In search of the limits of CuO thermal oxidation nanowire growth by combining experiment and theory

In the present study, we report on the temperature limiting conditions for the growth of copper oxide nanowires via thermal oxidation of copper, which have been puzzling scientists for decades and were up until now unknown. We explore the lowest temperature limits for nanowire synthesis and find the lowest nanowire diameter that can be achieved via thermal oxidation. This was achieved by gradually lowering the temperature of the oxidation and observing when the nanowire growth will cease with the use of electron microscopy techniques. The lowest temperature, where the growth of nanowires was observed, corresponded to 187 ± 5 °C, and the lowest nanowire diameter which can be achieved was found to be between 3 and 4 nm. Experimental results are supported by theoretical modeling of the nanowire nucleation processes, providing deterministic aspects. The nanowire limiting diameter is governed by the temperature dependence of the critical nucleus size.