The synergistic effects of acid treatment and silver (Ag) loading for substantial improvement of photoelectrochemical and photocatalytic activity of Na2Ti3O7/TiO2 nanocomposite

Abstract

This study investigated the effects of acid treatment and silver (Ag) loading on a Na2Ti3O7/TiO2 nanocomposite (NTO) synthesized through a hydrothermal method to improve its photoelectrochemical (PEC) performance and photodegradation of Rhodamine B (RhB). Due to the high specific surface area of this nanocomposite (199.06 m2/gr) and the high dispersal of the Ag nanoparticles on the surface of the catalyst, the best photocatalytic efficiency was obtained by using a very small percentage of optimized silver loading. The changes in the morphology, chemical state, and optical property of the NTO caused by the acid treatment and Ag loading were investigated by different analyses. Under visible light irradiation, 97.3% of the RhB in the aqueous solution was photodegraded by the optimized NTO with 0.1 M HCl treatment and 0.5 wt% Ag loading (NTOH0.1/Ag0.5), which is substantially higher than that photodegraded by the pristine NTO. The PEC properties of the NTOH0.1/Ag0.5 photoanode showed 2.7 times higher photocurrent density than that of untreated NTO. Combined analyses of Mott-Schottky plots and electrochemical impedance spectroscopy (EIS) of the NTOH0.1/Ag0.5 nanocomposite confirmed that the acid treatment and silver (Ag) loading increased both the donor concentration (ND) and the charge carrier transfer efficiency, resulting in substantially improved PEC performance.