Effects of annealing temperature on the structure, morphology, and photocatalytic properties of SnO₂/rGO nanocomposites

Abstract

Water pollution abatement is a problem in today’s society that requires urgent attention. Moreover, photocatalysts are an effective method to treat environmental pollution, and SnO2/reduced graphene oxide composite photocatalysts have been extensively studied in recent years. The synthesis parameters for these photocatalysts significantly affect their morphologies, structures, and properties. In this study, we investigated the effects of annealing temperatures on the properties of SnO2/reduced graphene oxide nanocomposites, which were hydrothermally fabricated at 180 °C for 24 h and annealed at 200 °C–800 °C. The structural characteristics of the fabricated nanocomposites were studied via x-ray diffraction, field emission scanning electron microscopy, and Raman scattering analyses. The observed results indicated that increasing the annealing temperature from 200 °C to 800 °C increased the average SnO2 nanoparticle size from 4.60 nm to 9.27 nm; in addition, the Raman scattering peaks of the SnO2 increased, and those of the reduced graphene oxide significantly decreased as the annealing temperature was increased. Furthermore, the specific surface area of the samples decreased due to the increase in calcination temperature. The amount of reduced graphene oxide content in all the samples was measured using thermo-gravimetric analysis. The optical properties of the samples were studied using ltraviolet–visible absorption spectra, and their photocatalytic activity was evaluated by decomposing methylene blue under visible light using the samples as catalysts. In particular, the photocatalytic properties of nanocomposites decreased significantly with increasing annealing temperature. Among the samples, the photocatalytic activity of that annealed at 200 °C is most satisfactory as it has the smallest particle size and the largest specific surface area. The results of our research could facilitate the production of efficient catalysts with suitable properties.

Analyzing the role of Ni dopant to change the structural, optical and photocatalytic properties of SnO2 nanoparticles

“…This mode is related to the expansion and contraction of Sn-O bond. Raman peaks at 474 cm −1 , 690 cm −1 and 774 cm −1 correspond to the E g , A 2u(LO) and B 2g vibration modes respectively [30][31][32], where the subscript LO in A 2u(LO) stands for longitudinal optical phonon mode. The E g mode is observed due to vibration of two oxygen atoms parallel to c-axis, but in opposite direction.…”

Reduction of graphene oxide (GO) to reduced graphene oxide (rGO) at different hydrothermal temperatures and enhanced photodegradation of zinc oxide/rGO composites

“…ZnO nanostructures are fabricated through various methods, such as hydrothermal method, sol-gel method, chemical vapor deposition, and thermal evaporation [4,5]. The hydrothermal method is popularly used because of its many advantages, such as simplicity, low temperature, energy saving, and controllable technological parameters [1,3,4,9,10].…”

“…Hybrid semiconductors equipped with graphene have attracted considerable attention because the latter can enhance photocatalytic properties and reduce the recombination of electron-hole pairs [1,3,7,[9][10][11][12][13]20]. Kumar et al fabricated rGO-ZnO nanocomposites through hydrothermal reaction [21].…”

Facile Fabrication of F-Doped SnO2 Nanomaterials for Improved Photocatalytic Activity

“…Generally, doping non-metal (C, B, I, F, S, and P) will introduce structural defects, altering the band gap of metal oxide and resulting in higher absorption [14,15]. Tuan et al [16] modified SnO 2 using reduced graphene oxide. The photocatalytic activity for MB has been improved because of the raised specific surface area.…”