摘要
Facile preparation of cost-effective and durable porous carbon-supported non-precious-metal/nitrogen electrocatalysts for oxygen reduction reaction(ORR)is extremely important for promoting the commercialized applications of such catalysts.In this work,the FeCl3-containing porphyrinato iron-based covalent porous polymer(FeCl3·FeP or-CPP)was fabricated in-situ onto porous corncob biomass supports via a simple one-pot method.Subsequent thermal-reduction pyrolysis at 700℃-900℃with CO2 gas as an activating agent resulted in Fe2O3-decorated and N-doped graphitic carbon composite Fe2O3@NC&bio-C with a high degree of graphitization of Fe-involved promotion during pyrolysis(Fe2O3=FeCl3·FePor-CPP derived Fe2O3;NC=N-doped graphene analog;bio-C=the corncob-derived hierarchically porous graphitic biomass carbon framework).The derivedα-Fe2O3 andγ-Fe2O3 nanocrystals(5-10 nm particle diameter)were all immobilized on the N-doped bio-C micro/nanofibers.Notably,the Fe2O3@NC&bio-C obtained at the pyrolysis temperature of 800℃(Fe2O3@NC&bio-C-800),exhibited unusual ORR catalytic efficiency via a 4-electron pathway with the onset and half-wave potentials of 0.96 V and 0.85 V vs.RHE,respectively.In addition,Fe2O3@NC&bio-C-800 also exhibited a high and stable limiting current density of-6.0 mA cm-2,remarkably stability(larger than 91%retention after 10000 s),and good methanol tolerance.The present work represents one of the best results for iron-based biomass material ORR catalysts reported to date.The high ORR activity is attributed to the uniformly distributedα-Fe2O3 andγ-Fe2O3 nanoparticles on the N-enriched carbon matrix with a large specific surface area of 772.6 m^2 g^-1.This facilitates favor faster electron movement and better adsorption of oxygen molecules on the surface of the catalyst.Nevertheless,comparative studies on the structure and ORR catalytic activity of Fe2O3@NC&bioC-800 with Fe2O3@bio-C-800 and NC&bio-C-800 clearly highlight the synergistic effect of the coexisting Fe2O3 nanocrystals,NC,and bio-C on the ORR performance.
Facile preparation of cost-effective and durable porous carbon-supported non-precious-metal/nitrogen electrocatalysts for oxygen reduction reaction（ORR） is extremely important for promoting the commercialized applications of such catalysts. In this work, the FeCl3-containing porphyrinato iron-based covalent porous polymer（FeCl3·FeP or-CPP） was fabricated in-situ onto porous corncob biomass supports via a simple one-pot method. Subsequent thermal-reduction pyrolysis at 700 ℃–900 ℃ with CO2 gas as an activating agent resulted in Fe2O3-decorated and N-doped graphitic carbon composite Fe2O3@NC&bio-C with a high degree of graphitization of Fe-involved promotion during pyrolysis（Fe2O3= FeCl3·FePor-CPP derived Fe2O3; NC = N-doped graphene analog; bio-C = the corncob-derived hierarchically porous graphitic biomass carbon framework）. The derived α-Fe2O3 and γ-Fe2O3 nanocrystals（5–10 nm particle diameter）were all immobilized on the N-doped bio-C micro/nanofibers. Notably, the Fe2O3@NC&bio-C obtained at the pyrolysis temperature of 800 ℃（Fe2O3@NC&bio-C-800）, exhibited unusual ORR catalytic efficiency via a 4-electron pathway with the onset and half-wave potentials of 0.96 V and 0.85 V vs. RHE, respectively. In addition, Fe2O3@NC&bio-C-800 also exhibited a high and stable limiting current density of-6.0 mA cm-2, remarkably stability（larger than 91% retention after 10000 s）, and good methanol tolerance.The present work represents one of the best results for iron-based biomass material ORR catalysts reported to date. The high ORR activity is attributed to the uniformly distributed α-Fe2O3 and γ-Fe2O3 nanoparticles on the N-enriched carbon matrix with a large specific surface area of 772.6 m2 g-1. This facilitates favor faster electron movement and better adsorption of oxygen molecules on the surface of the catalyst. Nevertheless, comparative studies on the structure and ORR catalytic activity of Fe2O3@NC&bioC-800 with Fe2O3@bio-C-800 and NC&bio-C-800 clearly highlight the synergistic effect of the coexisting Fe2O3 nanocrystals, NC, and bio-C on the ORR performance.
基金
the National Natural Science Foundation of China(Nos.21771192,21631003,21871024)
the Major Program of Shandong Province Natural Science Foundation(No.ZR2017ZB0315)
Fundamental Research Funds for the Central Universities(Nos.18CX06001A,19CX05001A)
Research Foundation from China University of Petroleum(East China)(No.Y1510051)
Taishan Scholar Program of Shandong Province(ts201712019,ts201511019).
