Peak Potential Difference Research Articles

An electrochemical sensor for simultaneous voltammetric detection of ascorbic acid and dopamine enabled by higher electrocatalytic activity of co-modified MCM-41 mesoporous molecular sieve

It is of great value to develop effective methods for accurately and simultaneously detecting ascorbic acid (AA) and dopamine (DA) in the field of biochemistry. This work reports a nonenzymatic electrochemical sensor for the simultaneous detection of AA and DA by employing a Co-modified MCM-41 (CoMCM-41) mesoporous molecular sieve as an efficient electrocatalytic material, which was synthesized by a two-step hydrothermal method. Subsequently, the high structural organization of the CoMCM-41 mesoporous structure was characterized, and the electrocatalytic performance of CoMCM-41 toward AA and DA oxidation was then evidenced by the catalytic effect of different electrodes modified with or without CoMCM-41. By virtue of the superior electrocatalytic activity of the CoMCM-41, a much wider peak potential difference (ΔEpa) of 310 mV was obtained for the oxidation of AA and DA in their mixture solution, and the parameters that influenced the electrochemical signals of the modified electrode were also optimized. Under optimal conditions, a good linear response to AA and DA was observed on the CoMCM-41 modified electrode. For individual detection of AA and DA, the linear ranges were 7 ~ 105 μM and 5 ~ 110 μM respectively, while the linear response range was 20 ~ 100 μM for simultaneous detection of AA and DA. Satisfactory recovery results were obtained when the fabricated sensor was applied to determine AA in orange juice and DA in madopar pill samples.

Investigation of ELectrochemical Behavior of Ferri/Ferrocyanide Redox on Carbon Paste Based Electrodes for Mercury (II) Electrochemical Sensor

The electrochemical characterisation of the materials used to make sensors is mostly based on the cyclic voltametry method. Cyclic voltametry is an electrical method for the dynamic study of electrochemical systems. Through a reversible potential sweep, the material is studied in contact with the ferri/ferrocyanide. Ferri/Ferrocyanide is one of the most studied chemical compounds in electrochemistry and photo-electrochemistry because of its singular known and controlled reactivity. The appearance of voltamorams and mathematical expressions make it possible to collect the information necessary for understanding the reaction. An electrode material is considered active if it shows a reversible peak in contact with the redox marker in cyclic voltametry. The mechanism of the reaction is also assessed using the peak potential difference ΔEp. The nature of the mass transport is determined by the anodic and cathodic peak current ratio Ipa/Ipc. The aim of this work is to compare the electrochemical activity of the Feri/Ferrocyanide couple achieved with carbon paste-based electrodes for application to the electrochemical sensor. The study of the peak potential difference ΔEp showed that the composition of the electrode material influences the reaction mechanism at the interface. Material transport and electronic charge transfer are impacted by complex phenomena. By studying the electrical quantities potential difference ΔEp, formal standard potential E° and current ratio Ipa/Ipc, the electrochemical sensors developed can be optimised.

A Novel Cerium Oxide/Gold/Carbon Nanocomposite-Based Electrochemical Sensor for Detecting Hydroxyl Radicals

