Sonochemical synthesis and characterization of Ho₂Sn₂O₇/Er₂Sn₂O₇ nanocomposites and their application as photocatalyst for degradation of water-soluble organic pollutants under UV light

We examined the bimetallic stannate Ho₂Sn₂O₇/Er₂Sn₂O₇ nanosized semiconductor as a new material for reducing organic pollutants in drinking water to further enhance the photo-catalytic efficiency of the nanophoto-catalysts. A simple sonochemical method, followed by calcination at 900 °C, was employed to fabricate the novel Ho₂Sn₂O₇/Er₂Sn₂O₇ nanocomposites, in addition to pure Ho₂Sn₂O₇ and Er₂Sn₂O₇ nanoparticles. The results of the X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements revealed a stable connection between cubic Ho₂Sn₂O₇ and cubic Er₂Sn₂O₇ nano-semiconductors in composite nature, with particle dimensions between 40 and 120 nm. According to Brunauer-Emmett-Teller (BET) analysis, the specific surface area of Ho₂Sn₂O₇/ Er₂Sn₂O₇ nanocomposites was found as 19.95 m² g⁻¹. Ho₂Sn₂O₇/Er₂Sn₂O₇ nanocomposites were compared in terms of their photo-degradation efficiency with pure Ho₂Sn₂O₇ and Er₂Sn₂O₇ nanoparticles under UV light to eliminate a variety of anionic and cationic synthetic dyes. In this study, the effects of nano-catalyst type, pollutant type, pollutant concentration, catalyst dosage, and scavenger parameters were considered on the UV-assisted catalytic ability of stable semiconductors. For the degradation of Eriochrome black T (EBT) pollutant, Ho₂Sn₂O₇/Er₂Sn₂O₇ nano-products with a degradation efficiency of 95.34 % were suitable candidates for UV-assisted catalyst activity. In the present study, it was shown that a novel simultaneous coupling between Ho₂Sn₂O₇ and Er₂Sn₂O₇ nanostructures with optical band gaps of 3.90 and 3.92 eV can substantially reduce the recombination of photogenerated carriers and therefore improve photocatalytic efficiency.