As a candidate for photocatalyst, the photocatalytic performance of cuprous oxide (Cu.sub.2O) is severely restricted by its high charge carrier recombination rate, self-photocorrosion and the ...uncertainty of crystal plane. In order to improve the photocatalytic performance and deeply analyze the photocatalytic mechanism, the Cu.sub.2O nanocrystals with cubic, cuboctahedral and octahedral structures were combined with n-type ZnO to prepare Cu.sub.2O/ZnO heterojunction photocatalysts. The effects of crystal facet of Cu.sub.2O and Zn/Cu ratios on the photocatalytic performances of Cu.sub.2O/ZnO heterojunctions were explored into. The results show that the cuboctahedron Cu.sub.2O with {100} and {111} facets exhibits more surprising catalytic performance due to the energy-level difference between the two facets, leading to higher electron-hole pair separation efficiency when compared with the octahedral Cu.sub.2O with {111} facets and cubic Cu.sub.2O with {100} facets. In addition, optimized Cu.sub.2O/ZnO heterojunction with appropriate Zn/Cu ratio exhibits the collaborative advantages of the two materials, so the catalytic activity and stability are effectively improved.
In this work, we designed a novel and ultrasensitive sandwich-type electrochemical immunosensor for quantitative detection of α-fetoprotein (AFP), using β-cyclodextrin functionalized graphene (CD-GS) ...as the platform and platinum hybrid multiwalled carbon nanotubes adhered copper oxide (Pt@CuO-MWCNTs) as labels. CD-GS has high specific surface area, ideal dispersibility and good biocompatibility, which was used to efficiently capture more primary antibodies (Ab1). Pt, CuO and multiwalled carbon nanotubes (MWCNTs) can be used as catalysts for the decomposition of hydrogen peroxide. The Pt@CuO-MWCNTs realized multiple amplified signals due to their synergy. Therefore, Pt@CuO-MWCNTs was used as the marker, combined with secondary antibodies (Ab2) and this has the effect of multiple amplified signals to catalyze hydrogen peroxide. Under optimal conditions the designed immunosensor exhibited a wide linear range from 1pgmL−1 to 20ngmL−1 with a low detection limit of 0.33pgmL−1 (S/N=3) for AFP. The designed immunosensor showed good selectivity, reproducibility and stability, which could provide potential applications in clinical monitoring of AFP.
Copper oxide deposited sodium and phosphorus co-modified g-C.sub.3N.sub.4 composite catalysts (CuO/Na-P-g-C.sub.3N.sub.4) were successfully designed and prepared by a facile thermal polycondensation ...and chemical deposition. The structural and photoelectrochemical properties of the prepared photocatalysts were studied by XRD, FT-IR, BET, SEM, TEM, EDX, XPS, UV-vis DRS, PL, and EIS techniques, and the photocatalytic performance in the naphthalene photodegradation under visible light irradiation was evaluated. The results showed that the successful construction of heterojunction structure would be formed between CuO and Na-P-g-C.sub.3N.sub.4 interfaces, and the most weak PL intensity for the (6%)CuO/Na-P-g-C.sub.3N.sub.4 sample with the lowest bandgap energy of 1.90 eV would be obtained. The (6%)CuO/Na-P-g-C.sub.3N.sub.4 sample exhibited highest naphthalene degradation among all the g-C.sub.3N.sub.4-based catalyst of 87.1% in 180 min owing to the promotion for the migration and separation of photoexcited electron and hole pairs. The photocatalytic degradation rate for the (6%)CuO/Na-P-g-C.sub.3N.sub.4 sample would not be significantly dropped after repeated use for 5 times. The excellent catalytic performance with good stability and durability suggested that it would be a potential candidate for the naphthalene photodegradation to protect the environment.
