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.

One-Step Synthesis of Ultrathin Carbon Nanoribbons from Metal–Organic Framework Nanorods for Oxygen Reduction and Zinc–Air Batteries

“…arises from the major existence of Fe NPs, while the Fe 2+ and Fe 3+ might be attributed to the formation of FeC x or FeN x in the matrix (Figure 3e). 32 As expected, Fe-N/CNRib exhibited a typical 2D belt-like structure, which is different from the Fe-N/CNRod with the 1D morphology, suggesting the advantage of this synthesis approach (Figure 3f, S18). Considering the ultrafine size of metal nanoclusters that are hardly observed from SEM and TEM images (Figure S19), HAADF-STEM and EDS elemental mappings were performed to have a further investigation on this kind of catalysts.…”

“…Attributed to the presence of large pores or abundant slits caused by the stacked CNRibs, CNRibs (2.94 cm 3 g −1 ) show a much higher pore volume than that of CNRods (1.33 cm 3 g −1 ). 32 It has been demonstrated that the large porosity of electrode materials facilitate the mass transport and electrolyte diffusion during catalytic reactions. 37,38 The SEM images display that the MOF-NRod-L can retain the original 1D morphology after carbonization, giving the porous CNRods with diameters of about 100-200 nm and length of 2-3 m (Figure 1d,e, Figure S2).…”

“…challenges. Owing to the decomposition of ligands and aggregation of metals during pyrolysis, thermal transformation of MOFs is accompanied by the partial or complete collapse of their original morphologies, 31,32 and the falling fragments might reorganize into a new profile under high pyrolysis temperatures, which provide us a rare opportunity to tailor the structure of resulting carbons, for example, from the 1D MOF nanorods to porous 2D carbon nanostructures. Scheme 1.…”

Engineering local coordination environments and site densities for high‐performance Fe‐N‐C oxygen reduction reaction electrocatalysis

“…Furthermore, both metal sites can serve as active centers during ORR, leading to new reaction pathways with lower reaction barriers. Various dual metal sites have been reported with enhanced ORR performance, including Fe‐Co, 59–63 Fe‐Mn, 64,65 and Fe‐Fe 66 …”

Advances in Hydrogen Production from Natural Gas Reforming

“…The available Ni catalyst may have a problem caused by coking which is due to diffusion and dissolution of C. On the contrary, noble metals have minimum coking because of the insolubility of C in the medium. [55,56] Various metals of this type (Ru, Rh, Pd, Ir, and Pt) are investigated to identify the quality of reforming. Only, ruthenium and rhodium have been found to have high reforming properties and low C formation activities.…”