Efficient Photocatalytic Degradation of Pharmaceutical Pollutants Using Plasma‐Treated g‐C₃N₄/TiO₂

Abstract

A series of oxygen plasma–treated g‐C 3 N 4 /TiO 2 nanotubes are prepared, which exhibit excellent photocatalytic performance for degrading pharmaceutical pollutants under simulated solar light irradiation. The structure and optical properties of photocatalysts are characterized using scanning electron microscope, transmission electron microscopy, X‐ray diffraction, UV–vis, atomic force microscopy, and X‐ray photoelectron spectroscopy analyses. The g‐C 3 N 4 nanoparticles are coated on the surface of TiO 2 forming a heterojunction structure, which extends the light‐absorption region and inhibits the recombination of electrons with holes. Ibuprofen is used as a model pharmaceutical pollutant. The heterojunction structure allows the g‐C 3 N 4 /TiO 2 high photocatalytic efficiency that is two times larger than that of TiO 2 nanotubes. The efficiency of g‐C 3 N 4 /TiO 2 is further enhanced by oxygen plasma treatment. The oxygen plasma–treated g‐C 3 N 4 /TiO 2 exhibits a photocatalytic efficiency of 95% within 90 min, which is much larger than that of TiO 2 nanotubes (28%), g‐C 3 N 4 (52%), and g‐C 3 N 4 /TiO 2 nanotubes (70%). The kinetics of the photocatalytic degradation are also investigated. The plasma‐treated g‐C 3 N 4 /TiO 2 exhibits the largest rate constant, which results from massive surface‐active species and surface oxygen. Finally, the structural evolution and reaction mechanism are investigated using molecular dynamics simulations, which offer a deep insight into the photocatalytic reaction.