Chemical Impedance Spectroscopy Research Articles

Electrochemical behavior and L-tyrosine sensing properties of nanostructured Cr, Sn and La-doped α-Fe2O3 interfaces

L-tyrosine (Tyr) is a promising biomarker for the diagnosis and monitoring of metabolic disorders and neurodegenerative diseases. This study reports on the electrochemical properties of α-Fe2O3 nanostructures doped with Cr, Sn and La, referred to as CrFeOx, SnFeOx and LaFeOx, respectively, and their application in the enzyme-free electrochemical Tyr sensors. These disposable sensors offer accurate Tyr concentration analysis at room temperature, addressing the limitations of current point-of-care diagnostic methods. The CrFeOx, SnFeOx, and LaFeOx nanostructures serve as selective agents for binding and recognizing Tyr, deposited onto disposable graphite pencil electrodes to form the electrochemical interface. The interfacial resistance, charge-transfer kinetics, mechanism, and reversibility are studied via extensive electrochemical measurements employing electro¬chemical impedance spectroscopy and cyclic voltammetry. Furthermore, differen¬tial pulse voltammetry demonstrates excellent Tyr sensing performance in the concen¬tration range of 0 to 80 μM with 2.65 µA µM-1 cm-2 sensitivity and 360 nM thres¬hold detection limit for the best-performing CrFeOx sensors. Hence, these α-Fe2O3-based sensor systems are practical and efficient for selective Tyr detection, offering potential advancements in personalized healthcare and early disease diagnosis.

An Electrically Resistive Switching Nonvolatile Memory System Based on PEDOT:PSS

The current density–voltage (J–V) curves of poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) are examined at room temperature, which reveal nonlinear behavior and hysteresis loop‐like patterns. Herein, the potential of the material for nonvolatile applications requiring resistive random access memory (ReRAM) is demonstrated. The resistive switching effect is explained using a Schottky barrier and the space‐charge‐limited conduction model. Additionally, dielectric and electrical characteristics are analyzed in the frequency range from 20 Hz to 10 MHz. The impedance, electric modulus, dielectric loss tangent, and AC conductivity are explored through On‐ and Off‐states of resistive switching. A modified Debye function and Jonscher's power law are used for data fitting. The resistive switching memory behavior of PEDOT:PSS are studied using J–V and chemical impedance spectroscopy (CIS) measurements. The Cu/PEDOT:PSS/Cu sandwich‐type devices show bipolar switching behavior, and an equivalent circuit model based on the impedance spectra is proposed to describe the CIS response in both states. The switching process is attributed to the electrical‐field‐induced effect of dipolar reorientation on the electrical conductivity of PEDOT:PSS at grain boundaries.

Efficient electro catalytic performance of palladium nanoparticles assisted on bi-composite material (GRNPs-GCN) for electro chemical oxidation of methanol in alkaline media

This study reports a novel co-deposited catalyst which covalently coupled composite of Pd@ GRNPs-GCN for methanol electro-oxidation was investigated. The prepared nanocomposite material was further characterized through FTIR, XRD, SEM, and EDX analysis. The results showed that the Pd@GRNPs-GCN has stronger interaction, active specific area & rich content of pyridine & pyrrole nitrogen species which promotes the dispersion of PdNPs on GRNPs-GCN to present superior catalytic efficiency towards MOR. Moreover, the electrochemical analysis of cyclic voltammetry (CV), chronoamperometry (CA) & electro chemical impedance spectroscopy (EIS) proved that fabricated Pd@GRNPs-GCN electro catalyst showed significant catalytic activity, lesser oxidation potential & longevity for the electrochemical oxidation of methanol in alkali media. All these results revealed that the nanocomposite hybrid electro catalyst for feature endeavours in DMFCs (Direct methanol fuel cells) applications.

