Supplementary Information Formation of oxygen radical sites on MoVNbTeOx by cooperative electron redistribution Yuanyuan Zhu,* Peter V. Sushko, Daniel Melzer, Eric Jensen, Libor Kovarik, Colin Ophus, Maricruz Sanchez-Sanchez, Johannes A. Lercher* and Nigel D. Browning* Table of contents 1. Synthesis of M1 catalyst, elemental composition and morphology characterization ..... 2 2. Environmental scanning transmission electron microscopy ........................................... 2 2.1 Low-angle annular dark field (LAADF) STEM mode and strain contrast .......... 3 2.2 Critical electron dose for the M1 sample and low-dose STEM acquisition ........ 4 3. ESTEM images (raw) of M1 catalysts ............................................................................ 6 4. Measurement of M1 particle thickness ........................................................................... 7 5. Statistical intensity profiling of the M1 active center “diamond” .................................. 8 6. STEM image simulation and Te depletion rate ............................................................ 11 7. Overall M1 crystal structure before and after heating in ethane ................................... 13 8. Density functional theory simulations .......................................................................... 14 9. Catalytic activity of M1 in oxidative dehydrogenation of ethane................................. 16