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 WO 3 /N-rGO nanocomposites. Photoluminescence spectra revealed that there were a few transitions in which the intensity in WO 3 /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.

In Situ Synthesis of Mixed-Phase WO3 on Nitrogen-Doped Graphene with Enhanced Photoelectric Properties

“…Compared to WO 3 (0.35 × 10 –4 A/cm 2 ), WO 3 /rGO (0.78 × 10 –4 A/cm 2 ), and WO 3 /N-rGO (2.04 × 10 –4 A/cm 2 ) exhibit stronger photocurrent, which is considered as the strategy of integrating WO 3 with rGO and N-rGO. Graphene can rapidly transfer photogenerated carriers to external circuits due to its high electrical conductivity. , In addition, the photocurrent of WO 3 /N-rGO is 2.6 times as high as that of WO 3 /rGO due to the formation of phase junction between monoclinic WO 3 and orthorhombic WO 3 , − and the doping of N. , The phase junction effectively promotes the separation of electron–hole pairs, while the nitrogen doping lowers the Schottky junction barrier of WO 3 /N-rGO and facilitates the transfer of electrons from WO 3 to N-rGO . The rise–decay dynamics of transient photocurrent measurement provide direct information on trapping, recombination, and charge transport .…”