Synthesis and photoelectrochemical performance of Co doped SrTiO3 nanostructures photoanode

AbstractIt is pertinent to realize that scientific research indicates that the most promising method for producing H2 is photo electrochemical water splitting through a photo anode. Cobalt‐doped SrTiO3 (Co‐SrTiO3) composite nanostructures were created in this study via hydrothermal synthesis. The impact of cobalt concentration change on Co‐SrTiO3 has been identified using morphological, structural, and photo electrochemical research. Surface morphology of pure SrTiO3 nanoparticles using SEM and TEM reveals that the particles are intermittently agglomerated. The inclusion of Cobalt lowered the particle size of the nanostructures to 23 nm than pure SrTiO3 (41 nm). In addition, the peak profile has been influenced by cubic phase also identified from the x‐ray diffraction analysis. The purity and composition of the materials were revealed by XPS analysis. The Co‐SrTiO3 composite's produced the best charge transfer and recombination capabilities at 3% Co doping, according to electrochemical chemical impedance (EIS) spectroscopy. At 0.2 V applied potential, the obtained 3% Co‐doped SrTiO3 photoanode system displays a photocurrent density of around 3.45 mA/cm2. The outcomes show that a promising application for the Co‐doped SrTiO3 photoanode in photoelectrochemical water splitting.

Novel Development of Corrosion Resistant Paint Using Printed Circuit Board from Modern Electronic Wastes

The growth in the industrial technology and communication sectors has enhanced the usage of electronic gadgets exponentially. Thus, it becomes highly essential to find new solution to utilize or dispose these e-wastes, in order to reduce the e-waste generation. Various reports mentioned that the major component of these e-wastes is their Printed Circuit Boards. Therefore, a new ideology is proposed to use these boards to produce a new coating with good corrosion resistance. At first the boards were separated from the discarded electronic appliances and various electrical elements were separated from these boards. Then the plain circuit boards are pulverized into fine particles and mixed with paint in 3 different proportions ranging from 1:4 to 1:2. The resulting mix was applied over the steel specimen and tested for corrosion resistance. The assessment was done in the aspects of contact angle, weight loss percentage, potentio dynamic polarization technique and electro chemical impedance spectroscopy. From the results it was clear that increase in the addition of printed circuit powder content in the corrosion proof paint coating enhanced the efficiency of the corrosion resistant behaviour 3.5 times than the specimen with uncoated steel specimens. This development of corrosion resistant behaviour of printed circuit powder was attributed from the inertness offered by the presence of silicon dioxides towards the corrosive fluids. Although, the coating of 1:2 proved to be optimum to protect the steel elements from the aggressive corrosion environment, by considering the workability aspects the 1:3 combination was suggested for the innovative development of anti-corrosion paint coating from the e-waste resources.
 HIGHLIGHTS
 
 Life cycles of every electronic wastes end with the hazardous challenging disposals
 Innovative utilizations of these electronic wastes for the corrosion resistant structural applications were detailed
 An anti corrosive coating for steel reinforcement was developed from the waste printed circuit boards
 Coating by printed circuit board powder enhanced 3.5 times more protection from the corrosion
 
 GRAPHICAL ABSTRACT

Evaluation and Comparative Study of Cell Balancing Methods for Lithium-Ion Batteries Used in Electric Vehicles

Vehicle manufacturers positioned electric vehicles (EVs) and hybrid electric vehicles (HEVs) as reliable, safe and environmental friendly alternative to traditional fuel based vehicles. Charging EVs using renewable energy resources reduce greenhouse emissions. The Lithium-ion (Li-ion) batteries used in EVs are susceptible to failure due to voltage imbalance when connected to form a pack. Hence, it requires a proper balancing system categorised into passive and active systems based on the working principle. It is the prerogative of a battery management system (BMS) designer to choose an appropriate system depending on the application. This study compares and evaluates passive balancing system against widely used inductor based active balancing system in order to select an appropriate balancing scheme addressing battery efficiency and balancing speed for E-vehicle segment (E-bike, E-car and E-truck). The balancing systems are implemented using “top-balancing” algorithm which balance the cells voltages near the end of charge for better accuracy and effective balancing. The most important characteristics of the balancing systems such as degree of imbalance, power loss and temperature variation are determined by their influence on battery performance and cost. To enhance the battery life, Matlab-Simscape simulation-based analysis is performed in order to fine tune the cell balancing system for the optimal usage of the battery pack. For the simulation requirements, the battery model parameters are obtained using least-square fitting algorithm on the data obtained through electro chemical impedance spectroscopy (EIS) test. The achieved balancing time of the passive and active cell balancer for fourteen cells were 48 and 20 min for the voltage deviation of 30 mV. Also, the recorded balancing time was 215 and 42 min for the voltage deviation of 200 mV.

