In situ anchoring of Co9S8 nanoparticles on N and S co-doped porous carbon tube as bifunctional oxygen electrocatalysts

The development of cost-effective yet highly active and robust bifunctional electrocatalyst for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) has been at the forefront of research into regenerative fuel cells and metal-air batteries. Here we report Co9S8 nanoparticles grown in situ on nitrogen-and sulfur-doped porous carbon (Co9S8/NSPC) as a bifunctional catalyst for OER and ORR using poly(2-aminothiazole) as a novel all-in-one multifunctional precursor. Unexpectedly, Co9S8/NSPC exhibits a low OER overpotential, positive ORR half-wave potential, small potential gap and high durability, thus making it one of the best bifunctional OER and ORR catalysts. This may be attributed to the heteroatom doping, porous structure and synergistic effects of Co9S8 and NSPC, as confirmed by density functional theory calculations. More importantly, as a proof-of-concept application, the air electrode with Co9S8/NSPC9-45 endows the Zn-air battery with a low discharge/charge overpotential and good cycling stability.