Facile synthesis of N-doped porous carbon encapsulated bimetallic PdCo as a highly active and durable electrocatalyst for oxygen reduction and ethanol oxidation
The development of high performance non-platinum electrocatalysts is highly desirable for the commercialization of fuel cells. Herein, we present a facile and effective strategy for the synthesis of ultrafine PdCo bimetallic nanoparticles (NPs, diameter ≈ 4.1 nm) encapsulated in N-doped porous carbon nanocapsules (PdCo@NPNCs) by a one-pot PdCl42− and Co2+-mediated polymerization of dopamine on SiO2 nanospheres, followed by carbonization and chemical etching. The N-doped porous carbon shell that is formed in situ from a dopamine coating could effectively prevent the coalescence of NPs during the carbonization process. Also the carbon shell protects the NPs from detachment and agglomeration as well as dissolution during fuel cell operation. Benefiting from the synergistic effect from their unique structures and chemical compositions, the optimized PdCo@NPNCs exhibit better electrocatalytic activity and enhanced durability for the oxygen reduction reaction (ORR) and ethanol oxidation reaction (EOR) in alkaline solution than those of commercial Pt/C (20 wt%) and Pd/C (10 wt%) catalysts, even though the content of PdCo is as low as 3.68 wt%. Furthermore, the synthetic method described here can be generalized to other bimetallic NPs confined in NPNCs that can be used in a broad range of applications such as catalysis, environmental protection, drug delivery, chemical and biological sensing, and so forth.