▎ 摘　　要

We report the construction of a graphene/tourmaline/TiO2 (G/T/TiO2) composite system with enhanced charge-carrier separation, and therefore enhanced photocatalytic properties, based on tailoring the surface-charged state of graphene and/or by introducing an external electric field arising from tourmaline. A simple two-step hydrothermal method was used to synthesize G/T/TiO2 composites and poly(diallyldimethylammonium chloride)-G/T/TiO2 composites. In the photocatalytic degradation of 2-propanol (IPA), the catalytic activity of the composite containing negatively charged graphene was higher than of the composite containing positively charged graphene. The highest acetone evolution rate (223 mu mol/h) was achieved using the ternary composite with the optimum composition, i.e., G0.5/T5/TiO2 (0.5 wt% graphene and 5 wt% tourmaline). The involvement of tourmaline and graphene in the composite is believed to facilitate the separation and transportation of electrons and holes photogenerated in TiO2. This synergetic effect could account for the enhanced photocatalytic activity of the G/T/TiO2 composite. A mechanistic study indicated that O-2(center dot-) radicals and holes were the main reactive oxygen species in photocatalytic degradation of IPA. (C) 2017, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.