Entropy-driven design of non-metallic heteroatoms codoped hollow carbon nanocages for superior oxygen...

The design of functional materials with increasing entropy has become a hot field in recent years. Motivated by the traditional concept of high entropy (HE), the anionic doping with multiple heteroelements towards increasing entropy has been considered to be a new clue to design highly efficient catalysts. In present work, we report the design of a non-metallic anion high-entropy (AHE) codoped hollow carbon nanocage as an oxygen catalyst for Zn-air batteries (ZAB). A series of non-metallic heteroatoms, including nitrogen (N), phosphorus (P), sulfur (S), boron (B), and fluorin (F), are employed as anionic dopants to construct the AHE codoped carbon nanocages. The influences of AHE engineering on the electrocatalytic behaviors of the hollow carbon nanocages in the oxygen reactions are explored. Through synergistic modulations on anionic doping engineering and structure design, the AHE doped hollow carbon nanocages achieve the superior oxygen reduction reaction (ORR) activities and faster kinetics in comparison to the counterparts of anionic medium-entropy (AME, e. g. N, P, S, B), anionic low-entropy (ALE, e. g. N, P, S, or N, P/S, or N) doped and undoped samples. Density functional theory (DFT) calculations reveal that the AHE engineering regulates the electronic structure, adjust the energy barrier, and modulate oxygen intermediates adsorption capability, which synergistically accelerate the ORR behaviors. In addition, the full ZAB battery integrated with the AHE codoped hollow carbon nanocages cathode delivers the high power density (212.1 W kg^-1) and long cycle life (500 h cycling). More impressively, the solid-state ZAB with the hydrogel electrolyte and AHE doped carbon nanocage cathode shows the good flexibility and high adaptation in a wide temperature range. Therefore, this work not only introduces a synergistic modulation strategy to optimize the anion high-entropy catalysts for oxygen catalysis, but also promotes the fast development of high-performance ZAB towards different working conditions.