Hybrid capacitive deionization(HCDI)shows promise for desalinating brackish and saline water by utilizing the pseudocapacitive properties of faradaic electrodes.Organic materials,with their low environmental impact an...Hybrid capacitive deionization(HCDI)shows promise for desalinating brackish and saline water by utilizing the pseudocapacitive properties of faradaic electrodes.Organic materials,with their low environmental impact and adaptable structures,are attractive for this application.However,their scarcity of active sites and tendency to dissolve in water-based solutions remain significant challenges.Herein,we synthesized a polynaphthalenequinoneimine(PCON)polymer with stable long-range ordered framework and rough three-dimensional floral surface morphology,along with high-density active sites provided by C=O and C=N functional groups,enabling efficient redox reactions and achieving a high Na^(+)capture capability.The synthesized PCON polymer showcases outstanding electroadsorption characteristics and notable structural robustness,attaining an impressive specific capacitance of 500.45 F g^(-1) at 1 A g^(-1) and maintaining 86.1%of its original capacitance following 5000 charge–discharge cycles.Benefiting from the superior pseudocapacitive properties of the PCON polymer,we have developed an HCDI system that not only exhibits exceptional salt removal capacity of 100.8 mg g^(-1) and a remarkable rapid average removal rate of 3.36 mg g^(-1) min-1 but also maintains 97%of its initial desalination capacity after 50 cycles,thereby distinguishing itself in the field of state-ofthe-art desalination technologies with its comprehensive performance that significantly surpasses reported organic capacitive deionization materials.Prospectively,the synthesis paradigm of the double active-sites PCON polymer may be extrapolated to other organic electrodes,heralding new avenues for the design of high-performance desalination systems.展开更多
In recent decades,capacitive pressure sensors(CPSs)with high sensitivity have demonstrated significant potential in applications such as medical monitoring,artificial intelligence,and soft robotics.Efforts to enhance ...In recent decades,capacitive pressure sensors(CPSs)with high sensitivity have demonstrated significant potential in applications such as medical monitoring,artificial intelligence,and soft robotics.Efforts to enhance this sensitivity have predominantly focused on material design and structural optimization,with surface microstructures such as wrinkles,pyramids,and micro-pillars proving effective.Although finite element modeling(FEM)has guided enhancements in CPS sensitivity across various surface designs,a theoretical understanding of sensitivity improvements remains underexplored.This paper employs sinusoidal wavy surfaces as a representative model to analytically elucidate the underlying mechanisms of sensitivity enhancement through contact mechanics.These theoretical insights are corroborated by FEM and experimental validations.Our findings underscore that optimizing material properties,such as Young’s modulus and relative permittivity,alongside adjustments in surface roughness and substrate thickness,can significantly elevate the sensitivity.The optimal performance is achieved when the amplitude-to-wavelength ratio(H/)is about 0.2.These results offer critical insights for designing ultrasensitive CPS devices,paving the way for advancements in sensor technology.展开更多
Low-electrode capacitive deionization(FCDI)is an emerging desalination technology with great potential for removal and/or recycling ions from a range of waters.However,it still suffers from inefficient charge transfer...Low-electrode capacitive deionization(FCDI)is an emerging desalination technology with great potential for removal and/or recycling ions from a range of waters.However,it still suffers from inefficient charge transfer and ion transport kinetics due to weak turbulence and low electric intensity in flow electrodes,both restricted by the current collectors.Herein,a new tip-array current collector(designated as T-CC)was developed to replace the conventional planar current collectors,which intensifies both the charge transfer and ion transport significantly.The effects of tip arrays on flow and electric fields were studied by both computational simulations and electrochemical impedance spectroscopy,which revealed the reduction of ion transport barrier,charge transport barrier and internal resistance.With the voltage increased from 1.0 to 1.5 and 2.0 V,the T-CC-based FCDI system(T-FCDI)exhibited average salt removal rates(ASRR)of 0.18,0.50,and 0.89μmol cm^(-2) min^(-1),respectively,which are 1.82,2.65,and 2.48 folds higher than that of the conventional serpentine current collectors,and 1.48,1.67,and 1.49 folds higher than that of the planar current collectors.Meanwhile,with the solid content in flow electrodes increased from 1 to 5 wt%,the ASRR for T-FCDI increased from 0.29 to 0.50μmol cm^(-2) min^(-1),which are 1.70 and 1.67 folds higher than that of the planar current collectors.Additionally,a salt removal efficiency of 99.89%was achieved with T-FCDI and the charge efficiency remained above 95%after 24 h of operation,thus showing its superior long-term stability.展开更多
Capacitive voltage transformers (CVTs) are essential in high-voltage systems. An accurate error assessment is crucial for precise energy metering. However, tracking real-time quantitative changes in capacitive voltage...Capacitive voltage transformers (CVTs) are essential in high-voltage systems. An accurate error assessment is crucial for precise energy metering. However, tracking real-time quantitative changes in capacitive voltage transformer errors, particularly minor variations in multi-channel setups, remains challenging. This paper proposes a method for online error tracking of multi-channel capacitive voltage transformers using a Co-Prediction Matrix. The approach leverages the strong correlation between in-phase channels, particularly the invariance of the signal proportions among them. By establishing a co-prediction matrix based on these proportional relationships, The influence of voltage changes on the primary measurements is mitigated. Analyzing the relationships between the co-prediction matrices over time allows for inferring true measurement errors. Experimental validation with real-world data confirms the effectiveness of the method, demonstrating its capability to continuously track capacitive voltage transformer measurement errors online with precision over extended durations.展开更多
