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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]

In this work, we report a stable g-C3N4, Bi2S3, and g-C3N4/Bi2S3 composite catalysts were prepared via a facile one-pot microwave-assisted method and characterized. The orthorhombic phase and nearly spherical shape of the particles with an average diameter of 5–25 nm of g-C3N4/Bi2S3 composite were obtained from XRD and TEM. The composite also exhibits a high surface area (32.15 m2/g), which may provide convenient transportation and diffusion for substrate molecule. The optical studies were displayed the g-C3N4/Bi2S3 composite has a sharp absorption band in the visible region, higher charge separation, and reduced recombination rate. These results show that the Bi2S3 NPs have good crystallinity and are uniformly deposited on the surface of the g-C3N4 sheet. The catalytic performance of the g-C3N4/Bi2S3 composite for the reduction of 4-NP to 4-AP was exhibited approximately 100%, which is 1.48 and 2.34 times higher than the Bi2S3 and g-C3N4 catalysts, respectively. The pseudo-first-order rate constant was estimated as 1.648 × 10 −2 min−1 for the reduction of 4-NP using g-C3N4/Bi2S3 composite in 1 h reaction time. The effect of catalyst dosage (0–30 mg) was also investigated for the reduction of 4-NP using g-C3N4/Bi2S3 composite catalyst. Moreover, the reusability of the g-C3N4/Bi2S3 composite was exhibited a better reduction of the 4-NP even after 5 cycles and it was found that 8% reduction in the initial reduction rate. The obtained results from this study show that g-C3N4/Bi2S3 composite has the potential efficiency and stability to make it an ideal catalyst for the reduction of toxic effluents and wastewater treatment. [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]

The objective of this research was to prepare and characterize the solvent-free ternary semiconductor CdxAg1–xS nanocomposites as photocatalysts by a simple hydrothermal method using without any surfactant. We have accessed the photocatalytic ability of the prepared composites in the degradation of pesticides under simulated UV light irradiation. The Cd0.5Ag0.5S composites show a significant photocatalytic activity, higher than the bare CdS and Ag2S samples. It indicates that the heterostructured combination of Ag and CdS provides synergistic photocatalytic activity through an efficient electron transfer process. The stability and reusability assays indicated that the Cd0.5Ag0.5S composite retained more than 90% of activity after five cycles of use. On the basis of the results, a possible photocatalytic mechanism of the prepared samples was proposed. The synthesized CdS, Ag2S, and Cd0.5Ag0.5S samples were screened against selected bacterial and fungal species. The investigated results confirm the synthesized Cd0.5Ag0.5S is a potential candidate for antimicrobial activity applications. [ABSTRACT FROM AUTHOR]

A green method for the solvothermal synthesis of copper sulphide nanoparticles (CuS NPs) using xanthan gum as a capping agent was developed. The CuS NPs were characterised by scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction, Brunauer–Emment–Teller, zeta analysis, thermal gravimetric– differential thermal analysis, Fourier transform infrared and UV–visible absorption spectra. These characterisations together determine the composition, structural, thermal and optical properties. The UV–visible spectrum had a broad absorption in the visible range. The particle size of the products was observed by TEM in the range of 8–20 nm. The photocatalytic performance of the CuS NPs was evaluated for the degradation of organic dyes (methylene blue, rhodamine B, eosin Y and congo red) under irradiation of solar, visible and UV lights. The CuS NPs showed good photocatalytic activity. Kinetic analyses indicate that the photodegradation rates of dyes usually follow pseudo-first-order kinetics for degradation mechanisms. [ABSTRACT FROM AUTHOR]