Conventional absorption spectroscopy (CAS) with a blank reference has only a slight capacity to detect high concentrations at characteristic wavelengths owing to the corresponding large molar absorption coefficient (ε) on the scale of 103 or 104 cm–1 M–1. To monitor concentrated analytes as high as the molar range in a plating bath and on a chemical production line, we propose a new approach using sideband differential absorption spectroscopy (SDAS). SDAS is obtained by subtracting the absorption spectra of the samples, A(λ,Cx), from that of a reference containing a concentrated standard analyte, A(λ,Cref>Cx), resulting in concave spectra with peaks at the sideband of conventional spectra with generally low ε values on the scale of 100 cm–1 M–1 or less. The negative absorbance changes linearly with the sample concentration at a certain peak wavelength, obeying Lambert–Beer’s law. In this work, SDAS was obtained and verified using inorganic and organic substances, such as chromate potassium, rhodamine B, and paracetamol.

We report for the first time that conducting objects could be propelled in folded liquid filled channels by bipolar electrochemistry. This approach was based on controlling the formation of hydrogen bubbles at one extremity of a bipolar electrode. In this work, copper wires used as microswimmers could move in folded channels with angles from 30° to 180° by bubble propulsion and the velocity fluctuated over time. A proportional relation between polarization voltage and average velocity in linear channel was verified. The motion of microswimmers could be controlled within these types of channels in space and time, which might broaden the applications of micromachines in bipolar electrochemistry.

•A model is established for understanding the temperature change of an electrode.•An electrode is fabricated with the surface temperature modulating from room temperature to − 10 °C.•The diffusion coefficient of the ferricyanide ion has been measured at supercooled temperatures.•The diffusion activation energy for ferricyanide is calculated from above 0 °C down to supercooled temperatures.A model is established for understanding the temperature change of an alternate hot and cold micro-band graphite electrode. It consists of two symmetrically placed thermoelectric coolers with an embedded graphite sheet as interlayer. By measuring the open circuit behaviors of a standard redox couple, the electrode surface temperature can be detected. And the electrode surface temperature can be regulated from 40 °C to − 10 °C in aqueous solution without freezing. The model is described as Qh = γh ΔT, Qc = γc ΔT, where the temperature change (ΔT) of electrode surface is assumed to be proportional to power of heating (Qh) or cooling (Qc). In addition, the diffusion activation energy of ferricyanide ion is firstly achieved by extending the temperature range from above zero degree down to the supercooled temperature (− 10 °C) with this specially designed electrode. Diffusion coefficient of ferricyanide ion is ca. 0.22 × 10− 5 cm2 s− 1 at − 10 °C, and activation energy is 23.2 kJ mol− 1. The experimental data are consistent with data obtained by Stokes–Einstein equation for the determination of diffusion coefficient and activation energy.

•Au-Fe/Ni/(Mo/Co) alloy microsphere motors (AMSM) were fabricated based on physical vapor deposition.•The ejection of O2 bubbles from the exposed alloy provides propulsion only in the mixed fuel of N2H4 and H2O2.•The microsphere motor can be guided by the magnetic force.Au–Fe/Ni/(Mo/Co) alloy microsphere motors (AMSM), having an average diameter of 7 ~ 9 μm, were fabricated though a rapid and effortless method than the template direct electroplating (TDEP), which only requires physical vapor deposition (PVD) of inert metal coat on commercially available microspheres; thus, several kinds of AMSM with different alloy composition can be manufactured readily. Via co-catalytic decomposing reaction in the mixed fuel of hydrogen peroxide and hydrazine, the ejection of oxygen bubbles generated from the Fe/Ni/(Mo/Co) alloy hemisphere provides a powerful directional propulsion. The AMSM's moving ability closely depends upon the content of mixed fuel and the composition of alloy, especially the content of nickel. The AMSM can move as fast as 548.63 μm/s (ca. 64 body-lengths/s). Because of the permalloy composition, the AMSM also can be guided by the magnetic force besides controlled with the propelling force generated by the bubble thrust. Compared with the nanowire motor, the AMSM could facilitate different biomedical applications, such as targeted drug delivery in future research, because of its bigger specific surface area.Au–Fe/Ni/(Mo/Co) alloy microsphere motors (AMSM) can move at the speed of 548.63 μm/s in the fuel containing H2O2 and N2H4 and can be controlled by the propelling force and magnetic one.

