Graphite Paper Electrode Research Articles

High areal-capacitance based extremely stable flexible supercapacitors using binder-free exfoliated graphite paper electrode

The highly porous and binder-free flexible paper electrodes can enhance the specific capacitance of symmetric supercapacitors (SCs) due to their large surface and effective ion diffusion pathways. We synthesized the exfoliated graphite (ExG) by the thermal exfoliation method of chemically treated graphite flakes and compressed it into a paper-like thin sheet (binder-free) of ∼0.15 mm thickness. The coin cell SCs with copper (Cu) and stainless steel (SS) as current collectors have been fabricated for the electrochemical measurement. The cyclic voltammetry and galvanostatic charge/discharge measurements are investigated at various scan rates and current densities. The SCs with Cu foil as a current collector perform better than SS-based SCs. The Cu current collector-based SCs showed a specific capacitance of 37.08 mF cm−2, whereas it was ∼29.98 mF cm−2 for SS-based SCs at a 0.01 V s−1 scan rate across a 0–0.6 V potential window. Approximately no degradation in charge storage capacity for more than 15 000 cycles at 0.1 V s−1 shows the ultra-stability of the flexible ExG-based binder-free electrodes. A digital watch is powered using the fabricated pouch cell supercapacitor with copper-based current collectors to show the potential of SCs.

A Wearable Pressure Sensor Based on Ultrathin Ionic Nanopaper for Wide-Range Human Signal Detection

Power consumption is a crucial parameter for wearable sensors to approach practical applications. As an ideal candidate for low consumption device, capacitive pressure sensor can make up for the defects of low capacitance and sensitivity by introducing the iontronic sensing mechanism, and can further improve the sensing performance through the construction of micro-nano structures at electrode-electrolyte interface. To explore a facile-effective microstructure construction method for promoting the mass manufacturing and cost reduction, in this study, an easily prepared ionic cellulose nanopaper (CNP) is served as dielectric layer, and sandwiched between two graphite paper electrodes. The combination of the CNP and graphite paper provides a typical microstructure interface, and the device is endowed with the characteristics of ultra-light and ultra-thin. The iontronic paper-based pressure (IPBP) sensor exhibits a high sensitivity of 67.5 kPa <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> and an excellent linearity above 0.99 over a broad pressure range of 0-30 kPa, and a low detection limit of 0.5 Pa, together with good mechanical stability for over 3000 loading-unloading cycles. Finally, the applications of the IPBP sensor for monitoring of human motion and physiological signals such as joint bending, walking state, radial artery and breathing are demonstrated, which prove the great potential in wearable electronics, human health monitoring and human-computer interface.

A facile one-step electrosynthesis of polypyrrole/nano-SbOx composite for supercapacitors

The study depicts a one-step electrochemical synthesis of composite based on polypyrrole (PPy) and SbOx (Sb2O3, Sb2O5) on the graphite surface for the supercapacitor electrode in an acetonitrile solution including pyrrole monomer and Sb(BF4)3. PPy/SbOx composite on graphite plate is characterized using XPS, XRD, TEM, BET, and FESEM by comparing it with PPy homopolymer prepared in the same way. SbOx forms in nano-size and homogeneously encapsulates in PPy due to their simultaneous synthesis. The average pore size of the composite coating is 23.9 nm. The coated PG electrodes are tested in an H2SO4 electrolyte using CV, EIS, and GCD methods. SbOx nanoparticles enhance the capacitive performance of PPy due to the contribution of its catalytic and pseudocapacitive properties. The specific capacitance of the PPy/SbOx-coated PG electrode is 389.5 F g−1 at 5 A g−1 for 1.0 mg cm−2 loading. PPy/SbOx is synthesized in the presence of carboxymethyl cellulose (CMC) to provide stability to the coating. An asymmetric supercapacitor cell is fabricated by assembling the PPy/SbOx/CMC-coated and activated carbon-based graphite paper electrodes (10 mg cm−2 loading). While the potential window expands to 1.4 V, it delivers an energy density of 8.3 Wh kg−1, a power density of 3.5 kW kg−1, and a coulombic efficiency of 90% at 5 A g−1. Post-mortem analysis reveals that structural degradation of PPy in the composite limits long-term stability.

