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We have developed a green and environmentally friendly approach for the synthesis of silver nanoparticles (Ag NPs) using Pithecellobium dulce seeds (PDS) extract via a simple route and characterized by several techniques. Ag NPs have an average particle size is 8 nm and used as a catalyst for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) within 3 min of reaction. Ag NPs could be easily recovered and reused five times without significant loss in its catalytic activity. The synthesized Ag NPs were investigated for optical sensing of various metal ions in aqueous solutions by monitoring their surface plasmon resonance (SPR), results showed that the selective response to mercury (Hg2+) ions. Ag NPs exhibited significant antibacterial activity against several microorganisms including Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus subtilis by a paper-disk method. The synthesized Ag NPs also exhibited virtuous antioxidant activity. [ABSTRACT FROM AUTHOR]

The g-C3N4 nanosheets, CdS NPs, and g-C3N4/CdS composite were fabricated using sonochemical method for the efficient photocatalytic degradation of CV dye, MCP pesticide and catalytic reduction of 4-NP using NaBH4 as a reducing agent. The synthesized nanocatalysts were characterized by various physicochemical techniques. The g-C3N4/CdS composite was capably degradation of CV and MCP, and catalyze the reduction of 4-NP to 4-AP in the presence of NaBH4 very efficiently with good recyclability up to five cycles than g-C3N4 and CdS NPs. Further, the temperature effect on the catalytic reduction of 4-NP using g-C3N4/CdS composites was also studied. The catalytic reduction reaction follows the pseudo-first-order kinetics. The corresponding rate constants increased with the temperature, revealing activation energy of 26.42 kJ/mol. The scavenging radicals from the antioxidant activity of the synthesized composites were determined by DPPH method. In addition, the synthesized composites showed good antibacterial and antifungal activities using paper disc method. [ABSTRACT FROM AUTHOR]

Abstract A one-pot sonochemical process was used for the synthesis of cost-effective g-C 3 N 4 nanosheets decorated Ag 2 S composite catalysts and characterized by various techniques. Furthermore, the UV–vis spectroscopy was used to monitor the catalytic reduction of 4-NP in the presence of g-C 3 N 4 /Ag 2 S composite with an excess of NaBH 4. The g-C 3 N 4 /Ag 2 S composite exhibited higher catalytic activity toward the reduction of 4-NP than the pure g-C 3 N 4 and Ag 2 S. In addition, the upward shift of the energy band of g-C 3 N 4 due to the location of Ag 2 S led to stronger reducibility of charge carriers. As a consequence, the catalytic performance of g-C 3 N 4 /Ag 2 S has been remarkably improved in the catalytic reduction of 4-NP and exhibited excellent stability up to 5 cycles. The effect of NaBH 4 concentration was also investigated for the reduction of 4-NP using g-C 3 N 4 /Ag 2 S composite. The scavenging radicals from the antioxidant activity of the synthesized composites were determined by DPPH method. In addition, the synthesized composites showed good antimicrobial activities using paper disc method. The results indicate that the synthesized g-C 3 N 4 /Ag 2 S composite exhibits superior catalytic, antioxidant and antimicrobial activities and potential applications in near future in the field of biomedicine, wastewater treatment for purification and nanobiotechnology. Graphical abstract Image 1025 Highlights • The g-C 3 N 4 /Ag 2 S composite catalysts were synthesized using ultrasound method. • The catalytic reduction of 4-NP was studies using the synthesized catalysts. • The effect of NaBH 4 concentration on catalytic reduction of 4-NP was studied. • The g-C 3 N 4 /Ag 2 S composite exhibited higher catalytic activity than g-C 3 N 4 and Ag 2 S. • The composite catalysts were investigated for antioxidant and antimicrobial activities. [ABSTRACT FROM AUTHOR]

This work focuses on the synthesis of undoped and doped lanthanum oxide nanoparticles (La2O3 NPs) by a simple co-precipitation method for the catalytic reduction of 4-nitrophenol (4-NP) using NaBH4 as a reducing agent. Their optical properties, morphologies, structure, chemical compositions and electronic properties were carefully characterized by XRD, FTIR, SEM, TEM, PL and UV–visible absorption spectroscopy. The SEM and TEM images showed various shape morphologies and sizes of the particles. The XRD pattern revealed a polycrystalline nature with the hexagonal structure of the La2O3 NPs. The synthesized undoped and doped La2O3 NPs were also employed as catalysts for the reduction of 4-nitrophenol, it shows that the doped (Sm3+, Gd3+ and Hf3+) La2O3 NPs provided better catalytic activity than the undoped La2O3 NPs. Moreover, Hf3+ doped La2O3 NPs exhibited an enhanced catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol in 90 min. The catalytic conversion was studied by UV–vis spectroscopy with high reduction rate (k = 2.048 min−1). The applications of the present study may utilize in the removal of toxic pollutants in a cleaning of environmental pollution as well as in industrial applications. [ABSTRACT FROM AUTHOR]