Background: The photocatalytic degradation of toxic organic compounds has received great attention for the past several years. Dyes, such as methyl orange (MO), are one of the major pollutants which create environmental hazards in the hydrosphere, living organisms and human beings. During photocatalytic degradation, NPs are activated in the presence of UV–Vis radiation which in turn creates a redox environment in the system and behaves as a sensitizer for light-induced redox mechanisms. Tin oxide (SnO2) is one of the prominent, but less investigated, nanomaterials compared to titanium oxide (TiO2) and Zinc oxide (ZnO) nanoparticles (NPs). Methods: Herein, Buxus wallichiana (B. wallichiana) leaf extract was utilized as a reducing and capping agent for the biosynthesis of SnO2 NPs. The effects of the calcination temperature on their photocatalytic, structure and surface properties were then examined. The degree of crystallinity and the crystallite size were determined through X-ray diffraction (XRD) analysis. The pore size and surface area were calculated by Burnett–Emmitt–Teller (BET) and Barrett–Joyner–Halenda (BJH) methods based on nitrogen desorption data. Morphological changes were assessed by scanning electron microscopy (SEM). The optical behavior was analyzed through UV–Vis diffuse reflectance spectroscopy (DRS) data and the band gap subsequently calculated. The photocatalytic efficiency of SnO2 NPs was evaluated by double beam UV–Vis spectrophotometry under the influence of initial MO concentration, catalyst dose and pH of MO solution. The surface functional moieties were identified using Fourier transform infrared (FTIR) spectroscopy. All the calcined SnO2 NPs were used as photocatalysts for the mineralization of MO in aqueous media. Results: The degree of crystallinity and the crystallite size increased with the calcination temperature. The transmittance edge obtained for all the calcined SnO2 NPs shows a maximum absorbance in the visible range (λ-max = 464 nm). Moving toward higher wavelengths, a sudden intense red shift (from 464 nm to 500 nm), attributed to the incorporation of a hydroxyl radical at the ortho-position in the benzene ring associated with the dimethylamine group of MO, was observed in the absorbance of the samples calcined up to 300 °C. The percentage degradation of MO was found to decrease with increasing calcination temperatures. The optimal photocatalytic activity toward MO (15 ppm) in a solution of pH = 6 was obtained with 15 mg SnO2 NPs calcined at 100 °C. Conclusions: UV–Vis absorption spectroscopy demonstrates that the absorption spectra of MO are strongly modified by the calcination temperature. This work opens new avenues for the use of SnO2 NPs as photocatalysts against the degradation of industrial effluents enriched with different dyes.

This study was planned to synthesize a multifunctional nanomaterial that can effectively encounter the organic pollutants, multidrug-resistant bacteria and reactive free radicals. The Bergenia ciliate (B. ciliate) leaves extract was used as a reducing and capping agent for the synthesis of nickel oxide nanoparticles (NiO NP). The physicochemical properties were studied through X-ray diffractometre (XRD), energy dispersive X-ray (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-visible and Fourier transform infrared (FTIR) spectroscopies. The highly crystalline monoclinic NiO NPs were synthesized with crystallite size of 27.45 nm. The average particle size derived from TEM micrograph was 49.35 nm whereas the calculated band gap for NiO NPs was 3.78 eV. The photocatalytic study shows that 92.17% of the rhodamine 6G (Rh-6G) was efficiently degraded in the presence of NiO NPs. The agar well diffusion method was applied to examine the antibacterial activity of NiO NPs and the activity was found higher against Gram-negative bacteria (GNB) as compared to Gram-positive bacteria (GPB). The ABTS free radical scavenging activity was also performed, however, the activity was found less than the standard.

Tin dioxide nanoparticles (SnO2 NPs) are synthesized by using Buxus wallichiana (B. Wallichiana) leaf extract. To determine the surface area (138.2 m2/g) and pore size of the SnO2 NPs, the nitrogen adsorption-desorption method used. The average crystallite size was determined to be 38 nm using X-ray diffraction (XRD). Scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), were used to investigate the structural and optical properties of SnO2 NPs with a band gap of 3.69 eV. Fourier transform infrared (FTIR) spectroscopy was used for the chemical analysis. In this experiment, methyl orange (MO) was deteriorated in the presence of artificial sun light for 140 min, where 97.50 percent of the dye decolorized. A 15 ppm solution of MO with the pH 6, was treated in the presence of 20 mg of the catalyst, resulting in the highest photocatalytic activity.

Transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray diffraction (XRD), energy dispersive X-ray (EDX), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), and Fourier transform infrared (FTIR) spectroscopy were applied to evaluate the tin dioxide nanoparticles (SnO2 NPs) amalgamated by the sol-gel process. XRD was used to examine the tetragonal-shaped crystallite with an average size of 26.95 (±1) nm, whereas the average particle size estimated from the TEM micrograph is 20.59 (±2) nm. A dose-dependent antifun3al activity was performed against two fungal species, and the activity was observed to be increased with an increase in the concentration of SnO2 NPs. The photocatalytic activity of SnO2 NPs in aqueous media was tested using Rhodamine 6G (Rh-6G) under solar light illumination. The Rh-6G was degraded at a rate of 0.96 × 10−2 min for a total of 94.18 percent in 350 min.

The antimicrobial drug resistance is increasing with the passage of time due to wide and improper use of broad spectrum drugs and the demand of the new drug increases day by day. The present study was planned to encounter this problem by synthesizing titanium dioxide nanoparticles (TiO2 NPs) by an eco‐friendly route using Cannabis sativa leaves extract. The synthesized TiO2 NPs were calcined at 100, 300, 600, and 900°C in a muffle furnace. The crystallographic parameters were studied by X‐ray diffraction and the phase transition occurred above 600°C. The surface morphology of the synthesized samples was studied by transmission electron microscopy (TEM), and scanning electron microscopy (SEM) and the particle size was measured through the ImageJ software. The elemental composition and purity of all the samples were studied by performing energy dispersive X‐ray (EDX). All the synthesized TiO2 NPs were tested for their antimicrobial effect against Gram‐positive and Gram‐negative bacteria using the agar well diffusion method. The activity was found higher against Gram‐negative bacteria and compared to Gram‐positive bacteria.

The synthesis of zinc stannate nanocomposite (Zn2SnO4 NC) was carried out using an environment friendly process that included the use of Ficus carica (F. carica) leaves extract as a capping and reducing agent. X-ray diffraction (XRD) analysis was used to analyze the structural and crystallographic parameters, and the crystallite was discovered to have cubic geometry. The elemental composition of the studied Zn2SnO4 NC was investigated using energy dispersive X-ray (EDX), which revealed that it was extremely pure. The band gap (3.12 eV) was calculated through Tauc plot using diffuse reflectance (DRS) data where the functional groups were explored through Fourier transform infrared (FTIR) spectroscopy. Prior to the photocatalytic reaction, some preliminary experiments were performed, which proposed that pH 9 is suitable for the mineralization of methylene blue (MB) (10 ppm) in the presence of 20 mg of Zn2SnO4 NC and simulated solar light. The 96 % of MB was degraded in 80 min with the degradation rate of 0.038 min-1.