Bio-Synthesized Tin Oxide Nanoparticles: Structural, Optical, and Biological Studies

Construction of SnO2/CuO/rGO nanocomposites for photocatalytic degradation of organic pollutants and antibacterial applications

Water contamination by reactive dyes is a serious concern for human health and the environment. In this study, we prepared high efficient SnO₂/CuO/rGO nanocomposites for reactive dye degradation. For structural analysis of SnO₂/CuO/rGO nanocomposites, XRD, UV-Vis DRS, SEM, TEM-EDAX, and XPS analysis were used to characterize the physicochemical properties of the material. The characterization results confirmed great crystallinity, purity, and optical characteristics features. For both Rhodamine B (RhB) and Reactive Red 120 (RR120) degradation processes, SnO₂/CuO/rGO nanocomposites were tested for their photocatalytic degradation performance. The SnO₂/CuO/rGO nanocomposites have expressed the degradation rate exposed to 99.6% of both RhB and RR120 dyes. The main reason behind the photocatalytic degradation was due to the formation of OH radical's generation by the composite materials. Moreover, the antibacterial properties of synthesized SnO₂/CuO/rGO nanocomposites were studied against E. coli, S. aureus, B. subtilis and P. aeroginosa and exhibited good antibacterial activity against the tested bacterial strains. Thus, the synthesized SnO₂/CuO/rGO nanocomposites are a promising photocatalyst and antibacterial agent. Furthermore, mechanisms behind the antibacterial effects will be ruled out in near future.

Natural sunlight driven photocatalytic dye degradation by biogenically synthesized tin oxide (SnO2) nanostructures using Tinospora crispa stem extract and its anticancer and antibacterial applications

In the present study, tin oxide (SnO₂) was synthesized by advocating the principles of green chemistry for the photo-mediated degradation of pollutants, antimicrobial, and as an antitumor agent. Bioactive SnO₂ (nanorods & nanospheres) were fabricated using Tinospora crispa stem extract (TCSE) via sol-gel technique and characterized extensively. XRD, UV-VIS, FTIR, and XPS studies confirmed the formation of crystalline and well stoichiometric pure phase of SnO₂ nanostructures with optical bandgap 3.2 to 3.5 eV. The transmission electron microscopy (TEM) results demonstrated the effect of secondary phytoconstituents on the shape of SnO₂ in a concentration dependent manner. The morphological variations in the obtained nanostructures attributed to the nucleation density and coalescence effect leading to the formation of nanorods with an average diameter 23-25 nm whereas the average particle size of the nanospheres obtained was found to be 23-30 nm. The zeta potential value of SnO₂ nanorods was high (- 58.9 mV) indicating the higher stability compared to nanospheres (- 15.6 mV). The SnO₂ nanostructures were investigated for the simultaneous degradation of methylene blue with degradation efficiency of 92.3% and 47.3% for rhodamine B in mono system and 72.3%, 47.7% respectively for binary dye system. The anticancer activity of SnO₂ nanorods explored against human breast cancer (MCF-7) cells revealed a concentration dependent cytotoxic effect reactive oxygen species (ROS) induced cell death. Additionally, efficient antibacterial activity of SnO₂ was established using E.coli. Multifaceted applications of Tinospora crispa stem extract mediated SnO₂ nanostructures.

Structural, optical and magnetic properties of pure and 3d metal dopant-incorporated SnO2 nanoparticles

Dilute magnetic oxide semiconductors doped with transition metals have attracted significant attention both theoretically and experimentally due to their interesting and debatable magnetic behavior. In this work, we investigated the influence of Fe, Co and Ni doping on the structural, optical and magnetic properties of SnO2 nanoparticles, which were produced via a simple sol-gel technique. Raman spectroscopy, XRD, XPS, TEM, FT-IR characterizations were performed to study the crystal structure and morphology of the pure and doped nanoparticles, which confirmed the tetragonal rutile structure of the SnO2 nanoparticles. The XPS analysis revealed the incorporation of divalent dopant ions in the host matrix. The Raman plots indicated the generation of the cassiterite crystal structure, structural disorder and oxygen vacancies in the pure and doped SnO2 nanoparticles. The UV-visible plots indicated a decrease in the bandgap for the doped SnO2 nanoparticles because doping introduced defect levels in the band gap. The photoluminescence study showed the creation of oxygen vacancies due to the doping of different charge states of dopants. The magnetic study based on varying the temperature and field of magnetization revealed the diamagnetic nature of SnO2 at 300 K and 5 K respectively, and the concurrence of ferromagnetic (FM) and paramagnetic (PM) nature in doped SnO2 nanoparticles. The bound polaron model was used to explain the co-existence of FM and PM behavior in all the doped SnO2 nanoparticles.