Crystal structures
of hydrothermally synthesized BiEuWO6 and BiTbWO6 nanomaterials are deduced for the first time
by combined Rietveld refinement of neutron and synchrotron data using
the ordered and disordered models available in literature. The ordered
model is validated for the average structure of these nanomaterials,
and it is further supported by the local structure analysis using
neutron pair distribution function. Nanomaterials are characterized
by field-emission scanning electron microscopy, transmission electron
microscopy, Brunauer–Emmett–Teller surface area, diffused
reflectance spectroscopy, and Raman Spectroscopy. Rare-earth-substituted
nanomaterials are found to be efficient photocatalysts over the parent
Bi2WO6 under visible light irradiation for Congo-red
dye degradation. Particularly, BiTbWO6 shows an enhanced
photocatalytic (PC) activity compared to BiEuWO6, as evidenced
from the photoelectrochemical and time-resolved fluorescence studies.
The difference in the observed PC activity of these nanomaterials
is also explored through a detailed comparison of crystal structure
and electronic structure calculated through the density functional
theory method.