Evaluation and Comparative Study of Cell Balancing Methods for Lithium-Ion Batteries Used in Electric Vehicles

Vehicle manufacturers positioned electric vehicles (EVs) and hybrid electric vehicles (HEVs) as reliable, safe and environmental friendly alternative to traditional fuel based vehicles. Charging EVs using renewable energy resources reduce greenhouse emissions. The Lithium-ion (Li-ion) batteries used in EVs are susceptible to failure due to voltage imbalance when connected to form a pack. Hence, it requires a proper balancing system categorised into passive and active systems based on the working principle. It is the prerogative of a battery management system (BMS) designer to choose an appropriate system depending on the application. This study compares and evaluates passive balancing system against widely used inductor based active balancing system in order to select an appropriate balancing scheme addressing battery efficiency and balancing speed for E-vehicle segment (E-bike, E-car and E-truck). The balancing systems are implemented using “top-balancing” algorithm which balance the cells voltages near the end of charge for better accuracy and effective balancing. The most important characteristics of the balancing systems such as degree of imbalance, power loss and temperature variation are determined by their influence on battery performance and cost. To enhance the battery life, Matlab-Simscape simulation-based analysis is performed in order to fine tune the cell balancing system for the optimal usage of the battery pack. For the simulation requirements, the battery model parameters are obtained using least-square fitting algorithm on the data obtained through electro chemical impedance spectroscopy (EIS) test. The achieved balancing time of the passive and active cell balancer for fourteen cells were 48 and 20 min for the voltage deviation of 30 mV. Also, the recorded balancing time was 215 and 42 min for the voltage deviation of 200 mV.

Oxidation of chalcopyrite in air-equilibrated acidic solution: Inhibition with phenacyl derivatives

Abstract The effects of 4-(2-hydroxyphenyl)-2-(morpholin-4-yl)-1,3-thiazole (Pr02), 1-(3,5-dibromo-2-hydroxyphenyl)- 1-oxoethan-2-yl-N,N-diethyldithiocarbamate (Pr04) and 1-(5-bromo-2-hydroxy-3-methylphenyl)-1-oxoethan-2-yl-O- ethyl xanthate (Pr06) on the aqueous oxidation of chalcopyrite (CuFeS2) in air-equilibrated solution at a temperature of 25 °C and a pH of 2.5 were studied. The effects were investigated by using potentiodynamic polarization, electro- chemical impedance spectroscopy (EIS), scanning electron microscopy coupled with energy dispersive X-ray (SEM/EDX) analysis, aqueous batch experiments, Fourier transform infrared (FTIR) spectroscopy, Raman scattering and quantum chemical calculations. It is found that the anodic current densities decrease in the order of EtOH > Pr02 > Pr04 > Pr06. These results, along with those of the EIS measurements, show that Pr02, Pr04 and Pr06 are effective anodic inhibitors of chalcopyrite aqueous oxidation. Both Raman scattering and FTIR spectroscopy indicate that the elemental sulfur, polysulfide and ferric oxyhydroxides that form on the surface of the mineral are not responsible when it comes to the aqueous oxidation inhibition of chalcopyrite. Quantum chemical calculations show that the adsorption of the tested compounds on the chalcopyrite surface is energetically favorable and so, it can explain the inhibiting effects that were observed.

