Indian Institute of Technology Ropar

About: Indian Institute of Technology Ropar is a education organization based out in Ropar, India. It is known for research contribution in the topics: Catalysis & Computer science. The organization has 1014 authors who have published 2878 publications receiving 35715 citations.

Nanoscale charge transport and local surface potential distribution to probe defect passivation in Ag doped Cu2ZnSnS4 absorbing layer.

Abstract: The performance of earth abundant Cu2ZnSnS4 (CZTS) material is limited by high deficit of open circuit voltage (VOC) which is mainly due to the easy formation of CuZn antisite defects. Suppression of CuZn defects is thus inevitably required for further developments in CZTS based solar cells. We studied systematic increase of Ag doping in CZTS thin film and investigated the nanoscale electrical properties using Kelvin probe force microscopy and current sensing atomic force microscopy (CAFM) to probe CuZn defects. Crystallographic analysis indicated the successful partial substitution of Cu+ ions by large size Ag+ ions. The considerable decrease in grain boundary potential from 66.50 ± 5.44 mV to 13.50 ± 2.61 mV with Ag doping, suggesting the substantial decrease in CuZn defects. Consequently, CAFM measurement confirms the remarkable increment in minority carrier current with Ag doping and their local mobility in CZTS layer. Finally, the lower persistent photoconductivity and fast decay response of photogenerated carriers for Ag doped CZTS photodetector further validate our results. This study provides a fresh approach of controlling deleterious CuZn defects in CZTS by tuning Ag content that may guide researchers to develop next generation high-performance CZTS based solar cells.

An efficient and sustainable catalytic reduction of carbon–carbon multiple bonds, aldehydes, and ketones using a Cu nanoparticle decorated metal organic framework

Abstract: Transition metal (Cu, Mn, Ni, Zr) substituted metal organic frameworks (MOFs) are prepared for the reduction of carbon–carbon multiple bonds with hydrazine hydrate in ethanol under mild reaction conditions. Among the MOFs investigated in this study, the Cu framework substituted MOF exhibited the best activity in this study. Further, Cu nanoparticles (CuNPs) are supported on the surface of a Cu framework substituted MOF to achieve excellent reduction activity. The catalyst exhibits efficient recyclability with no appreciable loss in the catalytic activity even after five recycles. In order to establish the reaction mechanism, reactions are performed under N2 and Ar atmospheres. A reaction is also performed under an Ar atmosphere but in the presence of H2O2 to elucidate the mechanism. The catalyst exhibits excellent activity in the reduction of alkynes. Under the optimum reaction conditions, the catalyst is also successful in reducing a wide range of aldehydes and ketones. The present catalytic process demonstrates several key advantages such as mild and convenient reaction conditions, a low substrate to hydrazine ratio, reusability, and cost-effectiveness of the catalyst (Pt or Pd free catalyst).

Nucleophilic addition of amines, alcohols, and thiophenol with epoxide/olefin using highly efficient zirconium metal organic framework heterogeneous catalyst

Abstract: A zirconium metal–organic framework catalyst was synthesized and investigated in the ring opening of epoxides with nucleophiles such as amines, alcohols, and thiophenol. For comparative study, Cu and Zn metal–organic framework catalysts were prepared. The zirconium based porous metal–organic framework catalyst was characterized by powder X-ray diffraction, nitrogen adsorption, scanning electron microscopy, thermo gravimetric analysis, and Fourier transform infrared spectroscopic techniques. Application of these catalysts was also investigated in the nucleophilic addition of amines/thiophenol with activated olefins. Among the catalysts investigated in this study, zirconium metal–organic framework catalysts exhibited the highest activity in these reactions. In this study, systematic assessment of the catalytic activity of zirconium metal–organic framework for a wide range of aromatic and heterocyclic compounds is shown under one umbrella. Catalysts can be easily recovered and reused with negligible loss in the catalytic activity.