A series of TiO(2)-reduced graphene oxide (RGO) nanocomposites were prepared by simple one-step hydrothermal reactions using the titania precursor, TiCl(4) and graphene oxide (GO) without reducing agents. Hydrolysis of TiCl(4) and mild reduction of GO were simultaneously carried out under hydrothermal conditions. While conventional approaches mostly utilize multistep chemical methods wherein strong reducing agents, such as hydrazine, hydroquinone, and sodium borohydride are employed, our method provides the notable advantages of a single step reaction without employing toxic solvents or reducing agents, thereby providing a novel green synthetic route to produce the nanocomposites of RGO and TiO(2). The as-synthesized nanocomposites were characterized by several crystallographic, microscopic, and spectroscopic characterization methods, which enabled confrimation of the robustness of the suggested reaction scheme. Notably, X-ray diffraction and transmission electron micrograph proved that TiO(2) contained both anatase and rutile phases. In addition, the photocatalytic activities of the synthesized composites were measured for the degradation of rhodamine B dye. The catalyst also can degrade a colorless dye such as benzoic acid under visible light. The synthesized nanocomposites of biphasic TiO(2) with RGO showed enhanced catalytic activity compared to conventional TiO(2) photocatalyst, P25. The photocatalytic activity is strongly affected by the concentration of RGO in the nanocomposites, with the best photocatalytic activity observed for the composite of 2.0 wt % RGO. Since the synthesized biphasic TiO(2)-RGO nanocomposites have been shown to effectively reduce the electron-hole recombination rate, it is anticipated that they will be utilized as anode materials in lithium ion batteries.

Silver impregnated on polymer-titania nanocomposite films exhibit excellent antibacterial properties with the added advantage of repeated use. The polyethylene glycol-polyurethane-titania designated as PEG-PU-TiO 2 polymer nanocomposite films were synthesized by simple solution casting technique. Silver has been incorporated into these films by photochemical reduction of silver nitrate solution. The TiO 2 facilitated the UV photoreduction of AgNO 3 to Ag, which is active as an antibacterial agent. Fourier Transformed Infrared Spectroscopy (FT-IR) confirms the formation of the polymer, polyurethane. X-ray Diffraction (XRD) determined the structure and scanning electron microscopy (SEM), the morphology of the films. XPS confirms the Ag to be in zero oxidation state and the amount of silver impregnated in the films as estimated by scanning electron microscopy-energy-dispersive X-ray analysis (SEM-EDAX), and atomic absorption spectroscopy (AAS) is about 2-4 at %. The antibacterial properties of these films were studied on Escherichia coli and Bacillus subtilis by the disk-diffusion method and this has been correlated with the percentage of Ag in the films. One very encouraging observation is that the antibacterial activity of the Ag in polymer-titania nanocomposite films showed reasonable activity even when tested in the microbial broth.

No abstract

Exploring new single, active photocatalysts for solar-water splitting is highly desirable to expedite current research on solar-chemical energy conversion. In particular, Z-scheme-based composites (ZBCs) have attracted extensive attention due to their unique charge transfer pathway, broader redox range, and stronger redox power compared to conventional heterostructures. In the present report, we have for the first time explored CuP, a new, single photocatalyst for solar-water splitting applications. Moreover, a novel ZBC system composed of BiWO-CuP was designed employing a simple method of ball-milling complexation. The synthesized materials were examined and further investigated through various microscopic, spectroscopic, and surface area characterization methods, which have confirmed the successful hybridization between BiWO and CuP and the formation of a ZBC system that shows the ideal position of energy levels for solar-water splitting. Notably, the ZBC composed of BiWO-CuP is a mediator- and co-catalyst-free photocatalyst system. The improved photocatalytic efficiency obtained with this system compared to other ZBC systems assisted by mediators and co-catalysts establishes the critical importance of interfacial solid-solid contact and the well-balanced position of energy levels for solar-water splitting. The promising solar-water splitting under optimum composition conditions highlighted the relationship between effective charge separation and composition.

Varied morphologies and compositions of bismuth tungstate nanocomposites have been investigated as promising materials for photocatalytic applications. Among these nanocomposites, hierarchically structured bismuth sulphide (Bi 2 S 3 )/bismuth tungstate (Bi 2 WO 6 ) hybrids have significant photocatalytic efficiency toward heavy metal ions. In order to simplify the synthetic procedure for this desirable composite, we developed a robust single-step hydrothermal synthesis for the formation of hierarchically structured hetero-catalysts of Bi 2 S 3 /Bi 2 WO 6 with a high yield (>95%). The synthesized heterostructures were characterized by various spectroscopic, microscopic, and surface area analysis techniques, which confirmed the successful incorporation of Bi 2 S 3 into the Bi 2 WO 6 matrix and were used to optimize pore size for enhanced catalytic activity. The resulting Bi 2 S 3 /Bi 2 WO 6 heterocatalysts were used to remove toxic Cr(VI) ions via reduction to water insoluble Cr(III) utilizing visible-light irradiation. We also investigated the role of citric acid as a hole scavenger in the reduction of Cr(VI) with minimizing the rate of electron-hole recombination during photocatalysis. Likewise, the observed catalytic activity was significantly enhanced under a condition of an appropriate balance between hierarchical structure of catalysts and the amount of hole scavenger. ASSOCIATED CONTENT Supporting informationAdditional information about FESEM images of Bi 2 WO 6 synthesized under different conditions, comparative XPS of Bi 4f and W 4f, BET surface area and BJH pore size distribution, digital photograph of Cr(VI) reduction to Cr(III) along with effect of CA on Cr(VI) reduction in dark, energy level diagram of composite. This material is available free of charge via internet at

With growing interest in the photocatalytic performance of TiO2-graphene composite systems, the ternary phase of TiO2, graphene, and Ag is expected to exhibit improved photocatalytic characteristics because of the improved recombination rate of photogenerated charge carriers and potential contribution of the generation of localized surface plasmon resonance at Ag sites on a surface of the TiO2-graphene binary matrix. In this work, Ag-TiO2-reduced graphene oxide ternary nanocomposites were successfully synthesized by a simple solvothermal process. In a single-step synthetic procedure, the reduction of AgNO3 and graphene oxide and the hydrolysis of titanium tetraisopropoxide were spontaneously performed in a mixed solvent system of ethylene glycol, N,N-dimethylformamide and a stoichiometric amount of water without resorting to the use of typical reducing agents. The nanocomposites were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, along with different microscopic and spectroscopic techniques, enabling us to confirm the successful reduction of AgNO3 and graphite oxide to metallic Ag and reduced graphene oxide, respectively. Due to the highly facilitated electron transport of well distributed Ag nanoparticles, the synthesized ternary nanocomposite showed enhanced photocatalytic activity for degradation of rhodamine B dye under visible light irradiation.

Methane is an important fossil fuel and widely available on the earth's crust. It is a greenhouse gas that has more severe warming effect than CO 2. Unfortunately, the emission of methane into the atmosphere has long been ignored and considered as a trivial matter. Therefore, emphatic effort must be put into decreasing the concentration of methane in the atmosphere of the earth. At the same time, the conversion of less valuable methane into value-added chemicals is of significant importance in the chemical and pharmaceutical industries. Although, the transformation of methane to valuable chemicals and fuels is considered the "holy grail," the low intrinsic reactivity of its C-H bonds is still a major challenge. This review discusses the advancements in the electrocatalytic and photocatalytic oxidation of methane at low temperatures with products containing oxygen atom(s). Additionally, the future research direction is noted that may be adopted for methane oxidation via electrocatalysis and photocatalysis at low temperatures.

No abstract