Zn and N Codoped TiO₂ Thin Films: Photocatalytic and Bactericidal Activity

Abstract

We explore a series of Zn and N codoped TiO 2 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 2•− ) formation was assessed using a 2,3-bis(2methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-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 E. coli under both UVA and fluorescent light (similar to what is found in a clinical environment). The 0.4% Zn,N:TiO 2 thin film demonstrated the highest formal quantum efficiency in degrading stearic acid (3.3 × 10 −5 molecules•photon −1 ), while the 1.0% Zn,N:TiO 2 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.

Enhanced Photocatalytic and Photokilling Activities of Cu-Doped TiO2 Nanoparticles

“…There are several methods of reducing the band gap of TiO 2 , but one of the most well-known methods involves doping with transition metals. Many metals have been introduced for this purpose, such as Mn [ 12 ], Co [ 13 ], Zn [ 14 ] and Cu [ 15 ]. The latter has several significant advantages; for example, Cu can create multi-bands, act as inhibitor of grain growth and extend the electron-hole (e − , h + ) pair recombination.…”

Recent Advances in Processing and Applications of Heterobimetallic Oxide Thin Films by Aerosol‐Assisted Chemical Vapor Deposition

“…In comparison, the 1.0 % Zn in N : TiO 2 film had the maximum bactericidal activity (>3 log kill). The transient absorption spectroscopy (TAS) measurements revealed a relationship between higher charge carrier lifetime and improved film efficiency [92] …”

Sol–Gel Ceramics for SEIRAS and SERS Substrates

“…Zirconia, titania, hydroxyapatite, and lithium niobate have also been obtained with the sol-gel method via the use of alkoxides (Table 1). Examples such as a zirconia membrane for the separation of hydrogen from a mixture of gases [32], zirconia-silver oxide nanoparticles for antibacterial applications [33], titania-polymer thin film composites for catalytic activity [34], titania thin films doped with zinc and nitrogen with bactericidal and photocatalytic activities [35], hydroxyapatite powder doped with silver nanoparticles with antimicrobial activity [36], bioactive poly-ε-caprolactone with alumina and hydroxyapatite composite fibers [37], lithium niobate thin films with optical properties [38], lithium niobate thin films with piezoelectric properties [39], and copper oxide-lithium niobate composites with photocatalytic activity for environmental purposes prepared through the Pechini method [40]. Examples of alumina prepared using alkoxides include the synthesis of γ-alumina using aluminum sec-butoxide [41], γ-alumina microspheres [42], alumina thin films on steel for corrosion protection using aluminum isopropoxide [43], and the use of aluminum triethoxide to improve the properties of a graphene oxide nanocomposite [44].…”