First-principles insight into helical distortion in chiral WSe₂ for promoting C–C coupling in CO₂ reduction

Catalytic conversion of CO₂ into multi-carbon products represents a promising route for sustainable carbon utilization, yet its practical realization remains limited by the high energy barrier associated with C–C coupling. Here, we demonstrate that the out-of-plane helical distortion in chiral WSe₂ (CWS), serving as a structural origin of symmetry breaking, induces a pronounced spin-momentum locking effect due to asymmetric spin-orbit coupling (SOC) introduced by helical distortion. This effect subsequently stabilizes the *OCCO intermediate, which markedly lowers the activation energy barrier for C–C coupling. Spin-polarized density functional theory (DFT) calculations incorporating SOC reveal that the helical distortion breaks inversion symmetry and generates an asymmetric spin-dependent potential landscape, producing momentum-locked spin textures and valley-contrasting Berry curvature. These spin-geometric features enable carrier populations near the band edges and induce localized spin polarization at the catalytic interface. At the catalytic interface, this chiral environment enhances *OCCO adsorption through stronger orbital overlap and interfacial charge transfer. Concurrently, out-of-plane lattice distortion facilitates electronic delocalization and spin-matched hybridization between CWS surface and adsorbed state *OCCO, thereby efficiently driving the conversion of *OCCO to the final product. This study establishes a quantum design principle for chiral helical catalysts that harnesses chirality-induced spin polarization to enhance CO₂ conversion into multi-carbon products.