C-N co-doped titanium dioxide. Key aspects in the assessment of the air pollutants abatement capability

In this work titanium dioxide modified by the simultaneous presence of both carbon and nitrogen dopants (C-N/TiO2) has been prepared (starting from a commercial TiO2 multiphasic matrix) and characterized according to two distinct lines of comparison, namely a) the typology of chemicals used in the doping and, b) the type of visible light (monochromatic or polychromatic) used to irradiate the solid. Singly doped systems C/TiO2 and N/TiO2 have also been prepared and compared to the co-doped one. All materials have been characterized by X-ray diffraction, UV–VIS spectroscopy and EPR (Electron Paramagnetic Resonance). The air pollutants remediation capability was evaluated by means of nitric oxide (NO) abatement tests according to the standard ISO 22197–1. Photoactivity of the pristine matrix is not modified by the presence of carbon (C/TiO2) while it markedly increases when nitrogen is present (N/TiO2 and C-N/TiO2) confirming an essential role of this element in VLA photocatalytic systems. The photocatalytic tests indicate that the Illumination with monochromatic blue light is much more effective than that using a white LED light, which however represents a more common light source in indoor or occupational contexts. The effect of milling (a procedure often used to prepare photocatalytic devices for indoor air remediation) on the activity of the photocatalysts is slightly detrimental on the catalytic performances which however remain good enough to allow practical applications.