Solar-driven interface evaporation with high solar-to-steam conversion efficiency has shown great potential in seawater desalination.However,due to the influence of latent heat and condensation efficiency,the water yi...Solar-driven interface evaporation with high solar-to-steam conversion efficiency has shown great potential in seawater desalination.However,due to the influence of latent heat and condensation efficiency,the water yield from solar-driven interface evaporation remains insufficient,posing a significant challenge that requires resolution.In this work,we designed a dual-mode high-flux seawater desalination device that combines solar-driven interface evaporation and capacitive desalination.By utilizing coupled desalination materials exhibiting both photothermal conversion and capacitance activity,the device demonstrated photothermal evaporation rates of 1.41 and 0.97 kg m^(-2)h^(-1)for condensate water yield under one-sun irradiation.Additionally,the device exhibited a salt adsorption capacity of up to48 mg g^(-1)and a salt adsorption rate of 2.1 mg g^(-1)min-1.In addition,the salt adsorption capacity increased by approximately 32%under one-sun irradiation.Furthermore,photo-enhanced capacitive desalination performance was explored through numerical simulations and theoretical calculations.Theoretical calculations and characterizations confirmed that the defect energy levels formed by the introduction of sulfur vacancies can effectively widen the light absorption range,improve photothermal conversion performance,and stimulate more photoelectrons to participate in capacitive desalination.Concurrently,the electron distribution state of molybdenum disulfide with sulfur vacancies and surface defect sites contributes to ion/electron transport at the solid-liquid interface.This work provides a novel pathway for integrating solar vapor generation with other low-energy desalination technologies.展开更多
Conductive hydrogel membranes with nanofluids channels represent one of the most promising capacitive electrodes due to their rapid kinetics of ion transport.The construction of these unique structures always requires...Conductive hydrogel membranes with nanofluids channels represent one of the most promising capacitive electrodes due to their rapid kinetics of ion transport.The construction of these unique structures always requires new self-assembly behaviors with different building blocks,intriguing phenomena of colloidal chemistry.In this work,by delicately balancing the electrostatic repulsions between 2D inorganic nanosheets and the electrostatic adsorption with cations,we develop a general strategy to fabricate stable free-standing 1T molybdenum disulphide(MoS_(2))hydrogel membranes with abundant fluidic channels.Given the interpenetrating ionic transport network,the MoS_(2)hydrogel membranes exhibit a highlevel capacitive performance 1.34 F/cm^(2)at an ultrahigh mass loading of 11.2 mg/cm^(2).Furthermore,the interlayer spacing of MoS_(2)in the hydrogel membranes can be controlled with angstrom-scale precision using different cations,which can promote further fundamental studies and potential applications of the transition-metal dichalcogenides hydrogel membranes.展开更多
Electrode materials with high desalination capacity and long-term cyclic stability are the focus of capacitive deionization(CDI) community. Understanding the causes of performance decay in traditional carbons is cruci...Electrode materials with high desalination capacity and long-term cyclic stability are the focus of capacitive deionization(CDI) community. Understanding the causes of performance decay in traditional carbons is crucial to design a high-performance material. Based on this, here, nitrogen-doped activated carbon(NAC) was prepared by pyrolyzing the blend of activated carbon powder(ACP) and melamine for the positive electrode of asymmetric CDI. By comparing the indicators changes such as conductivity, salt adsorption capacity, pH, and charge efficiency of the symmetrical ACP-ACP device to the asymmetric ACP-NAC device under different CDI cycles, as well as the changes of the electrochemical properties of anode and cathode materials after long-term operation, the reasons for the decline of the stability of the CDI performance were revealed. It was found that the carboxyl functional groups generated by the electro-oxidation of anode carbon materials make the anode zero-charge potential(E_(pzc)) shift positively,which results in the uneven distribution of potential windows of CDI units and affects the adsorption capacity. Furthermore, by understanding the electron density on C atoms surrounding the N atoms, we attribute the increased cyclic stability to the enhanced negativity of the charge of carbon atoms adjacent to quaternary-N and pyridinic-oxide-N.展开更多
Flow-electrode capacitive deionization(FCDI)represents a promising approach for ion separation from aqueous solutions.However,the optimization of spacer,particularly for nitrate-contaminated groundwa-ter systems,has o...Flow-electrode capacitive deionization(FCDI)represents a promising approach for ion separation from aqueous solutions.However,the optimization of spacer,particularly for nitrate-contaminated groundwa-ter systems,has often been overlooked.This research comprehensively investigates the influence of using a conductive(carbon cloth,CC)spacer on nitrate removal performance within FCDI system,comparing it to a non-conductive(nylon net,NN)spacer.In both CC and NN FCDI systems,it is unsurprisingly that nitrate removal efficiency improved notably with the increasing current density and hydraulic retention time(HRT).Interestingly,the specific energy consumption(SEC)for nitrate removal did not show obvious fluctuations when the current density and HRT varied in both systems.Under the auspiciously optimized process parameters,CC-FCDI attained a 20%superior nitrate removal efficiency relative to NN-FCDI,ac-companied by a notably diminished SEC for CC-FCDI,registering at a mere 28%of NN-FCDI.This great improvement can be primarily attributed to the decrement in FCDI internal resistance after using con-ductive spacer,which further confirmed by electrochemical tests such as linear sweep voltammetry(LSV)and electrochemical impedance spectroscopy(EIS).Upon prolonged continuous nitrate removal at the optimized conditions,the CC-FCDI system achieved a consistent 90%nitrate removal efficiency with a low SEC of 2.7-7.8 kWh/kg NO_(3)-N,underscoring its steady performance.Overall,this study highlights the pivotal importance of careful spacer design and optimization in realizing energy-efficient groundwater treatment via FCDI.展开更多
Flexible pressure sensors have many potential applications in the monitoring of physiological signals because of their good biocompatibil-ity and wearability.However,their relatively low sensitivity,linearity,and stab...Flexible pressure sensors have many potential applications in the monitoring of physiological signals because of their good biocompatibil-ity and wearability.However,their relatively low sensitivity,linearity,and stability have hindered their large-scale commercial application.Herein,aflexible capacitive pressure sensor based on an interdigital electrode structure with two porous microneedle arrays(MNAs)is pro-posed.The porous substrate that constitutes the MNA is a mixed product of polydimethylsiloxane and NaHCO3.Due to its porous and interdigital structure,the maximum sensitivity(0.07 kPa-1)of a porous MNA-based pressure sensor was found to be seven times higher than that of an imporous MNA pressure sensor,and it was much greater than that of aflat pressure sensor without a porous MNA structure.Finite-element analysis showed that the interdigital MNA structure can greatly increase the strain and improve the sensitivity of the sen-sor.In addition,the porous MNA-based pressure sensor was found to have good stability over 1500 loading cycles as a result of its bilayer parylene-enhanced conductive electrode structure.Most importantly,it was found that the sensor could accurately monitor the motion of afinger,wrist joint,arm,face,abdomen,eye,and Adam’s apple.Furthermore,preliminary semantic recognition was achieved by monitoring the movement of the Adam’s apple.Finally,multiple pressure sensors were integrated into a 33 array to detect a spatial pressure distribu-×tion.Compared to the sensors reported in previous works,the interdigital electrode structure presented in this work improves sensitivity and stability by modifying the electrode layer rather than the dielectric layer.展开更多
