Designing bifunctional electrocatalytic sites with outstanding activity and durability in one component toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is quite essential for rechargeable Zn-air batteries. Herein, a novel core-shell composition of Co₉S₈/Co embedded multi-channel carbon nanofiber was successfully developed as efficient electrocatalysts for ORR and OER by step pyrolysis. The precursor of polystyrene was degraded while polyacrylonitrile was cross-linked to hexatomic ring during the pro-oxidation process, therefore, endowing the longitudinal and parallel channels along the fibers’ skeleton in the subsequent carbothermal reduction steps, which affords the superhighway for competent mass transmission and outstanding electrochemical specific area. On the other hand, the potent synergistic effect from precision-designed core–shell species of Co₉S₈/Co allows the composite multi-channel carbon fiber excellent ORR/OER bifunctional catalytic activities, with a gap of 0.89 V between the half-wave potential toward ORR and potential of OER at a current density of 10 mA/cm². Additionally, the rechargeable Zn-air batteries were capable of operating steadily over 500 discharging/charging cycles at a constant current density of 5 mA/cm².

中文翻译：

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可控制备嵌入多通道碳纳米纤维的核壳 Co9S8/Co 作为可充电锌空气电池的高效氧电催化剂

设计在一种组分中具有出色活性和耐久性的双功能电催化位点，以实现氧还原反应 (ORR) 和析氧反应 (OER)，这对于可充电锌空气电池来说非常重要。在此，Co ₉ S ₈的新型核壳组成/Co 嵌入多通道碳纳米纤维被成功开发为 ORR 和 OER 的高效电催化剂，通过逐步热解。聚苯乙烯的前驱体在促氧化过程中被降解，而聚丙烯腈交联成六原子环，因此，在随后的碳热还原步骤中沿纤维骨架形成纵向和平行通道，为有效的传质提供了高速公路和优异的电化学比面积。另一方面，精确设计的 Co ₉ S ₈核壳物质的有效协同作用/钴允许复合多通道碳纤维优异的ORR / OER双功能催化剂活性，与半波电位朝向ORR和潜在的OER的0.89之间的V在10毫安/平方厘米的电流密度的间隙²。此外，可充电锌空气电池能够在 5 mA/cm ²的恒定电流密度下稳定运行超过 500 次放电/充电循环。