Immobilization of Glucose Oxidase on Glutathione Capped CdTe Quantum Dots for Bioenergy Generation

An efficient immobilization of Glucose oxidase (GOx) on an appropriate substrate is one of the main challenges of developing fuel cells that allow energy to be obtained from renewable substrates such as carbohydrates in physiological environments. The research importance of biofuel cells relies on their experimental robustness and high compatibility with biological organisms such as tissues or the bloodstream with the aim of obtaining electrical energy even from living systems. In this work, we report the use of 5,10,15,20 tetrakis (1-methyl-4-pyridinium) porphyrin and glutathione capped CdTe Quantum dots (GSH-CdTeQD) as a support matrix for the immobilization of GOx on carbon surfaces. Fluorescent GSH-CdTeQD particles were synthesized and their characterization by UV-Vis spectrophotometry showed a particle size between 5–7 nm, which was confirmed by DLS and TEM measurements. Graphite and Toray paper electrodes were modified by a drop coating of porphyrin, GSH-CdTeQD and GOx, and their electrochemical activity toward glucose oxidation was evaluated by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. Additionally, GOx modified electrode activity was explored by scanning electrochemical microscopy, finding that near to 70% of the surface was covered with active enzyme. The modified electrodes showed a glucose sensitivity of 0.58 ± 0.01 μA/mM and an apparent Michaelis constant of 7.8 mM. The addition of BSA blocking protein maintained the current response of common interferent molecules such as ascorbic acid (AA) with less than a 5% of interference percentage. Finally, the complex electrodes were employed as anodes in a microfluidic biofuel cell (μBFC) in order to evaluate the performance in energy production. The enzymatic anodes used in the μBFC allowed us to obtain a current density of 7.53 mAcm−2 at the maximum power density of 2.30 mWcm−2; an open circuit potential of 0.57 V was observed in the biofuel cell. The results obtained suggest that the support matrix porphyrin and GSH-CdTeQD is appropriate to immobilize GOx while preserving the enzyme’s catalytic activity. The reported electrode arrangement is a viable option for bioenergy production and/or glucose quantification.

Fabrication of an ultrasensitive and single-use graphite paper based immunosensor for Neuropeptide Y detection: A promising biosensing system for early detection of childhood obesity

The purpose of this study was to develop a label-free impedimetric immunosensing system as an analysis technique for hypothalamic Neuropeptide Y hormone with the goal of determining childhood obesity. A novel process for producing a bioelectrode modified with reduced graphene oxide and its biocompatibility with neuropeptide Y was discussed. The immobilization process is based on the adsorption of reduced graphene oxide (dispersed in dimethylformamide solution) onto a novel graphite paper electrode. Anti-neuropeptide Y antibodies were covalently immobilized on the reduced graphene oxide modified electrode surface using ethyl(dimethylaminopropyl) carbodiimide / N-Hydroxysuccinimide coupling chemistry. Electrochemical impedance spectroscopy and cyclic voltammetry techniques were used to monitor and evaluate all immobilization stages, optimization studies, and analytical characterization of the biosensor. The scanning electron microscopy was used to observe the surface morphology during the immobilization steps of the biosensor. The applicability of the designed biosensor to real serum samples was evaluated for clinical use. The biosensor demonstrated high sensitivity for determining neuropeptide Y in real serum samples. The developed immunosensor had a large linear range (0.005 pg mL -1 -10 pg mL -1 ) and a low limit of detection for neuropeptide Y antigen (0.11 fg mL -1 ). Additionally, the designed immunosensor demonstrated high repeatability, reproducibility, long storage stability (after the fifth week, up to 87% of initial activity), and reusability (20 times). Immobilization scheme of the Neuropeptide Y biosensor