A two-dimensional fluid model based on COMSOL Multiphysics is developed to investigate the modulation of static magnetic field on plasma homogeneity in a capacitively coupled plasma(CCP)chamber. To generate a static m...A two-dimensional fluid model based on COMSOL Multiphysics is developed to investigate the modulation of static magnetic field on plasma homogeneity in a capacitively coupled plasma(CCP)chamber. To generate a static magnetic field, direct current is applied to a circular coil located at the top of the chamber. By adjusting the magnetic field's configuration, which is done by altering the coil current and position, both the plasma uniformity and density can be significantly modulated. In the absence of the magnetic field, the plasma density exhibits an inhomogeneous distribution characterized by higher values at the plasma edge and lower values at the center. The introduction of a magnetic field generated by coils results in a significant increase in electron density near the coils. Furthermore, an increase in the sets of coils improves the uniformity of the plasma. By flexibly adjusting the positions of the coils and the applied current,a substantial enhancement in overall uniformity can be achieved. These findings demonstrate the feasibility of using this method for achieving uniform plasma densities in industrial applications.展开更多
The self-excited second harmonic in radio-frequency capacitively coupled plasma was significantly enhanced by adjusting the external variable capacitor.At a lower pressure of 3 Pa,the excitation of the second harmonic...The self-excited second harmonic in radio-frequency capacitively coupled plasma was significantly enhanced by adjusting the external variable capacitor.At a lower pressure of 3 Pa,the excitation of the second harmonic caused an abnormal transition of the electron energy probability function,resulting in abrupt changes in the electron density and temperature.Such changes in the electron energy probability function as well as the electron density and temperature were not observed at the higher pressure of 16 Pa under similar harmonic changes.The phenomena are related to the influence of the second harmonic on stochastic heating,which is determined by both amplitude and the relative phase of the harmonics.The results suggest that the self-excited high-order harmonics must be considered in practical applications of lowpressure radio-frequency capacitively coupled plasmas.展开更多
The effect of a negative DC bias,|V_(dc)|,on the electrical parameters and discharge mode is investigated experimentally in a radiofrequency(RF)capacitively coupled Ar plasma operated at different RF voltage amplitude...The effect of a negative DC bias,|V_(dc)|,on the electrical parameters and discharge mode is investigated experimentally in a radiofrequency(RF)capacitively coupled Ar plasma operated at different RF voltage amplitudes and gas pressures.The electron density is measured using a hairpin probe and the spatio-temporal distribution of the electron-impact excitation rate is determined by phase-resolved optical emission spectroscopy.The electrical parameters are obtained based on the waveforms of the electrode voltage and plasma current measured by a voltage probe and a current probe.It was found that at a low|V_(dc)|,i.e.inα-mode,the electron density and RF current decline with increasing|V_(dc)|;meanwhile,the plasma impedance becomes more capacitive due to a widened sheath.Therefore,RF power deposition is suppressed.When|V_(dc)|exceeds a certain value,the plasma changes toα–γhybrid mode(or the discharge becomes dominated by theγ-mode),manifesting a drastically growing electron density and a moderately increasing RF current.Meanwhile,the plasma impedance becomes more resistive,so RF power deposition is enhanced with|V_(dc)|.We also found that the electrical parameters show similar dependence on|V_(dc)|at different RF voltages,andα–γmode transition occurs at a lower|V_(dc)|at a higher RF voltage.By increasing the pressure,plasma impedance becomes more resistive,so RF power deposition and electron density are enhanced.In particular,theα–γmode transition tends to occur at a lower|V_(dc)|with increase in pressure.展开更多
A novel capacitive pressure sensor is presented, whose sensing structure is a solid-state capacitor consisting of three square membranes with Al/SiO2/n-type silicon. It was fabricated using pn junction self-stop etchi...A novel capacitive pressure sensor is presented, whose sensing structure is a solid-state capacitor consisting of three square membranes with Al/SiO2/n-type silicon. It was fabricated using pn junction self-stop etching combined with adhesive bonding,and only three masks were used during the process. Sensors with side lengths of 1000,1200,and 1400μm were fabricated,showing sensitivity of 1.8,2.3, and 3.6fF/hPa over the range of 410～ 1010hPa, respectively. The sensi- tivity of the sensor with a side length of 1500μm is 4. 6fF/hPa,the nonlinearity is 6. 4% ,and the max hysteresis is 3.6%. The results show that permittivity change plays an important part in the capacitance change.展开更多
A novel capacitive biaxial microaccelerometer with a highly symmetrical microstructure is developed. The sensor is composed of a single seismic mass, grid strip, supporting beam, joint beam, and damping adjusting comb...A novel capacitive biaxial microaccelerometer with a highly symmetrical microstructure is developed. The sensor is composed of a single seismic mass, grid strip, supporting beam, joint beam, and damping adjusting combs. The sensing method of changing capacitance area is used in the design,which depresses the requirement of the DRIE process, and de- creases electronic noise by increasing sensing voltage to improve the resolution. The parameters and characteristics of the biaxial microaccelerometer are discussed with the FEM tool ANSYS. The simulated results show that the transverse sensitivity of the sensor is equal to zero. The testing devices based on the slide-film damping effect are fabricated, and the testing quality factor is 514, which shows that the designed structure can improve the resolution and proves the feasibility of the designed process.展开更多
A novel capacitive microwave MEMS switch with a silicon/metal/dielectric as a membrane is fabricated successfully by bonding and etching-stop process. Its principal, design, and fabricating process are described in de...A novel capacitive microwave MEMS switch with a silicon/metal/dielectric as a membrane is fabricated successfully by bonding and etching-stop process. Its principal, design, and fabricating process are described in detail. A patterned dielectric layer, Ta2O5, with dielectric constant of 24 is reached. Experiment results show this novel structure,where the switch＇s dielectric layer is not prepared on the transmission line, features very low insertion loss. The insertion loss is 0.06dB at 2GHz and lower than 0.5dB in the wider range from De up to 20GHz,especially when the transmission line metal is only 0. 5μm thick.展开更多
