Solution precursor plasma deposition of nanostructured ZnO coatings

Zinc oxide (ZnO) is a wide band gap semiconducting material that has various applications including optical, electronic, biomedical and corrosion protection. It is usually synthesized via processing routes, such as vapor deposition techniques, sol–gel, spray pyrolysis and thermal spray of pre-synthesized ZnO powders. Cheaper and faster synthesis techniques are of technological importance due to increased demand in alternative energy applications. Here, we report synthesis of nanostructured ZnO coatings directly from a solution precursor in a single step using plasma spray technique. Nanostructured ZnO coatings were deposited from the solution precursor prepared using zinc acetate and water/isopropanol. An axial liquid atomizer was employed in a DC plasma spray torch to create fine droplets of precursor for faster thermal treatment in the plasma plume to form ZnO. Microstructures of coatings revealed ultrafine particulate agglomerates. X-ray diffraction confirmed polycrystalline nature and hexagonal Wurtzite crystal structure of the coatings. Transmission electron microscopy studies showed fine grains in the range of 10–40 nm. Observed optical transmittance (∼65–80%) and reflectivity (∼65–70%) in the visible spectrum, and electrical resistivity (48.5–50.1 mΩ cm) of ZnO coatings are attributed to ultrafine particulate morphology of the coatings.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The solution precursor route employed is an inexpensive process with capability to produce large scale coatings at fast rates on mass scale production. ► It is highly capable of developing tailorable nanostructures. ► This technique can be employed to spray the coatings on any kind of substrates including polymers. ► The ZnO coatings developed via solution precursor plasma spray process have good electrical conductivity and reflectivity properties in spite of possessing large amount of particulate boundaries, porosity and nanostructured grains.