Tailoring of nanocrystals Bi2WO6 glass ceramics decorated with Sm3+ and Eu3+ ions for improving photocatalytic activity

For the first time in glass ceramics, pure Bi2WO6 nanocrystals were synthesized. This was achieved by preparing glass samples have a specific composition of SiO2-B2O3-NaF-WO3-SeO2-Na2O-Bi2O3 with 0.05 mol.% (Sm3+ or/ and Eu3+) via melt-quenching technique. Then through a differential scanning calorimetry (DSC) study, the controlled heat treatment process for the glass samples was determined at 500 degree celsius/2hrs to obtain their glassceramic counterparts. Doping by Sm3+ or/and Eu3+ decreased the glass transition temperature (Tg) from 467, 426, 350 to 344 degree celsius and the crystallization temperature from 535, 508, 481 to 433 degree celsius for the samples in the order of W, WSm, WEu, and WSE, respectively. Vibrational modes associated with SiO4 , BO4 and BO3 units were confirmed by FTIR measurements. RE-doped glass showed characteristic visible - NIR absorption peaks due to the respective rare earth ions. Orthorhombic Bi2WO6 nanocrystals were obtained in glass ceramic samples, except WSE sample exhibited crystallization of Bi-2 WO6 as a major phase beside traces of Bi2O3 , as shown by X-rays. Bi-2 WO6 crystallized in 2D sheet-like nanocrystals measuring less than 10 nm in size based on SEM and TEM studies. XPS analysis confirmed the triple valence of Eu3+ and Sm3+ ions into Bi-2 WO6. Photoluminescence measurements revealed distinct emission peaks from Sm and Eu ions in both glass and glass-ceramic samples, ranging from red to white light. Using UV - vis DRS, the optical band gap energy (E opt ) was estimated for glassceramic samples, showing values within the semiconductor range (similar to 2.8 eV). Photocatalytic activity was evaluated by degradation of methylene blue (MB) under UV and natural sunlight. All studied glass ceramics showed high photocatalytic efficiency. Remarkably, doping with Eu3+ significantly enhanced photocatalytic activity, exceeding 85% after 1 hour under UV or sunlight irradiation, followed by Sm3+ doping, and then doping with both Eu3+ + Sm3+ . Based on the obtained results, the studied samples are potentially useful as visible light photocatalysts, semiconductors, and photoluminescent glass ceramics.