A new instrument called capacitive drop analyser (CDA) for measuring the physical properties of liquid is developed.A delivery head with a specialized wetting design was constructed for forming drops.The capacitive tr...A new instrument called capacitive drop analyser (CDA) for measuring the physical properties of liquid is developed.A delivery head with a specialized wetting design was constructed for forming drops.The capacitive transducer uses the delivery head as one of its plates and a cylindrical ring plate.Excellent linearity is achieved by optimising the design,with an accuracy of drop volume measurement of approximately 2 μL.It is suitable for measuring both drops in equilibrium and those in the process of growing.Its capability of real time measurement makes it particularly useful for volatile liquids,in which instance the measurement of drop volume using a flowmeter or a pump is no longer reliable.The CDA can also be used to determine concentration.It is found that concentration curve is linear for aqueous glycerol solutions although not so for aqueous ethanol solution.The CDAs capability of measuring surface tension is also explored and experimental results are presented.展开更多
Electronic skin(e-skin) and flexible wearable devices are currently being developed with broad application prospects. Transforming electronic skin(e-skin) into true ¨skin¨is the ultimate goal. Tactile sensin...Electronic skin(e-skin) and flexible wearable devices are currently being developed with broad application prospects. Transforming electronic skin(e-skin) into true ¨skin¨is the ultimate goal. Tactile sensing is a fundamental function of skin and the development of high-performance flexible pressure sensors is necessary to realize thus. Many reports on flexible pressure sensors have been published in recent years,including numerous studies on improving sensor performance, and in particular, sensitivity. In addition,a number of studies have investigated self-healing materials, multifunctional sensing, and so on. Here,we review recent developments in flexible pressure sensors. First, working principles of flexible pressure sensors, including piezoresistivity, capacitance, and piezoelectricity, are introduced, as well as working mechanisms such as triboelectricity. Then studies on improving the performance of piezoresistive and capacitive flexible pressure sensors are discussed, in addition to other important aspects of this intriguing research field. Finally, we summarize future challenges in developing novel flexible pressure sensors.展开更多
The lack of methods to modulate intrinsic textures of carbon cathode has seriously hindered the revelation of in-depth relationship between inherent natures and capacitive behaviors,limiting the advancement of lithium...The lack of methods to modulate intrinsic textures of carbon cathode has seriously hindered the revelation of in-depth relationship between inherent natures and capacitive behaviors,limiting the advancement of lithium ion capacitors(LICs).Here,an orientateddesigned pore size distribution(range from 0.5 to 200 nm)and graphitization engineering strategy of carbon materials through regulating molar ratios of Zn/Co ions has been proposed,which provides an effective platform to deeply evaluate the capacitive behaviors of carbon cathode.Significantly,after the systematical analysis cooperating with experimental result and density functional theory calculation,it is uncovered that the size of solvated PF6-ion is about 1.5 nm.Moreover,the capacitive behaviors of carbon cathode could be enhanced attributed to the controlled pore size of 1.5-3 nm.Triggered with synergistic effect of graphitization and appropriate pore size distribution,optimized carbon cathode(Zn90Co10-APC)displays excellent capacitive performances with a reversible specific capacity of^50 mAh g-1at a current density of 5 A g-1.Furthermore,the assembly pre-lithiated graphite(PLG)//Zn90Co10-APC LIC could deliver a large energy density of 108 Wh kg-1 and a high power density of 150,000 W kg-1 as well as excellent long-term ability with 10,000 cycles.This elaborate work might shed light on the intensive understanding of the improved capacitive behavior in LiPF<sub>6 electrolyte and provide a feasible principle for elaborate fabrication of carbon cathodes for LIC systems.展开更多
In this paper, first a circular diaphragm is modeled using the classical plate theory. An analytical solution based on differential transformation method （DTM） and Runge-Kutta method is employed for solving the gove...In this paper, first a circular diaphragm is modeled using the classical plate theory. An analytical solution based on differential transformation method （DTM） and Runge-Kutta method is employed for solving the governing differential equation for the first time. Then the influences of various parameters on central deflection of the diaphragm, stress distribution and capacitance of pressure sensor with a time-dependent pressure are examined. Several case studies are compared with simulations to confirm the proposed method. The analytical results compared with ABAQUS simulation show excellent agreement with the simulation results. This method is very promising for time saving in calculating micro-device characteristics.展开更多
Biochars are low-cost and sustainable materials for environmental technologies.In this work,we pre-pared three biochars using pomelo peel(P-BC),algae(A-BC),and corncob(C-BC)to recover Cd^(2+)from wastewater via capaci...Biochars are low-cost and sustainable materials for environmental technologies.In this work,we pre-pared three biochars using pomelo peel(P-BC),algae(A-BC),and corncob(C-BC)to recover Cd^(2+)from wastewater via capacitive deionisation(CDI).A-BC possesses the highest amount of mesopores and nitro-gen functionality and attains the highest removal of Cd^(2+)via physical adsorption.For the electro-sorption capacity,C-BC and A-BC perform better capacitive removal of Cd^(2+)than P-BC due to the smaller charge-transfer and mass-transfer resistances.Also,this work investigated the impacts of surface morphology,cell voltage,NaCl,initial pH,and Cd^(2+)concentrations on Cd^(2+)capacitive removal and electrode regen-eration performances.The results indicated that A-BC and C-BC may be prospective materials for Cd^(2+)removal from wastewater by CDI.However,the presence of competing cations at high concentrations may influence the removal of Cd^(2+)at a low level,requiring the modification of A-BC and C-BC in future work.展开更多
基金supported by the National Key R&D Program of China(Grant Nos.2023YFC3009900)National Natural Science Foundation of China(Grant Nos.61904116)+1 种基金Natural Science Foundation of Jiangsu Province(Grant Nos.BK20211029)the young scientific talent lifting project of Jiangsu Association for Science and Technology(Grant Nos.JSTJ-2023-018).