•A heated gold particles modified gold disk electrode (Au-HAuDE) was fabricated.•HRP-DNAzyme as signal label for DNA detection at Au-HAuDE was realized.•With elevated electrode temperature, the detection limit was greatly improved.•This method can easily be extended to other biological molecule measurements.A new method for electrochemical detection of DNA hybridization with elevated electrode temperature at gold particles modified heated gold disk electrode (Au-HAuDE) is demonstrated. This method employs a hairpin DNA probe for target DNA capture and incorporates a specific DNAzyme sequence into the probe as electrocatalytic label. The hairpin DNA probes are immobilized on the Au-HAuDE. The presence of target DNA opens the hairpin structure, releases the DNAzyme sequence, and forms the hemin/G-quadruplex peroxidase-mimicking DNAzyme (HRP-DNAzyme) with hemin addition. With elevated electrode temperature, the electrocatalytic activity of HRP-DNAzyme for H2O2 reduction by oxidation of hydroquinone (used as an electron transfer mediator) can be significantly improved, resulting in an enhanced electrochemical reduction current of benzoquinone for DNA detection. With an electrode temperature of 50 °C, the detection limit for target DNA measurements can be decreased ca. one magnitude compared with that at 0 °C.

Hypoxanthine, a purine heterocyclic compound with N and O atoms, has capability to combine metal ions or adsorb on metals. By using density functional theory (DFT) method calculation, the energy, charge distribution, molecular orbital and vibration spectra information of tautomeric hypoxanthine were given. Combined with these DFT results, the influence of pH on the structure of tautomeric hypoxanthine was studied by surface enhanced Raman spectroscopy (SERS). Electrochemical SERS was applied to study the properties of hypoxanthine/gold interface. It is found that the structure of adsorbed hypoxanthine was changed from slightly tilted to upright with negatively moving of potentials.

We previously introduced a novel Au–Fe/Ni alloy nanomotor that could move with a speed of up to 850 μm s−1 in a mixed fuel (H2O2 and N2H4) environment. However, the propulsion mechanism and the role of hydrazine were not fully elucidated. To this end, Tafel plots, linear sweep voltammetry (LSV) and oxygen sensing were employed and integrated to explore hydrazine's function and explain the locomotive behaviour of Au–Fe/Ni nanomotors. It was found that the speed of Au–Fe/Ni nanomotors was not positively correlated with the mixed potential difference between the composite metal pair, which had not been found in similar self-electrophoresis propelled nanomotors. Moreover, the results showed that the oxidation of H2O2 can also be facilitated by hydrazine in mixed fuels, resulting in oxygen bubbles propelling Au–Fe/Ni nanomotors forward.

The ECL phenomenon of nano Cd2Ge2O6, both amorphous and crystallized, is described in this paper. This is the first report on the ECL of semiconductor nanocrystals involving three elements and also the first paper dealing with the amorphous nanomaterials, which shed some light on the exploration of new ECL nanomaterials. The ECL mechanism could be ascribed to the cadmium-rich surface state of amorphous Cd2Ge2O6. The ECL intensity linearly increased along with the square of the H2O2 concentration. Therefore, it was employed to detect hydrogen peroxide, and the linear range was 5.0 × 10−6 to 4.0 × 10−4 mol L−1.

•A supercooled electrode is fabricated with surface temperature below –10 ºC in water.•Supercooled region is restricted within a small volume around the disk electrode.•Electrochemical behaviors of cytochrome c were investigated at supercooled electrode.A supercooled disk electrode is fabricated, around which the temperature of aqueous solution is below its normal freezing point. The supercooled electrode demonstrates thermal stability and its surface temperature can be adjusted by changing an additional heating current. Theoretical simulation shows that the supercooled region is restricted within a small volume around the disk electrode. The electrochemical behavior of cytochrome c was investigated at supercooled electrode for the first time.

