Low-Cost One-Step Fabrication of Highly Conductive ZnO:Cl Transparent Thin Films with Tunable Photocatalytic Properties via Aerosol-Assisted Chemical Vapor Deposition

Low-cost, high-efficiency, and high quality Cl-doped ZnO (ZnO:Cl) thin films that can simultaneously function as transparent conducting oxides (TCOs) and photocatalysts are described. The films have been fabricated by a facile and inexpensive solution-source aerosol-assisted chemical vapor deposition technique using NH4Cl as an effective, cheap, and abundant source of Cl. Successful ClO substitutional doping in the ZnO films was evident from powder X-ray diffraction, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry results, while scanning electron microscopy reveals the impact of Cl doping on the ZnO thin film morphology. All ZnO:Cl films deposited were transparent and uncolored; optical transmittance in the visible region (400−700 nm) exceeded 80% for depositions using 5−20 mol % Cl. Optimal electrical properties were achieved when using 5 mol % Cl with a minimum measured resistivity of (2.72 ± 0.04) × 10−3 Ω·cm, in which the charge carrier concentration and mobility were measured at (8.58 ± 0.16) × 1019 cm−3 and 26.7 ± 0.1 cm2 V−1 s −1 respectively, corresponding to a sheet resistance (Rsh) of 41.9 Ω□−1 at a thickness of 650 nm. In addition to transparent conducting properties, photocatalytic behavior of stearic acid degradation in the ZnO:Cl films was also observed with an optimal Cl concentration of 7 mol % Cl, with the highest formal quantum efficiency (ξ) measured at (1.63 ± 0.03) × 10−4 molecule/photon, while retaining a visible transparency of 80% and resistivity ρ = (9.23 ± 0.13) × 10−3 Ω·cm. The dual functionality of ZnO:Cl as both a transparent conductor and an efficient photocatalyst is a unique combination of properties making this a particularly unusual material

Photocatalytic and electrically conductive transparent Cl-doped ZnO thin films: Via aerosol-assisted chemical vapour deposition

A simple, economical and effective solution-based chemical vapour deposition (CVD) technique, aerosol-assisted CVD, has been successfully applied to produce inexpensive Cl-doped ZnO films using Zn acetate dihydrate and FeCl3. X-ray photoelectron spectroscopy and the increase in cell parameters from powder X-ray diffraction determined that Cl had been doped into the wurtzite ZnO lattice. The Cl-doping had a significant effect on the morphology of the thin films synthesised and resulted in an improvement in the visible light transmission and lower electrical resistance (typical resistivities of doped films ∼10−2 Ω cm). The highest transmittance (% T) of 85% was obtained when 7 mol% FeCl3 was used in the precursor solution and the lowest resistivity of 4.28 ± 0.41 × 10−2 Ω cm was obtained with 5 mol% FeCl3. The greatest photocatalytic activity of stearic acid degradation under UVA irradiation was obtained on using 10 mol% FeCl3, resulting in the highest formal quantum efficiency (FQE) of 3.0 ± 0.1 × 10−4 molecule per photon. These films, therefore, display transparent conducting oxide and photocatalytic properties, giving multifunctional characteristics and promising applications

Photocatalytic NOₓ oxidation of BiOCl nanostructure-based films grown using aerosol-assisted chemical vapor deposition

Coating of photocatalytic nanomaterials on various surfaces enables interesting applications. This work demonstrates the ability of the aerosol-assisted chemical vapor deposition (AACVD) approach to prepare high-quality BiOCl nanostructure-based films and also to tune the nanostructure and photocatalytic properties of the films by varying the solvent and carrier gas. Solvents have a dramatic impact on the surface morphologies and crystallite size. X-ray diffraction (XRD) and grazing incidence X-ray diffraction (GIXRD) analyses indicate that BiOCl crystals displayed preferential growth in the (101) plane in most samples, while both the (101) and (102) planes were favored in films deposited using ethyl acetate and methanol. Surface energy and adsorption energy calculation reveal that the preferred growth depends on the interaction between the Bi atom and solvent molecules. X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDS) characterizations showed that all films did not contain any impurity elements but did contain some oxygen vacancies. The obtained nanostructured BiOCl films show good photocatalytic properties. The highest photocatalytic NOx removal efficiency is achieved in the film prepared using ethyl acetate and air, which we attribute to the large crystallite size and therefore high mobility of the carriers. Herein, we show that different crystal morphologies and sizes of BiOCl have strong impacts on the photocatalytic activity toward NO oxidation, and both factors can be effectively tuned in the AACVD process. Such knowledge may be useful for future research on coating materials for resolving environmental problems