文摘Hybrid capacitive deionization(HCDI)shows promise for desalinating brackish and saline water by utilizing the pseudocapacitive properties of faradaic electrodes.Organic materials,with their low environmental impact and adaptable structures,are attractive for this application.However,their scarcity of active sites and tendency to dissolve in water-based solutions remain significant challenges.Herein,we synthesized a polynaphthalenequinoneimine(PCON)polymer with stable long-range ordered framework and rough three-dimensional floral surface morphology,along with high-density active sites provided by C=O and C=N functional groups,enabling efficient redox reactions and achieving a high Na^(+)capture capability.The synthesized PCON polymer showcases outstanding electroadsorption characteristics and notable structural robustness,attaining an impressive specific capacitance of 500.45 F g^(-1) at 1 A g^(-1) and maintaining 86.1%of its original capacitance following 5000 charge–discharge cycles.Benefiting from the superior pseudocapacitive properties of the PCON polymer,we have developed an HCDI system that not only exhibits exceptional salt removal capacity of 100.8 mg g^(-1) and a remarkable rapid average removal rate of 3.36 mg g^(-1) min-1 but also maintains 97%of its initial desalination capacity after 50 cycles,thereby distinguishing itself in the field of state-ofthe-art desalination technologies with its comprehensive performance that significantly surpasses reported organic capacitive deionization materials.Prospectively,the synthesis paradigm of the double active-sites PCON polymer may be extrapolated to other organic electrodes,heralding new avenues for the design of high-performance desalination systems.
基金supported by the National Natural Science Foundation of China(Grant No.12272369)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0620101).
文摘In recent decades,capacitive pressure sensors(CPSs)with high sensitivity have demonstrated significant potential in applications such as medical monitoring,artificial intelligence,and soft robotics.Efforts to enhance this sensitivity have predominantly focused on material design and structural optimization,with surface microstructures such as wrinkles,pyramids,and micro-pillars proving effective.Although finite element modeling(FEM)has guided enhancements in CPS sensitivity across various surface designs,a theoretical understanding of sensitivity improvements remains underexplored.This paper employs sinusoidal wavy surfaces as a representative model to analytically elucidate the underlying mechanisms of sensitivity enhancement through contact mechanics.These theoretical insights are corroborated by FEM and experimental validations.Our findings underscore that optimizing material properties,such as Young’s modulus and relative permittivity,alongside adjustments in surface roughness and substrate thickness,can significantly elevate the sensitivity.The optimal performance is achieved when the amplitude-to-wavelength ratio(H/)is about 0.2.These results offer critical insights for designing ultrasensitive CPS devices,paving the way for advancements in sensor technology.
基金supported by the Shenzhen Science and Technology Program(JCYJ20230808105111022,JCYJ20220818095806013)Natural Science Foundation of Guangdong(2023A1515012267)+1 种基金the National Natural Science Foundation of China(22178223)the Royal Society/NSFC cost share program(IEC\NSFC\223372).
文摘Low-electrode capacitive deionization(FCDI)is an emerging desalination technology with great potential for removal and/or recycling ions from a range of waters.However,it still suffers from inefficient charge transfer and ion transport kinetics due to weak turbulence and low electric intensity in flow electrodes,both restricted by the current collectors.Herein,a new tip-array current collector(designated as T-CC)was developed to replace the conventional planar current collectors,which intensifies both the charge transfer and ion transport significantly.The effects of tip arrays on flow and electric fields were studied by both computational simulations and electrochemical impedance spectroscopy,which revealed the reduction of ion transport barrier,charge transport barrier and internal resistance.With the voltage increased from 1.0 to 1.5 and 2.0 V,the T-CC-based FCDI system(T-FCDI)exhibited average salt removal rates(ASRR)of 0.18,0.50,and 0.89μmol cm^(-2) min^(-1),respectively,which are 1.82,2.65,and 2.48 folds higher than that of the conventional serpentine current collectors,and 1.48,1.67,and 1.49 folds higher than that of the planar current collectors.Meanwhile,with the solid content in flow electrodes increased from 1 to 5 wt%,the ASRR for T-FCDI increased from 0.29 to 0.50μmol cm^(-2) min^(-1),which are 1.70 and 1.67 folds higher than that of the planar current collectors.Additionally,a salt removal efficiency of 99.89%was achieved with T-FCDI and the charge efficiency remained above 95%after 24 h of operation,thus showing its superior long-term stability.
文摘Capacitive voltage transformers (CVTs) are essential in high-voltage systems. An accurate error assessment is crucial for precise energy metering. However, tracking real-time quantitative changes in capacitive voltage transformer errors, particularly minor variations in multi-channel setups, remains challenging. This paper proposes a method for online error tracking of multi-channel capacitive voltage transformers using a Co-Prediction Matrix. The approach leverages the strong correlation between in-phase channels, particularly the invariance of the signal proportions among them. By establishing a co-prediction matrix based on these proportional relationships, The influence of voltage changes on the primary measurements is mitigated. Analyzing the relationships between the co-prediction matrices over time allows for inferring true measurement errors. Experimental validation with real-world data confirms the effectiveness of the method, demonstrating its capability to continuously track capacitive voltage transformer measurement errors online with precision over extended durations.
