Strategic Synthesis of Heptacoordinated Fe^III Bifunctional Complexes for Efficient Water Electrolysis

Abstract

In this research, highly efficient heterogeneous bifunctional (BF) electrocatalysts (ECs) have been strategically designed by Fe coordination (CR) complexes, [Fe2L2(H2O)2Cl2] (C1) and [Fe2L2(H2O)2(SO4)].2(CH4O) (C2) where the high seven CR number synergistically modifies the electronic environment of the Fe centre for facilitation of H2O electrolysis. The electronic status of Fe and its adjacent atomic sites have been further modified by the replacement of −Cl− in C1 by −SO42− in C2. Interestingly, compared to C1, the O−S−O bridged C2 reveals superior BF activity with extremely low overpotential (η) at 10 mA cm−2 (140 mVOER, 62 mVHER) and small Tafel slope (120.9 mV dec−1OER, 45.8 mV dec−1HER). Additionally, C2 also facilitates a high‐performance alkaline H2O electrolyzer with cell voltage of 1.54 V at 10 mA cm−2 and exhibits remarkable long‐term stability. Thus, exploration of the intrinsic properties of metal–organic framework (MOF)‐based ECs opens up a new approach to the rational design of a wide range of molecular catalysts.

Synthesis of Conductive MOFs and Their Electrochemical Application

“…[ 83–85 ] Metal ions and organic ligands in MOFs play various roles, such as serving as acids, bases, or redox mediators, enabling them to catalyze a broad range of reactions. [ 86–89 ] Moreover, the pores of MOFs can be utilized for incorporating noble metal nanoparticles, such as Au, Pd, and Pt, which possess high catalytic activity.…”

Deciphering the active species and reaction mechanism in water oxidation catalyzed by a copper complex with redox-active ligands

“…Consequently, there is a pressing need to explore cost-effective and efficient alternatives in the form of base metal catalysts for water oxidation. Over the past decade, considerable attention has been directed towards first-row transition metals, specifically Mn-, 12–14 Fe-, 15,16 Co-, 17,18 Ni-, 19 and Cu-based 20–25 water oxidation catalysts (WOCs), leading to notable advancements.…”