Porous layered cobalt nanocrystal/nitrogen-doped carbon composites as efficient and CO-resistant electrocatalysts for methanol oxidation reaction

Abstract

The development of active, stable and poison-resistant electrocatalysts for methanol oxidation reaction (MOR) has become a key challenge to improve the performance of direct methanol fuel cells (DMFCs). Herein, we report a simple strategy to prepare cobalt nanoscrystal/nitrogen-doped carbon (Co/N-C) composites as efficient and carbon monoxide (CO) resistant electrocatalysts for MOR. The Co/N-C composites are synthesized by the pyrolysis of porous CoCl2-polyaniline hydrogels. While CoCl2 is reduced to Co nanocrystals as active electrocatalyst for MOR, the polyaniline hydrogel is pyrolyzed to porous layered N-doped carbon that immobilize and protect Co nanocrystals, and also facilitate the mass and charge transfer through the electrolyte and electrode. After systematically exploring the preparation conditions of Co/N-C composites, we have found the optimal Co/N-C-1-500 (pyrolyzed at 500 °C) can achieve a high current density of 231 mA∙cm−2 at 0.8 V vs SCE for MOR in alkaline media. Meanwhile, the Co/N-C-1-500 catalyst presents a good durability and a high resistance to CO poisoning (93.5% retention of MOR activity), superior to the performance of Pt/C catalysts. With its high activity, good stability and superior resistance to CO poisoning, Co/N-C-1-500 is promising as a low-cost and efficient anode catalyst for DMFCs.