Use of Mesoporous Tin Dioxide Containing Zinc Oxide Nanoparticles for Degradation of Phenol by Sunlight

A crystalline mesoporous tin dioxide (SnO₂) framework containing zinc oxide (ZnO) nanoparticles was synthesized under ambient pressure. The structural and bulk/surface properties of the framework were analyzed using the Brunauer-Emmett-Teller method, X-ray diffraction analysis, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectrometry, and ultraviolet-visible spectroscopy. The BET surface area of the synthesized material was 115 m² g^–1, which is the highest ever reported for this material after been subjected to two heat treatments (at 400 and 500 °C). The synthesized material exhibited a narrow pore size distribution (2–6 nm), indicating that its pore size and the size of the clusters (3 nm) within the pores were controllable. This makes the synthesized material the first ever mesoporous SnO₂–ZnO composite with a narrow pore size distribution and a very high BET surface area. We believe that a few ZnO nanoparticles occupied the pores in the mesoporous SnO₂, which restricted their further growth. The mean size of the ZnO nanoparticles was 3.4 nm. Further, the synthesized SnO₂–ZnO material exhibited a bandgap of 2.8 eV, as determined by the Kubelka-Munk function. Finally, the photocatalytic activity of the SnO₂–ZnO material was tested against the degradation of phenol in water using sunlight in the absence of other chemicals.