Relay Catalysis of Multi‐Sites Promotes Oxygen Reduction Reaction

Abstract

The two‐electron pathway to form hydrogen peroxide (H2O2) is undesirable for the oxygen reduction reaction (ORR) in iron and nitrogen doped carbon (Fe–N–C) material as it not only lowers the catalytic efficiency but also impairs the catalyst durability. In this study, a relay catalysis pathway is designed to minimize the two‐electron selectivity of Fe–N–C catalyst. Such a design is achieved by introducing two other sites, that is, MnN4 site and α‐Fe(110) face. A combination of transmission electron microscopy image and X‐ray absorption spectra verify the three site formation. Electrochemical test coupled with post‐treatment confirm the improvement of MnN4 site and α‐Fe(110) face on catalyst performance. Theoretical calculation proposes a relay catalysis pathway of three sites, that is, H2O2 released from the FeN4 site migrates to the MnN4 site or α‐Fe(110) face, on which the captive H2O2 is further reduced to H2O. The relay catalysis pathway positioned the as‐prepared catalyst among the best ORR catalysts in both aqueous electrode and alkaline direct methanol fuel cell test. This study examples an interesting relay catalysis pathway of multi‐sites for the ORR, which offers insights into the design of efficient electrocatalysts for fuel cells or beyond.

Mechanism of Particle-Mediated Inhibition of Demetalation for Single-Atom Catalytic Sites in Acidic Electrochemical Environments

“…Efficient strategies for preventing the demetalation of SACSs have been reported sparingly. , Recent studies have shown that interaction with metallic particles such as clusters and nanoparticles can inhibit the demetalation of SACs, making it one of the few strategies that offer promise for inhibiting demetalation. , However, the mechanisms that underlie the stabilization of SACs by metallic particles remain poorly understood. The specific property or properties of SACSs that are altered following the introduction of particles and how such modifications prevent demetalation are yet to be fully elucidated.…”

Revealing Distance-Dependent Synergy between MnCo2O4 and Co–N–C in Boosting the Oxygen Reduction Reaction

“…As illustrated in Figure a, H 2 O 2 released from Co–N 4 can migrate to MnCo 2 O 4 and be further reduced to H 2 O. In this way, a 2e – + 2e – relay pathway is realized through the interaction of two different types of catalytic sites. ,, This calculation is conventionally based on sufficiently separated active sites. However, synergy between adjacent active sites remains an open question.…”

“…Many electrochemical reactions, such as the oxygen reduction reaction (ORR), nitrogen reduction reaction (NRR), carbon dioxide reduction reaction (CO 2 RR), etc., involve multielectrons and intermediates, thus imposing high requirements on electrocatalysts. − To smoothly complete the entire chemical reaction, the catalysts need to properly adsorb all intermediates. Since it is difficult for a single type of active site to have moderate adsorption/desorption strengths to all intermediates, relay catalysis has been developed as a solution. − Relay catalysis is essentially a kind of synergistic catalysis. The intermediate species formed on one type of active site migrate to another active site on the same catalyst to complete the reaction.…”

Mn Single-Atom Tuning Fe-N-C Catalyst Enables Highly Efficient and Durable Oxygen Electrocatalysis and Zinc–Air Batteries

“…After 15 000 CV cycles, Mn 1 @Fe-N-C/CNTs exhibit a slight decay of E 1/2 of 14 mV, which is much smaller than Fe-N-C/CNTs (26 mV) (Figure S20 in the Supporting Information). It has been reported that the radicals attack on the Fe-N x sites is an important reason for ORR activity attenuation when a Fe-N-C catalyst is used . Therefore, we design a radical scavenging experiment to ascertain the scavenging ability of the radical for the catalysts.…”

“…It has been reported that the radicals attack on the Fe-N x sites is an important reason for ORR activity attenuation when a Fe-N-C catalyst is used. 50 Therefore, we design a radical scavenging experiment to ascertain the scavenging ability of the radical for the catalysts. According to recent reports, 26 the 2,2-azinobis(3-rthylbenzoline-6-sulfonate) (ABTS) was chosen as the probe molecule and Youke UV-vis spectroscopy was used to monitor the change of radical concentrations with ABTS.…”