基金financially supported by research grants from the Natural Science Foundation of China(52173235,22265010,12204071,62074022)National Key Research and Development Program of China(2022YFB3803300)+2 种基金Youth Talent Support Program of Chongqing(CQYC2021059206)Hainan Province Science and Technology Special Fund(ZDYF2024SHFZ038)Science and Technology Innovation and Improving Project of Army Medical University(No.2021XJS24)。
文摘Solar-driven interface evaporation with high solar-to-steam conversion efficiency has shown great potential in seawater desalination.However,due to the influence of latent heat and condensation efficiency,the water yield from solar-driven interface evaporation remains insufficient,posing a significant challenge that requires resolution.In this work,we designed a dual-mode high-flux seawater desalination device that combines solar-driven interface evaporation and capacitive desalination.By utilizing coupled desalination materials exhibiting both photothermal conversion and capacitance activity,the device demonstrated photothermal evaporation rates of 1.41 and 0.97 kg m^(-2)h^(-1)for condensate water yield under one-sun irradiation.Additionally,the device exhibited a salt adsorption capacity of up to48 mg g^(-1)and a salt adsorption rate of 2.1 mg g^(-1)min-1.In addition,the salt adsorption capacity increased by approximately 32%under one-sun irradiation.Furthermore,photo-enhanced capacitive desalination performance was explored through numerical simulations and theoretical calculations.Theoretical calculations and characterizations confirmed that the defect energy levels formed by the introduction of sulfur vacancies can effectively widen the light absorption range,improve photothermal conversion performance,and stimulate more photoelectrons to participate in capacitive desalination.Concurrently,the electron distribution state of molybdenum disulfide with sulfur vacancies and surface defect sites contributes to ion/electron transport at the solid-liquid interface.This work provides a novel pathway for integrating solar vapor generation with other low-energy desalination technologies.
基金supported by the National Natural Science Foundation of China(Nos.22078214,21905206,and 22065013)Special Fund for Science and Technology Innovation Team of Shanxi Province(No.202204051001009)。
文摘Conductive hydrogel membranes with nanofluids channels represent one of the most promising capacitive electrodes due to their rapid kinetics of ion transport.The construction of these unique structures always requires new self-assembly behaviors with different building blocks,intriguing phenomena of colloidal chemistry.In this work,by delicately balancing the electrostatic repulsions between 2D inorganic nanosheets and the electrostatic adsorption with cations,we develop a general strategy to fabricate stable free-standing 1T molybdenum disulphide(MoS_(2))hydrogel membranes with abundant fluidic channels.Given the interpenetrating ionic transport network,the MoS_(2)hydrogel membranes exhibit a highlevel capacitive performance 1.34 F/cm^(2)at an ultrahigh mass loading of 11.2 mg/cm^(2).Furthermore,the interlayer spacing of MoS_(2)in the hydrogel membranes can be controlled with angstrom-scale precision using different cations,which can promote further fundamental studies and potential applications of the transition-metal dichalcogenides hydrogel membranes.
文摘Electrode materials with high desalination capacity and long-term cyclic stability are the focus of capacitive deionization(CDI) community. Understanding the causes of performance decay in traditional carbons is crucial to design a high-performance material. Based on this, here, nitrogen-doped activated carbon(NAC) was prepared by pyrolyzing the blend of activated carbon powder(ACP) and melamine for the positive electrode of asymmetric CDI. By comparing the indicators changes such as conductivity, salt adsorption capacity, pH, and charge efficiency of the symmetrical ACP-ACP device to the asymmetric ACP-NAC device under different CDI cycles, as well as the changes of the electrochemical properties of anode and cathode materials after long-term operation, the reasons for the decline of the stability of the CDI performance were revealed. It was found that the carboxyl functional groups generated by the electro-oxidation of anode carbon materials make the anode zero-charge potential(E_(pzc)) shift positively,which results in the uneven distribution of potential windows of CDI units and affects the adsorption capacity. Furthermore, by understanding the electron density on C atoms surrounding the N atoms, we attribute the increased cyclic stability to the enhanced negativity of the charge of carbon atoms adjacent to quaternary-N and pyridinic-oxide-N.
基金supported by Shanxi Province Basic Research Program(Free Exploration Category)(No.202203021221041)National Natural Science Foundation of China(No.52300016)+1 种基金China Postdoctoral Science Foundation(No.2023M733379)Students Innovation and Entrepreneurship Foundation of USTC(No.CY2022G12).
文摘Flow-electrode capacitive deionization(FCDI)represents a promising approach for ion separation from aqueous solutions.However,the optimization of spacer,particularly for nitrate-contaminated groundwa-ter systems,has often been overlooked.This research comprehensively investigates the influence of using a conductive(carbon cloth,CC)spacer on nitrate removal performance within FCDI system,comparing it to a non-conductive(nylon net,NN)spacer.In both CC and NN FCDI systems,it is unsurprisingly that nitrate removal efficiency improved notably with the increasing current density and hydraulic retention time(HRT).Interestingly,the specific energy consumption(SEC)for nitrate removal did not show obvious fluctuations when the current density and HRT varied in both systems.Under the auspiciously optimized process parameters,CC-FCDI attained a 20%superior nitrate removal efficiency relative to NN-FCDI,ac-companied by a notably diminished SEC for CC-FCDI,registering at a mere 28%of NN-FCDI.This great improvement can be primarily attributed to the decrement in FCDI internal resistance after using con-ductive spacer,which further confirmed by electrochemical tests such as linear sweep voltammetry(LSV)and electrochemical impedance spectroscopy(EIS).Upon prolonged continuous nitrate removal at the optimized conditions,the CC-FCDI system achieved a consistent 90%nitrate removal efficiency with a low SEC of 2.7-7.8 kWh/kg NO_(3)-N,underscoring its steady performance.Overall,this study highlights the pivotal importance of careful spacer design and optimization in realizing energy-efficient groundwater treatment via FCDI.
基金supported in part by the National Natural Science Foundation of China(Grant No.62104056)the Zhejiang Provincial Natural Science Foundation of China(Grant No.LQ21F010010)+4 种基金the National Natural Science Foundation of China(Grant Nos.62141409 and 62204204)the National Key R&D Program of China(Grant No.2022ZD0208602)the Zhejiang Provincial Key Research&Development Fund(Grant Nos.2019C04003 and 2021C01041)the Shanghai Sailing Program(Grant No.21YF1451000)the Key Research and Development Program of Shaanxi(Grant No.2022GY-001).
