Fabrication of C/X-TiO2@C3N4 NTs (X = N, F, Cl) composites by using phenolic organic pollutants as raw materials and their visible-light photocatalytic performance in different photocatalytic systems

A series of nonmetallic elements co-doped titanium dioxide coated carbon nitride nanotubes (C/X-TiO 2 @C 3 N 4 NTs, X   =   N, F, Cl) was successfully prepared by a simple sol-gel-pyrolysis process using phenolic organic pollutants, titanium butoxide, and carbon nitride nanotubes as precursors. The morphology, porosity, phase and chemical structure, and optical and electronic property of as-prepared C/X-TiO 2 @C 3 N 4 NTs were well characterized. The as-prepared C/X-TiO 2 @C 3 N 4 NTs exhibited excellent visible-light photocatalytic activity in the conventional degradation and hydrogen evolution systems compared with traditional TiO 2 /g-C 3 N 4 heterojunction, which is attributed to their unique tubular nanostructure and nonmetallic elements co-doped TiO 2 component. Subsequently, the visible-light photocatalytic activity of C/X-TiO 2 @C 3 N 4 NTs was further studied in the simultaneous hydrogen evolution with organic pollutant degradation system on the basis of our previous work. The reaction mechanisms in different photocatalytic systems were further discussed in detail.