Formation of one-dimensional oxide nanostructures by intermediate deposition of noble metals

2022

Авіаційно-космічна техніка та технологія, Vol 0, Iss 2, Pp 21-30 (2022)

A method for forming the geometry of one-dimensional nanostructures (nanowires) of copper oxide is proposed, which allows for a significant increase in the ratio of their length to diameter, which is critical for certain practical applications. The essence of the method is that after reaching the saturation regime of the dependence of the length of the nanowire on the time of its growth, the stage of deposition of precious metal (gold) is realized, the nanoparticles of which are fixed on the side surface of the nanowire. In the saturation mode, the entire flow of copper atoms moving from the root to the top of the nanowire reacts on the side surface of the nanowire due to collisions with oxygen molecules adsorbed by this surface. But the presence of a metal that does not react with oxygen significantly reduces the concentration of the latter on the side surface of the nanowire. The presence of a noble metal, which covers most of the nanowire, significantly reduces the intensity of the oxidation reaction of copper on the side of the nanowire, thus lengthening the diffusion path of copper from root to tip of the nanowire, thereby increasing its length. Therefore, after the stage of intermediate deposition, the growth process of the nanowires is restored. The process of intermediate deposition of unreacted metal can be applied more than once, which allows for flexible control of the process of nanowire formation. From the viewpoint of the general productivity of the process, it is critical to use plasma to implement the process of nanowire growth because it is the processes in the plasma environment that are characterized by the rapid achievement of the saturation mode of time dependence, which is proven experimentally. As a result, the overall productivity of the combined process using the intermediate deposition of the noble metal can be accelerated up to five times compared to the currently common thermal growth processes. Calculations using a modified mathematical model of growth of one-dimensional nanostructures of copper oxide in a thermal reactor, which is used to predict growth in plasma under atmospheric pressure (radiofrequency, capacitive, etc.), where conditions are similar to thermal growth. The method is general and can be applied to other growth processes that depend on the reactions on the surfaces of nanostructures.

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National Aerospace University «Kharkiv Aviation Institute», 2022.

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