Preparation of single-crystalline zinc nitride dandelion-like nanostructures: Their photoluminescence and hydrogen-absorption properties

We report zinc nitride dandelion-like nanostructures with single crystalline character prepared by catalystassisted CVD route via heating zinc powder at 600 °C for 240 minutes under NH₃ gas flow inside horizontal tube furnace. Zinc nitride dandelion-like nanostructures (ZNDNSs) with average size of 30-40 μm consist of a large bundle of nanowires having 40-45 nm diameter emerging out of a single concurrent point. ZNDNSs were obtained on Ni coated silicon substrates placed at 3-4 mm over the source material. The structural, compositional and morphological characterizations of the as-obtained product were performed by XRD, EDS, SEM, TEM, HRTEM and SAED. Room temperature photoluminescence (PL) spectrum of zinc nitride nanostructures exhibited UV emission band at 372 nm and defect related feeble orange emissions at 664 and 703 nm. The investigations on hydrogen-absorption characteristics of ZNDNSs were performed at three different temperatures (373 K, 473 K, and 573 K). A maximum absorption capacity of about 2.17 wt% was observed at 573 K. A growth mechanism proposed for the formation of ZNDNSs is also discussed briefly.