Hierarchical Modulation in Cu‐Aerogel Enables Breakthrough CO ₂ Electroreduction for Combating Stability‐Efficiency‐Selectivity Tradeoff

Abstract Design of electrocatalyst combining low overpotential, high selectivity and stability for combating the stability‐efficiency‐selectivity tradeoff in CO ₂ electroreduction remains a crucial challenge. Herein, a hierarchical modulation strategy is proposed for the precise assembly of Boron (B) and Tin (Sn), resulting in novel copper (Cu)–aerogel (BSnCu3) structures with both structural and functional hierarchies for advanced CO ₂ electroreduction. Superficial assembled Tin creates Cu ⁰ protective layer for high stability, the body assembled Boron improves the binding affinity to intermediates and shifts Cu d‐band upward for enhanced charge transfer. BSnCu3 achieves exceptional performance, including an ethanol selectivity of 93.2%, a Faradaic efficiency (FE) of 90.3%, and an ultralow overpotential of 0.12 V, alongside remarkable stability. Leveraging the synergistic effects of regionally assembled Boron/Tin and the efficient charge/mass transfer of the 3D nanowire network, BSnCu3 attains a record‐breaking tradeoff index of 2.74, surpassing all reported values. This work presents an inspiring strategy and sets a new benchmark for advanced electrocatalyst design.