Hydroxyl radicals (•OH), a type of reactive oxygen species (ROS), play a crucial role in maintaining the normal physiological processes of human cells. Nevertheless, an excessive accumulation of these radicals may perturb cellular mechanisms, so triggering the onset of severe diseases, including cancer, neurological disorders, and heart disease. The detection of •OH is thus of utmost importance in the early diagnosis of these disorders. The combination of an electrochemical methodology with a recognition system is considered as a promising approach for the detection of •OH. This is primarily due to its capacity to provide fast and direct readings without the need for any preliminary sample preparation. This study presents the development of a new electrochemical sensor for the detection of •OH. The sensor was developed by modifying a screen-printed carbon electrode (SPCE) with a nanocomposite consisting of cerium oxide nanoclusters (CeOx), gold nanoparticles (AuNPs), and a highly conductive carbon. The synthesis of AuNPs supported by carbon was carried out using a deposition-precipitation process. Subsequently, the meticulous deposition of CeOx nanoclusters onto the AuNPs was achieved by the use of surface organometallic chemistry (SOMC). Energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM) were applied to assess the distribution of AuNPs on the carbon substrate and their subsequent embellishment with CeOx nanoclusters. The actual loadings of Ce and Au present in the nanocomposite were measured using inductively coupled plasma optical emission spectroscopy (ICP-OES). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were employed to analyze the electrochemical responses resulting from the interaction of the CeOx-Au/Carbon nanocomposite with •OH. The CV results demonstrated that the proposed sensor exhibited the capability to effectively identify the presence of •OH in the Fenton reaction, with a notably low limit of detection of 58 µM. The sensor demonstrated a linear correlation between the current response and the concentration of •OH, within the range of 0.05 to 5 mM. Compared to a sensor modified with CeOx/Carbon, the CeOx-Au/Carbon-modified sensor exhibited enhanced electrochemical performance, as demonstrated by an increased current response and a reduced peak potential difference when detecting •OH radicals. Furthermore, the EIS studies showed that the sensor could distinguish •OH from other comparable ROS, such as hydrogen peroxide (H2O2).

Influence of Lithium Triflate Salt Concentration on Structural, Thermal, Electrochemical, and Ionic Conductivity Properties of Cassava Starch Solid Biopolymer Electrolytes.

Cassava starch solid biopolymer electrolyte (SBPE) films were prepared by a thermochemical method with different concentrations of lithium triflate (LiTFT) as a dopant salt. The process began with dispersing cassava starch in water, followed by heating to facilitate gelatinization; subsequently, plasticizers and LiTFT were added at differing concentrations. The infrared spectroscopy analysis (FTIR-ATR) showed variations in the wavenumber of some characteristic bands of starch, thus evidencing the interaction between the LiTFT salt and biopolymeric matrix. The short-range crystallinity index, determined by the ratio of COH to COC bands, exhibited the highest crystallinity in the salt-free SBPEs and the lowest in the SBPEs with a concentration ratio (Xm) of 0.17. The thermogravimetric analysis demonstrated that the salt addition increased the dehydration process temperature by 5 °C. Additionally, the thermal decomposition processes were shown at lower temperatures after the addition of the LiTFT salt into the SBPEs. The differential scanning calorimetry showed that the addition of the salt affected the endothermic process related to the degradation of the packing of the starch molecules, which occurred at 70 °C in the salt-free SBPEs and at lower temperatures (2 or 3 °C less) in the films that contained the LiTFT salt at different concentrations. The cyclic voltammetry analysis of the SBPE films identified the redox processes of the glucose units in all the samples, with observed differences in peak potentials (Ep) and peak currents (Ip) across various salt concentrations. Electrochemical impedance spectroscopy was used to establish the equivalent circuit model Rf-(Cdl/(Rct-(CPE/Rre))) and determine the electrochemical parameters, revealing a higher conduction value of 2.72 × 10-3 S cm-1 for the SBPEs with Xm = 17 and a lower conduction of 5.80 × 10-4 S cm-1 in the salt-free SBPEs. It was concluded that the concentration of LiTFT salt in the cassava starch SBPE films influences their morphology and slightly reduces their thermal stability. Furthermore, the electrochemical behavior is affected in terms of variations in the redox potentials of the glucose units of the biopolymer and in their ionic conductivity.

The Effect of the Capping Agents of Nanoparticles on Their Redox Potential.

