Two-Dimensional Cobalt Sulfide/Iron–Nitrogen–Carbon Holey Sheets with Improved Durability for Oxygen Electrocatalysis

Abstract

Transition-metal sulfide as a promising bifunctional oxygen electrocatalyst alternative to scarce platinum-group metals has attracted much attention, but it suffers activity loss over time owing to poor structural/compositional stability during catalysis. Herein, we report a self-template method for preparing a two-dimensional cobalt sulfide holey sheet superstructure with hierarchical porosity followed by the encapsulation of thin iron–nitrogen–carbon as a protective layer. The iron–nitrogen–carbon layer to some degree precludes the phase transition of cobalt sulfide underneath and preserves the structural integrity during catalysis, therefore rendering an exceptional durability in terms of no obvious activity loss after 10,000 cycles of the accelerated durability test. It also noticeably enhances the intrinsic activity of cobalt sulfide and does not influence its exposure into the electrolyte, resulting in showing an extraordinary electrochemical performance in terms of a potential difference of 0.69 V for the overall oxygen redox. A rechargeable zinc-air battery assembled by a cobalt sulfide/iron–nitrogen–carbon air cathode delivers approximately 4.2 times higher power density than that without an iron–nitrogen–carbon layer and stably operates for 300 h with a high voltaic efficiency. This work gives a facile and effective strategy for improving the long-term durability of transition-metal sulfide electrocatalysts.

Understanding Advanced Transition Metal‐Based Two Electron Oxygen Reduction Electrocatalysts from the Perspective of Phase Engineering

“…In fact, exerting the composition tuning of the first CS, including altering the type and amounts of the non‐metallic atoms, the abovementioned phenomenon has been also widely observed in other TM‐based atomic‐site catalysts for 2e − ORR beyond the Co‐based ones, [ 19,100,206,209,216 − 219 ] i.e., the interaction with the ORR intermediates was finely modified to favor a 2e − ORR process, probably resulting from the charge polarization between the non‐metallic atoms in the first CS and the central TM atoms. The corresponding representative cases include the Fe‐C‐O motif where O replaces the N atoms within the typical 4e − ORR‐favorable Fe‐C‐N type coordination, [ 209 ] the unique terdentate configuration of W 1 N 1 O 2 motif where the central W atom was coordinated with two O atoms and one N atom, [ 110 ] as well as the super‐coordinated N 4 Ni 1 O 2 unit consisting the single Ni atom with surrounding four N and two O atoms.…”

Synthesis and Electrocatalytic Applications of Layer‐Structured Metal Chalcogenides Composites

“…In particular, the fabricated MoS 2 /Fe 2 O 3 presented a good electrochemical performance of 612 mAh g −1 under the current density of 5 A g −1 , which is higher than MoS 2 /MnO, MoS 2 /CoO, and MoS 2 /NiO composites, respectively. In addition, the CoS 2 /MoS 2 /NiS 2 composites, [ 177 ] MoS 2 /NiS 2 heterostructures, [ 178 ] Cu/Co/CoS 2 /S,N‐doped carbon composites, [ 179 ] Co 9 S 8 /Fe─N─C composites, [ 180 ] and 1T‐MoTe 2 [ 181 ] have also been synthesized as active materials for ORR.…”

Bifunctional 2D structured catalysts for air electrodes in rechargeable metal-air batteries

“…To enhance the reactive surface area, many structures have been developed to promote the exposure of active sites. For instance, Cheng et al synthesized carbon cloth-supported cobalt phosphide (CoP@CC) by in situ thermal phosphorylation [52] . As illustrated in Figure 7A, the crisscrossing sheets promote mass transfer between reactants and intermediates, thus avoiding aggregation of the CoP nanosheets that provide the active sites.…”