Development of photocatalytic chip seal for nitric oxide removal on the surface of pavement using g-C3N4/TiO2 composite

Nitric oxide (NO) emitted from vehicle exhausts are associated with adverse health effects on the public. This study prepared a graphitic carbon nitride (g-C3N4)/TiO2 composite using melamine and titanium dioxide (TiO2) and then applied the composite on chip seal for the photocatalytic removal of NO. The g-C3N4/TiO2 composite was synthesised by an ultrasonic-assisted solid-phase synthetic method. The results of X-ray powder diffraction, Fourier-transform infrared spectroscopy, and a scanning electron microscope indicated that g-C3N4 and TiO2 were successfully synthesised and most of the sheet structures of g-C3N4 were attached by approximately spherical TiO2 particles. The UV–Vis and PL characterisation suggested that optical absorption range of TiO2 was broadened and the separation of electronic-holes was hindered, which contributed significantly to the enhancement of the visible-light photocatalytic activity. The loading capacity of 0.0092 kg/m2 g-C3N4/TiO2 composite on chip seal specimens had the highest NO removal efficiency of 31.41% within 30 min.