Abstract: TiO₂ is the most photoactive material because of its superstrong photooxidizing ability, and TiO₂ photocatalysis has been widely applied in sustainable water treatment and environmental remediation. However, poor sunlight or visible-light harvesting efficiency and fast recombination rate of the photogenerated charge carriers severely limit the practical applications of TiO₂. To overcome these problems, the present work demonstrates a facile in-situ co-condensation method combined with hydrothermal treatment to prepare a series of graphitized carbon/TiO₂ composite photocatalysts, and anatase TiO₂ phase and p-p-conjugated polycyclic aromatic carbon structure are created simultaneously. As-prepared TiO₂/C composites exhibit remarkably high visible-light photocatalytic activity in the degradation of aqueous emerging phenolic pollutants, acetaminophen (APAP) and methylparaben (MPB), and apparent rate constant of the TiO₂/C composite with carbon doping level of 10.3% for APAP and MPB removal is 7.6 and 2.8 times higher than that of bare TiO₂, and 6.2 and 2.6 times higher than that of Degussa P25 TiO₂. Based on the results of photoelectrochemical experiments, indirect chemical probe measurements, and ESR spectroscopy, it is verified that doping TiO₂ with graphitized carbon is responsible for this enhanced photocatalytic activity, which renders the improved visible-light harvesting ability, the accelerated separation of the photogenerated charge carriers, and enlarged BET surface areas. Through analyzing the intermediates yielded in the photodegradation process, the pathway of visible-light photocatalytic degradation of APAP and MPB over the TiO₂/C composite is proposed.

Key words: Titanium dioxide, Carbon, Visible-light photocatalysis, Composite, Phenolic compound, Water treatment