In-Situ TEM Observation of E-Beam Irradiation Induced Porous Molybdenum-Oxide Nanowires

Abstract

The Mo5O14-type structure is an important and representative to the MoO-based catalyst in the selective oxidation process. In the petrochemical industries, the MoO-based catalyst has been widely doped with other elements like V, Nb and Te to have distinct properties with high activity, selectivity and conversion efficiency. The specific facet and bonding relationship would affect the catalyst properties and functionality. The catalyst is usually synthesized as nanoparticles, which have random configuration and uniformity. Therefore, we successfully synthesized the single-crystalline Mo5O14 nanowires, which have uniform structure and controllability about diameter and length by CVD process. Besides, nanowire catalyst with nanoporous structure could possess both advantages of nanoparticles and nanowires. Therefore, we aimed at systematically analyzing Mo5O14 nanowires and then fabricating nanoporous structure in nanowires by e-beam irradiation. Utilizing advanced TEM techniques could reveal the overall atomic structure, which have intrinsic tunnel structure and unique periodicity. In addition, the e-beam irradiation on the intrinsic tunnel structure is observed by in-situ TEM. During the e-beam irradiation process, the oxygen atoms would be removed and result in the structure transformation. Using this technology, the irradiation region could be definable and controllable by electron beam size to define the distribution of nanoporous in nanowires. These results would benefit to realizing the catalytic selective oxidation related with Mo5O14-type structure but also fabricating nanoporous nanowires with rapid and convenient methods. Figure 1