Immobilization of Iron Phthalocyanine on Pyridine-Functionalized Carbon Nanotubes for Efficient Nitrogen Reduction Reaction

Abstract

An electrochemical nitrogen reduction reaction (NRR) under mild conditions offers a promising alternative to the traditional Haber–Bosch process in converting abundant nitrogen (N2) to high value-added ammonia (NH3). In this work, iron phthalocyanine (FePc) was homogeneously immobilized on pyridine-functionalized carbon nanotubes to form a well-tuned electrocatalyst with an FeN5 active center (FePc-Py-CNT). Synchrotron X-ray absorption and Fourier transform infrared spectroscopy proved the presence of an Fe–N coordination bond between FePc and surface-bound pyridine. The resulting hybrid exhibited notably enhanced electrocatalytic NRR performance compared to FePc immobilized on CNTs based on π–π stacking interactions (FePc-CNT), resulting in doubled NH3 yield (21.7 μg mgcat –1 h–1) and Faradaic efficiency (22.2%). Theoretical calculations revealed that the axial coordination on FePc resulted in partial electron transfer from iron to pyridine, which efficiently suppresses the adsorption of H+ and improves the chemisorption of N2 at Fe sites. Meanwhile, the interfacial electron transfer was facilitated by pyridine as an electron transfer relay between FePc and CNTs. This work provides a unique strategy for the design of highly efficient NRR electrocatalysts at the molecular level.

Novel (Pt‐Ox)‐(Co‐Oy) Nonbonding Active Structures on Defective Carbon from Oxygen‐Rich Coal Tar Pitch for Efficient HER and ORR

“…(Pt‐O x )‐(Co‐O y ) shows the optimal adsorption strength toward H species with a low ∆ G H* value of −0.114 eV, which may be related to lower Pt‐d band center. [ 33,39,63 ] To identify the true active site of (Pt‐O x )‐(Co‐O y ), ∆ G H* values of the Co sites are further calculated (Figures S31 and S32, Supporting Information). In Figure S32 (Supporting Information), ∆ G H* values are more than zero for two typical Co sites (0.926 and 0.380 eV, respectively).…”

“…The phase difference between Pt-O in Pt SA /Co AC -O@ACTP and PtO 2 may be caused by different O coordination numbers. [23,39,51] According to the fitting results (Figure S13 and Table S6, Supporting Information), Pt-O coordination number in Pt SA /Co AC -O@ACTP is 4.4 ± 0.7. The result confirms that unique Pt-O x active sites are formed on the carbon support with abundant oxygencontaining defects from CTP.…”

“…as heteroatoms possess lower electronegativity than Pt and O, and can serve as electron donors to Pt-O x . [36][37][38][39] The bonded "heteroatom-central atom" (M-M) structures are usually developed to modulate the charge density of central atoms. [29,[40][41][42] For example, in Pt-Fe pair sites, strong electronic coupling induces the electron transfer from Fe to Pt, resulting in special occupied orbitals.…”

Introducing a Synergistic Ligand Containing an Exotic Metal in Metal–Organic Framework Nanoarrays Enabling Superior Electrocatalytic Water Oxidation Performance

“…In principle, metallocene, metal phthalocyanine, , metal porphyrin, metal cyanide, and other metal complexes or analogues can be easily combined with an exotic metal to prepare heterometallic MOFs and modulate the corresponding electronic structure. Taking a kind of transition-metal organometallic compound, ferrocene (Fc), as an example, it has a sandwich-like structure, as a central Fe atom is located between two parallel aromatic cyclopentadienyl rings with a complete dislocation configuration. − The Fc and its derivatives have a unique electronic structure, aromatic property, reversible redox property, and robust chemical stability, endowing them with great potential in the fields of adsorption and separation, , resource recovery, sensor, , biomedicine, catalysis, ,, etc.…”

“…However, the heterogeneous phases would be generated due to the difference in coordination rate and mode among different metal ions, ligands, and solvents. In principle, metallocene, 43 metal phthalocyanine, 44,45 metal porphyrin, 46 metal cyanide, 47 and other metal complexes or analogues can be easily combined with an exotic metal to prepare heterometallic MOFs and modulate the corresponding electronic structure. Taking a kind of transition-metal organometallic compound, ferrocene (Fc), as an example, it has a sandwich-like structure, 48 as a central Fe atom is located between two parallel aromatic cyclopentadienyl rings with a complete dislocation configuration.…”