Heterointerface-mediated oxidation state enhances oxygen evolution reaction on iron organic framework/cobalt-nickel layered double hydroxide

This is the authors' abstract. We don't add key points for this paper.

Achieving stable, low-cost electrocatalysts able to perform oxygen evolution reaction (OER) is still a challenging task. We demonstrate an electrocatalyst based on Fe-HHTP organic framework coupled with CoNi layered double hydroxide (Fe-HHTP/CoNi LDH; HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene), where lattice-matched heterointerface enables strong interaction of the two constituents. Charge redistribution induced by the heterointerface results in a higher oxidation state of Co and Ni cations in CoNi LDH, leading to enhanced electron-withdrawing property and a strengthened adsorption of oxygenated intermediates during OER. Fe-HHTP/CoNi LDH exhibits an overpotential of 206 mV to reach a current density of 10 mA cm -2 , which is lower than those of CoNi LDH (250 mV) and Fe-HHTP (301 mV). The assembled anion exchange membrane water electrolyzer with Fe-HHTP/CoNi LDH as an anode experiences only a slight increase (19 mV) for the cell voltage after 20-h electrolysis at 100 mA cm -2 , significantly outperforming the one based on CoNi LDH (100 mV). In-situ Raman spectra show that Fe-HHTP anchors on CoNi-O octahedral layers, preserving their integrity under anodic potentials, whereas pristine CoNi LDH undergoes a complete phase transformation to γ -(CoNi)OOH x . This study offers useful insights on how strong heterointerface interaction enhances activity and stability of heterostructured electrocatalysts.