Pd Nanoparticles with Twin Structures on F-Doped Graphene for Formic Acid Oxidation

The formic acid oxidation (FAO) on palladium (Pd) particles is relevant with their crystal structures. Here, silicon nanowires are employed as a sacrifice template to grow Pd nanoparticles with various twin structures, including two-fold, three-fold and five-fold ones, as confirmed by the high-resolution TEM image. These nanoparticles are well dispersed on the semi-ionic fluorine (F) ions doped reduced graphene oxides, which have high activity toward FAO due to their appropriate binding energy to intermediates. The as-prepared products show an excellent performance on FAO. The peak current of the optimal product is 0.697 A . mg(Pd)(-1) in 0.1 M HClO4 and 0.5 M HCOOH, which is 2.9 times than that of the commercial Pd/C catalyst. The electrochemical active surface area of the catalyst (0.322 m(2) . mg(-1)) is 3.5 times than that of the commercial Pd/C (0.091 m(2) . mg(-1)). This outstanding performance is due to the twin structure of Pd nanoparticles and the electron-deficient surface caused by the strong electrophilicity of F ions.