文摘Flexible pressure sensors have many potential applications in the monitoring of physiological signals because of their good biocompatibil-ity and wearability.However,their relatively low sensitivity,linearity,and stability have hindered their large-scale commercial application.Herein,aflexible capacitive pressure sensor based on an interdigital electrode structure with two porous microneedle arrays(MNAs)is pro-posed.The porous substrate that constitutes the MNA is a mixed product of polydimethylsiloxane and NaHCO3.Due to its porous and interdigital structure,the maximum sensitivity(0.07 kPa-1)of a porous MNA-based pressure sensor was found to be seven times higher than that of an imporous MNA pressure sensor,and it was much greater than that of aflat pressure sensor without a porous MNA structure.Finite-element analysis showed that the interdigital MNA structure can greatly increase the strain and improve the sensitivity of the sen-sor.In addition,the porous MNA-based pressure sensor was found to have good stability over 1500 loading cycles as a result of its bilayer parylene-enhanced conductive electrode structure.Most importantly,it was found that the sensor could accurately monitor the motion of afinger,wrist joint,arm,face,abdomen,eye,and Adam’s apple.Furthermore,preliminary semantic recognition was achieved by monitoring the movement of the Adam’s apple.Finally,multiple pressure sensors were integrated into a 33 array to detect a spatial pressure distribu-×tion.Compared to the sensors reported in previous works,the interdigital electrode structure presented in this work improves sensitivity and stability by modifying the electrode layer rather than the dielectric layer.
基金financially supported by the National MCF Energy R&D Program of China(No.2022YFE03190100)National Natural Science Foundation of China(Nos.11935005,12105035 and U21A20438)+2 种基金the Guangdong Basic and Applied Basic Research Foundation(No.2021B1515120018)the Fundamental Research Funds for the Central Universities(No.DUT21TD104)the Advanced Space Propulsion Laboratory of BICE and Beijing Engineering Research Center of Efficient and Green Aerospace Propulsion Technology(No.Lab ASP-2020-01).
文摘A two-dimensional fluid model based on COMSOL Multiphysics is developed to investigate the modulation of static magnetic field on plasma homogeneity in a capacitively coupled plasma(CCP)chamber. To generate a static magnetic field, direct current is applied to a circular coil located at the top of the chamber. By adjusting the magnetic field's configuration, which is done by altering the coil current and position, both the plasma uniformity and density can be significantly modulated. In the absence of the magnetic field, the plasma density exhibits an inhomogeneous distribution characterized by higher values at the plasma edge and lower values at the center. The introduction of a magnetic field generated by coils results in a significant increase in electron density near the coils. Furthermore, an increase in the sets of coils improves the uniformity of the plasma. By flexibly adjusting the positions of the coils and the applied current,a substantial enhancement in overall uniformity can be achieved. These findings demonstrate the feasibility of using this method for achieving uniform plasma densities in industrial applications.
文摘The self-excited second harmonic in radio-frequency capacitively coupled plasma was significantly enhanced by adjusting the external variable capacitor.At a lower pressure of 3 Pa,the excitation of the second harmonic caused an abnormal transition of the electron energy probability function,resulting in abrupt changes in the electron density and temperature.Such changes in the electron energy probability function as well as the electron density and temperature were not observed at the higher pressure of 16 Pa under similar harmonic changes.The phenomena are related to the influence of the second harmonic on stochastic heating,which is determined by both amplitude and the relative phase of the harmonics.The results suggest that the self-excited high-order harmonics must be considered in practical applications of lowpressure radio-frequency capacitively coupled plasmas.
基金financially supported by National Natural Science Foundation of China(NSFC)(Nos.12275043 and 11935005)the Fundamental Research Funds for the Central Universities(No.DUT21TD104)China Scholarship Council(No.202106060085)。
文摘The effect of a negative DC bias,|V_(dc)|,on the electrical parameters and discharge mode is investigated experimentally in a radiofrequency(RF)capacitively coupled Ar plasma operated at different RF voltage amplitudes and gas pressures.The electron density is measured using a hairpin probe and the spatio-temporal distribution of the electron-impact excitation rate is determined by phase-resolved optical emission spectroscopy.The electrical parameters are obtained based on the waveforms of the electrode voltage and plasma current measured by a voltage probe and a current probe.It was found that at a low|V_(dc)|,i.e.inα-mode,the electron density and RF current decline with increasing|V_(dc)|;meanwhile,the plasma impedance becomes more capacitive due to a widened sheath.Therefore,RF power deposition is suppressed.When|V_(dc)|exceeds a certain value,the plasma changes toα–γhybrid mode(or the discharge becomes dominated by theγ-mode),manifesting a drastically growing electron density and a moderately increasing RF current.Meanwhile,the plasma impedance becomes more resistive,so RF power deposition is enhanced with|V_(dc)|.We also found that the electrical parameters show similar dependence on|V_(dc)|at different RF voltages,andα–γmode transition occurs at a lower|V_(dc)|at a higher RF voltage.By increasing the pressure,plasma impedance becomes more resistive,so RF power deposition and electron density are enhanced.In particular,theα–γmode transition tends to occur at a lower|V_(dc)|with increase in pressure.
文摘A novel capacitive pressure sensor is presented, whose sensing structure is a solid-state capacitor consisting of three square membranes with Al/SiO2/n-type silicon. It was fabricated using pn junction self-stop etching combined with adhesive bonding,and only three masks were used during the process. Sensors with side lengths of 1000,1200,and 1400μm were fabricated,showing sensitivity of 1.8,2.3, and 3.6fF/hPa over the range of 410～ 1010hPa, respectively. The sensi- tivity of the sensor with a side length of 1500μm is 4. 6fF/hPa,the nonlinearity is 6. 4% ,and the max hysteresis is 3.6%. The results show that permittivity change plays an important part in the capacitance change.
文摘A novel capacitive biaxial microaccelerometer with a highly symmetrical microstructure is developed. The sensor is composed of a single seismic mass, grid strip, supporting beam, joint beam, and damping adjusting combs. The sensing method of changing capacitance area is used in the design,which depresses the requirement of the DRIE process, and de- creases electronic noise by increasing sensing voltage to improve the resolution. The parameters and characteristics of the biaxial microaccelerometer are discussed with the FEM tool ANSYS. The simulated results show that the transverse sensitivity of the sensor is equal to zero. The testing devices based on the slide-film damping effect are fabricated, and the testing quality factor is 514, which shows that the designed structure can improve the resolution and proves the feasibility of the designed process.
