Large-scale synthesis of WO3 nanoplates by a microwave-hydrothermal method

Abstract Tungsten oxide (WO 3 ) nanoplates were synthesized by a 270 W microwave-hydrothermal reaction of Na 2 WO 4 ·2H 2 O and citric acid (C 6 H 8 O 7 ·H 2 O) in deionized water. X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), and selected area electron diffraction (SAED) were used to reveal the synthesis of WO 3 complete rectangular nanoplates in the solution of 0.2 g citric acid for 180 min, with O–W–O FTIR stretching modes at 819 and 741 cm −1 , and two prominent O–W–O Raman stretching modes at 804 and 713 cm −1 . The 2.71 eV indirect energy gap, and 430–460 nm blue emission wavelength range of WO 3 complete rectangular nanoplates were determined using UV–visible and photoluminescence (PL) spectrometers. The formation mechanism was also proposed according to the experimental results.