The emerging single-atom field spans single-atom catalysis in chemistry and single-atom manipulation in physics up to the state-of-the-art characterization via imaging and spectroscopy. These interdisciplinary progresses have been interacted closely with the development of materials science, underscoring the principle that the single atom excels as the smallest functional material. This simple concept not only permits to reinvent our understanding of the nature of materials, but also promises unambiguously to have a great impact on other physical sciences.

The complex (Mo,V)-based multicomponent M1 phase with a characteristic network of pentagonal, hexagonal, and heptagonal channels is the key catalyst for the catalytic oxidation from propane to acrylic acid. Herein, the atomic-scale structural dynamics in the orthorhombic Mo-V-Te-Nb oxide were probed under electron-beam stimulation. The recorded in situ scanning transmission electron microscopy images unravel the strong bonding and correlation between the (Mo,V)O₆ octahedra and the central Nb moieties in the pentagonal channels. Such dynamic electron microscopy imaging can pave the way to chemically tailoring structural units of a general catalogue of functional polyoxometalates through applying top-down electron-beam probing.