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Bismuth vanadate (BiVO4), W-doped BiVO4 (BiVO4:W), and Mo-doped BiVO4 (BiVO4:Mo) nanoparticles were synthesized at pH = 4 using a green hydrothermal method. The effects of 2 at% W or Mo doping on the microstructural and optical characteristics of as-prepared BiVO4 nanoparticles and the effect of combining particle morphology modification and impurity dopant incorporation on the visible-light-derived photocatalytic degradation of dilute Rhodamine B (RhB) solution are studied. XRD examination revealed that these obtained BiVO4-based nanoparticles had a highly crystalline and single monoclinic phase. SEM and TEM observations showed that impurity doping could modify the surface morphology, change the particle shape, and reduce the particle diameter to enlarge their specific surface area, increasing the reactive sites of the photocatalytic process. XPS and FL measurements indicated that W- and Mo-doped nanoparticles possessed higher concentrations of oxygen vacancies, which could promote the n-type semiconductor property. It was found that the BiVO4:W and BiVO4:Mo powder samples exhibited better photocatalytic activity for efficient RhB removal than that shown by pristine BiVO4 powder samples under visible light illumination. That feature can be ascribed to the larger surface area and improved concentration of photogenerated charge carriers of the former. [ABSTRACT FROM AUTHOR]

Vertical-aligned CuO nanowires have been directly fabricated on Cu foil through a facile thermal oxidation process by a hotplate at 550 °C for 6 h under ambient conditions. The intermediate layer of resorcinol–formaldehyde (RF) and silver (Ag) nanoparticles can be sequentially deposited on Cu nanowires to form CuO@RF@Ag core-shell nanowires by a two-step wet chemical approach. The appropriate resorcinol weight and silver nitrate concentration can be favorable to grow the CuO@RF@Ag nanowires with higher surface-enhanced Raman scattering (SERS) enhancement for detecting rhodamine 6G (R6G) molecules. Compared with CuO@Ag nanowires grown by ion sputtering, CuO@RF@Ag nanowires exhibited a higher SERS enhancement factor of 5.33 × 108 and a lower detection limit (10−12 M) for detecting R6G molecules. This result is ascribed to the CuO@RF@Ag nanowires with higher-density hot spots and surface-active sites for enhanced high SERS enhancement, good reproducibility, and uniformity. Furthermore, the CuO@RF@Ag nanowires can also reveal a high-sensitivity SERS-active substrate for detecting amoxicillin (10−10 M) and 5-fluorouracil (10−7 M). CuO@RF@Ag nanowires exhibit a simple fabrication process, high SERS sensitivity, high reproducibility, high uniformity, and low detection limit, which are helpful for the practical application of SERS in different fields. [ABSTRACT FROM AUTHOR]

• CuO/ZnO heterostructured nanomaces have directly grown on the copper gauze. • CuO/ZnO heterostructures exhibit high photocatalytic efficiency and reusability. • CuO/Ag/ZnO/Ag heterostructured nanomaces exhibited higher photocatalytic activity. • Ag nanoparticles play a critical role to enhance the photocatalytic efficiency. • This study provides a new strategy to construct the quaternary heterostructured arrays. The CuO/ZnO heterostructured nanomaces can be directly grown on the copper gauze substrates with CuO nanowires by a wet chemical approach at the lower reaction temperature. The concentration of ZnO precursor can easily control the sizes of ZnO branched nanowires. CuO/ZnO heterostructured nanomaces presented superior photocatalytic activity toward rhodamine 6 G removal compared with commercial ZnO or TiO 2 nanoparticles under low-powered UV-light irradiation. Further investigation has revealed that CuO/ZnO heterostructured nanomaces significantly improved activity as a recyclable photocatalyst for the degradation of rhodamine 6 G. Also, the uniform sizes of Ag nanoparticles can decorate onto the interface and surface of CuO/ZnO heterostructured nanomaces via a sample ion-beam sputtering method. The quaternary CuO/Ag/ZnO/Ag heterostructured nanomaces can provide the adequate separation of photoinduced electron-hole pairs and more surface active sites, which exhibited a higher photocatalytic efficiency rather than CuO/ZnO heterostructured nanomaces. [ABSTRACT FROM AUTHOR]

