high-rate and long-life Na-storage anode materials.
基金National Natural Science Foundation of China (No. 21503116)The Taishan Scholars Program of Shandong Province (Nos. tsqn20161004 and ts201712011)the Youth 1000 Talent Program of China are also acknowledged.
文摘Rechargeable lithium-iodine (Li-I2) battery is a promising energy storage system because of the high energy and power density. However, the shuttle effects of iodine species and the unstable features of l2 block the practical applications of Li-I2 batteries. Herein, a dual heteroatom doped porous carbon cloth is fabricated as the host material for lithium iodide (Lil). Specifically, the self-standing nitrogen, phosphorus co-doped carb on cloth with high Lil loading exhibits a large specific capacity (221 mAh·g^-1 at 1 C), excelle nt rate capability (95.8% capacity rete ntion at 5 C) and superior I ong cycli ng stability (2,000 cycles with a capacity rete ntion of 96%). Electrochemical kin etic an alysis con firms the domi nant contribution of capacitive effects at high sean rates, which is responsible for the good high-rate performance. The improved electrochemical performance mainly stems from two unique features of nitrogen, phosphorus co-doped porous carbon cloth. Heteroatom doping provides extra active sites for strong adsorption of iodine species while the highly porous structure with large surface area favors the capacitive effects at high rates. This work provides a facile yet efficient approach to regulating both redox reaction and capacitive effects via adjusting surface composition and pore structure of carbon materials for en hanced battery performance.
基金support from the National Natural Science Foundation of China(nos.51722207 and 51372131)973 Program of China(nos.2015CB932500 and 2014CB932401)+2 种基金Beijing Nova Program(no.Z161100004916099)the International Collaboration Project of Tsinghua University Initiative Scientific Research Program(no.20173080001)Chinese Postdoctoral Science Foundation(no.2015M570092)
文摘Developing high-performance noble metal-free and free-standing catalytic electrodes are crucial for overall water splitting. Here, nickel sulfide（NiS） and nickel selenide（Ni Se） are synthesized on nickel foam（NF） with a one-pot solvothermal method and directly used as free-standing electrodes for efficiently catalyzing hydrogen evolution reaction（HER） and oxygen evolution reaction（OER） in alkaline solution.In virtue of abundant active sites, the NiS/NF and the NiS e/NF electrodes can deliver a current density of 10 m A cmat only 123 m V, 137 m V for HER and 222 m V, 271 m V for OER. Both of the hierarchical NiS/NF and Ni Se/NF electrodes can serve as anodes and cathodes in electrocatalytic overall watersplitting and can achieve a current density of 10 m A cmwith an applied voltage of.59 V and 1.69 V,respectively. The performance of as-obtained NiS/NF||NiS/NF is even close to that of the noble metalbased Pt/C/NF||IrO/NF system.
基金financially supported by the National Natural Science Foundation of China(Nos.52072151,52171211,52102253,52271218 and U22A20145)Jinan Independent Innovative Team(No.2020GXRC015)+1 种基金the Major Program of Shandong Province Natural Science Foundation(No.ZR2021ZD05)the Science and Technology Program of University of Jinan(Nos.XKY2119 and XKY2304)。
文摘The shuttling diffusion of polysulfides is a bottleneck that seriously limits the performance of Li-S batteries.Purposeful construction of sulfur cathodes with reliable trapping ability of polysulfides is the key to overcome such limitation.Herein,a hierarchical porous architecture,i.e.,Co(OH)_(2)sheets bonded Ti_3C_(2)T_x MXene aerogel(Co(OH)_(2)/MXA),is constructed via a facile selfassembled approach and used as an efficient free-standing polysulfides reservoir.The interconnected three-dimensional(3D)porous network with void space and strong interfacial interaction not only enables high sulfur loading but facilitates fast ion and electron transport.Experimental and theoretical results confirm the hetero-framework exhibits outstanding immobilization and conversion ability for polysulfides due to its polar surface and bifunctional catalytic activities toward both formation and decomposition of Li2S.The optimized Co(OH)_(2)/MXA cathode delivers excellent rate capability(407 mAh·g^(-1)at 5C)with a sulfur loading of 2.7 mg·cm^(-2),and ultra-stable cycling performance as an extremely small capacity decay of~0.005%per cycle within 1700 cycles at 1C is achieved with a high sulfur loading of 6.7 mg·cm^(-2).More significantly,our design structural/componential methodology here promises the MXene-based aerogel electrodes for LiS batteries and beyond.
基金China Scholarship Council/University College London for joint PhD scholarships,Engineering and Physical Sciences Research Council(EPSRC,EP/V027433/1,EP/L015862/1,EP/R023581/1)supported by the Royal Academy of Engineering under the Research Chairs and Senior Research Fellowships scheme(Brett and Shearing)the Royal Society(RGS\R1\211080,IEC\NSFC\201261)for funding support.