Engineered metallic nanoparticles, which are found in numerous applications, are usually stabilized by organic ligands influencing their interfacial properties. We found that the ligands affect tremendously the electrochemical peak oxidation potentials of the nanoparticles. In this work, identical gold nanoparticles were ligand-exchanged and carefully analyzed to enable a precise and highly reproducible comparison. The peak potential difference between gold nanoparticles stabilized by various ligands, such as 2- and 4-mercaptobenzoic acid, can be as high as 71 mV, which is substantial in energetic terms. A detailed study supported by density functional theory (DFT) calculations aimed to determine the source of this interesting effect. The DFT simulations of the ligand adsorption modes on Au surfaces were used to calculate the redox potentials through the thermodynamic cycle method. The DFT results of the peak potential shift were in good agreement with the experimental results for a few ligands, but showed some discrepancy, which was attributed to kinetic effects. The kinetic rate constant of the oxidation of Au nanoparticles stabilized by 4-mercaptobenzoic acid was found to be twice as large as that of the Au nanoparticles stabilized by citrate, as calculated from Laviron's theory and the Tafel equation. Finally, these findings could be applied to some novel applications such as determining the distribution of nanoparticle population in a dispersion as well as monitoring the ligand exchange between nanoparticles.

Control of Peak Potential Difference of Cyclic Voltammetry Using Taguchi Method

Control of Peak Potential Difference of Cyclic Voltammetry Using Taguchi Method

Qualitative and quantitative analysis of electrons donated by pollutants in electron transfer-based oxidation system: Electrochemical measurement and theoretical calculations

In order to gain a profound understanding of the fate of pollutants in advanced oxidation processes (AOPs), this study analyzed the electron contribution of pollutants qualitatively and quantitatively which rarely reported before. The rich electron transfer system was constructed by mesoporous carbon nitride (MCN) coupling with persulfate (PS) driven by visible light and the sulfanilamide antibiotics (SULs) were used as target contaminants. Firstly, the qualitative analysis of electron transfer in the system was confirmed systematically. The electron flow direction tested by i-t curves indicated that PS absorbed electrons, while SULs released electrons. The flow rate of electrons was also accelerated after the addition of SULs. The fitting curve between the kinetics and the peak potential difference tested by CV curve showed that the larger potential difference, the slower rate of oxidative degradation. Secondly, the quantification of electron transfer was achieved through theoretical calculations to simulate the interactions of the ‘catalyst-oxidant-antibiotic’ system. After the addition of SULs, the adsorption energy of the ‘catalyst-oxidant-antibiotic’ system was enhanced and the bond length of the peroxide bond was stretched. Notably, the electron transfer analysis results showed that the charge of SULs was around 0.032–0.056e, indicating that SULs pollutants played the role of electron contributors in the system. The oxidative degradation pathway included the direct cracking of S-N bond, shedding of marginal groups, ring-opening and hydroxyl addition reaction. This study clarified the electronic contribution of SULs in the oxidation system, providing necessary theoretical supplement for the analysis of the transformation of pollutants in AOPs.

Multiwalled-Carbon-Nanotube-Modified Li2ZnTi3O8 as Anode with Improved Cycling Stability and Rate Capability for Lithium-Ion Batteries

Due to its better electronic conductivity and larger lithium intercalation capacity, a multiwalled-carbon-nanotube (MWCNT)-modified Li2ZnTi3O8 (LZTO) has significant potential for use as an anode material for Li-ion batteries. The rapid and affordable ball-mill-aided solid state approach is used to synthesize LZTO with MWCNT-modified Li2ZnTi3O8 (LZTO@MWCNTs). Electrochemical performance tests of the anode material were carried out using cyclic voltammetry (CV), galvanostatic charge-discharge measurement, and electrochemical impedance spectroscopy (EIS). The CV experiments reveal that the LZTO@MWCNT electrode has a lower anodic and cathodic peak potential difference (0.184 V) than the LZTO electrode (0.211 V) and LZTO@MWCNT electrode has better electrochemical reversibility than that of pristine electrode after five cycles utilizing the same procedure. LZTO@ MWCNTs anode material has a higher charge-discharge capacity than LZTO anode material at 0.1–5 C rates. After 100 cycles, the initial discharge capacities of LZTO@MWCNT electrode are 227 and 142 mAh g−1 at the 1C–5C rate, respectively, whereas the initial discharge capacities of LZTO electrode are only144 and 28 mAh g−1 in the same condition. The charge transfer and SEI resistance of the LZTO anode are 19.31 and 62.74 ohms, respectively, after 30 cycles at 1C, according to the EIS data. Additionally, the values for the LZTO@MWCNTs anode are 7.93 and 12.06 ohms for charge transfer and SEI resistance, respectively.