Au–Fe/Ni alloy nanowire motors, having an average length of 5.4 ± 1.2 μm and a diameter of 280 ± 10 nm, can move fast in a mixed fuel containing H2O2 and N2H4. The powered motion is attributed to the bubble thrust produced from catalytic decomposition of hydrogen peroxide on the Fe/Ni alloy segments, while hydrazine seems to act as a co-catalyst. The regulation of speed can be achieved by modulating the proportion of alloy composition, and the highest speed obtained is up to 850 μm s−1 (ca. 157 body-length per s), which is the fastest among all nanowire motors. Because of the ferronickel segment's magnetism, the Au–Fe/Ni alloy nanomotors also can be guided by the magnetic force, in addition to being controlled by the propelling force generated by the bubble thrust.

A indirectly heated pencil lead disk electrode (HPLDE) with direct current was fabricated. The dramatic temperature effect on the adsorptive accumulation of luteolin was demonstrated. A detection limit of 1.0 × 10− 9 M could be obtained (S/N = 3) with an electrode temperature of 44 °C, which was more than one magnitude lower than that at room temperature. It was applied to the determination of luteolin in simulated human urine with good accuracy. This heated electrode shows many merits such as easy fabrication and simple heating equipments, low cost, high thermal stability, high sensitivity and good reproducibility.Highlights► A heated pencil lead disk electrode (HPLDE) was firstly fabricated. ► The heating current would not interfere with the electrochemical signal. ► This heated electrode has high thermal stability and high sensitivity. ► The dramatic temperature effect on luteolin detection at HPLDE was demonstrated. ► This electrode holds great promising for constructing electrochemical biosensor.

In this work, the electrochemical catalytic properties of the topological insulator bismuth selenide (Bi2Se3) were first studied. In the presence of Bi2Se3 the reduction current of dissolved O2 could be significantly enhanced. The electron transfer resistivity (Rct) was greatly reduced at the Bi2Se3–PVP modified electrode as evidenced by the electrochemical impedance spectrometry, implying that the topological insulator Bi2Se3 could facilitate the electron transfer at the interface due to the excellent surface conductivity. Based on the high electrochemical catalytic activity for the reduction of dissolved O2, the Bi2Se3–PVP modified electrode was used to detect glucose with the modification of glucose oxidase, and applied for the detection of glucose in human blood serum.Highlights► We first studied the electrochemical catalytic properties of the topological insulator Bi2Se3. ► Bi2Se3 has the high electrochemical catalytic activity for the reduction of dissolved O2. ► A glucose sensor was developed based on the electrochemical catalytic activity of Bi2Se3. ► With the modification of GOD, it is possible to use Bi2Se3 modified GCE to detect glucose in serum.

We report the visual detection of Al3+ using unlabeled gold nanoparticles (AuNPs) based on the complexation of Al3+ with citric acid, resulting in the aggregation of AuNPs. The distinction of color change can be observed by the naked eye at concentrations down to 1.0 μM which is lower than the permissable level (7.4 μM) for drinking water as defined by the World Health Organization.

Hot electron-induced cathodic electrochemiluminescence of the Ru(bpy)32+/S2O82− system was investigated at an oil film-covered carbon paste electrode (CPE) under cathodic pulse polarization for the first time. Compared with other electrodes, the CPE is of lower background, better stability and reproducibility. The method is also applied to the determination of catechol. Under the optimum conditions, the linear correlation between the quenched ECL intensity (ΔI) and the logarithm of catechol concentration (log Ccatechol) was observed over the range of 2.0×10−10 mol/L–4.0×10−9 mol/L and 4.0×10−9 mol/L–4.0×10−7 mol/L with the limit of detection (LOD) of 2.0×10−10 mol/L, which is lower than the other reported methods. The proposed method is applied to determine catechol in reservoir water. The mean recoveries of 83.3%–99.0% and the relative standard deviations (RSDs) of 0.8%–2.2% were obtained.Highlights► An oil film-covered CPE suitable for cathodic ECL was reported. ► The oil film-covered CPE exhibited excellent sensitivity and perfect stability. ► It is applied to the determination of catechol based on the quenching effect of phenols. ► The LOD of catechol is lower than the other reported methods. ► It is applied to determine catechol in water sample.

