Fig. 5. Hypothesized mode of action for the reaction between nitrous acid and UiO-66-NH2. (a) The reaction of gas-phase nitrous acid with –OH group on Zr-based node producing the nitrosonium cation and water. (b) The formation of the diazonium intermediate with concomitant loss of water. (c) The diazonium intermediate reacting with water producing UiO-66-OH with nitrogen gas as a benign reaction byproduct.
