Highly effective removal of volatile organic pollutants with p-n heterojunction photoreduced graphene oxide-TiO2 photocatalyst

Abstract

Volatile organic compounds (VOCs) are among the most common gaseous pollutants found indoors. Photocatalytic oxidation (PCO) is an effective technique to remove VOCs, and recently, photoreduced graphene oxide (PRGO) has emerged as a carbon-based photocatalyst. The p-n heterojunction photocatalyst composed of p-type PRGO and n-type titanium dioxide (TiO2) was synthesised via a benign and facile ultraviolet (UV)-assisted photoreduction method. The optimised PRGO-TiO2 photocatalyst (GT-12) exhibited enhanced photoactivity that removed 100% and 24.3% of VOC (50 mg/m3 of methanol) under UV and visible light, respectively. The enhancement was due to the larger built-in potential of p-n heterojunction (+ 0.05 eV)) and smaller band gap (2.90 ⎯ 3.15 eV) of the GT-12, which retarded the charge carrier recombination and improved light absorption, respectively. The main reactive species responsible for the photocatalytic activities were hVB+ species and ⦁O2− radicals. This work provides new insights into the potentials of PRGO-TiO2 as a p-n heterojunction photocatalyst.