Effect of pH in the Hydrothermal Preparation of Bi<sub>2</sub>WO<sub>6</sub> Nanostructures
Teodóra Nagyné-Kovács,
Gubakhanim Shahnazarova,
István Endre Lukács,
Anna Szabó,
Klara Hernadi,
Tamás Igricz,
Krisztina László,
Imre M. Szilágyi,
György Pokol
Affiliations
Teodóra Nagyné-Kovács
Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Műegyetem rakpart 3., H-1111 Budapest, Hungary
Gubakhanim Shahnazarova
Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Műegyetem rakpart 3., H-1111 Budapest, Hungary
István Endre Lukács
Research Institute for Technical Physics and Materials Science, Hungarian Academy of Sciences, Konkoly Thege M. út 29-33., H-1121 Budapest, Hungary
Anna Szabó
Department of Applied and Environmental Chemistry, University of Szeged, Rerrich B.tér 1., H-6720 Szeged, Hungary
Klara Hernadi
Department of Applied and Environmental Chemistry, University of Szeged, Rerrich B.tér 1., H-6720 Szeged, Hungary
Tamás Igricz
Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, Műegyetem rakpart 3., H-1111 Budapest, Hungary
Krisztina László
Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, Műegyetem rakpart 3., H-1111 Budapest, Hungary
Imre M. Szilágyi
Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Műegyetem rakpart 3., H-1111 Budapest, Hungary
György Pokol
Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Műegyetem rakpart 3., H-1111 Budapest, Hungary
In this study, Bi2WO6 was prepared by the hydrothermal method. The effects of reaction temperature (150/170/200 °C) and reaction time (6/12/24 h) were investigated. The role of strongly acidic pH (1 >) and the full range between 0.3 and 13.5 were studied first. Every sample was studied by XRD and SEM; furthermore, the Bi2WO6 samples prepared at different temperatures were examined in detail by EDX and TEM, as well as FT-IR, Raman and UV-vis spectroscopies. It was found that changing the temperature and time slightly influenced the crystallinity and morphology of the products. The most crystallized product formed at 200 °C, 24 h. The pure, sheet-like Bi2WO6, prepared at 200 °C, 24 h, and 0.3 pH, gradually transformed into a mixture of Bi2WO6 and Bi3.84W0.16O6.24 with increasing pH. The nanosheets turned into a morphology of mixed shapes in the acidic range (fibers, sheets, irregular forms), and became homogenous cube- and octahedral-like shapes in the alkaline range. Their band gaps were calculated and were found to vary between 2.66 and 2.59 eV as the temperature increased. The specific surface area measurements revealed that reducing the temperature favors the formation of a larger surface area (35.8/26/21.6 m2/g belonging to 150/170/200 °C, respectively).