Abstract This work describes the direct fabrication of Ag nanoparticles on pyramidal silicon using a facile, one-step, electroless deposition process at room temperature with short reaction time (3 min). The resulting device could use for rapid drug detection based on surface-enhanced Raman scattering (SERS). The size of the silicon pyramids controlled by altering the texturing time of the silicon substrate. Spin coating was used to enable the rapid deposition of rhodamine 6G molecules (3 min) on the Ag nanoparticles. The resulting pyramidal silicon decorated with Ag nanoparticles provides large specific area as well as hot spots to promote localized surface plasmon resonance, resulting in notable SERS enhancement and a low 5-fluorouracil detection limit (10−6 M). Highlights • Facile electroless deposition to grow Ag nanoparticles (NPs) on pyramidal silicon. • Room temperature growth of Ag NPs using short (3 min) reaction time. • Surface-enhanced Raman scattering (SERS) tests using rhodamine 6G on Ag NPs/Si pyramids • Size of the silicon pyramids controlled by the texturing time appears to be critical. • Very low detection limit (10−6 M) of the Ag NP-based SERS sensor for 5-fluorouracil. [ABSTRACT FROM AUTHOR]

Abstract In this study, we report a facile replacement reduction method to directly deposit the large-scale Ag nanoparticles on a silicon substrate at the room temperature and short reaction time (3 min). The reaction process is a straightforward wet chemistry approach using silver nitrate and hydrogen fluoride as a silver source and reducing reagent, respectively. The Ag nanoparticles as a surface-enhanced Raman scattering (SERS) substrate present high sensitivity, excellent uniformity, and high stability for rhodamine 6G molecules. Also, Ag nanoparticles are also shown to provide a unique platform for the SERS detection of melamine, 5-fluorouracil, amoxicillin in different aqueous media. The fabrication of Ag nanoparticles is facile, low cost, strong enhancement, low detection limit, high reproducibility, and stability, which is advantageous for the applications of other SERS-based sensors. Highlights • Ag nanoparticles have grown on the Si by a facile a replacement reduction method. • The growth condition is at room temperature and short reaction time (3 min). • Ag nanoparticles revealed high SERS enhancement, uniformity and reusability. • The SERS substrate used to detect toxic chemicals and drugs under the different water-based. • The SERS substrate also exhibited very low detection limit for the detection of toxic chemicals and drugs. [ABSTRACT FROM AUTHOR]

We demonstrate the synthesis of heterostructured photocatalysts that the double-sided plasmonic Au nanoparticles have been deposited on the Cu-doped ZnO/ZnO heterostructures by a facile ion sputtering method. The resultant quaternary Cu-doped ZnO/Au/ZnO/Au heterostructures exhibit excellent photocatalytic activity in the photodegradation of rhodamine 6G under 10 W UV light irradiation, which is much higher than Cu-doped ZnO/ZnO heterostructures. Moreover, the Cu-doped ZnO/Au/ZnO/Au heterostructures can be reused for degradation of R6G during a five-cycle experiment without significant decrease in the photocatalytic efficiency. [ABSTRACT FROM AUTHOR]

Abstract: This study examines the usage of well-patterned Au nanoparticles (NPs) as a catalyst for one-dimensional growth of single crystalline Si nanowires (NWs) through the vapor-liquid-solid (VLS) mechanism. The study reports the fabrication of monolayer Au NPs through the self-assembly of Au NPs on a 3-aminopropyltrimethoxysilane (APTMS)-modified silicon substrate. Results indicate that the spin coating time of Au NPs plays a crucial role in determining the density of Au NPs on the surface of the silicon substrate and the later catalysis growth of Si NWs. The experiments in this study employed optical lithography to pattern Au NPs, treating them as a catalyst for Si NW growth. The patterned Si NW structures easily produced and controlled Si NW density. This approach may be useful for further studies on single crystalline Si NW-based nanodevices and their properties. [Copyright &y& Elsevier]

Abstract: This paper describes the use of reversed-phase liquid chromatography (RPLC) to rapidly characterize Au/Pt core/shell nanoparticles (NPs) produced through seed-assisted synthesis. We monitored the sizes of Au/Pt core/shell NPs by using a porous silica-based RPLC column (pore size: ca. 100nm) and 30mM sodium dodecyl sulfate in deionized water as the mobile phase; the plot of the retention time with respect to the logarithm of the size of the Au NPs was linear (R 2 =0.997) for diameters falling in the range from 5.3 to 40.1nm; from five consecutive runs, the relative standard deviations of these retention times were less than 0.4%. We used the optimal separation conditions of the RPLC system to study the effects that the rate of addition of the reducing agent and the volumes of the seed, shell precursor metal ion, and reducing agent solutions had on the sizes of the Au/Pt core/shell NPs. A good correlation existed between the sizes of the Au/Pt core/shell NPs determined through RPLC and those determined using transmission electron microscopy. RPLC appears to be a useful technique for monitoring the sizes of NPs and nanomaterials in general. [Copyright &y& Elsevier]