The effect of copper doping in α-MnO2 as cathode material for aqueous Zinc-ion batteries

Copper-doped Manganese Dioxide has been synthesised through a simple hydrothermal method at different doping levels. The synthesised materials have been characterized by X-ray diffraction (XRD), and scanning electron microscopy (SEM) to determine the composition, structure, and morphology. All the Cu doped MnO2 are found to be single phased. Their electrochemical properties as cathode for Zinc-ion batteries are studied by cyclic voltammetry (CV), galvano-static charge / discharge (GCD) and electrochemical impedance spectroscopy (EIS), using 3 M ZnSO4 + 0.3 MnSO4 solution as the electrolyte. 3.8% Cu doped MnO2 has shown the highest initial capacity of 379.5 mAh g−1 at 0.02 A·g−1, and 304.4 mA h g−1 at 0.5 A g−1, but experienced fast fading with a poor capacity retention of 56.8% after 100 cycles. 7.4% Cu doping gives lower capacity, while 5.9% doping shows a higher discharging capacity (320.0 mAh·g−1 at 0.02 A·g−1 and 269.3 mAh·g−1 at 0.5 A·g−1) and improved stability (85.8% capacity retention after 100 cycles), better than non-doped MnO2 electrode (284.4 mAh g−1 at 0.02 A g−1 and 252.1 mAh·g−1 at 0.5 A g−1, capacity retention 76.7%). The samples show satisfactory capacity and rate capability while the cycling stability is not ideal, which may relate to the needle like morphology and nanoscale particle size. CV tests revealed that the electrochemical process is mainly diffusion controlled. The zinc ion diffusion coefficient is tested to be in the range of 10−12 cm2·s−1 from both CV and EIS tests and showed the same trend in their electrochemical capacity. Doping of Copper in MnO2 reduced the polarization on electrode, improved the electrochemical reversibility, as evidenced by the reduction of the redox peak potential difference from 0.31 to 0.24 V at 1.1 mV·s−1, and from 0.45 V to 0.31 V at 5 mV·s−1. Whilst the cell resistance of non-doped MnO2 increased from 1.78 Ω to 7.39 Ω after cycling, the cell resistances of all Cu-doped cathodes reduced, indicating improved electronic conductivities after cycling. These results indicate that Cu-doping is effective to increase the conductivity of the materials, reduce the polarization during charge and discharge, and improve the cycling stability of MnO2 cathode.

On site portable detection of gaseous I2 using green and pollution-free electrochemical methods.

A poly(ionic liquid) probe material was prepared that is conductive, uniformly film-forming, and rich in I2 interaction sites by structural design. Green and pollution-free electrochemical detection of gaseous I2 was achieved based on the variation of redox peak currents, and the limit of detection was 1.44 nM. The differences in redox peak potentials were utilized for the specific detection of gaseous I2.

Simultaneous detection of norepinephrine and 5-hydroxytryptophan using poly-alizarin/multi-walled carbon nanotubes-graphene modified carbon fiber microelectrode array sensor

Multi-walled carbon nanotubes, graphene and alizarin polymer composites coated carbon fiber microelectrode array sensor (p-AZ/MWCNT-GR/CFMEA) was constructed and used for the simultaneous detection of norepinephrine (NE) and 5-hydroxytryptophan (5-HT). The morphology and structural characteristics of sensor are characterized using scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Its electrochemical behavior has been studied with cyclic voltammetry and electrochemical impedance spectroscopy. The sensor exhibits excellent electrochemical activity for the oxidation of NE and 5-HT, two well separated oxidation peaks with the peak potential difference of 220 mV are observed on the cyclic voltammogram. NE and 5-HT both show two electrons and two protons electrochemical reaction on the p-AZ/MWCNT-GR/CFMEA. Under the optimized experiment conditions, the linear ranges of the sensor for NE and 5-HT are 0. 08- 8 μM and 0. 1–20 μM with detection limits of 4. 22 nM and 14. 2 nM (S/N = 3), respectively. In addition, the microsensor array show good reproducibility, stability and selectivity for the determination of NE and 5-HT. Finally, the p-AZ/MWCNT-GR/CFMEA is applied to the simultaneous detection of NE and 5-HT in human serum samples and macrophages.

