In situ manipulation of E-beam irradiation-induced nanopore formation on molybdenum oxide nanowires

Abstract

Abstract The Mo5O14-type structure is representative of the MoO-based catalyst in the selective oxidation process. Single-crystalline Mo5O14 nanowires can be synthesized in a controlled manner by chemical vapor deposition (CVD). A nanowire catalyst with a porous structure combines the advantages of both nanoparticles and nanowires, leading to a substantial increase in the specific surface area. Therefore, we aim to manipulate the e-beam irradiation process on Mo5O14 nanowires to induce the nanoporous structures in selected regions. In situ transmission electron microscopy (TEM) enabled us to visualize the structural transformation through gradual e-beam irradiation. The e-beam irradiation process removes oxygen atoms and renders the internal structure unstable. After the irradiated region is exposed to air, atoms tend to escape to decrease the internal energy. This results in the formation of nanopores because of the irradiation effect. By nanoscale modification method, the irradiated region is controlled by the electron beam size, which determines the nanopore distribution in the selected region. The study is beneficial for increasing the surface area of Mo5O14-type catalysts with variable nanopore densities and for modifying nanomaterials using a convenient method.