Towards effective design of active nanocarbon materials for integrating visible-light photocatalysis with ozonation.

We herein present systematic insights into the potential of a wide variety of dimension-structured nanocarbons in visible light-O 3 integrated process for metal-free water decontamination. Single-walled carbon nanotube (SWCNT), multi-walled carbon nanotube (MWCNT), reduced graphene oxide (rGO) and fullerene (C 60 ) demonstrated high activities in catalytic ozonation, while graphitic carbon nitride (g-C 3 N 4 ) and C 60 outshined in visible light-O 3 coupled process. The advantageous properties of nanocarbon materials in both catalytic ozonation and photocatalytic ozonation were acquired as further guidance for catalyst design. The effects of both liquid-phase and surface hydroxyl radicals ( OH) were determined by trapping experiments and in-situ electron paramagnetic resonance. The coupling coefficient of visible light and ozone on g-C 3 N 4 was 95.8, which was never achieved in the previous literature. The OH yield of Vis/O 3 /g-C 3 N 4 , interpreted from oxalic acid removal rate, was superior to those of O 3 /nanocarbon (MWCNT, rGO and C 60 ) and field-leading Vis/O 3 /metal oxides (WO 3 and TiO 2 ) systems. Further strategies on g-C 3 N 4 optimization were also proposed. This study contributes to the development of active metal-free nanocatalysts in photocatalytic ozonation for water treatment. [ABSTRACT FROM AUTHOR]