Oxygen vacancy-enriched NiCo2O4 spinels/N-doped carbon nanotubes-graphene composites for the ethylene glycol electro-oxidation

The efficient electro-oxidation of alcohol fuels on non-platinum group metals (non-PGMs) is a crucial challenge in advanced fuel cell technology. This study presents a novel approach, focusing on systematically designing highly efficient composites through strategic interface engineering. The method harnesses the intrinsic potential of oxygen vacancies (Ov) in the NiCo2O4 spinel, while synergistically incorporating nitrogen heteroatoms into multi-walled carbon nanotubes mixed with graphene (N-CNTG). Ethylene glycol (EG) was employed as defect promoter at 0, 33, 66 and 100 % v/v EG. Micrographs showed that nanobars were the predominant morphology at 0 % v/v EG, and this shape shifted to nanometric hemispheres with the shift to EG. X-ray photoelectron spectroscopy (XPS) showed that the Ov increased from 23 % to 36 % shifting from 0 to 100 % v/v EG. Comparative electrocatalytic studies showed the remarkable performance of the engineered composites compared to Vulcan carbon (C), a standard support. The best onset potential (1.08 V) was found on NiCo2O4 EG33/N-CNTG. The onset potential was 330 mV higher to that of a gold nanomaterial, but the peak potential difference was only 140 mV. This was associated with the improvement of the electronic structure as revealed by chemical calculations, changing adsorption energies, apparent activation energies and resistances to charge transfer. These findings highlight the potential of interface engineering in achieving non-PGMs electrocatalysts.

Hierarchical Nano-Electrocatalytic Reactor for High Performance Polysulfides Redox Flow Batteries.

The aqueous polysulfides is an important Earth-abundant and multielectron redox couple to construct high capacity density and low-cost aqueous redox flow batteries (RFB) ; nevertheless, the sluggish conversion and kinetic behavior of S2-/Sx2- result in a low power density output and poor active material utilizations. Herein, we present nanoconfined self-assembled ordered hierarchical porous Co and N codoped carbon (OHP-Co/NC) as an electrocatalytic reactor to enhance the mass transfer and redox activity of aqueous polysulfides. Finite element method simulation proves that the OHP-Co/NC with interconnected macropores and mesopores exhibits an enhanced mass transfer and delivers a larger redox electrolyte utilization of 50.1% compared to 23.3% of conventional Co/NC. Notably, the OHP-Co/NC obtained at 850 °C delivers the smallest redox peak potential difference (ΔE = 99 mV). Comparison studies of in operando Raman for aqueous polysulfides in the redox electrolyte and in situ electrochemical Raman on the single OHP-Co/NC particle for the adsorbed polysulfides were carried out. And it confirms that the OHP-Co/NC-850 catalyst has a strong adsorption of S42- and can retard the strong disproportionation and hydrolysis behavior of polysulfides on the electrocatalyst interface. Therefore, the polysulfide/ferrocyanide RFB with an OHP-Co/NC-850 based membrane-electrode assembly (MEA) exhibited a high power density of 110 mW cm-2, as well as a steady capacity retention over 99.7% in 300 cycles.

MOF-derived Cu/N–C Composite Based Electrochemical Sensor for Simultaneous Detection of Catechol and Hydroquinone

In this work, Cu/N-C derived from MOF composites were synthesized and characterized by SEM, XRD, FTIR, XPS and EIS, which was modified on the glassy carbon electrode (GCE) to construct a novel electrochemical sensor (Cu/N-C/GCE). Due to the good electrical conductivity and abundant catalytic active sites of Cu/N-C, Cu/N-C/GCE exhibited excellent electrocatalytic performance for catechol (CC) and hydroquinone (HQ) with the oxidation peak potential difference of 112 mV. The proposed sensor could realize the simultaneous detection of CC and HQ successfully. Under optimal conditions, the redox peak currents of both CC and HQ have good linear relationship with their concentrations in the ranges of 0.50–100.00 μM and 0.50–150.00 μM with the detection limits for CC and HQ of 0.12 μM and 0.09 μM, respectively. At the same time, the sensor exhibits good stability, reproducibility and selectivity in the analysis of practical samples.

