Cobalt nanoparticle embedded nitrogen doped carbon/carbon nanotube frameworks derived from a metal organic framework for tri functional ORR, OER and HER electrocatalysis
Developing active and stable electrocatalysts of earth abundant elements towards the oxygen reduction reaction (ORR) oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) still remains a crucial challenge. Herein, a cobalt containing metal organic framework using adenine as a ligand was synthesized and pyrolyzed without any other precursors, forming a cobalt nanoparticle embedded nitrogen doped carbon/carbon nanotube framework (Co@N CNTF) Due to the abundant active sites of homogeneously distributed cobalt nanoparticles within nitrogen doped graphitic layers, the resultant Co@N CNTF catalysts exhibit an efficient and stable electrocatalytic performance as a tri functional catalyst towards the ORR, OER and HER, including a high half wave potential of 0.81 V vs. RHE for the ORR, and a low overpotential at 10 mA cm 2 for the OER (0.35 V) and HER (0.22 V) As a proof of concept, the Co@N CNTF as an OER/HER bifunctional catalyst for full water splitting affords an alkaline electrolyzer with 10 mA cm 2 under a stable voltage of 1.71 V. Moreover, an integrated unit of a water splitting electrolyzer using the Co@N CNTF catalysts, which is powered with a rechargeable Zn air battery using the Co@N CNTF as an ORR/OER bifunctional catalyst on air electrodes, can operate under ambient conditions with high cycling stability, demonstrating the viability and efficiency of the self powered water splitting system.