Effect of N-rGO Decoration on the Structure and Optical Properties of WO3 Nanoplates

Abstract

In this research, tungsten trioxide (WO $$_{3}$$ ) nanoplates and WO $$_{3}$$ /N-doped reduced graphene oxide (WO $$_{3}$$ /N-rGO) nanocomposites were synthesized with various amounts of N-rGO using the hydrothermal method. X-ray diffraction analysis showed that WO $$_{3}$$ /N-rGO nanocomposites (with 3%, 6%, and 9% of N-rGO) had a hexagonal structure with (200) preferential radial of the crystal plane. According to transmission electron microscopy images, WO $$_{3}$$ has a nanoplate structure with a width within the range of 20–40 nm and length of 500 nm. The result of bandgap energy calculation was 3.69 eV for WO $$_{3}$$ , while for WO $$_{3}$$ /N-rGO 3%, WO $$_{3}$$ /N-rGO 6%, and WO $$_{3}$$ /N-rGO 9%, it was 2.65 eV, 2.84 eV, and 2.61 eV, respectively. Dynamic light scattering confirmed particle sizes 86.7 nm, 56.9 nm, and 76.9 nm for the samples with 3%, 6%, and 9% N-rGO, respectively. The minimum of particle size was for WO3/N-rGO nanocomposites. Photoluminescence spectra revealed that there were a few transitions in which the intensity in WO3/N-rGO 3% was stronger than in the samples with 6% and 9% N-rGO. The origin of these emissions is associated with oxygen vacancies, defects, near-band edge transition, and band-to-band transition. The effective control of bandgap has a clear advantage for use in optical devices and makes the samples more applicable in electrical, photo-electrochemical, and photocatalytic applications.