Zn and N Codoped TiO Thin Films: Photocatalytic and Bactericidal Activity.

We explore a series of Zn and N codoped TiO thin films grown using chemical vapor deposition. Films were prepared with various concentrations of Zn (0.4-2.9 at. % Zn vs Ti), and their impact on superoxide formation, photocatalytic activity, and bactericidal properties were determined. Superoxide (O) formation was assessed using a 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2-tetrazolium sodium salt (XTT) as an indicator, photocatalytic activity was determined from the degradation of stearic acid under UVA light, and bactericidal activity was assessed using a Gram-negative bacterium under both UVA and fluorescent light (similar to what is found in a clinical environment). The 0.4% Zn,N:TiO thin film demonstrated the highest formal quantum efficiency in degrading stearic acid (3.3 × 10 molecules·photon), while the 1.0% Zn,N:TiO film showed the highest bactericidal activity under both UVA and fluorescent light conditions (>3 log kill). The enhanced efficiency of the films was correlated with increased charge carrier lifetime, supported by transient absorption spectroscopy (TAS) measurements.