Browsing by Author "Raza, N."
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Item H2O2 rejuvenation-mediated synthesis of stable mixed-morphology Ag3PO4 photocatalysts(Heliyon, 2018-04) Agbe, H.; Raza, N.; Dodoo-Arhin, D.; Chauhan, A.; Kumar, R.V.Ag3PO4 photocatalyst has attracted interest of the scientific community in recent times due to its reported high efficiency for water oxidation and dye degradation. However, Ag3PO4 photo-corrodes if electron accepter such as AgNO3 is not used as scavenger. Synthesis of efficient Ag3PO4 followed by a simple protocol for regeneration of the photocatalyst is therefore a prerequisite for practical application. Herein, we present a facile method for the synthesis of a highly efficient Ag3PO4, whose photocatalytic efficiency was demonstrated using 3 different organic dyes: Methylene Blue (MB), Methyl orange (MO) and Rhodamine B (RhB) organic dyes for degradation tests. Approximately, 19 % of Ag3PO4 is converted to Ag0 after 4.30 hours of continuous UV-Vis irradiation in presence of MB organic dye. We have shown that the Ag/Ag3PO4 composite can be rejuvenated by a simple chemical oxidation step after several cycles of photocatalysis tests. At an optimal pH of 6.5, a mixture of cubic, rhombic dodecahedron, nanosphere and nanocrystals morphologies of the photocatalyst was formed. H2O2 served as the chemical oxidant to re-insert the surface metallic Ag into the Ag3PO4 photocatalyst but also as the agent that can control morphology of the regenerated as-prepared photocatalyst without the need for any other morphology controlling Agent (MCA). Surprisingly, the as- regenerated Ag3PO4 was found to have higher photocatalytic reactivity than the freshly made material and superior at least 17 times in comparison with the conventional Degussa TiO2, and some of TiO2 composites tested in this work.Item Recent advances in photoinduced catalysis for water splitting and environmental applications(Journal of Industrial and Engineering Chemistry, 2019-01) Agbe, H.; Nyankson, E.; Raza, N.; Dodoo-Arhin, D.; Chauhan, A.; Osei, G.; Kumar, V.; Kim, K.H.To secure reliable alternative energy sources, the up-conversion of solar energy into storable chemical energy holds promise. This review is organized to highlight recent advances in the fields of solar energy utilization and conversion methods with the aid of various heterogeneous catalysts. Special emphasis has been placed on TiO2 photoanode catalysts, band-gap engineering, TiO2-coupled light-harvesting molecules, and photon-coupled electron transfer via electron transport mediator systems. Furthermore, the coverage of this review extends to the topics of oxygen evolution catalysts, water reduction catalysts, and a system assembly capable of completing the four-electron water-oxidation reaction for efficient photocatalytic water splitting.Item A simple sensing of hazardous photo-induced superoxide anion radicals using a molecular probe in ZnO-Nanoparticles aqueous medium(Environmental Research, 2019-03-25) Dodoo-Arhin, D.; Agbe, H.; Raza, N.; Kumar, R.V.; Kim, K.The generation of reactive oxygen species (ROS) during the photolysis of sunscreens and sun blockers poses consumer safety concerns while necessitating proper identification and quantitation of ROS species. Here, a colorimetric sensing approach has been developed based on a molecular probe (2,3-bis-(2-methoxy-4-nitro-5- sulfophenyl)-2-H-tetrazolium-5-carboxanilide (XTT) tetrazolium salt) to quantitatively measure the photo-induced superoxide anion radicals (%O2 .) generated from the photocatalysis of zinc oxide nanoparticles (ZnO-NPs) in aqueous solutions. Note that superoxide anion radicals are assumed to be the main reactive oxygen species (ROS) generated from such photocatalysis. The characterisation of ZnO-NPs before and after irradiation showed average particle sizes of 616.5 and 295.3 nm and ζ-potential values of 0 and -24.4 mV, respectively. It is hoped that this proposed protocol can be further developed to efficiently detect other ROS present in inorganic sun blockers and to optimize the utility of various sunscreen formulations.