MOF-derived hierarchical porous carbon octahedrons for aluminum-ion batteries

Rechargeable aluminum-ion batteries (AIBs) have aroused increasing interest due to good safety and economy, together with high theoretical volumetric capacities. Graphitized carbon materials and urea-based ionic liquid (IL) have been demonstrated as promising cathode materials and electrolyte of AIBs for high discharging voltage and low cost. Here we performed in situ Raman spectroscopy to investigate the reaction mechanism of Al/graphite in AlCl3/urea mixture IL electrolyte. The experimental evidences demonstrated that poor reaction kinetics of graphite cathode in urea-based IL at room temperature restricts the rate performance and further applications. In this work, we presented hierarchical porous carbon octahedrons (HPCO) derived from Cu-based metal organic framework (MOF) as a promising cathode material of AIBs. Advanced scanning electron microscopy (SEM) technologies were employed to reveal the hierarchical porous architecture. Benefited from the unique hierarchical porous structure and robust graphitic carbon nature, the Al/HPCO batteries exhibited a well-maintained specific capacity of ∼60.8 mA h g−1 after charge/discharge 200 cycles at a current density of 100 mA g−1 and a much better rate performance than graphite paper (GP) electrodes. This may provide extensive solutions to future research on AIBs and practical applications of AIBs technically.

Adaptable and Wearable Thermocell Based on Stretchable Hydrogel for Body Heat Harvesting

AbstractThe application of traditional inorganic thermoelectric materials to wearable energy harvesters has been hindered by the rigid bulkiness, while flexible organic conductive polymers have been long troubled by their intrinsic low thermopower. An ideal solution that possesses the merits of the two thermoelectric materials is desperately needed for practical application. Here it is demonstrated that a polyacrylamide (PAAm)‐based ultra‐stretchable hydrogel can be selected as a superior candidate matrix for flexible and stretchable thermocells to adapt to the curved surface of the human body and deformation of the ankle. Fe(ClO4)3/Fe(ClO4)2 is selected as n‐type ion pair for their comparable thermoelectric performance to K3[Fe(CN)6]/K4[Fe(CN)6]. The p‐n pair hydrogel electrolytes show a voltage output of 29 mV and current output of 8.5 Am−2 with an average maximum power density of 0.66 mW K−2 m−2 for each p‐n cell (ΔT = 10 K). By integrating with the graphite paper electrode, a body‐conformal and portable thermocell device, employing the hydrogel electrolytes, is fabricated and reached a voltage output of 0.16 V with 14 pairs of p‐n cells (ΔT = 4.1 K). This commercially‐effective blueprint demonstrates the bright future of hydrogel‐based ionic thermocell in daily wearable scenarios.

An electrochemical immunosensor based on graphite paper electrodes for the sensitive detection of creatine kinase in actual samples

• The electrochemical immunosensor designed very stable, low-cost and sensitive method for determination of Creatine Kinase. • CK immunosensor exhibited high analytical performance with a linear range 0.150 pg/mL and low detection limit (0.045 pg/mL). • Disposable graphite paper electrodes were firstly used to detection CK antigen for a novel biosensor system. • The optimization was performed for all fabrication steps of the electrochemical biosensor system. The enzyme creatine kinase (CK) is one of the most well-established biomarkers in cardiovascular disease. For acute myocardial infarction (AMI) diagnosis, CK has a clinical comorbidity rate of 90%. This study has developed a novel electrochemical immunosensor using disposable graphite paper electrodes (GP). The GP electrodes were modified with gold nanoparticles (AuNP) to facilitate CK detection. Afterwards, GP electrodes were covalently immobilized with 6-mercapto-1-hexanol (6-MH), resulting in self-assembled monolayers (SAMs). Then, the electrodes were formed with a 3-Glycidyloxypropyltrimethoxysilane (3-GOPE) agent. Afterwards, the electrodes were immobilized with anti-CK (antibody creatine kinase) protein. In the final immobilization step, BSA (bovine serum albumin) protein was used to block non-covalent interactions. All parameters of the proposed immunosensor were optimized, including concentrations and incubation times. Analytical characteristics such as square wave voltammetry, linear determination range, repeatability, reproducibility, and regeneration of biosensors were determined. All characterization steps were monitored by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV). Moreover, the single frequency impedance (SFI) technique interacted with anti-CK and CK antigens. Furthermore, the proposed immunosensor was characterized using scanning electron microscopy (SEM). The proposed immunosensor exhibited a wide detection range (0.1–50 pg mL −1 ), and low limit of detection (LOD), and a low limit of quantification (LOQ); 0.045 pg mL −1 and 0.171 pg mL −1 , respectively. Finally, the developed biosensor was tried in an actual blood sample, which showed it could be utilized in clinical applications.

