Prebridge Technique to Incorporate Transition Metal to Metal-Organic Frameworks for the Purposes of Catalysis and Hydrogen Storage Via Spillover Effect

Metal-organic frameworks, high surface area materials with the characteristics of adjustable structure and surface chemistry, are becoming promising candidates for hydrogen storage, gas separation, and catalyst supports.  In this paper, we explore MOF stability after various catalytic doping methods for IRMOF-8, Cu-BTC, and Cu-TDPAT.  After identifying a catalytic doping technique that maximizes stability and retains the surface area of the MOF precursor, we measure hydrogen isotherms at 300K up to 80 bar, and demonstrate catalyst addition significantly increases hydrogen storage via the hydrogen spillover effect.  Adsorption enhancement is most pronounced at low pressure, and kinetic limitations and MOF instability effects inhibit high-pressure adsorption via the spillover effect.  Novel hydrogen chemisorption sites are identified using spectroscopic techniques, for both undoped and doped MOFs.  An improved mechanistic understanding of the hydrogen spillover effect is developed by tracking of hydrogenation of N groups via spectroscopy, density functional theory, and comparison of defected versus pristine MOF structures.  Implications for hydrogen storage and use of MOFs as a catalyst support are discussed.