posted on 2020-03-11, 19:50authored byXianxian Qin, Hong Li, Songhai Xie, Kai Li, Tianwen Jiang, Xian-Yin Ma, Kun Jiang, Qing Zhang, Osamu Terasaki, Zhijian Wu, Wen-Bin Cai
Heterogeneous catalysis of formic acid dehydrogenation at room
temperature is a promising tactic for safely storing and producing
H2 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 H2 production performance.