Enhanced Electrochemical Detection of Circularly Polarized Light Enabled by Spin-Selective Oxygen Evolution Reaction.

The interaction between circularly polarized light (CPL) and chiral matter generates spin-polarized charge carriers; however, efficiently converting this microscopic spin imbalance into a macroscopic electrical signal remains a central challenge in CPL detection. Herein, we present an electrochemical CPL detection platform based on a metalated chiral covalent organic framework (CCOF), where CPL-induced spin polarization is coupled with the spin-selective oxygen evolution reaction (OER) to enable nonlinear transduction of spin polarization into an amplified electrical response. The nonlinear spin-dependent OER kinetics serves as an internal gain module that amplifies the electrical readout of spin imbalance, transforming CPL detection from a direct light-to-current conversion into a cascade process involving spin generation, nonlinear transduction of spin polarization, and current readout, resulting in a pronounced enhancement of the photocurrent anisotropy beyond that achievable in solid-state CPL detectors. Furthermore, systematic substitution of Co with heavier Ru and Re centers establishes a correlation among spin-orbit coupling (SOC) strength, microscopic chiroptical response (gCD and PCPL), and macroscopic device performance (GIph). This cascade spin generation-nonlinear electrochemical amplification strategy boosts the photocurrent anisotropy factor (GIph) to as high as 0.52, providing a rational approach for the systematic enhancement of CPL detection performance.