Autocatalytic Surface Explosion Chemistry Of 2d Metal-Organic Frameworks

Metal-organic frameworks are a combination of inorganic constituents and organic ligands with a high degree of variability which are, as coordination compounds in homogeneous catalysis, potentially highly selective heterogeneous catalysts. The synthesis and thermal stability of monolayer thin Cu-, Ni-, and Fe-squarate 2D MOFs are studied using X-ray photoelectron spectroscopy, scanning tunneling microscopy, and temperature-programmed reaction spectroscopy on a Cu(100) surface in ultrahigh vacuum. Highly ordered 2D squarate MOFs are obtained by mild annealing of squarate multilayers. Upon annealing at higher temperatures, the Ni- and Fe-squarate layers undergo autocatalytic surface explosion chemistry with carbon monoxide as a desorbing product in a very narrow temperature interval. Despite the different stabilities of Ni- and Fe-based MOFs, mixed {Ni + Fe}-MOFs also decompose in a narrow single temperature interval. Such autocatalytic behavior is explained by a numerical model which-unlike rate equation-based kinetics-explicitly considers the chemical nature of nearest neighbors.