•Carbon black is cheap, green, environmentally friendly, and incapable to secondary pollution.•The sp2-bonded carbon black possesses a great plenty of mesopores to enhance the sensing efficiency.•Carbon black as a metal-free electrocatalyst has an outstanding electrocatalytic performance for determination of Cr(VI).•High selectivity, good stability, wide linear range and high sensitivityHexavalent chromium is one of most toxic heavy metal contaminants in biological and environmental systems, thus the electrochemical method with high-sensitivity, excellent-accuracy, low-cost and easy-operation is desired to be developed for detecting Cr(VI). In this work, carbon black (CB) modified glassy carbon electrode (GCE), was proposed as a sensor for monitoring Cr(VI) concentrations. CB is cheap, green, environmentally friendly, and incapable to secondary pollution. Moreover, the sp2-bonded CB possesses a great plenty of mesopores as the charge transport channels in interior surface to enhance the sensing efficiency. Thus CB modified GCE demonstrated an outstanding electrocatalytic performance for reduction of Cr(VI), with a wide linear concentration range from 0.025 to 483.225 μM and a low detection limit (LOD) of 10 nM. The modified electrode also showed fast response, high stability, as well as good selectivity against interferences from other metal ions. These attributes suggest that CB as a metal-free electrocatalyst has an exciting prospects of sensing applications for determination of Cr(VI).Download high-res image (185KB)Download full-size image

•Small size Ni nanoparticles prepared via a facile and controlled route•The modified electrode was employed for simultaneous determination of AA, DA and UA.•High selectivity, good stability, wide linear range and high sensitivityA highly sensitive sensor based on carbon-supported Ni nanoparticles (Ni/C) with ultra-small size was prepared for the simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA). The electrochemical response showed excellent electrocatalytic activity toward the oxidation of AA, DA and UA with three well defined oxidation peaks and larger peak separation. Meanwhile, using the ultra-small Ni nanoparticles modified electrode with differential pulse voltammetry (DPV) method, the linear response ranges for the determination of AA, DA and UA were 20–2400, 1–55 and 5–180 μM in the coexistence systems of these three species under optimum condition and the detection limits (S/N = 3) were 5, 0.05 and 0.1 μM, respectively. Especially a much higher sensitivity for Ni/C modified electrode compared to other electrodes was also observed. Moreover, satisfactory results were achieved for the determination of AA, DA and UA in vitamin C tablet, DA hydrochloride injection, fetal bovine serum and human urine samples. The results demonstrated that the electrochemical sensor developed from the ultra-small Ni nanoparticles had advantages of high sensitivity and good selectivity for practical applications.

A new method for determination of glutathione (GSH) was carried out with acetaminophen (AAP) mediation on a NiPd nanoparticle modified electrode. The as-prepared sensor exhibited excellent electrocatalytic activity for determining GSH with a good linear correlation with GSH concentration in a broad range from 0.5 to 3000 μM, a high detection sensitivity (481.69 μA mM−1 cm−2), and a low detection limit of 0.5 μM. The mechanism for GSH oxidation was also investigated by cyclic voltammetry and linear sweep voltammetry. In addition, the proposed sensor was also successfully employed to detect GSH in real samples.

•High quality Cu2Se films prepared on electroless Cu coated p-Si by EC-ALD•The deposited Cu2Se films have good photoelectric properties.•A promising method for electrodepositing compound semiconductor films on p-SiCuprous selenide (Cu2Se) nanocrystalline thin films are grown onto electroless Cu coating on p-Si (100) substrates using electrochemical atomic layer deposition (EC-ALD), which includes alternate electrodeposition of Cu and Se atomic layers. The obtained films were characterized by X-ray diffraction (XRD), field emission scanning electronic microscopy (FE-SEM), FTIR, and open-circuit potential (OCP) studies. The results show the higher quality and good photoelectric properties of the Cu2Se film, suggesting that the combination of electroless coating and EC-ALD is an ideal method for deposition of compound semiconductor films on p-Si.

