Cobalt Sulfide Nanowires Core Encapsulated by a N, S Codoped Graphitic Carbon Shell for Efficient Oxygen Reduction Reaction

Abstract

Exploration of economical electrocatalysts for highly efficient and stable oxygen reduction reaction (ORR) is believed to be essential for diverse future renewable energy applications. Herein, cobalt sulfide nanowire core encapsulated in a N, S codoped graphitic carbon shell (CoS NWs@NSC) is successfully fabricated via the calcination of polydopamine-coated Co(CO ) (OH) H O NWs with sulfur powder under argon atmosphere. The uniform encapsulation of CoS core by N, S codoped graphitic carbon shell favors the interaction of the core-shell structure for generating stable and numerous ORR active sites homogeneously dispersed throughout the materials. Meanwhile, the wire-like CoS NWs@NSC stacks to form 3D mesoporous conductive networks, which improves the mass and charge transport capability of catalyst. Accordingly, the resultant CoS NWs@NSC electrocatalysts possess excellent ORR activity through the four-electron pathway with superior stability and methanol tolerance over the Pt/C in 0.1 m KOH. This strategy can offer inspiration for designing and fabricating novel core-shell-structured nanomaterials with active sites derived from uniform morphology as potential electrocatalysts for various vital renewable energy devices.

Simultaneously Integrating Single Atomic Cobalt Sites and Co9S8 Nanoparticles into Hollow Carbon Nanotubes as Trifunctional Electrocatalysts for Zn–Air Batteries to Drive Water Splitting

“…The deconvoluted S 2p spectra ( Figure S15a, Supporting Information) of CoSA + Co 9 S 8 /HCNT displays peaks of CoS at 161.9 and 162.8 eV, corresponding to S 2p 3/2 and S 2p 1/2 , respectively. [42] The high-resolution Co 2p spectra ( Figure S16a, Supporting Information) can be deconvoluted into Co 2p 3/2 (782.4 and 778.8 eV) and Co 2p 1/2 (793.8 and 798.5 eV), confirming the formation of Co 9 S 8 . [38] The X-ray absorption fine structure (XAFS) measurements were further conducted to confirm the coordination geometry of CoSA + Co 9 S 8 /HCNT.…”

“…The high-resolution C 1s spectra of CoSA + Co 9 S 8 /HCNT ( Figure S13a, Supporting Information) contain four peaks assigned to C  O (286.6 eV), CN (285.4 eV), CC (284.8 eV), and CS (283.9 eV). [42] The N 1s spectrum was deconvoluted into five peaks at 404, 401.2, 400.1, 399.2, and 398.4 eV, corresponding to the oxidized N, graphitic N, pyrrolic N, Co-N, and pyridinic N, respectively ( Figure S14a, Supporting Information). [43] Co-N, pyridinic N, and graphitic N are usually considered as important species for ORR/OER/ HER.…”

Fe/Fe3C Nanoparticles Encapsulated in N‐Doped Hollow Carbon Spheres as Efficient Electrocatalysts for the Oxygen Reduction Reaction over a Wide pH Range

“…The catalytic kinetics of the resulting Fe/Fe 3 C/NHCS were further investigated by the Tafel slope derived from the polarization curves. As shown in Figure E, the mass‐transfer‐corrected Tafel slope of Fe/Fe 3 C/NHCS was calculated to be 68 mV dec −1 , comparable to that of commercial Pt/C (65 mV dec −1 ), indicating that the ORR on the resulting Fe and N co‐doped hollow carbon material possesses more favorable kinetics . By comparison, the more positive onset potential and lower Tafel slope make the obtained Fe/Fe 3 C/NHCS a good catalyst compared with other heteroatom‐doped nonprecious metal ORR catalysts reported previously (Figure F and Table S1 in the Supporting Information).…”

One‐dimensional and two‐dimensional synergized nanostructures for high‐performing energy storage and conversion

“…The interaction derived from the core and shell materials guaranteed that abundant ORR active sites uniformly dispersed through the carbon matrix; the 1D‐2D synergized network could promote the electron transfer, ORR relevant species transport and active sites exposure; and the graphitic carbon shell can protect the active sites from the degeneration during ORR process. Accordingly, the resultant CoS NWs@NSC electrocatalysts possessed excellent ORR activity through the four‐electron pathway with superior stability and methanol tolerance over the Pt/C in 0.1 M KOH . Likewise, a core‐shell structured catalyst composed of AgNW core and a NG or nitrogen‐doped carbon shell were reported, which exhibited highly efficient ORR catalytic activity and improved stability in comparison to that of Pt/C catalyst in alkaline media, indicating the potential substitute for Pt‐based catalysts in fuel cells and MABs.…”