Abstract: Tin oxide–silica composite aerogels were successfully prepared with a co-fed precursor sol–gel process. The crystallinity of the tin oxide nanoparticles, embedded in the mesoporous SiO2 network, was improved with increasing the post-reaction thermal treatment temperature. The composite aerogels exhibited a rich photoluminescence (PL) emission contributed by both SnO2 and SiO2. The PL peak of 346nm was from the near band edge emission of the tin oxide nanoparticles, and the ones located at 310 and 476nm were attributable to the oxygen deficiencies of the silica network. Three more emission peaks, 387, 432, and 522nm, were observed, with the 387nm peak contributed by the oxygen vacancies VO ++, respectively, of the tin oxide nanoparticles. The intensities of these three defect level emissions were found decreased, as compared to that of the near band edge emission, with increasing the post-reaction thermal treatment temperature as the tin oxide crystallinity improved. [Copyright &y& Elsevier]O +, respectively, of the tin oxide nanoparticles. The intensities of these three defect level emissions were found decreased, as compared to that of the near band edge emission, with increasing the post-reaction thermal treatment temperature as the tin oxide crystallinity improved. [Copyright &y& Elsevier]

This paper reports the fabrication of self-assembled gold nanoparticles attached to 3-aminopropyltrimethoxysilane (APTMS) modified fused silica substrates by the spin coating method. With the spin coating method, the gold nanoparticles can be fabricated on fused silica substrates with highly packing density in a short processing time. Our results clearly demonstrate that the spin coating method takes advantages of shorter fabrication time, higher uniformity, and better reproducibility when compared with the traditional immersion method. [Copyright &y& Elsevier]

This present study used a simple aqueous chemical growth method to synthesize Al-doped ZnO (ZnO: Al) nanoneedles on ZnO seeds/glass substrates. The surface morphology and length of ZnO: Al nanostructures can suitably control by the concentration of aluminum sulfate. The surface-enhanced Raman scattering (SERS) effect of Ag sputtering durations on the ZnO: Al nanoneedles and the concentration of aluminum sulfate on the ZnO: Al/Ag heterostructures systematically investigated. The ZnO: Al/Ag heterostructures (2 mM aluminum sulfate and 60 s sputtering time) exhibited a more substantial enhancement, a lower detection limit (10−10 M), excellent uniformity, high reusability and stability for the SERS detection of rhodamine 6G molecule. The ZnO: Al/Ag heterostructures can also use to detect the lower concentration of melamine (10−9 M) and 5-fluorouracil (10−7 M). ZnO: Al/Ag heterostructures can provide a low-cost and straightforward manufacturing method with high enhancement, low detection limit, excellent uniformity, and reusability for the SERS applications in areas of chemical and medicine. Image 1 • A facile aqueous chemical growth method can use to grow ZnO: Al nanostructures on the ZnO seeds/glass substrates. • The morphology and length of ZnO: Al nanostructures can suitably control by the concentration of aluminum sulfate. • ZnO: Al/Ag heterostructures exhibited excellent SERS performance in the detection of rhodamine 6G molecule. • ZnO: Al/Ag heterostructures can use to detect the lower concentration of melamine (10−9 M) and 5-fluorouracil (10−7 M). [ABSTRACT FROM AUTHOR]

Carbon black/ZnO nanocomposites have been successfully synthesized via a simple aqueous chemical growth method. The preparation of the carbon black/ZnO nanocomposites by adding an appropriate weight of carbon black to the ZnO growth process can be favorable to improve photocatalytic degradation of methyl blue under irradiation of ultraviolet light. Compare with commercial TiO 2 and ZnO nanopowders, carbon black/ZnO nanocomposites can enhance the specific surface area, the light-harvesting ability, and the charge carrier separation for achieving highly efficient photocatalysts under irradiation of both ultraviolet and visible light. The carbon black/ZnO nanocomposites exhibited a low cost and sample approach, high reusability, and high visible-light-induced photocatalytic activity. Image 1 • CB/ZnO nanocomposites can synthesize by a facile aqueous chemical growth method. • CB/ZnO nanocomposites exhibit high photocatalytic efficiency and reusability. • CB/ZnO nanocomposites exhibit higher photodegradation than ZnO and TiO 2 nanopowders. • Carbon black (CB) play a critical role to enhance the photocatalytic efficiency. [ABSTRACT FROM AUTHOR]

