LAUSR

Abstract Catalytic Ru- or Fe-complexes bearing two ligands L1, L2, where L1 = phosphine and L2 = Schiff-base ligand, present remarkable H2 production efficiency from Formic Acid (FA) than their single-ligand counterparts. The optimum L1RuL2 and L1FeL2 catalysts were obtained using a phosphine = P(CH2CH2PPh2)3 (or PP3) as L1 and a Schiff-base ligand (abbreviated Lγ herein) as L2, while the using of amino functionalized nanoparticle H2N@SiO2 as cocatalyst further promotes the H2 production efficiency. In long term stability experiments [RuPP3Lγ]/H2N@SiO2 and [FePP3Lγ]/H2N@SiO2 achieve a total TONs >17,367 and >29,372 respectively without deactivation. Thermodynamic and spectroscopic data reveal a common catalytic mechanism for both Fe and Ru based systems, involving synergism between L1, L2 in order to promote the rate-limiting steps. The present work is the first example of “double-ligand catalyst” concept as a novel route for high-efficiency, HCOOH dehydrogenation catalysts, which can be operative for either noble-metal or earth-abundant metals.