A simple, low cost, stable and environmentally friendly gold plating electrolyte containing hypoxanthine as a complexing agent is introduced. Bright and compact gold deposits could be obtained by using PEI-1800 and SUNO (a compound that contains the element sulfur) as additives for electrodepositing gold on a nickel substrate.

We report a new application of gold nanoparticles for visual detection of copper ions with high sensitivity and selectivity based on the colorimetric difference due to the strong and specific inhibition of Cu(NH3)62+ to the corrosion of gold nanoparticles at low concentration.

For the first time, we reported the strong electrogenerated chemiluminescence of organic dye, bis[4-(dimethylamino)phenyl]squaraine (BDPSQ), a high quantum yield and light-stable species, which might find applications in ECL analysis and imaging.

Electrogenerated chemiluminescence (ECL) of Au clusters is observed for the first time using triethyamine (TEA) as the coreactant. The potential application of ECLAu clusters in analytical chemistry is also demonstrated using Pb2+ as an example.

In this paper, in situ Fourier Transform Infrared Spectroscopy (FTIRS) is used to study the electro-catalytic oxidation mechanism of shikimic acid (SA) at a copper electrode in H2O and D2O solution, respectively. As the potential is applied between 0.1 V and 0.2 V vs. SCE, SA is oxidized to 3-dehydroshikimic acid (DHS). Then a significant change appeared when the potential is scanned from 0.3 V to 0.8 V, DHS is decomposed to transaconitate and formate. As the potential is over 0.9 V, formate is further oxidized to CO2. Density functional theory (DFT) calculation of the IR spectra is in good agreement with the experimental observation. The adsorption of transaconitate through carboxyl on copper electrode is also evidenced by p- and s-polarized radiation in FTIRS.Highlights► We studied the electro-oxidation mechanism of Shikimic acid using FTIR technique. ► The strong interference from water was eliminated. ► The intermediates in the electro-oxidation process were infered. ► The final products, i.e. transaconitate and CO2 were determined.

A new disposable multi-walled carbon nanotubes modified single-sided heated screen-printed carbon electrode (MWNT/ss-HSPCE) was fabricated. The electrochemical behavior of silybin was investigated by cyclic voltammetry and the probable electrode reaction mechanism was proposed. A simple and cheap direct current heating supplier was used to heating the electrode for adsorptive accumulation of silybin. The square wave voltammetric stripping peak current of silybin at MWNT/ss-HSPCE with an elevated electrode temperature of 50 °C only during accumulation step was dramatically improved compared with that at bare single-sided heated screen-printed carbon electrode (ss-HSPCE) without heating. This enhancement was mainly contributed to the combination of the advantages of multi-walled carbon nanotubes and electrically heated electrodes. Under optimum conditions, two detection linear ranges of silybin were from 1.0 × 10−9 to 1.0 × 10−7 M and 3.0 × 10−7 to 1.0 × 10−6 M. A detection limit of 5.0 × 10−10 M could be obtained (S/N = 3), which was more than two magnitudes lower than that at bare ss-HSPCE without heating. To the best of our knowledge, this was also at least two magnitudes lower than any others for electrochemical detection of silybin in the literature. Finally, the method was successfully applied to the determination of silybin in pharmaceutical tablets.

Hot electron induced cathodic electrochemiluminescence (ECL) was found at a disposable CdS modified screen printed carbon electrodes (CdS-SPCEs) during cathodic pulse polarization. The ECL behavior of the modified electrode was investigated with two emissions located at 520 nm and 580 nm. The CdS-SPCEs show very stable and reproducible ECL signal. The ECL intensity was linear with the dissolved oxygen concentration in the range of 1.7–33 mg/L with a detection limit of 0.02 mg/L (S/N = 3). In addition, a possible mechanism for ECL behavior of the modified electrode was proposed. The developed method can be applied to detect the dissolved oxygen concentration or biochemical oxygen demand (BOD).

