Magnetic enhancements of defect-mediated spin polarized photocatalytic CO2 reduction of Sn2P2S6

Abstract

Manipulation of electron spin polarization has emerged as a promising strategy for regulating charge-carrier dynamics and enhancing photocatalytic activity. Vacancy (defect) engineering provides an effective approach to increase the population of unpaired spin electrons, thereby promoting photocatalytic CO₂ reduction. In this work, we demonstrate enhanced CO₂ reduction efficiency in Sn₂P₂S₆ by harnessing spin-polarized electrons through the synergistic introduction of sulfur vacancies and the application of an external magnetic field. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) measurements under an external magnetic field were employed to monitor reaction intermediate formation during CO₂ photoreduction on sulfur-vacancy-engineered Sn₂P₂S₆ (V_s-Sn₂P₂S₆). The results provide direct spectroscopic evidence that the magnetic field significantly promotes the formation of key reaction intermediates, including COOH*, CHO*, and CH₃O*, which are closely associated with CH₄ evolution. First-principles calculations further confirm that these intermediates can be stably accommodated on sulfur-deficient Sn₂P₂S₆ surfaces, providing theoretical support for the reaction pathways revealed by the in situ DRIFTS measurements. Collectively, these findings demonstrate that external magnetic fields facilitate intermediate formation and enhance CH₄ yield, highlighting the synergistic potential of integrating defect engineering with magnetic enhancement for the rational design of advanced photocatalysts.