Polymer Waste Valorization into Advanced Carbon Nanomaterials for Potential Energy and Environment Applications.

The rise in universal population and accompanying demands have directed toward an exponential surge in the generation of polymeric waste. The estimate predicts that world-wide plastic production will rise to ≈590 million metric tons by 2050, whereas 5000 million more tires will be routinely abandoned by 2030. Handling this waste and its detrimental consequences on the Earth's ecosystem and human health presents a significant challenge. Converting the wastes into carbon-based functional materials viz. activated carbon, graphene, and nanotubes is considered the most scientific and adaptable method. Herein, this world provides an overview of the various sources of polymeric wastes, modes of build-up, impact on the environment, and management approaches. Update on advances and novel modifications made in methodologies for converting diverse types of polymeric wastes into carbon nanomaterials over the last 5 years are given. A remarkable focus is made to comprehend the applications of polymeric waste-derived carbon nanomaterials (PWDCNMs) in the CO2 capture, removal of heavy metal ions, supercapacitor-based energy storage and water splitting with an emphasis on the correlation between PWDCNMs' properties and their performances. This review offers insights into emerging developments in the upcycling of polymeric wastes and their applications in environment and energy.

Template free synthesis of ZnO/Ag2O nanocomposites as a highly efficient visible active photocatalyst for detoxification of methyl orange.

A simple and effective route for the synthesis of ZnO/Ag2O nanocomposites with different weight ratios (4:1 to 4:4) have been successfully obtained by combination of thermal decomposition and precipitation technique. The structure, composition, morphology and optical properties of the as-prepared ZnO/Ag2O composites were characterized by XRD, FT-IR, EDS, SEM, TEM, UV-Vis DRS and PL, respectively. The photocatalytic performance of the photocatalysts was evaluated towards the degradation of a methyl orange (MO) under UV and visible light. More specifically, the results showed that the photocatalytic activity with highest rate constant of MO degradation over ZnO/Ag2O (4:2) nanocomposites is more than 22 and 4 times than those of pure ZnO and Ag2O under visible light irradiation, respectively. An improved photocatalytic activity was attributed to the formation of heterostructure between Ag2O and ZnO, the strong visible light absorption and more separation efficiency of photoinduced electron-hole pairs. Moreover, the ZnO/Ag2O (4:2) nanocomposite showed excellent stability towards the photodegradation of MO under visible light. Finally, a possible mechanism for enhanced charge separation and photodegrdation is proposed. Genotoxicity of MO before and after photodegradation was also evaluated by simple comet assay technique.