Thickness Effects on Boron Doping and Electrochemical Properties of Boron-Doped Diamond Film.

As a significant parameter in tuning the structure and performance of the boron-doped diamond (BDD), the thickness was focused on the mediation of the boron doping level and electrochemical properties. BDD films with different thicknesses were deposited on silicon wafers by the hot filament chemical vapor deposition (HFCVD) method. The surface morphology and composition of the BDD films were characterized by SEM and Raman, respectively. It was found that an increase in the BDD film thickness resulted in larger grain size, a reduced grain boundary, and a higher boron doping level. The electrochemical performance of the electrode equipped with the BDD film was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in potassium ferricyanide. The results revealed that the thicker films exhibited a smaller peak potential difference, a lower charge transfer resistance, and a higher electron transfer rate. It was believed that the BDD film thickness-driven improvements of boron doping and electrochemical properties were mainly due to the columnar growth mode of CVD polycrystalline diamond film, which led to larger grain size and a lower grain boundary density with increasing film thickness.

Electrochemical sensing of methotrexate in the presence of folic acid using PAMAM dendrimer-functionalized multiwalled carbon nanotube-modified electrode.

This works presents a novel electrochemical sensor based on the third-generation poly(amidoamine) dendrimer (G3 PAMAM)-functionalized multiwalled carbon nanotube (MWCNT)-modified screen-printed graphite electrode (SPGE) for the simple and sensitive detection of methotrexate (MTX). The carboxylated MWCNTs were covalently functionalized with amino groups of G3 PAMAM and characterized using different techniques. The sensing ability of the designed nanosensor (MWCNTs-PAMAM/SPGE) was tested using differential pulse voltammetry (DPV), chronoamperometry (CHA), linear sweep voltammetry (LSV), and cyclic voltammetry (CV). To investigate the electrocatalytic activity of PAMAM-functionalized MWCNTs, a comparative electrochemical analysis was carried out and it was determined that PAMAM-functionalized MWCNT-modified SPGE showed good electrocatalytic performance for MTX oxidation compared to the unmodified SPGE. The MWCNT-PAMAM/SPGE lead to a reduced overpotential of MTX oxidation of about 300 mV and enhanced current of about 9 μA of the unmodified SPGE. Experiments were performed for the quantitative determination of MTX using the DPV technique. The response peak current linearly related against MTX concentration in the ranges from 0.01 to 110.0 μM and a limit of detection (LOD) equal to 0.003 μM. Also, MWCNT-PAMAM/SPGE exhibits good catalytic ability toward MTX determination in the presence of folic acid (FA), and the separation of their oxidation peaks (peak potential difference = 320 mV) simultaneously detected the above compounds. To prove the applicability of the MWCNT-PAMAM/SPGE sensor, the concentrations of MTX and FA in pharmaceutical products and biological samples were determined. The calculated recoveries were close to 100%, which indicates that the method might be assumed to be accurate.

An electrochemical sensor based on metal–organic framework–chiral ionic liquid composites for the enantiorecognition of tryptophan enantiomers

Metal organic framework–chiral ionic liquid composites Fe-CIL was first used to construct the chiral sensor, which could be used to chiral recognize tryptophan (Trp) enantiomers based on the DPV peak potential difference (ΔEp) of l/d-Trp.