• H 2 Ti 3 O 7 nanowires have directly synthesized on the Ti foil by simple hydrothermal and ion‐exchange processes. • H 2 Ti 3 O 7 nanowires revealed very prominent blue emission from surface oxygen vacancies. • H 2 Ti 3 O 7 nanowires exhibited high efficient and reusable photocatalysts under visible-light irradiation. • Holes and hydroxyl radicals played central roles in rhodamine 6G photodegradation. • H 2 Ti 3 O 7 @Ag heterostructures can provide an excellent SERS-active substrate. In the present work, we reported one kind of photocatalytic and surface-enhanced Raman scattering substrate, H 2 Ti 3 O 7 nanowires, which prepared on the Ti foil by the hydrothermal and ion‐exchange methods. The morphologies, crystal structures, chemical compositions, optical properties of the as-prepared substrates investigated via the different kinds of characterization techniques. H 2 Ti 3 O 7 nanowires revealed remarkably enhanced visible-light photocatalytic activity for the degradation of rhodamine 6 G solution compared to Na 2 Ti 3 O 7 nanowires, TiO 2 nanowires, and commercial photocatalysts (TiO 2 and ZnO nanoparticles). These results attributed to the H 2 Ti 3 O 7 nanowires with a higher concentration of oxygen vacancies can enhance the visible-light absorbance, resulting in the higher photocatalytic activity under the visible-light irradiation. The radical-trapping test shows that holes and hydroxyl radicals played central roles in rhodamine 6 G photodegradation. The deposition of Ag nanoparticles on the H 2 Ti 3 O 7 nanowires can also use as a highly sensitive surface-enhanced Raman scattering substrate for detecting rhodamine 6 G solution with a concentration as low as 10−9 M by the ion-sputtering system. [ABSTRACT FROM AUTHOR]

Cerium dioxide (CeO2, ceria), a promising and abundant catalytic material with high-efficiency, nontoxicity, photochemical stability, and affordability, can be used as a photocatalyst to photocatalytically degrade organics and split water for hydrogen production under ultraviolet (UV) irradiation (about 5% of solar energy). However, the applications of the CeO2 photocatalyst are limited due to low photocatalytic efficiency under sunlight irradiation. In this study, a nanosized CeO2 powder was prepared by the precipitation method. Subsequently, various amounts of polyaniline (PANI) nanoparticles were deposited onto the surface of the CeO2 nanoparticles to form a heterostructure by the polymerization method. The crystal structure, morphology, surface and optical properties of the CeO2/PANI nanoparticles were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-Vis) absorption spectroscopy, and photoluminescence (PL). Experimental results demonstrated that PANI deposition improved the light absorption of CeO2 nanoparticles in the visible light region. The heterostructured CeO2/PANI nanoparticle with 4 wt % PANI deposition exhibited optimal photocatalytic activities with a hydrogen production rate of 462 μmolg−1 within 6 h and a methyl orange (MO) degradation rate of 45% within 4 h under visible light irradiation. The photocatalytic mechanisms of the composite powder are also proposed in this report. [ABSTRACT FROM AUTHOR]

A polyaniline (PANI)/tin oxide (SnO2) composite for a CO sensor was fabricated using a composite film composed of SnO2 nanoparticles and PANI deposition in the present study. Tin oxide nanoparticles were synthesized by the sol-gel method. The SnO2 nanoparticles provided a high surface area to significantly enhance the response to the change in CO concentration at low operating temperature (<75 °C). The excellent sensor response was mainly attributed to the relatively good properties of PANI in the redox reaction during sensing, which produced a great resistance difference between the air and CO gas at low operating temperature. Therefore, the combination of n-type SnO2 nanoparticles with a high surface area and a thick film of conductive PANI is an effective strategy to design a high-performance CO gas sensor. [ABSTRACT FROM AUTHOR]

In this study, we report a feasible aqueous chemical method to synthesize Au core–Ag shell nanoparticles (NPs) by seeding growth approach. The concentration of Au NPs plays an important role in growing the different thicknesses of Ag shells. The design of signaling aptamer utilizes the target-induced switching between an aptamer/DNA duplex and an aptamer/target complex. The surface enhanced Raman scattering (SERS) signal was enhanced upon the hybridization of the Raman reporter-labeled DNA released from the target-induced displacement with the captured DNA immobilized on the silicon substrate with Au–Ag core–shell NPs. This substrate with 12.4 nm Ag shell shows high reproducibility, strong enhancement, and a low detection limit (1 nM). The enhancement in DNA-based adenosine detection properties shall be advantageous in applications for other aptamer sensing systems. [ABSTRACT FROM AUTHOR]