Controllable Fabrication of Core‐Shell Co₉S₈/Co Embedded on Multi‐Channel Carbon Nanofibers as Efficient Oxygen Electrocatalysts for Rechargeable Zn‐air Batteries

Abstract

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.

Metal–Organic Frameworks-Derived FeS–Co9S8/NCA Porous Aerogel Electrocatalyst as a High-Performance Cathode for Zinc–Air Batteries

“…As shown in Figure b, the peaks around 162.01 and 164.02 eV are parallel to the typical Co–S and C–S–C bonds, respectively. Besides, the peaks at 167.9 eV are ascribed to the characteristic peaks of the sulfur oxides, owing to the modest oxidation of FeS–Co 9 S 8 /NCA . The deconvolution plots of C 1s are implied in Figure c.…”

“…Besides, the peaks at 167.9 eV are ascribed to the characteristic peaks of the sulfur oxides, owing to the modest oxidation of FeS−Co 9 S 8 / NCA. 36 The deconvolution plots of C 1s are implied in Figure 2c The high-resolution N 1s XPS spectrum (Figure 2d) was deconvolved into components centered at 399, 400.1, and 401.3 eV, amounting to pyridinic N, pyrrolic N, and graphitic N, respectively. 39 Thereinto, more graphitic N enables higher electrical conductivity.…”

Electrospinning-derived transition metal/carbon nanofiber composites as electrocatalysts for Zn-air batteries

“…44 Beyond the coaxial method, the core-shell architecture of TM/CNFs can be realized through the indirect method. 48 Metallic compounds are in situ grown on NFs, and subsequent pyrolysis induces the formation of a core-shell structure, with a metallic layer as the shell and CNFs as the core. This strategy affords robust controllability in manipulating the metal layer's structure on the fibre surface, thereby regulating the specific morphology of the core-shell structure.…”