Unveiling the Interfacial Species Synergy in Promoting CO₂ Tandem Electrocatalysis in Near-Neutral Electrolyte

The interfacial species-built local environments on Cu surfaces impact the CO₂ electroreduction process significantly in producing value-added multicarbon (C₂₊) products. However, intricate interfacial dynamics leads to a challenge in understanding how these species affect the process. Herein, with <i>ab initio</i> molecular dynamics (AIMD) and finite element method (FEM) simulations, we reveal that the highly concentrated interfacial species, including the *CO, hydroxide, and K⁺, could synergistically promote the C-C coupling on the one-dimensional (1D) porous hollow structure regulated interfacial environment. The Cu-Ag tandem catalyst was then synthesized with the as-designed structure, exhibiting a high C₂₊ Faradaic efficiency of 76.0% with a partial current density of 380.0 mA cm^-2 in near-neutral electrolytes. Furthermore, <i>in situ</i> Raman spectra validate that the 1D porous structure regulates the concentration of interfacial CO intermediates and ions to increase *CO coverage, local pH value, and ionic field, promoting the CO₂-to-C₂₊ activity. These results provide insights into the design of practical ECR electrocatalysts by regulating interfacial species-induced local environments.