Smart harvesting and in-situ application of piezoelectricity in membrane filtration systems

Fouling remains one of the key challenges in membrane technology. In pressure-driven membrane separations, the vibrational energy induced by hydraulic pumps often dissipates unexploited. We present an innovative concept, in which the hydraulic pressure vibration is converted to electrical energy in the outlet of a filtration pump through an embedded piezoelectric nanogenerator (PENG) ceramic. We found that by increasing the average pressure of the hydraulic pump, the dynamic pressure fluctuation increased. The maximum output voltage of 219.6 V was obtained at 20 psi average pressure. The generated piezoelectricity was directly applied to an electro-assisted membrane cell in either alternating mode or positive/negative rectified form to mitigate membrane fouling. In the first configuration, ultrafiltration (UF) membrane was placed between two metallic electrodes. The optimum fouling resistance was achieved when the positive rectified piezoelectric pole was connected to the electrode. Water flux decline (FD) and water flux recovery ratio (FRR) were improved by 28.6% and 52.1%, respectively, compared to the case where no voltage was applied. In the second configuration, a piece of water-permeable and electro-conductive carbon nanotube (CNT) mat was mounted over the UF membrane and it was connected to the piezoelectric wafer using a wire. The alternating piezoelectricity provided the best antifouling performance in this configuration, with FD of 32.5% and FRR of 78.3%. The generated piezoelectricity was also used as a power source to drive an electro-Fenton (EF) reaction coupled with nanofiltration (NF) for reactive black 5 (RB5) dye separation. The results showed that the highest RB5 degradation rate (8.8%) was achieved when the rectified negative and positive poles were connected to the graphite paper and stainless-steel mesh electrodes, respectively. The proposed piezoelectric energy harvesting can revolutionize the traditional methods of fouling reduction in the electro-membrane processes where an external power should be applied for the oxidation reactions to occur.

Capacitors with sand-particle interlayer

Sand is common in desert and beach, with few other large-scale applications in history except for construction. The electricity storage phenomenon of sand particles is discovered, and for the first time the Sand Interlayer Capacitor (SIC) is developed with graphite paper electrodes and sand-particle interlayer. The SIC devices exhibit the best electrochemical performance in comparative experiments. Its specific capacitance per unit area can reach up to 24.68mF/cm2, as high as 1000 times that of capacitors with pure graphite electrodes, being compared with some of activated carbon capacitors and nano‑carbon capacitors, etc. In addition, the SIC shows excellent cycling durability. Under 5000 charge-discharge cycles, the coulombic efficiency and capacitance retention rate are both stable around 100 %. For 30-day continuous operation, the specific areal capacitance of the SIC can still be stable at around 28mF/cm2. The SIC is promising to be used in desert energy storage systems.

Construction of light-weight and flexible vanadium nitride coated graphite paper electrodes for supercapacitors

Construction of light-weight and flexible vanadium nitride coated graphite paper electrodes for supercapacitors

Facile electro-exfoliation of binder-free expanded graphite paper electrode at low-potential in alkaline environment for all-solid-state capacitor

Exfoliation is an effective strategy to improve the performance of graphite paper. In this paper, the expanded graphite paper is electro-exfoliated successfully by oxygen reduction reaction at low-potential in alkaline environment. As the surface of the electro-exfoliated expanded graphite paper becomes rough, the specific capacity and stability of the material are significantly improved, reaching 36.8 mAh g−1 at 0.5 A g−1 and 99.5% after cycling 10,000 times. After being further electro-oxidated and electrodeposited, the treated expanded graphite paper shows excellent electrochemical properties, proving that the electro-exfoliation is an effective synthesis strategy.

Titanium oxynitride coated graphite paper electrodes for light-weight supercapacitors

Titanium oxynitride coated graphite paper electrodes for light-weight supercapacitors

Highly Sensitive and Single-Use Biosensing System Based on a GP Electrode for Analysis of Adiponectin, an Obesity Biomarker.