文摘The development of low-cost,robust and efficient non-noble metal electrocatalysts is still a pursuit for the hydrogen evolution reaction(HER).Herein,a self-standing electrocatalyst,Ni_(2)P/CoP nanosheet,was fabricated directly on three-dimensional Ni foams by two facile steps,which illustrated both high activity and stability for HER in different electrolytes.Benefiting from the porous structures of nanosheets with large specific surface area and the hybrid Ni_(2)P/CoP,the as-prepared electrocatalyst presented remarkable HER with overpotentials of 65.2 and 87.8 mV to reach a current density of-10 mA cm^(-2)in neutral and alkaline media,respectively.Density function theory calculations revealed a lower activation energy of water dissociation and efficient HER steps of hybrid Ni_(2)P/CoP nanosheets compared with mono CoP.The self-standing electrocatalyst maintained excellent chemical stability.Additionally,the HER process in domestic wastewater was realized with more impressive performance by using Ni_(2)P/CoP nanosheets compared with commercial Pt/C.Hydrogen was continuously generated for 20 h in mildly alkaline dishwashing wastewater.This work provides a feasible way to fabricate non-noble metal and self-standing hybrid bimetallic phosphides for HER in neutral and alkaline media,showing great potential for efficient hydrogen production by re-utilizing wastewater resources.
基金This work was financially supported by National Natural Science Foundation of China(Grant Nos.52104309 and 52072274)We also acknowledge the fund of Hubei Natural Science Foundation(2021CFB011)the support of“Macao Young Scholars Program”,China(AM2020004).
文摘The structure of sulfur host materials plays a key role in alleviating the shuttle effect,volume expansion and sluggish redox reaction of lithium–sulfur batteries(LSBs).In this work,the well-designed multichannel carbon fibers decorated by carbon nanotubes(CNTs)and CoS nanoparticles(MCF/CoS/CNT)are synthesized and serve as the flexible sulfur host.The in situ grown CNTs network and embedded CoS enhance the overall conductivity of electrode and facilitate the redox reaction of sulfur-related electrochemistry.Benefitting from these merits,the MCF/CoS/CNT-based cathode exhibits a high reversible capacity of 927 mAh g^(−1) after 180 cycles with a low decay of 0.034%per cycle at 1.0 C.A superb areal capacity of 5.2 mAh cm^(−2) could be obtained under a high sulfur loading of 6.3 mg cm^(−2) and an ultralow electrolyte/sulfur ratio of 6.5μL mg^(−1) after 100 cycles.This work offers a promising approach to the reasonable design of flexible sulfur host for LSBs toward high energy density.
基金the National Natural Science Foundation of China(No.22005147)the Natural Science Foundation of Fujian Province(No.2020J01419,No.2020J05220).
文摘Developing effective electrodes with commercial-level active mass-loading(>10 mg cm^(−2))is vital for the practical application of supercapacitors.However,high active mass-loading usually requires thick active mass layer,which severely hinders the ion/electron transport and results in poor capacitive performance.Herein,a self-standing biochar electrode with active mass-loading of ca.40 mg cm^(−2) and thickness of 800μm has been developed from basswood.The basswood was treated with formamide to incorporate N/O in the carbon structure,followed by mild KOH activation to ameliorate the pore size and introduce more O species in the carbon matrix.The as-prepared carbon monoliths possess well conductive carbon skeleton,abundant N/O dopant and 3D porous structure,which are favorable for the ion/electron transport and promoting capacitance performance.The self-standing carbon electrode not only exhibits the maximum areal/mass/volumetric specific capacitance of 5037.5 mF cm^(−2)/172.5 F g^(−1)/63.0 F cm^(−3) at 2 mA cm^(−2)(0.05 A g^(−1)),but also displays excellent rate performance with 76%capacitance retention at 500 mA cm^(−2)(12.5 A g^(−1))in a symmetric supercapacitor,surpassing the state-of-art biomass-based thick carbon electrode.The assembled model can power typical electron devices including a fan,a digital watch and a logo made up of 34 light-emitting diodes for a proper period,revealing its practical application potential.This study not only puts forward a commercial-level high active mass-loading electrode from biomass for supercapacitor,but also bridges the gap between the experimental research and practical application.
基金National Natural Science Foundation of China,Grant/Award Numbers:22125110,U23A2094,22205233,22193042,21921001,U21A2069,22305248Natural Science Foundation of Fujian Province,Grant/Award Numbers:2023J02028,2023J01235+2 种基金Key Research Program of Frontier Sciences of Chinese Academy of Sciences,Grant/Award Number:ZDBSLY-SLH024Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China,Grant/Award Number:2021ZR126China Postdoctoral Science Foundation,Grant/Award Number:2023M733497。
文摘Soft molecule-based ferroelectrics with unique structural flexibility hold apromise for versatile applications of non-volatile memory, imaging and photovoltaicdevices. Except for few polymers (e.g., polyvinylidene fluoride, PVDF),it is challenging to exploit soft ferroelectric crystals toward free-standing flexiblephotoactive devices. We here report a multiaxial soft molecule-based ferroelectric,(n-PA)_(2)PbCl_(4) (1, where n-PA^(+)is n-pentylammonium), of whichspontaneous polarization can be reversibly switched in both crystal and powderforms. Strikingly, single crystals of 1 have unusual structural flexibility andbendability, achieving the self-standing bending with a bending radius of0.22 mm. Besides, the pyroelectric activities are also preserved for these singlecrystals after several bending cycles. Further, the bendable crystal-basedphotodetector of 1 allows broadband photoactivities via the photo-pyroelectriceffect, covering a wide range from 405 to 940 nm spectral region, breakingthrough the limit of optical absorption bandgap. As the first study of bendablefree-standing photo-pyroelectric detectors in ferroelectric crystals, our worksheds light on the assembly of flexible smart photoelectric devices.
