S. Ganesh Babu

Reduced graphene oxide wrapped Cu2O supported on C3N4: An efficient visible light responsive semiconductor photocatalyst

Herein, Cu2O spheres were prepared and encapsulated with reduced graphene oxide (rGO). The Cu2O–rGO–C3N4 composite covered the whole solar spectrum with significant absorption intensity. rGO wrapped Cu2O loading caused a red shift in the absorption with respect to considering the absorption of bare C3N4. The photoluminescence study confirms that rGO exploited as an electron transport layer at the interface of Cu2O and C3N4 heterojunction. Utmost, ∼2 fold synergistic effect was achieved with Cu2O–rGO–C3N4 for the photocatalytic reduction of 4-nitrophenol to 4-aminophenol in comparison with Cu2O–rGO and C3N4. The Cu2O–rGO–C3N4 photocatalyst was reused for four times without loss in its activity.

Magnetically retrievable lepidocrocite supported copper oxide nanocatalyst (Fe–CuO) for N-arylation of imidazole

A simple and efficient lepidocrocite-supported copper oxide catalyst (Fe–CuO) has been successfully prepared by a simple precipitation method in aqueous medium from readily available inexpensive starting materials and was used as a heterogeneous nanocatalyst for the N-arylation of imidazole with various aryl halides. The morphology, crystal structure, magnetic property, chemical state and surface area of the catalyst were studied. The N-arylation reaction was chosen to demonstrate the catalytic efficiency of the as-prepared Fe–CuO. Importantly, the catalyst can be easily recovered by magnetic attraction and its catalytic activity remains unaltered even after 6 consecutive cycles. Hence, Fe–CuO is an environmentally friendly, easily applicable and cost effective catalyst.

Ultrasound-assisted mineralization of organic contaminants using a recyclable LaFeO3 and Fe3+/persulfate Fenton-like system

A recyclable heterogeneous catalyst has been successfully developed for application in a Fenton-type advanced oxidation process without adding external H2O2. LaFeO3 was prepared from Fe(NO3)3·9H2O and La(NO3)·6H2O by a simple sol-gel method and its catalytic efficiency was evaluated for mineralization of 4-chlorophenol using a Fenton-like process. The mineralization process was carried out under ultrasonication in presence of heterogeneous LaFeO3 catalyst with H2O2 that was produced during ultrasonication. The mineralization process was monitored through total organic carbon (TOC) analysis. Very importantly, utmost 5-fold synergism was evidenced by the ultrasound mediated LaFeO3-catalyzed system. Besides, more than twofold synergism was observed by combining the ultrasound assisted LaFeO3 catalytic process and potassium persulfate (KPS) assisted advanced oxidation process. It is worth to mention that complete mineralization (∼96%) of 4-chlorophenol (initial concentration of 1.25×10-4M) was observed within 1h in the presence of LaFeO3 (0.5gL-1) and KPS (1.0mmol) under ultrasonication (40kHz). Even after four cycles, the activity of LaFeO3 remained intact which proved its recyclability. Extremely reusable heterogeneous LaFeO3 catalyst makes the system more interesting from both economic and environmental points of view.

Ruthenium based metallopolymer grafted reduced graphene oxide as a new hybrid solar light harvester in polymer solar cells.

A new class of pyridyl benzimdazole based Ru complex decorated polyaniline assembly (PANI-Ru) was covalently grafted onto reduced graphene oxide sheets (rGO) via covalent functionalization approach. The covalent attachment of PANI-Ru with rGO was confirmed from XPS analysis and Raman spectroscopy. The chemical bonding between PANI-Ru and rGO induced the electron transfer from Ru complex to rGO via backbone of the conjugated PANI chain. The resultant hybrid metallopolymer assembly was successfully demonstrated as an electron donor in bulk heterojunction polymer solar cells (PSCs). A PSC device fabricated with rGO/PANI-Ru showed an utmost ~6 fold and 2 fold enhancement in open circuit potential (Voc) and short circuit current density (Jsc) with respect to the standard device made with PANI-Ru (i.e., without rGO) under the illumination of AM 1.5 G. The excellent electronic properties of rGO significantly improved the electron injection from PANI-Ru to PCBM and in turn the overall performance of the PSC device was enhanced. The ultrafast excited state charge separation and electron transfer role of rGO sheet in hybrid metallopolymer was confirmed from ultrafast spectroscopy measurements. This covalent modification of rGO with metallopolymer assembly may open a new strategy for the development of new hybrid nanomaterials for light harvesting applications.