Mechanistic Analysis-Guided Pd-Based Catalysts for Efficient Hydrogen Production from Formic Acid Dehydrogenation

摘要

Heterogeneous catalysis of formic acid dehydrogenation at room temperature is a promising tactic for safely storing and producing H-2 as an efficient energy carrier. Up to now, the catalysts for this purpose are largely developed based on trial and error. In this work, we demonstrate that a careful analysis of the formic acid dehydrogenation mechanism can shed light on rational design and facile synthesis of efficient Pd-based catalysts, that is, carbon black-supported fine Pd nanoparticles with adatoms of an sp metal (including but not limited to Bi). In fact, Pd@Bi/C with an optimal atomic ratio doubles the Pd mass activity of the Pd/C in terms of hydrogen production rate, specifically with a global turnover frequency of 4350 h(-1) at 303 K in a mixed 1.1 M formic acid and 2.4 M sodium formate solution without engineering the catalyst support. Apparent kinetic measurement, in situ interfacial IR spectroscopy, and density functional theory calculation results further confirm that Bi adatoms favor the adsorption of the formate intermediate to facilitate the C-H bond cleavage and weaken the adsorption of H and CO on Pd sites, resulting in a prominently enhanced H-2 production performance.