Pearl Necklace Fibrous Carbon Sharing Fe–N/Fe–P Dual Active Sites as Efficient Oxygen Reduction Catalyst in Broad Media and for Liquid/Solid‐State Rechargeable Zn–Air Battery

Abstract

Optimized catalysts are attractive from the standpoint of energy storage and conversion. Herein, a pearl necklace fibrous carbon catalyst with Fe–N/Fe–P dual active sites (Fe–P/NHCF) is fabricated via carbonization–phosphidation of metal–organic framework (MOF)/polyacrylonitrile nanofibers. Benefiting from Fe–N/Fe–P doping‐induced active sites, accompanied by particular hierarchical porous merit and a 1D necklace network to facilitate the oxygen reduction reaction (ORR), it exhibits a half‐wave potential of 0.82 V in alkaline medium and outperforms commercial Pt/C in terms of stability in acid medium. Furthermore, a low voltage gap (1.04 V) is acquired in a liquid Zn–air battery with Fe–P/NHCF as the cathode. Meanwhile, the portable solid‐state Zn–air battery displays an open circuit voltage of 1.32 V and a power density of 42 mW cm−2. This strategy puts forward a protocol to develop tailored geometry with dual active sites for ORR in alkaline/acid media, which is expected to promote devices of practical significance.

Ultrafast Kinetics in a PAN/MgFe2O4 Flexible Free-Standing Anode Induced by Heterojunction and Oxygen Vacancies

“…The Fe 2p 3/2 of MFO in Figure b was fitted into three peaks at 710.8, 712.6, and 718.2 eV corresponding to Fe 3+ at the octahedral site, the tetrahedral site, and the shakeup satellite peak, respectively. , In Figure c, the O 1s spectrum of MFO at 529.8, 531.1, and 532.6 eV can be assigned to metal–oxygen bonds, oxygen vacancies, , and surface-adsorbed oxygen, respectively. For PAN-MFO 2/1, the intensity of pyridinic N peak reduces sharply, a new strong peak at 399.3 eV can be observed (Figure d); meanwhile, an extra peak appears at 706 eV in the Fe 2p spectrum (Figure e), implying the pyridinic N in PAN interacts with Fe in MFO to form an Fe–N bond. , The percentage of oxygen vacancies in PAN-MFO 2/1 (Figure f, 62.2%) increases significantly compared with that of MFO (Figure c, 28.1%), which is consistent with the result of EPR. Meanwhile, the peaks of Fe 3+ (Figure e) and metal–oxygen bond (Figure f) in PAN-MFO 2/1 both shift to lower binding energy, illustrating the weakened Fe–O bond, which is consistent with the results of the Raman and FTIR.…”

A Simple Synthesis of Fe2P Nanoparticles Encapsulated Doped Carbon Nanotube as Electrocatalysts for Oxygen Reduction Reaction and Zinc‐Air Battery

“…To further verify the ORR performance of Fe 2 P@NPCNTs-800 catalyst, ZAB is assembled using Fe 2 P@NPCNTs-800 as the catalyst. [54,55] As shown in Figure 5a, the rechargeable ZAB is composed of an anode (zinc foil), an electrolyte (6 M KOH þ 0.2 M zinc acetate), and a cathode (carbon paper loaded with catalyst). The results show that the ZAB with Fe 2 P@NPCNTs-800 as electrocatalyst has an open-circuit voltage of 1.49 V (Figure 5b), which is better than the ZAB with Pt/C-RuO 2 electrocatalyst (1.46 V).…”

Recent Advances on Electrospun Nanomaterials for Zinc–Air Batteries

“…[ 90 ] The metal‐organic framework (MOF) materials can be used as another ideal precursors to prepare the air catalysts with abundant M–N–C active sites. [ 91–97 ] For example, the ZIF‐67 derived Co/N–C particles on the PAN‐based carbon nanofibers (C‐PAN@ZIF‐67) with gems‐on‐string structure and more Co–N–C active sites exposure, which exhibit a long‐term stability of 965 h ( j = 10 mA cm −2 , 10 min per cycle) (Figure 8d). [ 98 ] Similarly, bimetallic Zn/Co–ZIF was used to synthesize the CNF@Zn/CoNC.…”