Lanthanum-modulated hollow CuO nanofibers enable selective CO₂ electroreduction to multicarbon products at high...

Electrochemical CO₂ reduction to multicarbon (C₂₊) products at high current densities remains a formidable challenge due to limited selectivity, severe hydrogen evolution competition, and catalyst instability under operating conditions. Herein, we report a lanthanum-modified hollow CuO nanofiber catalyst synthesized via an electrospinning-calcination strategy, enabling efficient and selective CO₂ conversion under industrially relevant conditions. The optimized catalyst with trace lanthanum incorporation exhibits markedly enhanced C₂₊ selectivity and activity, delivering a high Faradaic efficiency and a substantial partial current density at -700 mA cm^-2, while maintaining excellent operational stability. Notably, lanthanum doping effectively suppresses hydrogen evolution and promotes sustained catalytic performance under high-rate operation. Mechanistic investigations suggest that lanthanum simultaneously modulates the local electronic structure of Cu sites and the interfacial oxygen coordination environment. This modulation may facilitate the formation of Cu⁺-related species and promote lattice oxygen enrichment, which together enhance water activation and the generation of reactive hydrogen species for *CO hydrogenation toward *COH intermediates, while suppressing the competing hydrogen evolution reaction (HER). In situ spectroscopic analysis, isotope exchange experiments, and theoretical calculations collectively indicate a favorable modulation of interfacial reaction pathways toward enhanced C₂₊ formation. This work demonstrates the potential of rare-earth elements as efficient regulators for steering reaction selectivity in CO₂ electroreduction and provides a viable design strategy for high-performance catalysts toward practical carbon conversion technologies.