The nitridation of ZnO nanowires

Abstract

ZnO nanowires (NWs) with diameters of 50 to 250 nm and lengths of several micrometres have been grown by reactive vapour transport via the reaction of Zn with oxygen on 1 nm Au/Si(001) at 550°C under an inert flow of Ar. These exhibited clear peaks in the X-ray diffraction corresponding to the hexagonal wurtzite crystal structure of ZnO and a photoluminescence spectrum with a peak at 3.3 eV corresponding to band edge emission close to 3.2 eV determined from the abrupt onset in the absorption-transmission through ZnO NWs grown on 0.5 nm Au/quartz. We find that the post growth nitridation of ZnO NWs under a steady flow of NH3 at temperatures ≤600°C promotes the formation of a ZnO/Zn3N2 core-shell structure as suggested by the suppression of the peaks related to ZnO and the emergence of new ones corresponding to the cubic crystal structure of Zn3N2 while maintaining their integrity. Higher temperatures lead to the complete elimination of the ZnO NWs. We discuss the effect of nitridation time, flow of NH3, ramp rate and hydrogen on the conversion and propose a mechanism for the nitridation.

Facile Synthesis of Ultrathin ZnO Nanotubes with Well-Organized Hexagonal Nanowalls and Sealed Layouts: Applications for Lithium Ion Battery Anodes

“…These results are distinct from those achieved through the NH 3 etching process, emphasizing the surface passivation effect of the Zn 3 N 2 layer formed on the NH 3 treatment that prevents etching from the outside. 24 Second, to investigate the role the seed layer plays in initiating etching, we introduced a wellorganized ZnO hexagonal rod array grown on epitaxial seed layer and performed a time-resolved analysis on the morphology evolution at the initial etching stage (Figure S4 of the Supporting Information). 25 In this case, the seed layer became rough and porous, which was followed by etching from the rod bottom.…”

Zn3N2 nanowires: growth, properties and oxidation

“…Recently, we carried out a systematic investigation of the post-growth nitridation of ZnO NWs and the changes that occurred in the crystal structure using moderate flows of NH 3 and temperatures ≤600°C. These favour the formation of ZnO/Zn 3 N 2 core-shell NWs since we were able to observe not only the suppression of the XRD peaks related to ZnO but also the emergence of new ones corresponding to the cubic crystal structure of Zn 3 N 2 [16]. Higher temperatures, flows of NH 3 or the inclusion of H 2 did not lead to the complete conversion of ZnO into Zn 3 N 2 NWs, instead led to the complete elimination of the ZnO NWs.…”

Green and efficient synthesis of novel bispyrazoles through a tandem Knoevenagel and Michael type reaction using nanowire zinc oxide as a powerful and recyclable catalyst

“…ZnO nanowires exhibited prominent (100), (002), and (101) peaks corresponding to a ZnO wurtzite structure. 31…”