Pt‐Like Oxygen Reduction Activity Induced by Cost‐Effective MnFeO₂/N‐Carbon

Abstract

The development of effective and affordable electrocatalysts for the oxygen reduction reaction (ORR) is critical for the renewable‐energy technologies. Here, we present a new manganese iron oxide (MnFeO2) as a cost‐effective material for the ORR with Pt‐like electrochemical properties. Pyrolysis of hybrid agar hydrogel on NaCl nanocrystals furnishes a unique structure in which the active MnFeO2 particles are uniformly immobilized in the nitrogen‐doped porous carbon aerogels (MnFeO2/NPC). Nitrogen‐doped carbon is introduced to construct porous mass‐transfer channels and reduce self‐aggregation of the MnFeO2 particles. It is found that the formation of the MnFeO2 phase greatly depends on the pyrolysis temperature. Benefiting from the synergy of MnFeO2 and NPC, the MnFeO2/NPC can actually be as good as the Pt/C catalyst for the ORR, with an onset‐potential of 0.98 V and a half‐wave potential of 0.86 V, combined with demonstrating a superior stability and tolerance to methanol.

Atomically Dispersed CoN4/B, N-C Nanotubes Boost Oxygen Reduction in Rechargeable Zn–Air Batteries

“…Apart from the Co−N x species, pyridinic-N, pyrrolic-N, and graphitic-N were also detected at 398.1, 400.2, and 401.7 eV, respectively. 11,56 The Co−N x species, pyridinic-N, and graphitic-N have been generally accepted as the active centers of the ORR. 57 According to the statistics in Figure 1g, the as-prepared product shows a high content of ORR-active N species (60%), including Co−N x species (17%), pyridinic-N (7%), and graphitic-N (36%).…”

Low‐Load Pt Nanoclusters Anchored on Graphene Hollow Spheres for Efficient Hydrogen Evolution

“…[ 45 ] The intensity ratio of I D /I G can be used to obtain the relative intensity of the D band and G band. [ 46,47 ] As shown in Figure 3d, the I D /I G value of Pt/GHSs (1.54) is much higher than that of pristine GO nanosheets (1.13) and GHSs (0.86). The results show that the graphitization degree of carbon can be enhanced by calcining the pristine GO nanosheets at high temperatures, whereas the graphene carbon of Pt/GHSs has a high degree of defects and disorder.…”

Immobilization of Fe-Doped Ni2P Particles Within Biomass Agarose-Derived Porous N,P-Carbon Nanosheets for Efficient Bifunctional Oxygen Electrocatalysis

“…Here the EDTMPA not only effectively interacts with the iron and nickel cations, as demonstrated by UV-visible spectroscopy (Figure S1), but also serves as the dopant precursor of N and P. Then the mixture was transferred to a hot viscous agarose solution at 95°C. The hydroxyl groups in agarose tends to self-assemble and ultimately form a cross-linked hydrogel with metal and N,P precursors evenly embedded inside, when the temperature is dropped to a certain degree as agarose is a temperature sensitive polymer (Zhou et al, 2019). During the fabrication process, the hydrogel agarose not only serves as a smart linker to strongly coordinate with metal ions through abundant oxygen-containing functional groups in the molecular chains, but also as a rational media to effectively circumvent the agglomeration/detachment problem of Fe-Ni 2 P particles during carbothermal reduction.…”

“…During the fabrication process, the hydrogel agarose not only serves as a smart linker to strongly coordinate with metal ions through abundant oxygen-containing functional groups in the molecular chains, but also as a rational media to effectively circumvent the agglomeration/detachment problem of Fe-Ni 2 P particles during carbothermal reduction. Noticeably, the synthetic approach we proposed here enables lowering the product particle size because of the confinement effect of concrete agarose gel (Zhang et al, 2017; Zhou et al, 2019). After freeze-drying and thermal treatment in an inert atmosphere, the product of Fe-Ni 2 P@N,P-CNSs was finally obtained.…”