Catalyst-directed vibrational frequency disparity for isotopologue sieving in CO₂ electrolysis

Carbon-13 (¹³C) serves as a stable isotope tracer but the technologies conventionally used to separate it are energy intensive. Recent demonstrations of electrochemical isotope separation enable continuous enrichment at room temperature, substantially reducing energy requirements. However, the chemical mechanism dominating the ¹³C enrichment performance remains elusive, hindering the isotope electrochemical separation performance. Here we examine the relationship between catalyst-directed vibrational frequency disparity, Gibbs free energy and isotopic enrichment. Specifically, we propose a theoretical isotope factor (δ) that demonstrates high consistency with experimental isotope separation performance, and we further promote the δ value by adjusting the vibrational frequency and adsorption energy of intermediates in CO₂ electrolysis through nitrogen doping in tin-based catalysts. Ultimately, we realize over 14.0% ¹³CO₂ output from natural abundance (1.1%) under scaled-up conditions (10 A), and an enrichment rate exceeding 1,000% is achieved with the separation factor surpassing 14.1. This work proposes vibrational frequency modulation during electrolysis and theoretical evaluation methodologies for elevating ¹³C isotopologue enrichment.