Enhanced visible light photocatalytic activity of TiO2 based nanocomposit for water treatment

Abstract

An enhanced visible light TiO2-based photocatalyst was synthesised for organic degradation. TiO2 nanotubes (TNTs) were fabricated by electrochemical anodization on Ti foil. The electrolyte solution was ethylene glycol (EG)-DI water, which contains fluoride. The TNTs were modified with reduced graphene oxide (RGO) using one-step and two-step synthesis methods. The RGO was synthesised with a modified version of Hummer’s method using graphite powder as an RGO source. The synthesised catalyst was characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Raman spectroscopy, Auger electron spectroscopy (AES), and photoluminescence spectroscopy (PL). The photocatalytic (PC) and photoelectrocatalytic (PEC) activities of the visible light active catalyst were evaluated using methylene blue (MB) and phenol as a model pollutant. The optimum voltage in the PEC process for MB dye was 5 V, and for phenol, it was 0.5 V. A recycling experiment was also performed to investigate the stability of the photocatalyst. The synthesised visible light catalyst was excellent for the degradation of organics. RGO doping on TNTs is favourable for the separation of e- and h+, thereby increasing the formation of OH radicals and superoxides that degrade organics.