Carrier separation and charge transport characteristics of reduced graphene oxide supported visible-light active photocatalysts.

Extending the absorption to the visible region by tuning the optical band-gap of semiconductors and preventing charge carrier recombination are important parameters to achieve a higher efficiency in the field of photocatalysis. The inclusion of reduced graphene oxide (rGO) support in photocatalysts is one of the key strategies to address the above-mentioned issues. In this study, rGO supported AgI–mesoTiO2 photocatalysts were synthesized using a sonochemical approach. The physical effects of ultrasound not only improved the crystallinity of AgI–mesoTiO2 but also increased the surface area and loading of the AgI–mesoTiO2 nanocomposite on rGO sheets. The low intense oxygen functionalities (C–O–C and COOH groups) peak observed in the high resolution C1s spectrum of a hybrid AgI–mesoTiO2–rGO photocatalyst clearly confirmed the successful reduction of graphene oxide (GO) to rGO. The interfacial charge transfer between the rGO and the p–n junction of heterostructured photocatalysts has decreased the band-gap of the photocatalyst from 2.80 to 2.65 eV. Importantly, the integration of rGO into AgI–mesoTiO2 composites serves as a carrier separation centre and provides further insight into the electron transfer pathways of heterostructured nanocomposites. The individual effects of photo-generated electrons and holes over rGO on the photocatalytic degradation efficiency of rhodamine (RhB) and methyl orange (MO) using AgI–mesoTiO2–rGO photocatalysts were also studied. Our experimental results revealed that photo-generated superoxide (O2−˙) radicals are the main reactive species for the degradation of MO, whereas photo-generated holes (h+) are responsible for the degradation of RhB. As a result, 60% enhancement in MO degradation was observed in the presence of rGO in comparison to that of the pure AgI–mesoTiO2 photocatalyst. This is due to the good electron acceptor and the ultrafast electron transfer properties of rGO that can effectively reduce the molecular oxygen to produce a large amount of reactive O2−˙ radicals. However, in the case of RhB degradation, h+ is the main reactive species which showed a slightly increased photocatalytic activity (12%) in the presence of rGO support where the role of rGO is almost negligible. This study suggests the effective roles of rGO for the degradation of organics, i.e., the rate of photocatalytic degradation also depends on the nature of compound rather than rGO support

Improved performance of polymer light-emitting diodes with nanocomposites

The characteristics of a hybrid polymer light-emitting diode (HPLED) with an active layer of poly [2-methoxy,5-(2-ethylhexoxy)-1,4-phenylenevinylene] blended with Au-capped TiO(2) nanocomposites are reported. Both the increased current in the active layer and low turn-on voltage were attributed to incorporation of Au-capped TiO(2) in the electroluminescent polymer. The maximal brightness of 11 630 cd/m(2) was observed in HPLED with a 1:1 ratio of Au-capped TiO(2). The enhanced performance was attributed to the roughness assisted charge transport induced by the Au-capped TiO(2) nanocomposites in the active polymer.open111

Non-covalent polyhedral oligomeric silsesquioxane-polyoxometalates as inorganic-organic-inorganic hybrid materials for visible-light photocatalytic splitting of water (vol 5, pg 2666, 2018)

Correction for Non-covalent polyhedral oligomeric silsesquioxane-polyoxometalates as inorganic-organic-inorganic hybrid materials for visible-light photocatalytic splitting of water' by Rajendran Prabu et al., Inorg. Chem. Front., 2018, DOI: 10.1039/c8qi00449h

A review of combined advanced oxidation technologies for the removal of organic pollutants from water

Water pollution through natural and anthropogenic activities has become a global problem causing short-and long-term impact on human and ecosystems. Substantial quantity of individual or mixtures of organic pollutants enter the surface water via point and nonpoint sources and thus affect the quality of freshwater. These pollutants are known to be toxic and difficult to remove by mere biological treatment. To date, most researches on the removal of organic pollutants from wastewater were based on the exploitation of individual treatment process. This single-treatment technology has inherent challenges and shortcomings with respect to efficiency and economics. Thus, application of two advanced treatment technologies characterized with high efficiency with respect to removal of primary and disinfection by-products in wastewater is desirable. This review article focuses on the application of integrated technologies such as electrohydraulic discharge with heterogeneous photocatalysts or sonophotocatalysis to remove target pollutants. The information gathered from more than 100 published articles, mostly laboratories studies, shows that process integration effectively remove and degrade recalcitrant toxic contaminants in wastewater better than single-technology processing. This review recommends an improvement on this technology (integrated electrohydraulic discharge with heterogeneous photocatalysts) viz-a-vis cost reduction in order to make it accessible and available in the rural and semi-urban settlement. Further recommendation includes development of an economic model to establish the cost implications of the combined technology. Proper monitoring, enforcement of the existing environmental regulations, and upgrading of current wastewater treatment plants with additional treatment steps such as photocatalysis and ozonation will greatly assist in the removal of environmental toxicants