This study presents a disposable, novel, and sensitive biosensing system to determine adiponectin, an obesity biomarker, in real human serum. The graphite paper (GP) working electrode is a new material for impedimetric biosensors. In the literature, there is no study in which this electrode is used in impedance-based biosensors for adiponectin detection. Sensitive and useful techniques, such as electrochemical impedance spectroscopy and cyclic voltammetry, were utilized for investigation of the modification of the GP electrode surface and optimization and characterization of the constructed biosensor. The single frequency impedance technique was used to study the interactions between antiadiponectin and adiponectin. The morphology of the electrode surface for each immobilization step was examined with scanning electron microscopy. All experimental parameters were optimized to fabricate a rapid and sensitive biosensing system. The designed biosensor presents excellent performance with a wide detection range (0.05-25 pg mL-1) and a low limit of detection (0.0033 pg mL-1) for adiponectin determination. Also, it has been demonstrated that the biosensor sensitively allows for the detection of adiponectin in human serum. The affinity of the designed immunosensor toward other proteins and components was examined in the presence of the target protein (adiponectin), leptin (100 pg mL-1), creatine kinase (50 pg mL-1), parathyroid hormone (50 pg mL-1), and d-glucose (0.5 M). The selectivity of the adiponectin biosensor resulted in high capacity to neglect the interference effect. The constructed biosensor showed good linearity, long-term storage life (10 weeks), high reusability (18 times regenerability), and high ability to detect adiponectin concentrations at picogram levels.

Enhanced intercalation behaviors of edge-rich flakes-stacked graphite for Al-graphite dual-ion battery

Graphite has been almost proven to be the positive material with the highest voltage and superior cycle stability for Al-graphite dual-ion battery. However, the limited energy density of graphite as positive material still blocks the future practical application. It is of great significance to further improve the energy density of the battery to satisfy the growing demand. In this regard, an edge-rich flakes-stacked graphite prepared by intentionally eroding the outer dense graphitic layer of graphite paper is demonstrated to apply in Al-graphite dual-ion battery that the chloroaluminate anions can be directly transported from edge-rich graphene nanoflakes and diffused into interior graphitic layers, which will greatly shorten the diffusion pathway, thus revealing better rate capability. The edge-rich flakes-stacked graphite paper enables to deliver a reversible capacity of ~87 mAh g−1 at 50 mA g−1, significantly higher than that of the untreated graphite paper electrode. More importantly, owing to the ultrahigh areal mass loading advantage, the as-assembled batteries exhibit much enhanced areal capacity (1.2 mAh cm−2), which is distinctly the highest among the reported graphite-based electrodes.

In situ fabrication of mesoporous NiO@ Graphite paper electrode with multilayered nanosheet wall structures for high-performance supercapacitors

A mesoporous NiO@graphite paper with multilayered nanosheet wall structures (M- NiO@GP) was synthesized through a facile and low-cost hydrothermal reaction and thermal annealing process. The as-prepared M-NiO@GP electrode presents high specific capacitance (2.57 F cm−2), exhibits superior cyclic stability (92.3% capacitance retention after 10000 chargedischarge cycles) and brilliant rate capability (about 56.0% capacitance retention when the current density increased 20 times). Such high-performance capacitive behavior is attributed to the wall structure of NiO with the multilayer nanosheets, which could shorten the ion transfer distance. Meanwhile, the high specific surface area and mesoporous structure of the electrode could serve as an efficient path for OH− transfer and diffusion. The improved electrical conductivity of the electrode enabled stable and efficient electron transports and consequently improved the overall electrochemical performance of supercapacitors. Therefore, the demonstrated high conductive M-NiO@GP electrode is a promising candidate for practical supercapacitor applications.

An impedimetric biosensor system based on disposable graphite paper electrodes: Detection of ST2 as a potential biomarker for cardiovascular disease in human serum

In present study, we developed a highly sensitive, electrochemical immunosensor based on fullerene C60-modified disposable graphite paper (GP) electrode for determination of Suppression of Tumorigenicity 2 (ST2) in human serum. The synthesis of the ST2 immunosensor was monitored with electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) techniques and single frequency impedance (SFI) technique which is utilized for the specific interaction between anti-ST2 and ST2 antigen. Moreover, the morphological alteration of each GP surface was examined by scanning electron microscopy (SEM), SEM-energy dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM). All parameters such as fullerene C60 concentration, antibody concentration and antibody incubation time were optimized. Analytical characteristics such as linear determination range, repeatability, reproducibility, regeneration and surface coverage were determined for the immunosensor. The ST2 electrochemical immunosensor had excellent repeatability, reproducibility and a wide detection range (from 0.1 fg mL−1 to 100 fg mL−1). The proposed immunosensor also had low limit of detection (LOD) and limit of quantification (LOQ) values of 0.124 fg mL−1 and 0.414 fg mL−1, respectively. The proposed immunosensor was applied to real samples to test applicability in clinical practice.

