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In this work, hydrophilic polymers modified with iron oxide nanoparticles, such as iron oxide-poly(2-dimethylaminoethyl methacrylate) [P(DMAEMA)] magnetite-based and iron oxide-poly(acrylamide) [P(AAm)] magnetite-based polymers, were prepared via a single electron transfer-living radical polymerization approach. Bile acid and 2-bromo-2-methylpropionic acid were covalently attached onto the surface of Fe 3 O 4 nanoparticles, and these immobilized magnetite nanoparticles were used as an initiator for the polymerization. The binding capabilities of different ions, such as Hg 2+ , CN - , Cl - , F - , and NO 3 - , were tested using these polymeric sensors monitored by UV-vis spectroscopy. Magnetite-based P(DMAEMA) showed enhanced binding capability due to the presence of tertiary amine groups. In addition, it was possible to easily separate the bound ions from aqueous media using an external magnetic field., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

This work suggests a modest hydrothermal method applied for the synthesis of oxygen-deficient WO x ( x = 2.75, 2.83, and 2.94) nanomaterials with various morphologies, such as bundled nanorods (NR), nanobelts (NB), and nanosheets (NS), by changing the inorganic additives, such as HCl, NaHSO 4 , and HNO 3 . In addition, WO x -supported high- and low-index faceted Pd nanoparticles (Pd-WO 2.75 NB, Pd-WO 2.83 NR, and Pd-WO 2.94 NS) have been successfully synthesized by a facile sonochemical method to enhance the high electrocatalytic activity of electrocatalysts for alcohol electrooxidation, including ethanol, ethylene glycol, and glycerol. Among the three different electrocatalysts, the versatile high-index {520} faceted Pd nanoparticles on WO 2.75 NB (Pd-WO 2.75 NB) show better electrocatalytic performance compared to low-index {100} faceted Pd-WO 2.83 NR and Pd-WO 2.94 NS nanocomposites. This work has identified that the high-density low-coordinated surface atom of Pd strongly interacts with alcohol, which facilitates C-C bond cleavage and may prevent the CO poisoning of nanoparticles. Furthermore, the high concentration of oxygen-deficient nano composites provided additional benefit for the generation of OH species and boosted the electrocatalytic performance of alcohols as well.

Hierarchical mesoporous TiO 2 was synthesized via a solvothermal technique. The sonochemical method was adopted to decorate plasmonic nanoparticles (NPs) (Ag, Au) on the pores of mesoporous TiO 2 . The crystallinity, structure, and morphology were determined to understand the physicochemical nature of the nanocomposites. The catalytic efficiency of the plasmonic nanocatalysts was tested for the azo dyes (congo red, methyl orange, acid orange 10, and remazol red) under solar and visible light irradiations. The generation of hydroxyl radicals was also studied using terephthalic acid as a probe molecule. An attempt was made to understand the influence of size, work function and Fermi level of the metal NPs toward the efficiency of the photocatalyst. The efficiency of the nanocomposites was found to be in the order of P25 < mesoporous TiO 2 < mesoporous Ag-TiO 2 < mesoporous Au-TiO 2 nanospheres under both direct solar light and visible light irradiation. The results indicated that the adsorption of dye, anatase phase, and surface plasmon resonance of NPs favored the effective degradation of dyes in aqueous solution. Further, the efficiency of the catalyst was also tested for xanthene (rose bengal), rhodamine (rhodamine B, rhodamine 6G), and thiazine (methylene blue) dyes. Both TiO 2 and NPs (Ag & Au) possess a huge potential as an eco-friendly photocatalyst for wastewater treatment., Competing Interests: The authors declare no competing financial interest.

Gold triangular nanoprisms and nanodecahedra (pentagonal bipyramids) were synthesized in the absence and presence of nanoseeds by a simple solvothermal synthesis through the reduction of Auric Chloride (HAuCl 4 ) with poly(vinylpyrrolidone) (PVP) in N,N-dimethylformamide (DMF), respectively. These gold nanoparticles exhibit two plasmon resonance bands. The interaction of these gold nanoparticles with luminol was investigated using UV-vis and fluorescence spectroscopy since hefty number of environmental and biological sensors are based on the combination of luminol and gold nanoparticles. The gold nanoparticles quenches the fluorescence of luminol through a static quenching mechanism, i.e., ground state complex formation, which was confirmed by both absorption spectroscopy as well as time-resolved fluorescence spectroscopy. The Stern-Volmer quenching constant and the effective quenching constant determine that gold nanodecahedra has more interaction with luminol than that of triangular gold nanoprisms. The distance between the gold nanoparticles and luminol, calculated using FRET theory, is less than 8 nm, which indicates efficient energy transfer during interaction. These results are expected to be useful for the development of novel sensors.

