Establishing a Robust Nonlinear Targeted Switch for C₁ Electroproduction in Atomic Alloy Co_x/Pd Bimetallenes

Establishing a targeted switch for CO₂ conversion under electric drive is essential for achieving carbon-balance by enabling selective chemicals. However, engineering the topological assembly of active sites to precisely regulate the competing pathways for various intermediates has been plagued by unclear structure-function relationships. To tailor the CO/formate pathways, herein we established a robust nonlinear targeted switch with tunable active Co_x sites integrated into Pd metallene, which involves Co₁/Pd single-atom alloy (favoring CO) and Co₂/Pd diatomic alloy (favoring formate). Transitioning from Co₁/Pd to Co₂/Pd atomic alloy bimetallenes resulted in a nonlinear, high-contrast flip in selectivity, surpassing 94 % for CO and formate productions in both H-cell and flow cell. Furthermore, the superior selectivity and current efficiency for CO (>80 %) and formate (>88 %) were consistently maintained at -150 mA cm^-2 over continuous 200 h. Theoretical simulations and in situ spectroscopy analyses unveiled that appropriate adjacent metal site combinations (Pd-Pd, Pd-Co and Co-Co) lead to tunable d_z ² band center and a nonlinear shift in preferred adsorption configurations of intermediates, dictating the C₁ pathways. Our finding reveals a desired switch in C₁ selectivity and robust stability within Co_x/Pd system, providing a new perspective for fine-tuning energy conversion processes through specific topological assembly.