Effect of Low energy laser shock peening on plastic deformation, wettability and corrosion resistance of aluminum alloy 7075 T651

AA 7075 T651 alloys are often used in a variety of applications such as gears, shafts, chassis in automobile industries, missiles and extension tubes of rifles in defense and marine components, where wear and corrosion resistance is indispensable. It entails the enhancement in surface characteristics such as hardness, wear resistance and resistance to the corrosion emanate from high concentration of chlorides. This article is devoted to analyze the corrosion behavior of AA 7075 T651 alloy in 3.5 % NaCl solution subjected to the surface modification by low energy (200 mJ, 300 mJ and 400 mJ) pulsed Laser Shock Peening (LSP). Among the unpeened and peened specimens the specimen peened with pulse energy of 400 mJ exhibited the highest Ecorr value of −1200 V and lowest Icorr value of 0.0221 mA/cm2 in the potentiodynamic polarization test. The electro chemical impedance spectroscopy revealed a superior resistance to the localized corrosion. Further, the investigations on the variations in microstructure, plastic strain, dislocation density and Wettability due to LSP are carried out using Transmission Electron Microscope, Scanning Electron Microscope, X-ray diffraction (XRD) and Goniometry instrument. Besides the reduction in the grain size and 31 % increment in the micro strain, a transformation from hydrophilic to hydrophobic nature is observed in the specimen peened with 400 mJ LSP.

Ultrasound-accelerated covalent-functionalization of reduced graphene oxide with imidazolium-based poly(ionic liquid)s by Diels-Alder click reaction for supercapacitors

Herein, we developed an efficient method for covalent functionalization of reduced graphene oxide (rGO) with imidazolium-based poly(ionic liquid)s via the Diels-Alder (DA) click reaction in deep eutectic solvents (DESs). Firstly, poly(ionic liquid)s (P(F-IL)s) containing furfuryl and imidazolium were prepared by the reaction of poly(chloromethylstyrene-co-maleicanhydride), furfuryl amine and methylimidazole. Afterward, the P(F-IL)s were grafted directly on the rGO surface via the DA reaction in a deep eutectic solvent (DES) without catalyst under ultrasonication. The obtained hybrid materials were characterized by FT-IR, TGA, Raman spectroscopy, XPS, SEM, and TEM. The capacitive and electrochemical behaviors of the hybrid materials were studied by using cyclic voltammetry (CV) and electro chemical impedance spectroscopy (EIS). In CV, the rGO-P(F-IL) hybrid showed the largest capacitance and EIS revealed a lower diffusion resistance compared to that of rGO, which indicated a good electrochemical capacitor behavior of the hybrid.

Influence of Some Organic Derivatives on the Corrosion Inhibition of Udimet700 Alloy in 1 M HCl Solution

In this study, the electro-chemical behavior of Udimet700 alloys is studied in acidic media at 25°C. It deals with the corrosion inhibition process of nickel–based (Udimet700) alloy in 1M–HCl solution by some organic derivatives. The methods used include electro–chemical frequency modulation technique, electro–chemical impedance spectroscopy, and potentio–dynamic polarization. The derivatives are considered as mixed–type inhibitor depending on potentio–dynamic polarization analysis. Scanning electron microscope examination is executed to study the morphology of Udimet700 surface after immersion in a solution in the case of presence and absence of derivatives. The results of this research reveal that the inhibitors are absorbed by Udimet700 alloy surface and they insulate it from the acidic medium. The compound (C16H17) among the tested organic derivatives plays the best role as an inhibitor of the alloy in 1M–HCl.

Electrical measurement and quantification of different cell types by electro chemical impedance spectroscopy

Recently, in the field of regenerative tissue engineering, huge amount of cells are needed for developping new organs and tissues. However, during cell cultivation, cells sometimes show degeneration or change their original characters so that it is needed to separate those cells from original cells. Although fluorescent labeling and magnetic labeling of cells have been used for cell separation, invasive label-free methods are required from the point of view of cell damage. Therefore, our aim is to develop a high-efficiency label-free cell separation system based on the difference in electrical characteristics of cells. In this study, for its first step, an attempt was made to distinguish different type of cells by measuring their electrical properties.