CuO@TiO.sub.2 core-shell nanostructure catalyst with CuO core and TiO.sub.2 shell was prepared by a two-step method and then used in NH.sub.3-SCR reaction. FE-SEM, TEM and element mapping were used ...to investigate the morphologies of the sample. Their results indicated CuO nanorods were coated with TiO.sub.2 and thus forming a core-shell nanostructure. According to the results of N.sub.2 adsorption-desorption, XRD, Raman, XPS, NH.sub.3-TPD, H.sub.2-TPR and in situ DRIFTS, the core-shell nanostructure would benefit the formation of better redox ability, more oxygen vacancies, more acid sites and abundant adsorbed NO.sub.x species on the catalyst. Thus, the core-shell nanostructure catalyst presented significantly higher activity than pure CuO and TiO.sub.2. NH.sub.3-SCR reaction on CuO@TiO.sub.2 core-shell catalyst should follow both Eley-Rideal (E-R) mechanism and Langmuir-Hinshewood (L-H) mechanism. These findings may promote the development of the new effective non-vanadium-based SCR catalysts. Graphic
Current fundamental electrochemical research shows the potential of utilizing polymeric nanostructured materials as ion-to-electron transducers. In this paper, aniline was polymerized in the presence ...of TiOsub.2 and CuO nanoparticles to yield a bimetallic/PANI nanocomposite. It was applied as a transducer in a carbon paste electrode for the potentiometric determination of vildagliptin in the presence of 18-crown-6-ether as a recognition element. The electrode’s potentiometric performance was studied according to the IUPAC guidelines. It exhibited a wide linearity range of 1 × 10sup.−2 M to 1 × 10sup.−8 M, remarkable sensitivity (LOD of 4.5 × 10sup.−9 M), and a fast response time of 10 s ± 1.3. The sensor did not show any potential drift due to the absence of the water layer between the carbon paste and the metallic conductor. This endowed the sensor with high stability and a long lifetime, as 137 days passed without the need to change the carbon paste surface. The electrode was utilized for the determination of the concentration of vildagliptin in bulk, pharmaceutical tablets, and human plasma, with average recovery ranging from 97.65% to 100.03%.
Because the valence state of metal with variable valences is sensitive to oxidation atmosphere, it is difficult to fabricate single-phased metal oxide with intermediate valence by vapor or vacuum ...deposition. In this work, the copper valence state in oxides was controlled by introducing a nitrogen flow into the sputtering chamber. The surface chemical potential of oxygen can be efficiently tuned through adsorption competition on the growth surface. The transition process from CuO-Cu.sub.2O mixture to single Cu.sub.2O was observed with increasing the nitrogen flow rate. For the single-phased Cu.sub.2O, the hole concentration was tuned in a range of 2.6 x 10.sup.17 to 1.1 x 10.sup.18 cm.sup.-3.
In this paper, the optical and thermophysical properties of CuO nanofluid as the working fluid of low temperature direct absorption solar collector which is prepared by dispersing the CuO ...nanoparticles into mixture of distilled water and ethylene glycol (70%:30% in volume) as the base fluid is investigated at the different temperatures for different volume fractions. The results showed that the nanofluids had higher absorption coefficient compared to the base fluid in the whole wavelengths for solar energy, ranging from 200 to 2500nm. The absorbed energy fraction of CuO nanofluid with only 100ppm (volume fraction 0.01%) nanoparticle volume fraction is 4 times more than that of the base fluid at solar collector depth of 1cm. The viscosity increased with the increasing volume fraction and decreased exponentially with the increasing temperature. The thermal conductivity of CuO nanofluids increased with the increase of CuO volume fraction in the base fluid and temperature. At the investigated volume fractions, the thermal conductivity of the nanofluids was found to increase with respect to the base fluid up to about 13.7% for the 100ppm CuO nanoparticle volume fraction. Higher thermal conductivity and lower viscosity of CuO nanofluids by increasing temperature, together with the appropriate optical properties, introduce this kind of nanofluids as an appropriate candidate to effectively enhance the direct absorption solar collector efficiency.
•CuO nanofluid is introduced as working fluid of direct absorption solar collector.•Absorbed energy fraction of CuO nanofluid is 4 times more than that of base fluid.•Thermal conductivity of CuO nanofluid increased with the increase of volume fraction.•Thermal conductivity improvement of 13.7% is obtained by 100ppm CuO nanofluid.•Viscosity of CuO nanofluid increased with increasing volume fraction.
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![Utilization of a TiO[sub.2]...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/2073-4360/small "Utilization of a TiO[sub.2]–CuO Bimetallic/Polyaniline Nanocomposite as a Transducer in a Solid Contact Potentiometric Sensor for the Determination of Vildagliptin")