Electrogenerated chemiluminescence (ECL) of nanoparticles are known to be strongly dependent on the surface states, whereas the detailed mechanisms are not clear. Here, the detailed ECL mechanisms of CdS nanopaticles have been investigated. It was found that ECL emission observed at −0.95 V (600 nm, 700 nm) is assigned to the reduction of the surface S vacancy, whereas the luminescence at −1.25 V (520 nm) is attributed to the electron injection to the conduction band in the cathodic process. On the basis of these mechanisms, for the first time, we are able to observe the gradual ECL evolution of CdS nanoparticles in the presence of oxidant, therefore online monitoring the surface oxidation of CdS nanoparticles by the ECL method. This method will find more application in surface probing of nanomaterials because the ECL of nanomaterials is very sensitive to the surface.

A heated copper microdisk electrode (HCME) was fabricated and successfully applied to capillary electrophoresis (CE) and CE-Chip as an electrochemical detector (ECD) for the detection of three carbohydrates and shikimic acid (SA) in Illicium verum Hook F., respectively. The temperature of HCME was heated by twin-wire-wound coil with direct current to reduce the magnetic interference. Coupled with CE and CE-chip, this detector exhibits both extremely stable and sensitive performance at elevated temperature compared with that at room temperature. In successive detection of three carbohydrates and shikimic acid (SA), the HCME exhibits very stable response with RSD of ca. 2% with elevated temperature without renewing the electrode, while at room temperature, RSD of ca. 20% is obtained. This is very important in practical applications that tedious works, such as polishing and re-fixing the electrode at each detection, can be therefore avoided. In addition, the sensitivity is about 2 ∼ 6 time increased, and the linear range is about an order wider at elevated temperature (ca. 60 °C) than that at room temperature (ca. 25 °C).

Cathodic electrochemiluminescence (ECL) is firstly observed at a carbon oxide covered glassy carbon (C/CxO1−x) electrode as a large cathodic pulse polarization is applied. This insulating carbon oxide (CxO1−x) film is constructed on a glassy carbon (GC) substrate by electrochemical oxidization in basic media. The film properties, such as the composition of carbon and oxygen, and the thickness as well, can be controlled by the potential and the duration in the oxidizing process. X-Ray photoelectron spectroscopy (XPS) studies show that carbonyl and carboxyl dominate at the oxidized surface, to which antibodies can be covalently bound. The specific immunoreaction between antigen (Ag) and antibody (Ab) resulted in a decrease in the ECL intensity, thus creating an interesting basis for the development of a label-free cathodic ECL immunosensor. As an example, human IgG (hIgG) was sensitively determined in the concentration range of 0.01–100 ng mL−1, and the detection limit was ca. 1.0 pg mL −1 (S/N = 3). In addition, the content of hIgG in human serum has been assayed by the developed immunosensor and a commercially available immune turbidimetry method, respectively, and consistent results were obtained. The prepared immunosensor provides a promising approach for the clinical determination of IgG levels in human serum, because it is simple, rapid, highly sensitive, specific, and without the need of tedious labeling operations.

A new electrode was fabricated by electrodepositing luteolin at a screen printed carbon electrode (SPCE) modified with a composite of multi-walled carbon nanotube (MWNT) and ionic liquid (IL). Cyclic voltammograms of the modified electrode in phosphate buffer solution showed a pair of stable and reversible redox couple of luteolin with surface confined characteristics. This electrode possessed excellent electrocatalytic ability towards hydrazine oxidation. The overpotential was decreased significantly and the peak current was increased dramatically compared to those at bare SPCE. This enhancement of the responses was mainly contributed to the combination of the unique electrocatalytic and electronic properties of luteolin, MWNT and IL. The modified electrode was employed to the amperometric detection of hydrazine at an applied potential of 0.31 V vs. SCE with fast response, high sensitivity, good stability and reproducibility. Two linear ranges of hydrazine were from 2.0 × 10−8 to 2.0 × 10−7 M and from 2.0 × 10−7 to 1.2 × 10−4 M. Nanomolar detection limit of 6.6 × 10−9 M (S/N = 3) could be obtained, which is at least one magnitude lower than any others with electrochemical detection of hydrazine. The proposed method was also used to determine hydrazine residues in spiked drinking water and river water with average recoveries of 101.7% and 101.1%, respectively.

