Theoretical Insights into the Initial Hydrolytic Breakdown of HKUST-1

HKUST-1, i.e. Cu3(BTC)2 (BTC = benzene-1,3,5-tricarboxylate), has been considered as one of very promising copper-paddlewheel-based metal-organic frameworks (CP-MOFs) for a variety of practical applications such as gas separation and heterogeneous catalysis. The poor hydrolytic stability of HKUST-1 in the humid condition, especially in aqueous environment, however, severely hinders its practical applications. Understanding the hydrolytic mechanism of HKUST-1 is crucial in the improvement of the hydrolytic stability. In the present work, the hydrolytic breakdown mechanism of a Cu-Cu metal node at HKUST-1 in the presence of water molecules were investigated using density functional theory (DFT) calculations and ab initio molecular dynamics (AIMD) simulations. AIMD simulation trajectories show that the presence of water molecules induces pronounced oscillations of all Cu-O bonds at the Cu-Cu node, leading to the precursor state for the initial Cu-O bond-breaking. The hydrolytic breakdown mechanism that invol...