The role of mass transport for bubble generation reaction as formic acid (FA) dehydrogenation has been overlooked for a long time that the turnover frequency (TOF) values of the majority of the catalysts are limited to less than 1000 h−1. Here, we proposed a design principle of efficient catalyst for this type of reaction that the synergism of highly active catalytic components and developed porous structure of the support required for effective mass transport is indispensable. Based on this cognition, well-dispersed and ultrasmall PdAu alloy nanoparticles (∼2 nm) supported in amine-functionalized hierarchically porous carbon (HPC-NH2) have been prepared via an impregnation-reduction method. Notably, owing to the electronic effect of the PdAu alloy clusters and the introduced basic amine sites, as well as the hierarchically porous structure of the support, the optimal Pd60Au40/HPC-NH2 catalyst exhibits a TOF value up to 3763 h−1 at room temperature and 29,210 h−1 at 323 K.