Poplar-Catkin-Derived N, P Co-doped Carbon Microtubes as Efficient Oxygen Electrocatalysts for Zn-Air Batteries

In this study, poplar-catkin-derived N, P co-doped carbon microtube catalysts with highly active sites and a large accessible surface area exhibit desirable oxygen reduction reaction (ORR) activity in an alkaline solution and excellent applications in Zn-air batteries (ZABs). In particular, the catalytic activity of the N, P co-doped carbon microtubes toward the ORR is as good as that of benchmark Pt/C, albeit better in terms of tolerance and stability. Furthermore, a ZAB fabricated using the as-developed catalyst exhibits a specific capacity of 649mAhg(Zn)(-1) and a peak power density of 125mWcm(-2); these values are comparable to those of Pt/C catalysts (644mAhg(Zn)(-1) and 130mWcm(-2), respectively), indicative of the promising applications for sustainable energy storage. In addition, an alkaline water-splitting cell powered by this assembled ZAB can generate H-2 gas in a stable manner under ambient conditions. The successful conversion of considerable catkin sources to high-value carbon materials will provide insights into the future development of other high-performance electrocatalysts from abundant green bio-waste.