Correlation between the spin effect and catalytic activity of two-dimensional metal organic frameworks for the oxygen evolution reaction

Abstract

Spin state modulation has been demonstrated to be an effective strategy to tune the catalytic performance of metal organic frameworks for the electrochemical oxygen reduction reaction (OER). However, the undisclosed correlation between the spin-state and catalytic activity restricts the application of spin-regulation to electrocatalysis. Here, the spin polarization effect on the catalytic performance of 1,4,5,8,9,12-hexaazatriphenylene (HAT) coordinated transition metal (M₃(HAT)₂, M = Fe, Co, Ni, Mn, Cr, Ti) monolayers for the OER is systematically explored by performing density functional theory calculations. The designed M₃(HAT)₂ monolayers show good stability and high conductivity because of the d–π conjugation between transition metals and HAT ligands. The spin moment of the magnetic metals is quantitatively correlated with the d-band center, adsorption strength of crucial intermediates, charge transfer amount and overpotential. We suggest the spin moment as a promising catalytic descriptor for M₃(HAT)₂, which allows the rational optimization of catalytic activity by tuning the spin states of the metal center.