Nitin Kumar Labhasetwar

Perovskite-type catalytic materials for environmental applications

Abstract Perovskites are mixed-metal oxides that are attracting much scientific and application interest owing to their low price, adaptability, and thermal stability, which often depend on bulk and surface characteristics. These materials have been extensively explored for their catalytic, electrical, magnetic, and optical properties. They are promising candidates for the photocatalytic splitting of water and have also been extensively studied for environmental catalysis applications. Oxygen and cation non-stoichiometry can be tailored in a large number of perovskite compositions to achieve the desired catalytic activity, including multifunctional catalytic properties. Despite the extensive uses, the commercial success for this class of perovskite-based catalytic materials has not been achieved for vehicle exhaust emission control or for many other environmental applications. With recent advances in synthesis techniques, including the preparation of supported perovskites, and increasing understanding of promoted substitute perovskite-type materials, there is a growing interest in applied studies of perovskite-type catalytic materials. We have studied a number of perovskites based on Co, Mn, Ru, and Fe and their substituted compositions for their catalytic activity in terms of diesel soot oxidation, three-way catalysis, N2O decomposition, low-temperature CO oxidation, oxidation of volatile organic compounds, etc. The enhanced catalytic activity of these materials is attributed mainly to their altered redox properties, the promotional effect of co-ions, and the increased exposure of catalytically active transition metals in certain preparations. The recent lowering of sulfur content in fuel and concerns over the cost and availability of precious metals are responsible for renewed interest in perovskite-type catalysts for environmental applications.

Dragon's blood-aided synthesis of Ag/Ag2O core/shell nanostructures and Ag/Ag2O decked multi-layered graphene for efficient As(III) uptake from water and antibacterial activity

There has been a great interest to engineer surface characteristics of nanomaterials that are useful for various environmental applications. In this context, synthesis of nanomaterials using green methods is of great significance. Herein, new, easy, rapid and environmentally benign synthesis protocols to obtain Ag/Ag2O core/shell and Ag/Ag2O decorated multi-layered graphene (MLG) nanostructures are reported. The end products are obtained with the aid of “Dragons blood”, a resin extracted from the bark of the mysterious tree, Dracaena cinnabari. Dragons blood has a variety of antioxidant flavonoids and tannins, amongst many other constituents, which act as reducing and stabilizing agents. Ag/Ag2O core/shell and Ag/Ag2O decorated MLG nanostructures exhibited excellent adsorption characteristics in removing arsenite (As(III)) ions from water. The nanostructures also showed strong activity against E. coli and S. aureus bacteria.

The role of synthesis method on ZnO nanoparticles: implications for zinc dissolution and arsenite adsorption in water

aFaculty of Engineering and Information Technology, Taiz University, 6803 Taiz, Yemen, Tel. +967716186473; email: mokh_ali2007@yahoo.com bEnergy and Resource Management Division, CSIR-National Environmental Engineering Research Institute (CSIR-NEERI), Nehru Marg, Nagpur 440 020, India cDepartment of Chemical Engineering, College of Engineering, King Saud University, P.O. Box 800, Riyadh 11421, Saudi Arabia, Tel. +966-11-467-6859; Fax: +966-11-467-8770; email: aalfatesh@ksu.edu.sa