Indian Institute of Technology Kharagpur

About: Indian Institute of Technology Kharagpur is a education organization based out in Kharagpur, India. It is known for research contribution in the topics: Computer science & Dielectric. The organization has 16887 authors who have published 38658 publications receiving 714526 citations.

Emerging new generation electrocatalysts for the oxygen reduction reaction

Abstract: The design and development of a new economically viable electrocatalyst for the cathodic reduction of oxygen in fuel cells and metal–air batteries is of significant interest. The high cost, scarcity and lack of durability of traditional Pt-based electrocatalysts limit the widespread implementation of fuel cells for practical applications. The emergence of non-Pt and metal-free electrocatalysts for the oxygen reduction reaction (ORR) is promising in the development of energy conversion devices. In this review, we discuss the emerging new electrocatalysts, non-precious transition metals, metal nitrides and carbides and the nanoscale carbon-based metal-free electrocatalysts, for the ORR. Although the actual ORR mechanism and the active site of these catalysts are not well understood, their catalytic activity is undoubtful. The porosity and chemical and electronic environments of the catalysts control their activity. The activity of these catalysts is discussed in terms of onset potential, durability and their tolerance towards anode fuels. The metal-free heteroatom-doped carbon-based electrocatalysts are highly active in alkaline medium, paving the way for the development of alkaline fuel cells, though their long time durability in an actual fuel cell stack is not well explored. The challenges in the use of these catalysts and the lack of fundamental understanding of the catalytic activity are addressed.

A ternary Cu2O-Cu-CuO nanocomposite: a catalyst with intriguing activity.

Abstract: In this work, the syntheses of Cu2O as well as Cu(0) nanoparticle catalysts are presented. Copper acetate monohydrate produced two distinctly different catalyst particles with varying concentrations of hydrazine hydrate at room temperature without using any surfactant or support. Then both of them were employed separately for 4-nitrophenol reduction in aqueous solution in the presence of sodium borohydride at room temperature. To our surprise, it was noticed that the catalytic activity of Cu2O was much higher than that of the metal Cu(0) nanoparticles. We have confirmed the reason for the exceptionally high catalytic activity of cuprous oxide nanoparticles over other noble metal nanoparticles for 4-nitrophenol reduction. A plausible mechanism has been reported. The unusual activity of Cu2O nanoparticles in the reduction reaction has been observed because of the in situ generated ternary nanocomposite, Cu2O–Cu–CuO, which rapidly relays electrons and acts as a better catalyst. In this ternary composite, highly active in situ generated Cu(0) is proved to be responsible for the hydride transfer reaction. The mechanism of 4-nitrophenol reduction has been established from supporting TEM studies. To further support our proposition, we have prepared a compositionally similar Cu2O–Cu–CuO nanocomposite using Cu2O and sodium borohydride which however displayed lower rate of reduction than that of the in situ produced ternary nanocomposite. The evolution of isolated Cu(0) nanoparticles for 4-nitrophenol reduction from Cu2O under surfactant-free condition has also been taken into consideration. The synthetic procedures of cuprous oxide as well as its catalytic activity in the reduction of 4-nitrophenol are very convenient, fast, cost-effective, and easily operable in aqueous medium and were followed spectrophotometrically. Additionally, the Cu2O-catalyzed 4-nitrophenol reduction methodology was extended further to the reduction of electronically diverse nitroarenes. This concise catalytic process in aqueous medium at room temperature revealed an unprecedented catalytic performance which would draw attention across the whole research community.

Morphology Controlled Synthesis of SnS2 Nanomaterial for Promoting Photocatalytic Reduction of Aqueous Cr(VI) under Visible Light

Abstract: A mild, template free protocol has been demonstrated for SnS2 nanoflake formation at the gram level from SnCl2 and thioacetamide (TAA). The SnS2 nanoflakes congregate to nanoflowers and nanoyarns with variable TAA concentrations. BET measurements reveal that the synthesized nanomaterials are highly porous having very high surface area, and the nanoflower has higher surface area than the nanoyarn. The synthesized nanomaterial finds application for promoting photoreduction of extremely toxic and lethal Cr(VI) under visible light irradiation due to their porous nature. The nanoflowers photocatalyst is proved to be superior to nanoyarn due to the increased surface area and higher pore volume. It was also inferred that increased pH decreased the reaction rate. The present result suggests that the morphology-dependent photoreduction of Cr(VI) by SnS2 nanomaterial under visible light exposure will endorse a new technique for harvesting energy and purification of wastewater.