Atomic layer deposition of ZnO on ultralow-density nanoporous silica aerogel monoliths

摘要

We report on atomic layer deposition of an ～2-nm-thick ZnO layer on the inner surface of ultralow-density (～0.5% of the full density) nanoporous silica aerogel monoliths with an extremely large effective aspect ratio of ～ 10~5 (defined as the ratio of the monolith thickness to the average pore size). The resultant monoliths are formed by amorphous-SiO_2 core/wurtzite-ZnO shell nanoparticles which are randomly oriented and interconnected into an open-cell network with an apparent density of ～3% and a surface area of ～100 m~2 g~(-1). Secondary ion mass spectrometry and high-resolution transmission electron microscopy imaging reveal excellent uniformity and crystallinity of ZnO coating. Oxygen K-edge and Zn L_3-edge soft x-ray absorption near-edge structure spectroscopy shows broadened O p- as well as Zn s- and d-projected densities of states in the conduction band.