Powder diffraction (PD) measurements were conducted to identify the crystallite size of the WO3. This was done at the Australian Synchrotron in Melbourne, on the Powder Diffraction beamline. Mythen detectors were used to record the diffraction patterns in the 2θ range of 0°–60° at a fixed wavelength of 1.13 Å. The crystallite size (L) of the nano-sized WO3 was determined using the Scherrer equation as follows (Eq. (2)):