Highly dispersed Co nanoparticles confined by mesopore-rich N-doped hollow carbon nanotubes for efficient oxygen reduction reaction and Zn-air battery

Oxygen reduction reaction (ORR) is an important reaction process in Zn-air batteries, and the catalyst plays a crucial role as the cathode in the system. However, the reported catalysts often exhibit poor durability and stability in the operation of air batteries. Here, we used g-C3N4 as a precursor to mix Co nanoparticles for carbonization, and synthesized a large number of carbon nanotubes (CNTs) interwoven cluster catalysts, namely Co/CNT-800. The obtained catalyst has a rolling grass like morphology, forming a highly conductive network, which helps to improve the electron transfer ability in the ORR process. At the same time, the influence of materials at different carbonization temperatures on the ORR of Zn-air batteries was studied. In alkaline media, Co/CNT-800 showed the high ORR performance, with a half-wave potential of 0.839 V (vs. RHE, Pt/C 0.845 V). After 5000 cycles, the E1/2 of the Co/CNT-800 catalyst only decreased by 9 mV, and its performance in stability tests and methanol tolerance tests was superior to Pt/C. When Co/CNT-800 catalyst is used as the air cathode for Zn-air batteries, it exhibits an excellent specific capacity of 709.2 mAh/g and a power density of 142.2 mW cm- 2. This research achievement provides valuable insights for the development of high-performance Zn-air batteries and innovative guidance for the design of ORR catalysts.