Electro chemical impedance spectroscopy (EIS) study of modified SS316L using radio frequency sputtering Ti6Al4V coating in Ringer solution

PurposeSS316L alloy used in biomedical application and the alloy have Fe, Cr and Ni elements and release this ion into the human body causing dangerous effects for the human body, and make the SS316L, which is used as surgical implant failure in short time in biomedical application. This study aims to use Ti6Al4V as coating for SS316L alloy to make it have bio inert surface, and modified the surface alloy for biomedical application from another part in this study, we want to decrease the corrosion rate for SS316L in simulated body surface Ringer solution.Design/methodology/approachThe morphology, roughness, XRD of the coating, potential polarization and electrochemical impedance spectra investigation to study the effect of Ti6Al4V coating on corrosion behaviors of SS316L in the Ringer solution.FindingsThis study discusses the modification of SS316L surfaces by using Ti6Al4V radio magnetron frequency sputtering techniques, the results of the EIS and polarization of SS316L in Ringer’s solution at 37°C shows that improved resistance against corrosive ions for all the samples coating with Ti6Al4V and especially with a coating have a thickness of 850 nm at a sputtering power of 150 W.Research limitations/implicationsPolarization and electro chemical impedance spectra were assessed to investigate the effect of Ti6Al4V coating on corrosion behaviors of SS316L alloy in the Ringer solution.Practical implicationsThis study discussed the modification SS316L surfaces by using Ti6Al4V radio magnetron frequency sputtering techniques. The results of the EIS and polarization of SS316L in Ringer’s solution at 37°C improved resistance against corrosive ions for all the samples coating with a Ti6Al4V and specificity with the coating sample have a thickness 850 nm at a sputtering power of 150 W.Social implicationsThe goal of this study to modification SS316L alloy surface by using Ti6al4V RF Sputtering to give the SS316L alloy more resistance for biocorrosion.Originality/valueIn this research, Ti6Al4V RF sputtering as a coating for SS316L, study the bio corrosion behaviors in Simulated body fluid Ringer solution and investigation the corrosion by using EIS analysis.

Cetyltriammonium Bromide Assisted Synthesis of Lanthanum Containing Barium Stannate Nanoparticles for Application in Dye Sensitized Solar Cells

In present work, correlation of structural and optical behavior of pristine and lanthanum containing barium stannate nanoparticles (synthesized via cetyltriammonium bromide (CTAB) assisted facile wet chemical route), and its effect on photovoltaic properties of dye‐sensitized solar cell are reported. Thermo‐gravimetric analysis of the dried compound presumably BaSn(OH)6, leads to the formation of BaSnO3 nanoparticles through three endothermic decomposition processes, via liberation of one mole of water in each step, together with removal of remaining CTAB in initial cycle. The X‐ray diffraction patterns reveal that substitution of Ba2+ lattice sites by La3+ (upto ≈6 at.%), the lattice retains its cubic Pm3m symmetry, however, unit cell contracts. The dye sensitized solar cells are fabricated using pristine and La‐ containing BaSnO3 as photo anode; platinum coated FTO as counter electrode, N719 dye as sensitizer and I−/I3− as electrolyte. These show the highest power conversion efficiency (≈9.2%) at the La content of 6 at.% which is about threefold increase in efficiency in comparison to pristine BaSnO3. The electron transport properties of these DSSC devices are investigated by electro chemical impedance spectroscopy.