文摘A novel capacitive microwave MEMS switch with a silicon/metal/dielectric as a membrane is fabricated successfully by bonding and etching-stop process. Its principal, design, and fabricating process are described in detail. A patterned dielectric layer, Ta2O5, with dielectric constant of 24 is reached. Experiment results show this novel structure,where the switch＇s dielectric layer is not prepared on the transmission line, features very low insertion loss. The insertion loss is 0.06dB at 2GHz and lower than 0.5dB in the wider range from De up to 20GHz,especially when the transmission line metal is only 0. 5μm thick.
文摘A new instrument called capacitive drop analyser (CDA) for measuring the physical properties of liquid is developed.A delivery head with a specialized wetting design was constructed for forming drops.The capacitive transducer uses the delivery head as one of its plates and a cylindrical ring plate.Excellent linearity is achieved by optimising the design,with an accuracy of drop volume measurement of approximately 2 μL.It is suitable for measuring both drops in equilibrium and those in the process of growing.Its capability of real time measurement makes it particularly useful for volatile liquids,in which instance the measurement of drop volume using a flowmeter or a pump is no longer reliable.The CDA can also be used to determine concentration.It is found that concentration curve is linear for aqueous glycerol solutions although not so for aqueous ethanol solution.The CDAs capability of measuring surface tension is also explored and experimental results are presented.
基金supported by the National Natural Science Foundation of China(Nos.61775032,61475134 and 11604042)the Fundamental Research Funds for the Central Universities(N170405007,N180406002,N180408018 and N160404009)the 111 Project(B16009)。
文摘Electronic skin(e-skin) and flexible wearable devices are currently being developed with broad application prospects. Transforming electronic skin(e-skin) into true ¨skin¨is the ultimate goal. Tactile sensing is a fundamental function of skin and the development of high-performance flexible pressure sensors is necessary to realize thus. Many reports on flexible pressure sensors have been published in recent years,including numerous studies on improving sensor performance, and in particular, sensitivity. In addition,a number of studies have investigated self-healing materials, multifunctional sensing, and so on. Here,we review recent developments in flexible pressure sensors. First, working principles of flexible pressure sensors, including piezoresistivity, capacitance, and piezoelectricity, are introduced, as well as working mechanisms such as triboelectricity. Then studies on improving the performance of piezoresistive and capacitive flexible pressure sensors are discussed, in addition to other important aspects of this intriguing research field. Finally, we summarize future challenges in developing novel flexible pressure sensors.
基金financially supported by National Key Research and Development Program of China(2018YFC1901605)the National Postdoctoral Program for Innovative Talents(BX201600192)+1 种基金Hunan Provincial Science and Technology Plan(2017TP1001)Innovation Mover Program of Central South University(GCX20190893Y)。
文摘The lack of methods to modulate intrinsic textures of carbon cathode has seriously hindered the revelation of in-depth relationship between inherent natures and capacitive behaviors,limiting the advancement of lithium ion capacitors(LICs).Here,an orientateddesigned pore size distribution(range from 0.5 to 200 nm)and graphitization engineering strategy of carbon materials through regulating molar ratios of Zn/Co ions has been proposed,which provides an effective platform to deeply evaluate the capacitive behaviors of carbon cathode.Significantly,after the systematical analysis cooperating with experimental result and density functional theory calculation,it is uncovered that the size of solvated PF6-ion is about 1.5 nm.Moreover,the capacitive behaviors of carbon cathode could be enhanced attributed to the controlled pore size of 1.5-3 nm.Triggered with synergistic effect of graphitization and appropriate pore size distribution,optimized carbon cathode(Zn90Co10-APC)displays excellent capacitive performances with a reversible specific capacity of^50 mAh g-1at a current density of 5 A g-1.Furthermore,the assembly pre-lithiated graphite(PLG)//Zn90Co10-APC LIC could deliver a large energy density of 108 Wh kg-1 and a high power density of 150,000 W kg-1 as well as excellent long-term ability with 10,000 cycles.This elaborate work might shed light on the intensive understanding of the improved capacitive behavior in LiPF<sub>6 electrolyte and provide a feasible principle for elaborate fabrication of carbon cathodes for LIC systems.
文摘In this paper, first a circular diaphragm is modeled using the classical plate theory. An analytical solution based on differential transformation method （DTM） and Runge-Kutta method is employed for solving the governing differential equation for the first time. Then the influences of various parameters on central deflection of the diaphragm, stress distribution and capacitance of pressure sensor with a time-dependent pressure are examined. Several case studies are compared with simulations to confirm the proposed method. The analytical results compared with ABAQUS simulation show excellent agreement with the simulation results. This method is very promising for time saving in calculating micro-device characteristics.
基金financially supported by the fellow-ship of the China Postdoctoral Science Foundation(No.2022TQ0088)the National Natural Science Foundation of China(No.52000053)+1 种基金Shenzhen Science and Technology Program(No.GXWD20201230155427003-20200821174135002,RCBS20210706092219047,and KQTD20190929172630447)the Open Project of State Key Laboratory of Urban Water Resources and Environment(No.2021TS28).
文摘Biochars are low-cost and sustainable materials for environmental technologies.In this work,we pre-pared three biochars using pomelo peel(P-BC),algae(A-BC),and corncob(C-BC)to recover Cd^(2+)from wastewater via capacitive deionisation(CDI).A-BC possesses the highest amount of mesopores and nitro-gen functionality and attains the highest removal of Cd^(2+)via physical adsorption.For the electro-sorption capacity,C-BC and A-BC perform better capacitive removal of Cd^(2+)than P-BC due to the smaller charge-transfer and mass-transfer resistances.Also,this work investigated the impacts of surface morphology,cell voltage,NaCl,initial pH,and Cd^(2+)concentrations on Cd^(2+)capacitive removal and electrode regen-eration performances.The results indicated that A-BC and C-BC may be prospective materials for Cd^(2+)removal from wastewater by CDI.However,the presence of competing cations at high concentrations may influence the removal of Cd^(2+)at a low level,requiring the modification of A-BC and C-BC in future work.
