Plate-column-like graphene/carbon nanotube hybrid encapsulated with cobalt nanoparticles: A highly effective bifunctional catalyst for zinc-air batteries with ultra-long durability

The regulation of surface microenvironment and the construction of stable structure are crucial for the development of highly active and durable bifunctional oxygen catalysts for rechargeable zinc-air batteries (RZABs). This study pioneered a scalable strategy based on high-temperature pyrolytic in situ nitridation of ultrathin amorphous cobalt hydroxide nanosheets for the construction of cobalt nanoparticle-encapsulated plate-like columnar graphene/carbon nanotube hybrids (Co/NCNTs-NrGO). Brunauer-Emmett-Teller (BET) result reveals a 1.7-fold enhancement in specific surface area compared to conventional Co-rGO. This multiscale architecture synergistically optimizes mass/charge transfer dynamics while exposing high-density oxygen-redox active sites, exhibiting exceptional bifunctional activity with an OER potential of 1.578 V at 10 mA cm^-2 and an ORR E_1/2 of 0.806 V. The resulting performance is comparable to the Pt/C+RuO₂. Moreover, the Co/NCNTs-NrGO-based RZAB demonstrate a remarkable open-circuit voltage of 1.51 V and unparalleled operational stability, achieving approximately 1600 h of continuous performance. These advancements represent an 83.3 % increase in power density and a 272 % enhancement in cycle life compared to Pt/C+RuO₂-based RZAB. This study paves the way for the development of durable, economically scalable catalysts, effectively bridging the gap between laboratory breakthroughs and the large-scale industrial deployment of RZABs.