Surface plasmon resonance effect of Cu nanoparticles in a dye sensitized solar cell

Pure and copper doped titanium dioxide nanoparticles (TiO2 NPs) for Dye Sensitized Solar Cell (DSSC) photo anodes with different doping amounts of copper (Cu) 0.1, 0.3 and 0.5mole% are synthesized using modified sol-gel route. Addition of Cu in TiO2 matrix can enhance absorption towards visible spectrum and can reduce the charge carrier recombination due to Localized Surface Plasmon Resonance (LSPR). The samples are characterized by X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), UV–vis spectroscopy (UV-VIS), X-ray Photoelectron Spectroscopy (XPS), Electro Chemical Impedance Spectroscopy (EIS). The crystallite size is measured by XRD and surface morphology of the samples is analyzed using SEM. UV–vis measurement shows that the influence of Cu in TiO2 lattice altered its optical properties and extended absorption in the visible region. The resistances between different junctions of the cell are measured by EIS. The J-V measurement of the cell prepared using pure and Cu-doped TiO2 NPs is carried out by solar simulator. The optimized Cu doped DSSC with 0.3mole% Cu in TiO2 shows the best power conversion efficiency of 8.65% which is approximately 26% greater than the efficiency of undoped DSSC (6.41%).

Influence of tensile stresses on the corrosion resistance of titanium alloy VT22 in aqueous solution of NaCl

How tensile stresses and pH value influence the passivation, corrosion, and structure of a protective film of two-phase titanium alloy VT22 in 3% solution of NaCl is investigated with the help of potentiometry, potential and dynamical analysis, and electrical and chemical impedance spectroscopy. We simulate the process of electrical transfer through the protective film and we reveal that its structure is two-layered. The film consists of a layer based on titanium hydroxide under which there is a titanium oxide layer adjacent to the alloy and primarily it protects the alloy against corrosion. How tensile stresses and pH value influence the hydrogen saturation process and delayed fracture of titanium in an aqueous NaCl solution is investigated.

Hydrothermal Synthesis of Three Dimensional Graphene‐Multiwalled Carbon Nanotube Nanocomposite for Enhanced Electro Catalytic Oxidation of Caffeic Acid

AbstractThree dimensional graphene‐multiwalled carbon nanotube nano composite (3DG/MWCNTs−Nc) was synthesized by simple hydrothermal method for the amperometric determination of caffeic acid (CA). The prepared nanocomposite was characterized by scanning electron microscopic technique (SEM), ultraviolet‐visible spectroscopy (UV), Raman spectroscopy and infrared spectroscopy (IR). Moreover, the interfacial electron transfer properties of the modified electrode were carried out by the electro chemical impedance spectroscopy (EIS). Besides, the electro chemical performance of the modified electrode was carried out by the cyclic voltammetry (CV) and amperometric (i‐t) technique. The proposed electrode was exhibited an enhanced electrocatalytic activity towards the detection of CA. Under the optimal condition, the 3DG/MWCNTs−Nc modified electrode displayed a linear range from 0.2 to 174 μM, detection limit (LOD) 17.8 nM and sensitivity of 5.8308 μA μM−1 cm−2 and on applied potential + 0.2 V. These result showed, 3DG/MWCNTs−Nc modified electrodes showed good repeatability, reproducibility, and higher stability. In addition, the fabricated electrode was then successfully used to determine the CA in real samples with satisfactory recoveries. Which suggests that the 3DG/MWCNTs−Nc as a robust sensing materials for the electrochemical detection of CA.

The Application of Poly(Glutathione Disulfide)-poly(L-lysine) Multilayer Films for the Enantioselective Interaction with Ascorbic Acid and Isoascorbic Acid

Poly(glutathione disulfide)-poly(L-lysine) (PGSSG-PLY) multilayer films prepared by electropolymerization via cyclic voltammetry were constructed as a new chiral interface for recognition of ascorbic acid (AA) and isoascorbic acid (IAA). The morphology of the films was characterized by scanning electron microscopy (SEM), the electrochemical behaviors of the films were studied via chemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Meanwhile, differential pulse voltammetry (DPV) was used to study the interactions between PGSSG-PLY modified glassy carbon electrodes and AA or IAA. A strong interaction with AA was observed on the chiral interface. The results proved that PGSSG film could amplify eletrochemical signal, while PLY film could provide more recognition sites to discriminate AA and IAA enantiomers with satisfying recognition efficiency. The possible formation of the films on the electrode surface was described. And the influences of electropolymerization cycles and pH to the recognition process were explored. Under the optimum conditions, the method showed an acceptable linear response to AA and IAA in a range from 1.0 × 10−7 to 5.0 × 10−3 M with a low detection limit of 3.3 × 10−8 M (S/N = 3). The modified electrodes also displayed good stability and reproducibility.