Non-enzymatic lactose molecularly imprinted sensor based on disposable graphite paper electrode

Lactose (LAC) is a disaccharide - major sugar, present in milk and dairy products. LAC content is an important indicator of milk quality and abnormalities in food industries, as well as in human and animal health. The present study reports the development of an innovative imprinted voltammetric sensor for sensitive detection of LAC. The sensor was constructed using electropolymerized pyrrole (Py) molecularly imprinted polymer (MIP) on graphite paper electrode (PE). The MIP film was constructed through the electrosynthesis of polypyrrole (PPy) in the presence of LAC (template molecule) on PE (PPy/PE). To optimize the detection conditions, several factors affecting the PPy/PE sensor performance were assessed by multivariate methods (Plackett–Burman design and central composite design). Under optimized conditions, the proposed analytical method was applied for LAC detection in whole and LAC-free milks, where it demonstrated high sensitivity and selectivity, with two dynamic linear ranges of concentration (1.0–10 nmol L−1 and 25–125 nmol L−1) and a detection limit of 0.88 nmol L−1. The MIP sensor showed selective molecular recognition for LAC in the presence of structurally related molecules. The proposed PPy/PE sensor exhibited good stability, as well as excellent reproducibility and repeatability. Based on the results obtained, the PPy/PE is found to be highly promising for sensitive detection of LAC.

4.2 V Stack of metaloxide‐polypyrrole‐based composite electrodes and their power management

Polypyrrole (PPy)-based composites containing nanostructured VO x, PbO x, and MnO x are galvanostatically synthesized on exfoliated graphite papers (1.0 and 6.25 cm2) formed as a result of the intercalation with their metals. Both intercalation and synthesis are performed in the synthesis solution containing metal(II)tetrafluoroborate salts, pyrrole monomer, HBF4, H2O, Triton-X 100 (TX100), and carboxymethyl cellulose (CMC). The mass loading of the composite at the electrode is maintained at 10 mg cm−2. Symmetric and asymmetric unit cells are prepared in polyvinyl alcohol (PVA)/H2SO4 (1:1) gel electrolyte using composites synthesized on the treated graphite paper electrode. The electrical properties of these cells are examined by electrochemical impedance spectroscopy and their capacitive properties by cyclic voltammetry and galvanostatic-charge discharge test. The asymmetrical cell, prepared with PPy/PbO x/CMC composite having energy density and cycle life better than others, exhibits 7.77 Wh kg−1 and 0.51 kW kg−1 at a working voltage of 1.4 V, considering the total mass of all sub-components. The three-cell asymmetric stack design, which is prepared using these composite-coated electrodes, achieves a coulombic efficiency of 76% at 4.2 V. Finally, an electronic control system (DC/DC buck-boost converter) is designed and implemented to manage the charge and discharge cycles of single-cell and bipolarly connected stack to operate the asymmetric supercapacitor arrays with high performance.

A novel ultrasensitive immunosensor based on disposable graphite paper electrodes for troponin T detection in cardiovascular disease

Troponin T, which is a biomarker of cardiovascular disease, is vital for acute myocardial infarction (AMI). AMI is the most well-known cause of death in the world. In the present work, we designed a novel immunosensor using disposable, cheap, and very conductive graphite paper electrodes (GP). The proposed immunosensor was modified with hydrochloric acid (HCl) for immobilization of anti-TnT antibody. After carboxyl group formation on the surface, the GP electrodes were incubated with EDC/NHS pair as a cross-linker. Electrochemical impedance spectroscopy (EIS), single frequency impedance (SFI), cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques were used for electrochemical characterization of the label-free immunosensor. Furthermore, the fabrication process of the proposed immunosensor was examined by using scanning electron microscopy (SEM). The proposed electrochemical immunosensor had a wide detection range (0.5 fg - 1000 fg/mL), and low limit of detection (LOD) and low limit of quantification (LOQ) at 1.28 fg/mL and 4.29 fg/mL, respectively. The designed immunosensor exhibited very good sensitivity, reproducibility, repeatability, reusability and long storage life. Additionally, the immunosensor was successfully applied to detection of TnT in human serum.