Effect of high rGO ratio on structural properties, photoluminescence and adsorptive & photocatalytic performances under 365 nm-UV and simulated solar lightsofNaTaO3/rGO heterojunction composites

Abstract

Perovskite NaTaO3 nanocrystals were synthesized using hydrothermal route, and were employed as substrate to deposit several high rGO mass ratios (NaTaO3/rGOx, x = 0, 10, 15 and 20%). X-Ray Diffraction (XRD) proved that NaTaO3 has an orthorhombic perovskite crystalline structure; this phase was conserved after the deposit of rGO, noting a varying of the orientation at the interface. The composites were analyzed by Infrared-spectroscopy (IR), which the absorbed frequencies were all ascribed to different vibrational modes inside the NaTaO3 and rGO structures. Scanning Electron Microscope (SEM) images illustrate the formation of the heterojunction and the mixing of NaTaO3 and rGO sheets with grain seize around 300 nm, and RAMAN-spectroscopy illustrates the obtaining of weak stacked graphene and disordered nano-graphene sheets. In addition, Photoluminescence (PL) reveals large Stocks shift about 60 nm, both XRD and PL reveal that the electronic and structural properties are affected by the deposited rGO. The composites were evaluated for their enhanced adsorptive performance, about 12 mg/g was measured for NaTaO3/rGO20%; and various kinetic models were employed for the adsorption, proving that the adsorption mechanism is governed by film-diffusion and/or chemical reactions process. Finally, the combined process adsorption-photocatalysis for NaTaO3/rGOx illustrate a total elimination of pollutant compared to pristine NaTaO3.