Improving the Corrosion Resistance of Lead in H2SO4 4 M by the Addition of Phosphoric and Phosphonic Compounds for Lead Grid Batteries

The effect of the addition of phosphoric acid ((HO) 3P=O), potassium hydrogen phosphate ((HO) 2P(O)(O - K + )), dimethyl vinylphosphonate (CH 2=CH ―P(O)(OCH 3)2) and vinylphosphonic acid (CH 2=CHP(O)(OH) 2) on lead corrosion in 4 M H 2SO 4 was studied by potentiodynamic polarization and electro chemical impedance spectroscopy (EIS). The results show that phosphoric acid and po tassium hydrogen phosphate, added to an optimal concentration of 0.4 M, reduce the le ad passivation current and increase its corrosion current, with charge transfer as the main reaction mechanism at the interface metal/electrolyte. They also increase PbO 2 formation’s potential when they are added at larger concentrations, while adding dimeth yl vinylphosphonate and vinylphosphonic acid up to 0.3 M reduces corrosion current and lead passivation current. This last product appears to suppress the formation of PbO 2. The parameters of potentiodynamic polarization are in good agreement with those of EIS.

A Label-free Immunosensor based on Ionic Liquids Modified Mesoporous Silica for Simultaneous Determination of Two Tumor Markers

A label-free electrochemical immunoassay strategy was proposed for the simultaneous detection of two tumor markers, carcinoembryonic antigen (CEA) and α-fetoprotein (AFP). The functional mesoporous silica was synthesized for the construction of the label-free immunosensor. The Si-OH groups on the external surface of the mesoporous silica were termi- nated by trimethylchlorosilane (TMCS), while the Si-OH groups on the internal pore walls were modified with amino groups. The electrochemical substrates of ferrocenecarboxylic acid (FCA) and methylene blue (MB) were co-immobilized inside the channels of the ionic liquids (ILs) modified mesoporous silica (MPS), respectively. The monoclonal antibody of CEA (anti-CEA) and the monoclonal antibody of AFP (anti-AFP) were respectively co-immobilized inside the materials of FCA-IL-MPS and MB-IL-MPS. The ITO slide was separated lengthways into two uniform parts by insulation glue so as to avoid the cross-talk of the two portions. Finally, the suspension solutions were coated respectively onto the different areas of indium-tin oxide (ITO) electrode. The double-analyte immunosensor was constructed by the probes of CEA and AFP onto the different areas of ITO. When the double-analyte immunosensor was dipped into the sample solution, the antigens of CEA and AFP reacted with their corresponding monoclonal antibodies on the different area of the modified ITO electrode. After the immunological reaction, the nonconductive immunoconjugates formed inside the MPS channels. With the increasing concentrations of CEA and AFP antigens, the spatial blocking and impedance on the sensor surface increased, thus the elec- tric response transfer from the solution to the electrode surface was blocked and the DPV currents decreased. The electro- chemical signals for CEA were detected by using FCA as the electron mediator. The electrochemical signals for AFP were detected by using MB as the electrochemical substrates. Then, the simultaneous detection of CEA and AFP could be achieved. The electrode modification process was further characterized by cyclic voltammetric measurements and electro- chemical impedance spectroscopy. IL units inside the mesopores could promote the electron transportation through the pore channel. To clarify the adsorption of FCA and MB into the mesopores of ILs-modified MPS, the IR spectra were recorded. The linear ranges of CEA and AFP were 0.5~80 ngmL -1 and 0.5~100 ngmL -1 with the detection limits of 0.1 ngmL -1