Regulating Spin Density using TEMPOL Molecules for Enhanced CO2‐to‐Ethylene Conversion by HKUST‐1 Framework Derived Electrocatalysts

Abstract

The selectivity of multicarbon products in the CO2 reduction reaction (CO2RR) depends on the spin alignment of neighboring active sites, which requires a spin catalyst that facilitates electron transfer with antiparallel spins for enhanced C‐C coupling. Here, we design a radical‐contained spin catalyst (TEMPOL@HKUST‐1) to enhance CO2‐to‐ethylene conversion, in which spin‐disordered (SDO) and spin‐ordered (SO) phases co‐exist to construct an asymmetric spin configuration of neighboring active sites. The replacement of axially coordinated H2O molecules with TEMPOL radicals introduces spin‐spin interactions among the Cu(II) centers to form localized SO phases within the original H2O‐mediated SDO phases. Therefore, TEMPOL@HKUST‐1 derived catalyst exhibited an approximately two‐fold enhancement in ethylene selectivity during the CO2RR at ‐1.8 V versus Ag/AgCl compared to pristine HKUST‐1. In situ ATR‐SEIRAS spectra indicate that the spin configuration at asymmetric SO/SDO sites significantly reduces the kinetic barrier for *CO intermediate dimerization toward the ethylene product. The performance of the spin catalyst is further improved by spin alignment under a magnetic field, resulting in a maximum ethylene selectivity of more than 50%. The exploration of the spin‐polarized kinetics of the CO2RR provides a promising path for the development of novel spin electrocatalysts with superior performance.