Development of visible-light-driven photocatalysts by employing a relatively simple, efficient, and cost-effective one-step process is essential for commercial applications. Herein, we report for the first time the synthesis of in situ Cu-ion modified Ti 3+ self-doped rutile TiO 2 by such a facile one-step solution precursor plasma spray (SPPS) process using a water-soluble titanium precursor. In the SPPS process, Ti 3+ self-doping on Ti 4+ of rutile TiO 2 is found to take place because of electron transfer from the created oxygen vacancies to Ti 4+ -ions. In situ Cu modification of the above Ti 3+ self-doped rutile TiO 2 by additionally introducing a Cu solution into plasma plume is also demonstrated. While the Ti 3+ self-doping induces broad absorption in the visible-light region, the addition of Cu ion leads to even broader absorption in the visible region owing to resulting synergistic properties. The above materials were evaluated for various self-cleaning photocatalytic applications under visible-light illumination. Cu-ion modified Ti 3+ self-doped rutile TiO 2 is noted to exhibit a remarkably enhanced visible-light activity in comparison with Ti 3+ self-doped rutile TiO 2 , with the latter itself outperforming commercial TiO 2 photocatalysts, thereby suggesting the suitability of the material for indoor applications. The broad visible-light absorption by Ti 3+ self-doping, the holes with strong oxidation power generated in the valence band, and electrons in Ti 3+ isolated states that are effectively separated into the high reductive sites of Cu ions upon visible-light irradiation, accounts for improved photocatalytic activity. Moreover, the synthesis process (SPPS) provides a valuable alternative to orthodox multistep processes for the preparation of such visible-light-driven photocatalysts.

Herein, we report the development of a ZnO-based visible-light-driven photocatalyst by interfacial charge transfer process for the inactivation of pathogens under visible-light illumination. Surface modification by a cocatalyst on ZnO, prepared by flame spray pyrolysis process is carried out to induce the visible-light absorption in ZnO. Optical studies showed that surface modification of Cu(2+) induces the visible-light absorption in ZnO by interfacial charge transfer between ZnO and surface Cu(2+) ions upon light irradiation. The photocatalytic efficiency of pure and modified ZnO is evaluated for the inactivation of pathogens and the decomposition of methylene blue under visible-light illumination. The antibacterial activity of Cu(2+)-ZnO is several orders higher than pure ZnO and commercial Degussa-P25 and comparable with Cu(2+)-TiO2. Cu(2+)-ZnO nanorods show better photocatalytic activity than Cu(2+)-ZnO nanosphere, which is attributed to high surface area to volume ratio of former than later. The holes generated in the valence band and the Cu(1+) species generated during the interfacial charge transfer process may attribute for the inactivation of bacteria, whereas the strong oxidation power of hole is responsible for the decomposition of methylene blue. Besides the advantage of Cu(2+)-modified ZnO for visible-light-assisted photocatalytic applications, the method (FSP) used for the synthesis of ZnO in the present study is attractive for commercial application because the process has potential for the production of large quantities (2-3 kg/h) of semiconductors.

We develop a simple approach to fabricate graphene-loaded TiO(2) thin films on glass substrates by the spin-coating technique. Our graphene-loaded TiO(2) films were highly conductive and transparent and showed enhanced photocatalytic activities. More significantly, graphene/TiO(2) films displayed superhydrophilicity within a short time even under a white fluorescent light bulb, as compared to a pure TiO(2) film. The enhanced photocatalytic activity of graphene/TiO(2) films is attributed to its efficient charge separation, owing to electrons injection from the conduction band of TiO(2) to graphene. The electroconductivity of the graphene-loaded TiO(2) thin film also contributes to the self-cleaning function by its antifouling effect against particulate contaminants. The present study reveals the ability of graphene as a low cost cocatalyst instead of expensive noble metals (Pt, Pd), and further shows its capability for the application of self-cleaning coatings with transparency. The promising characteristics of (inexpensive, transparent, conductive, superhydrophilic, and highly photocatalytically active) graphene-loaded TiO(2) films may have the potential use in various indoor applications.

Single-crystalline rutile nanorods were synthesized by a facile acid treatment on titanate nanotubes. These rutile nanorods could be highly dispersed in water to form a stable colloidal solution. Cu(2+) ions were grafted onto these rutile nanorods, and the Cu(2+)-grafted nanorods could absorb visible light by the interfacial charge transfer between the valence band of rutile TiO(2) and surface-modified Cu(2+) ions. Transparent thin films of Cu(2+)-grafted nanorods were coated on substrates by a facile spin-coating method. These films exhibited superhydrophilic conversion under visible light irradiation.

An ESR study has been made on the adsorption of three types of aminoxyl radicals with different substituent groups in the nanochannel of MCM-41 in benzene. In the suspensions of MCM-41, all the aminoxyl radicals, usually called as spin probes, show the ESR spectra composed of two signals: the main broader one from the spin probes trapped in the nanochannel, and a sharp minor signal from those in the bulk. The spin probes adsorbed in the nanochannel retain considerable mobility especially at higher temperatures over 300 K. When fumed silica, having a surface structure similar to that of MCM-41, is employed, on the other hand, the relatively hydrophobic spin probe mainly remains in the bulk, but the hydrophilic one is mostly adsorbed and immobilized rigidly. From these results, the adsorption by the MCM-41 nanochannel in benzene is characterized by medium selectivity and considerable motional allowance to the adsorbate molecule. The mobility of the spin probe in the MCM-41 nanochannel increases and the adsorption efficiency decreases by either of the following changes made to the system: (a) increasing the channel diameter, (b) increasing the hydrophobicity of the spin probe, (c) adding a small amount of 2-propanol in the solution, (d) methylation of the surface OH groups of the nanochannel, and (e) elevating the system temperature. A model of this special type of adsorption has been proposed on the basis of the thermodynamic parameters and the ESR spectra for the modified systems including those with different solvents.