Photocatalytic carbon hybrids for the elimination of diverse pollutants under visible light:Performances, influencing factors and insight into the novel mechanism

Abstract

Carbon-based composites are widely used in water treatment, especially for adsorption and photocatalysis functional materials. Active sites introduced by doping process often play an important role in eliminating pollutants. Regrettably, the existing forms of active sites and the corresponding mechanism in a composite structure are not clear in most cases. Herein, we developed a novel porous carbon hybrid (PCH) based on an expanded graphite framework with TiO2/g-C3N4 and metal (Ag, Bi and Ni)-N co-doping. The PCH with optimized photocatalytic components displays remarkable performances for the removal of different pollutants (harmful algae: 95.2%, MC-LR: 88.1% and 2,4-DCP: 79.8%) with an efficient adsorption-photocatalysis process, which is approximately twice of the pristine PCH. Interestingly, it has been found that the metal doping not only introduced active sites in the TiO2/g-C3N4 part, but also formed active sites with graphene-based substrate. The metal-derived double-sites property of PCH composites can induce an electron bridge effect which can boost the electron transport in the composites, thus improving the efficiency of pollutant elimination under visible light irradiation.