Efficient anchoring of nanoscale Pd on three-dimensional carbon hybrid as highly active and stable catalyst for electro-oxidation of formic acid

Abstract

The commercialization of fuel cells requires the design and development of novel effective electrocatalysts. Thus, considerable efforts have been directed at the synthesis of supported electrocatalyst particles with an optimum size of <6 nm and controlled shape/size. To date, although most studies have focused on the exploitation of supports facilitating charge/mass transfer and capable of inhibiting catalyst sintering/detachment during the catalytic process, comprehensive and straightforward investigation of the anchoring effect and the stabilization mechanism of complex hybrid supports with tunable electronic properties and tuned morphologies remain challenging. Herein, we prepare nanoscale Pd supported by a three-dimensional hybrid of boron-doped graphene with carbon nitride (Pd/BG-CN). The results show that the mass (2215 mA mg−1) and specific (31.7 mA cm−2) activities of Pd/BG-CN for formic acid oxidation are 2.8- and 2.5-fold higher than those of commercial Pd/C, respectively. This enhanced activity was ascribed to the electronic effect of the BG-CN substrate and the high content of surface metallic Pd0 (55.2 at%). Moreover, identical-location transmission electron microscopy imaging show that the stabilization of Pd particles on BG-CN and the strong anchoring effect of this support reduced the extent of active Pd detachment, whereas the weakening of metal–carbon support interactions in commercial Pd/C resulted in remarkable performance degradation. Theoretical calculations of the intrinsic stabilization mechanism of Pd/BG-CN reveal that BG-CN could efficiently trap Pd atoms, which could accumulate and form Pd clusters at trapping (nucleation) sites.