Sulfur Mismatch Substitution in Layered Double Hydroxides as Efficient Oxygen Electrocatalysts for Flexible Zinc–Air Batteries

摘要

Although layered double hydroxides (LDHs) are extensively investigatedfor oxygen electrocatalysis, their development is hampered by their limitedactive sites and sluggish reaction kinetics. Here, sulfur mismatch substitutionof NiFe-LDH (S-LDH) is demonstrated, which are in-situ deposited onnitrogen-doped graphene (S-LDH/NG). This atomic-level sulfur incorporationleads to the construction of the tailored topological microstructure andthe modulated electronic structure for the improved catalytic activity anddurability of bifunctional electrocatalysts. The combined computational andexperimental results clarify that the electron transfer between the sulfur anionand Fe~(3+) generates the high-valence Fe~(4+) species, while the mismatch substitutionof the sulfur anion induces the metallic conductivity, an increased carrierdensity, and the reduced reaction barrier. Consequently, the as-fabricatedZn-air battery achieves a high power density of 165 mW cm~(?2), a large energydensity of 772 Wh kg_(Zn)~(?1) at 5 mA cm~(?2), and long cycle stability for 120 h,demonstrating its real-life operation.