Accelerating Electrochemical Hydrogen Evolution by Introducing Local Proton Source in Non‐Heme Iron (III) Complexes
Year: 2025
Type: article
Abstract: In the present study, we synthesized three non‐heme Fe III complexes (Fe III [L 1 ] 2 ) − ( 1 ), (Fe III [L 2 ] 2 ) − ( 2 ), and (Fe III [L 3 ] 2 ) − ( 3 ) with 4‐hydroxy pyridine‐2,6‐dicarboxamide (H 2 L 1 ), pyridine‐2,6‐dicarboxamide (H 2 L 2 ), and 4‐methoxy pyridine‐2,6‐dicarboxamide (H 2 L 3 ) based ligands and characterized by elemental analysis, single crystal X‐ray diffraction (for 1 and 2 ), EPR, Möβbauer (for 1 ), UV–visible and infrared spectroscopy. Hydrogen evolution reaction (HER) catalytic activity of 1 , 2 , and 3 was performed in the presence of acids such as acetic acid (AcOH) and triethylammonium chloride/triethylammonium tetrafluoroborate (HNEt 3 Cl/HNEt 3 BF 4 ) in dimethylformamide (DMF). In these compounds, the primary coordination sphere of Fe remained similar, forming bis‐chelated hexa‐coordinated complexes. However, single‐crystal X‐ray structures revealed that the Fe‐Npyridine bond distances are different in 1 and 2 . Noteworthily, complex 1 showed better electrocatalytic activity for HER with a k cat of 1.4 ± 0.07 × 10 5 M −1 s −1 in the presence of HNEt 3 Cl, highlighting the significant effect of internal hydroxy functional groups in HER. The presence of additional hydroxy groups in complex 1 plays the role of a local proton source and facilitates an intramolecular proton transfer, which enhances the catalytic rates for HER. The current study emphasizes how tuning the ligand scaffolds in Fe III complexes could potentially affect their catalytic activity for HER.
Source: Chemistry - An Asian Journal
DOI: 10.1002/asia.70259
Authors: Bharath M, Meenakshi Rana, Santanu Pattanayak, Pankaj Kumar, Vyom Prakash Tyagi, Suresh Bommakanti, Serhiy Demeshko, Rajeev Gupta, Aryya Ghosh, Munmun Ghosh
Language: English
Field: Energy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W4414424353