A diamine monomer o-phenylenedioxybis(5-amino-2-pyridine) was synthesized via reduction of a dinitro compound o-phenylenedioxybis(5-nitro-2-pyridine), producing a series of new polyimides from this diamine and various commercially available aromatic dianhydrides via conventional two-stage processes. The resulting polyimides are able to form tough and transparent films, with decomposition temperatures in the range of 529–551 °C, and can be dissolved in organic polar solvents. Meanwhile, these polyimides can be degraded in a hydrazine hydrate medium, a degradation mechanism proposed by analyzing the degradation products suggests that the degradable properties could be attributed to the phenyl-2-pyridyl ether structure in the polymer. In addition, the transformation of the compound structure from dinitro compound to damine monomer in the synthetic process is discussed in respect to X-ray structure.

Carbon-supported PdNi (PdNi/C) and PdCo (PdCo/C) nanoparticles (NPs) were synthesized and modified on a glassy carbon electrode (GCE) to fabricate highly sensitive amperometric nitrite sensors. Cyclic voltammetry (CV) and an amperometric i–t curve were used to characterize the electrochemical behavior of the electrodes in the presence of nitrite. From the results, both the PdNi/C- and PdCo/C NPs-modified electrodes exhibited better electrochemical properties than the commercial Pd/C catalyst with equal metal content (10%). Moreover, both the PdNi and PdCo sensors exhibited remarkable sensitivity of 5.23 and 5.52 mA mM−1 cm−2, respectively. Interference studies showed that the modified electrodes exhibited excellent selectivity toward nitrite. In addition, the proposed sensors were applied to determine the nitrite content in several foods and moat water with satisfactory results.

Polyimides are widely used in electronic, semiconductor industry, however, with the wide application, the degradation of the polymer has become a serious problem people have to face. In this work, a series of new fast degradable polyimides were synthesized from diamine p-phenylenedioxybis(5-amino-2-pyridine) with various commercially available aromatic dianhydrides via a conventional two-stage process. The resulting polyimides could degrade at room temperature under a certain condition, and we proposed a degradation mechanism by analyzing the degradation products. Compared with the traditional method, here, we provided a facile and effective method for polyimide degradation. The result suggested that introducing a phenyl-2-pyridyl ether structure into polymer chains may become a class of new method for polymer degradation.

Cuprous oxide microsphere material was fabricated by electrochemical deposition using polystyrene particles as template. The samples are characterized by scanning electron microscope (SEM), X-ray diffraction, and UV–vis spectrophotometer. The SEM image shows the morphology and size of the microspheres, and the thickness of covered Cu2O layer is about 100 nm. Due to the unique microspherical structure, the surface area is larger, and the optical absorption is better in Cu2O microsphere material than in bulk Cu2O film, which makes the degradation of methylene blue faster and photoelectrocatalytic oxidation of glucose stronger on Cu2O microsphere material than on bulk Cu2O film under visible light illumination. The enhanced photo- and photoelectro-catalytic activity makes the Cu2O microsphere material more suitable for solar applications.

Carbon-supported PdNi (PdNi/C) and PdCo (PdCo/C) nanoparticles (NPs) were synthesized and modified on a glassy carbon electrode (GCE) to fabricate highly sensitive amperometric nitrite sensors. Cyclic voltammetry (CV) and an amperometric i–t curve were used to characterize the electrochemical behavior of the electrodes in the presence of nitrite. From the results, both the PdNi/C- and PdCo/C NPs-modified electrodes exhibited better electrochemical properties than the commercial Pd/C catalyst with equal metal content (10%). Moreover, both the PdNi and PdCo sensors exhibited remarkable sensitivity of 5.23 and 5.52 mA mM−1 cm−2, respectively. Interference studies showed that the modified electrodes exhibited excellent selectivity toward nitrite. In addition, the proposed sensors were applied to determine the nitrite content in several foods and moat water with satisfactory results.