A reagentless signal-on electrochemiluminescence (ECL) biosensor for DNA hybridization detection was developed based on the quenching effect of ferrocene (Fc) on intrinsic cathodic ECL at thin oxide covered glassy carbon (C/CxO1−x) electrodes. To construct the DNA biosensor, molecular beacon (MB) modified with ferrocene (3′-Fc) was attached to a C/CxO1−x electrode via the covalent bound between labeled amino (5′-NH2) and surface functional groups. It was found that the immobilization of the probe on the electrode surface mainly depended on the fraction of surface carbonyl moiety. When a complementary target DNA (cDNA) was present, the stem-loop of MB on the electrode was converted into a linear double-helix configuration due to hybridization, resulting in the moving away of Fc from the electrode surface, and the restoring of the cathodic ECL signal. The restoration of the ECL intensity was linearly changed with the logarithm of cDNA concentration in the range of 1.0 × 10−11 to 7.0 × 10−8 M, and the detection limit was ca. 5.0 pM (S/N = 3). Additionally, single-base mismatched DNA can be effectively discriminated from the cDNA. The great advantage of the biosensor lies in its simplicity and cost-effective with ECL generated from the electrode itself, and no adscititious luminophore is required.

Thin antimony oxide covered AuSb alloy electrode was firstly found to be an excellent cold cathode for generating hot electrons during cathodic pulse polarization. Owing to the injection of hot electrons and the subsequent generation of hydrated electrons, fluorescein iso-thiocyanate (FITC) that cannot be excited in common ECL was cathodically excited at the alloy electrode. Self-assembled thiol monolayers were formed on the electrode surface due to the presence of Au in the alloy, to which strepavidin was covalently bound, and then biotinylated antibody was immobilized through the strepavidin–biotin interaction. As a simple model, an immunosensor for the detection of human IgG (hIgG) using FITC as labeling agent was fabricated. ECL signals were responsive to the amount of hIgG bounded to the immunosensor. The ECL intensity was linearly changed with the logarithm of hIgG concentration in the range of 1.0–1000 ng mL−1, and the detection limit was ca. 0.3 ng mL−1 (S/N = 3). The proposed immunosensor showed a broad linear range (three magnitudes), good reproducibility and stability, which is promising in detecting FITC-based labels in various types of bioaffinity assays.

A heated oxide covered copper electrode (HOCE) was facilely fabricated for the first time, providing a highly enhanced electrocatalytic oxidation, and cost effective and sensitive determination for polyhydroxy compounds such as glucose and shikimic acid.

The initial stage of silver electrodeposition on a glassy carbon electrode from a cyanide-free bath with 2-hydroxypyridine (2-HP) as the complexing agent is studied. The influence of polyethyleneimine (PEI) as an additive on the nucleation and growth of silver are also examined. Progressive nucleation mechanism is found for silver deposition according to Scharifker–Hills’ model with three-dimensional diffusion- controlled growth nucleation. This mechanism cannot be influenced by adding PEI. However, the diffusion coefficient of the silver–2-HP complexes and the density of nuclei exhibit a remarkable decrease with the addition of PEI. Smoother and brighter silver deposits with progressive nucleation features were obtained in the presence of PEI from the images of scanning electron microscopy.

The adsorption behavior of uracil, an excellent ligand in cyanide-free silver plating on silver electrodes was studied with potential-dependent surface-enhanced Raman spectroscopy (SERS). Uracil was adsorbed at the silver surface with N3-deprotonated tautomer at pH 10.2, while with N1- and N3-deprotonated tautomers at pH 13.6. Uracil and additive polyethyleneimine (PEI) exhibit a co-adsorption behavior that holds the same tendency as their adsorption on the silver surfaces alone. The effect of PEI on silver plating process is proposed from SERS and electrochemical analysis. PEI, acted as an efficient suppressor and grain refiner in this silver plating bath, was further confirmed by the AFM micrographs.

Electrochemical and electrogenerated chemiluminescence (ECL) properties of a glassy carbon electrode modified with CdS nanotubes (CdS−GCE) are investigated in neutral media. The cyclic voltammogram (CV) shows two cathodic peaks (PC1 and PC2) at −0.76 and −0.97 V and an anodic peak (PA) at −0.8 V, while two ECL peaks around −0.76 V are observed. Similar mechanisms of both ECLs are supposed and possibly related to the capture of an electron at a surface trap, that is, the surface sulfide vacancy (VS2+) of CdS nanotubes and its electrocatalytic reduction to H2O2 generated from the dissolved oxygen. PC2 and PA are ascribed to the two-electron redox at VS2+. Moreover, electrocatalysis to nitrate reduction is also found at PC2, with a good linear relationship between nitrate concentration and electrocatalytic peak current in CV.

