Growth of zinc oxide nanowires by a hot water deposition method.

Recently, various methods have been developed for synthesizing zinc oxide (ZnO) nanostructures, including physical and chemical vapor deposition, as well as wet chemistry. These common methods require either high temperature, high vacuum, or toxic chemicals. In this study, we report the growth of zinc oxide ZnO nanowires by a new hot water deposition (HWD) method on various types of substrates, including copper plates, foams, and meshes, as well as on indium tin oxide (ITO)-coated glasses (ITO/glass). HWD is derived from the hot water treatment (HWT) method, which involves immersing piece(s) of metal and substrate(s) in hot deionized water and does not require any additives or catalysts. Metal acts as the source of metal oxide molecules that migrate in water and deposit on the substrate surface to form metal oxide nanostructures (MONSTRs). The morphological and crystallographic analyses of the source-metals and substrates revealed the presence of uniformly crystalline ZnO nanorods after the HWD. In addition, the growth mechanism of ZnO nanowires using HWD is discussed. This process is simple, inexpensive, low temperature, scalable, and eco-friendly. Moreover, HWD can be used to deposit a large variety of MONSTRs on almost any type of substrate material or geometry.

Enhancing the antibacterial efficacy of aluminum foil by nanostructuring its surface using hot water treatment.

Bacterial biofilm has become one of the most frequent health problems as it contributes to persistent chronic infections. Therefore, it is vital to find alternatives to currently used bactericidal agents to prevent bacterial contamination on surfaces effectively and prevent the biofilms formation. Several metallic materials are well known for their antimicrobial activity; this includes copper, copper alloys, silver, gold, titanium, and zinc. On the other hand, some metals, such as aluminum, do not have noteworthy antimicrobial properties. In this study, we demonstrate that the antibacterial activity of household aluminum foil can be enhanced by nanostructuring the foil's surface by a simple hot water treatment (HWT) process. Cultures ofEscherichia coliandStaphylococcus aureuswere grown on nutrient agar while exposed to the samples of treated and untreated Al foils and left for 24 h. Our results indicate that treated Al foil can more effectively inhibit the bacteria growth compared to the regular untreated Al foil. This enhancement in antibacterial property might be due to a combination of chemical and morphological changes that the cell undergoes once it encounters nanofeatures of HWT-Al foil surface.

Metal oxide nanostructures by a simple hot water treatment.

Surfaces with metal oxide nanostructures have gained considerable interest in applications such as sensors, detectors, energy harvesting cells, and batteries. However, conventional fabrication techniques suffer from challenges that hinder wide and effective applications of such surfaces. Most of the metal oxide nanostructure synthesis methods are costly, complicated, non-scalable, environmentally hazardous, or applicable to only certain few materials. Therefore, it is crucial to develop a simple metal oxide nanostructure fabrication method that can overcome all these limitations and pave the way to the industrial application of such surfaces. Here, we demonstrate that a wide variety of metals can form metal oxide nanostructures on their surfaces after simply interacting with hot water. This method, what we call hot water treatment, offers the ability to grow metal oxide nanostructures on most of the metals in the periodic table, their compounds, or alloys by a one-step, scalable, low-cost, and eco-friendly process. In addition, our findings reveal that a "plugging" mechanism along with surface diffusion is critical in the formation of such nanostructures. This work is believed to be of importance especially for researchers working on the growth of metal oxide nanostructures and their application in functional devices.