Cross-Linked Double-Active Centers for Efficient pH-Universal Oxygen Reduction Catalysis

Abstract

Effective adjustment of the internal electron spin state and the external charge density of the metal is considered important for improving the catalytic activity of metal-nitrogen complex carbon (M/NC) electrocatalysts. Herein, we synthesize a FeMn/NC dual-atom catalyst with a local structure of FeN4–MnN4, which exhibits excellent oxygen reduction reaction (ORR) activity in acidic, neutral, and alkaline environments. In addition, the Zn–air battery based on the FeMn/NC catalyst has a high open-circuit voltage (1.27 V vs RHE), a satisfactory output power density (129 mW cm–2), and a strong charge and discharge stability (500 cycles), all of which are superior to those of commercial Pt/C. Such splendid catalytic performance is due to the change in the charge environment and the transition of the 3d orbital spin state at the metal center. Moreover, density functional theory calculations further demonstrate that the bimetallic synergy mechanism can optimize the adsorption energy of intermediates and improve the ORR efficiency. This work provides a new insight into the rational design of bimetallic catalysts with extraordinary comprehensive ORR capability.

Improving Electrocatalytic Oxygen Evolution through Local Field Distortion in Mg/Fe Dual‐site Catalysts

“…The n of Fe 2+ decreases from ≈2.12 in Fe−N−C to ≈0.38 in Mg/Fe−N−C. It is well known that the interactions between an unpaired electron and its surrounding environment will affect the shape of the signal peak [51,52] . As compared to Fe−N−C, the Mg/Fe−N−C presents an obvious signal attenuation in the EPR spectrum (Figure 5f), indicating that the number of unpaired electrons decreases.…”

“…The n of Fe 2 + decreases from � 2.12 in FeÀ NÀ C to � 0.38 in Mg/FeÀ NÀ C. It is well known that the interactions between an unpaired electron and its surrounding environment will affect the shape of the signal peak. [51,52] As compared to FeÀ NÀ C, the Mg/FeÀ NÀ C presents an obvious signal attenuation in the EPR spectrum (Figure 5f), indicating that the number of unpaired electrons decreases. Based on the spin analysis above, it can be inferred that the introduction of Mg enables the transition of the spin state from IS to LS for Fe 2 + , which agrees well with the DFT calculation results.…”

Dual and Triple Atom Electrocatalysts for Energy Conversion (CO2RR, NRR, ORR, OER, and HER): Synthesis, Characterization, and Activity Evaluation

“…Electrolyte is 0.1 M KOH in all cases, except for [M] which is conducted in 1 M KOH. References: [A], [B], [C], [D], [E], [F], [G], [H], [I], [J], [K], [L], [M], [N], [O], [P], [Q], [R], [S], [T], [U], [V], [W], [X], [Y], [Z], [AA], [AB], [AC], [AD] …”

“…Electrolyte is either 0.1 M HClO 4 or 0.5 M H 2 SO 4 (shaded gray). References: [A], [B], [C], [D], [E], [F], [G], [H], [I], [J], [K], [L], [M], [N], [O], [P], [Q], [R], [S], [T], [U], [V], [W] …”