In this paper, 2-hydroxypyridine (2-HP) and polyethyleneimine (PEI) were selected as ligand and additive, respectively, in a cyanide-free silver electroplating bath. Adsorption behaviors of 2-HP and PEI at silver electrodes were investigated by means of potential-dependent surface-enhanced Raman spectroscopy (SERS). The adsorption configuration variations of 2-HP and PEI at the silver surface with the negative shift of potential were discussed according to the SERS analysis. The possible effect of 2-HP and PEI on the silver electroplating process was also proposed. In the silver electroplating process, the SERS signal variations of 2-HP with the negative shift of potential were mainly due to the deposits’ morphology change. In the presence of PEI, fine grains and smoother surfaces are observed from the images of atomic force microscopy of the silver deposits.

A disposable heated screen-printed carbon electrode (HSPCE) is successfully fabricated. It demonstrates rapid responses to electrical heating and is easily elevated above the water boiling point by a high frequency alternating current. The temperature rise at the HSPCE was found to be strongly dependent on the square of the heating current and the electrode width. Carbofuran (CAF) could be rapidly hydrolyzed to carbofuran phenol at the HSPCE with raised temperature, and then determined at the same electrode at room temperature by differential potential voltammetry (DPV). The factors influencing the detection were examined, including pH, hydrolytic temperature and heating time. Under the optimum conditions, the detection linear range of CAF was from 4.0 × 10−7 to 4.0 × 10−4 mol L−1 and the detection limit was 5.0 × 10−8 mol L−1 (S/N = 3). This method was successfully applied to the analysis of CAF residues in real samples (spiked water, soil and vegetables), and satisfactory recoveries were obtained.

A heated oxide covered copper electrode (HOCE) was facilely fabricated for the first time, providing a highly enhanced electrocatalytic oxidation, and cost effective and sensitive determination for polyhydroxy compounds such as glucose and shikimic acid.

For the first time, we reported the strong electrogenerated chemiluminescence of organic dye, bis[4-(dimethylamino)phenyl]squaraine (BDPSQ), a high quantum yield and light-stable species, which might find applications in ECL analysis and imaging.

A new electrode was fabricated by electrodepositing luteolin at a screen printed carbon electrode (SPCE) modified with a composite of multi-walled carbon nanotube (MWNT) and ionic liquid (IL). Cyclic voltammograms of the modified electrode in phosphate buffer solution showed a pair of stable and reversible redox couple of luteolin with surface confined characteristics. This electrode possessed excellent electrocatalytic ability towards hydrazine oxidation. The overpotential was decreased significantly and the peak current was increased dramatically compared to those at bare SPCE. This enhancement of the responses was mainly contributed to the combination of the unique electrocatalytic and electronic properties of luteolin, MWNT and IL. The modified electrode was employed to the amperometric detection of hydrazine at an applied potential of 0.31 V vs. SCE with fast response, high sensitivity, good stability and reproducibility. Two linear ranges of hydrazine were from 2.0 × 10−8 to 2.0 × 10−7 M and from 2.0 × 10−7 to 1.2 × 10−4 M. Nanomolar detection limit of 6.6 × 10−9 M (S/N = 3) could be obtained, which is at least one magnitude lower than any others with electrochemical detection of hydrazine. The proposed method was also used to determine hydrazine residues in spiked drinking water and river water with average recoveries of 101.7% and 101.1%, respectively.

Electrogenerated chemiluminescence (ECL) of Au clusters is observed for the first time using triethyamine (TEA) as the coreactant. The potential application of ECLAu clusters in analytical chemistry is also demonstrated using Pb2+ as an example.

We report a new application of gold nanoparticles for visual detection of copper ions with high sensitivity and selectivity based on the colorimetric difference due to the strong and specific inhibition of Cu(NH3)62+ to the corrosion of gold nanoparticles at low concentration.