Fabricating Dual‐Atom Iron Catalysts for Efficient Oxygen Evolution Reaction: A Heteroatom Modulator Approach

Abstract

Understanding the thermal aggregation behavior of metal atoms is important for the synthesis of supported metal clusters. Here, derived from a metal–organic framework encapsulating a trinuclear FeIII2FeII complex (denoted as Fe3) within the channels, a well‐defined nitrogen‐doped carbon layer is fabricated as an ideal support for stabilizing the generated iron nanoclusters. Atomic replacement of FeII by other metal(II) ions (e.g., ZnII/CoII) via synthesizing isostructural trinuclear‐complex precursors (Fe2Zn/Fe2Co), namely the “heteroatom modulator approach”, is inhibiting the aggregation of Fe atoms toward nanoclusters with formation of a stable iron dimer in an optimal metal–nitrogen moiety, clearly identified by direct transmission electron microscopy and X‐ray absorption fine structure analysis. The supported iron dimer, serving as cooperative metal–metal site, acts as efficient oxygen evolution catalyst. Our findings offer an atomic insight to guide the future design of ultrasmall metal clusters bearing outstanding catalytic capabilities.

From double‐atom catalysts to single‐cluster catalysts: A new frontier in heterogeneous catalysis

“…The atomically dispersed metal catalysts can be determined by confirming no X‐ray diffraction spectrum of crystalline metals in the prepared samples. [ 30,64 ] Moreover, the measurement of BET is also necessary for nanomaterials, especially for catalyst materials. The commonly used measurement method of specific surface area is nitrogen adsorption BET method.…”

“…Very recently, Xu et al. [ 30 ] used the two‐solvent method to encapsulate the trinuclear complex into nitrogen‐doped carbon layer (AIST‐1) to obtain nano‐iron metal clusters, namely Fe III 2 M II (μ 3 ‐O)(CH 3 COO) 6 (H 2 O) 3 (M = Fe, Zn, Co). In order to suppress the excessive atoms aggregation, Fe II ions were replaced with other divalent metal ions (e.g., Zn II /Co II ) to synthesize the isostructural trinuclear complex precursors.…”

“…[ 29 ] Third, DACs/SCCs provide adjacent unsaturated coordination sites, which can adsorb multiple reactants at the same time. [ 30,31 ] At last, the synergistic effect between the metal atoms can change the adsorption mode of key intermediates and optimize reaction pathways, resulting in significantly improved catalytic activity and selectivity. [ 32–35 ]…”

Electrochemical Reduction of Carbon Dioxide and Iron Oxide in Molten Salts to Fe/Fe3C Modified Carbon for Electrocatalytic Oxygen Evolution

“…[6,7] However, the high-temperature routes for the preparation of iron carbides, namely the pyrolysis of Fe-containing organics at 700-1000 8C, tends to cause the severe agglomeration of iron species and loss of activity. [7,8] The pyrolysis of these organics causes CO 2 emissions. [8] Lessemission and low-temperature preparation of iron carbides is therefore important but remains a challenge, yet.…”

“…[7,8] The pyrolysis of these organics causes CO 2 emissions. [8] Lessemission and low-temperature preparation of iron carbides is therefore important but remains a challenge, yet. The surface redox capability of Fe species offers opportunities on in situ manipulation of surface/interface over/in Fe-C during catalytic operation, with the rationalization of dynamic structural evolution being key-enabling to understand the rationales of catalyst design.…”