Key Role of Anionic Doping for H2 Production from Formic Acid onPd(111)

Hydrogen evolution by the catalytic decomposition of formic acid in solution is a key reaction for hydrogen storage for which palladium is one of the most efficient catalysts. Based on density functional theory (DFT) computations, we explain why the presence of an anionic promoter renders palladium more active and more selective for formic acid dehydrogenation. The promotion is well-captured by modeling the anion by a negatively charged surface. This.promotional effect can be traced back to the modulation of the electric field at the catalyst surface, with a strongly contrasted action on the energy of the various species along the competing pathways through the electrostatic interaction between the electric field and the surface dipole moment. As a result, both the reaction kinetics and selectivity are markedly improved. This opens the door to a rational design of catalytic systems using promoters..

溶液中甲酸催化分解制氢是储氢的关键反应，钯是其中最有效的催化剂之一。基于密度泛函理论（DFT）计算，我们解释了为什么阴离子促进剂的存在会使钯对甲酸脱氢反应更具活性且更具选择性。通过用带负电的表面对阴离子进行建模，可以很好地理解这种促进作用。这种促进效应可追溯到催化剂表面电场的调节，通过电场与表面偶极矩之间的静电相互作用，对竞争途径中各种物质的能量产生强烈对比的作用。结果，反应动力学和选择性都显著提高。这为使用促进剂合理设计催化体系打开了大门。