Highly sensitive and selective electrochemical sensor based on ZIF-67-derived Co3O4-LaMn0.5Ni0.5O3/MWCNTs for simultaneous detection of protocatechuic acid and ascorbic acid

An electrochemical sensor based on ZIF-67 derived Co3O4-LaMn0.5Ni0.5O3/MWCNTs composite for the simultaneous determination of protocatechuic acid (PCA) and ascorbic acid (AA) was successfully fabricated by using the MOF template method. The results showed that the modified electrode significantly reduced the oxidation peak potential and increased the oxidation peak current of AA and PCA, and had a high electrocatalytic activity for their oxidation. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) plots showed the peak potential difference of PCA and AA was bigger enough to be beneficial to their simultaneous determination by the ZIF-67 derived Co3O4-LaMn0.5Ni0.5O3/MWCNTs modified glassy carbon electrode (GCE). The DPV tests showed that the current responses of PCA and AA were linearly with the concentration with the linear detection range being 9.31−272.28 μmol L−1, 9.26−210.68 μmol L−1 and the low detection limits being 8.83 μmol L−1 and 7.35 μmol L−1, respectively. The optimal ZIF-67 derived Co3O4-LaMn0.5Ni0.5O3/MWCNTs/GCE was successfully employed to the simultaneous determination of PCA and AA in real beverage samples. Moreover, the reaction mechanism of PCA and AA oxidation on the surface of ZIF-67-derived Co3O4-LaMn0.5Ni0.5O3/MWCNTs/GCE was also explored to understand deeply the reaction process.

Preparation and responsive performance study of AuNPs/RGO-MoO2/GCE composite modified electrodes based on its high sensitivity to acetaminophen and dopamine

To detect acetaminophen (AMP) and dopamine (DA) effectively and rapidly, the Au nanoparticles (AuNPs） were deposited on the surface of glassy carbon electrode (GCE) modified with Molybdenum dioxide-doped Reduced graphene oxide (RGO-MoO2) nanosheets to form AuNPs/RGO-MoO2/GCE composite modified electrode (electrochemical sensor) was prepared The modified electrode was studied regarding its composition, structure and the effect of process parameters such as the electrochemical response characteristics of AMP and DA, the pH value of the buffer, the scan rate, and the sensitivity of both simultaneous detections. The results show that the synergy between AuNPs and RGO-MoO2 nanomaterials can promote the electrochemical reaction of AMP and DA, and the oxidation peak potential differences of the two are greater than 180 mV. The linear ranges of the modified electrode are 0.05–320 μ mol/L for AMP and 0.6–260 μ mol/L for DA, and the detection limits are 7.2 nmol/L and 13 nmol/L (S/N = 3), respectively. The prepared AuNPs/MoO2-RGO/GCE modified electrode has a wider linear range, lower detection limit, excellent reproducibility, stability and selectivity.

Cleaning of LTCC, PEN, and PCB Au electrodes towards reliable electrochemical measurements

Surface cleaning of the working electrode has a key role in improved electrochemical and physicochemical properties of the biosensors. Herein, chemical oxidation in piranha, chemical cleaning in potassium hydroxide-hydrogen peroxide, combined (electro-) chemical alkaline treatment, and potential cycling in sulfuric acid were applied to gold finish electrode surfaces deposited onto three different substrates; low temperature co-fired ceramics (LTCC), polyethylene naphthalate (PEN), and polyimide (PI), using three different deposition technologies; screen printing, inkjet printing, and electroplating (printed circuit board technology, PCB) accordingly. The effects of the (electro-) chemical treatments on the gold content and electrochemical responses of LTCC, PEN, and PCB applicable for aptamer-based sensors are discussed. In order to assess the gold surface and to compare the efficiency of the respective cleaning procedures; cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) were employed. LTCC sensors electrochemically cycled in sulfuric acid resulted in the most gold content on the electrode surface, the lowest peak potential difference, and the highest charge transfer ability. While, for PEN, the highest elemental gold and the lowest peak-to-peak separation were achieved by a combined (electro-) chemical alkaline treatment. Gold content and electrochemical characteristics on the PCB surface with extremely thin gold layer could be slightly optimized with the chemical cleaning in KOH + H2O2. The proposed cleaning procedures might be generally applied to various kinds of Au electrodes fabricated with the same conditions comparable with those are introduced in this study.