Electrocatalytic CO 2 reduction (CO 2 RR) is governed by the cathode microenvironment. Despite efforts to engineer this microenvironment via surface chemical modification or doping with impurity elements, their inherent structural disorder obscures how interfacial architecture dictates CO 2 RR performance, limiting mechanistic understanding and rational optimization. Here, we employ high‐power laser etching to construct a superhydrophobic Cu 2 O electrode, enabling systematic interrogation of the microenvironment‐activity relationship. By tuning laser parameters, we achieve precise control over synergistic interfacial effects‐Cassie–Baxter phases superhydrophobic structure, confined *CO intermediates diffusion, and modulated local pH. Mass transfer modeling further quantifies how the gas–liquid‐solid interface enriches CO 2 within a few micrometers. These effects allow us to control the microenvironment and induce the reaction toward the path of multicarbon products without any chemical modification of the electrode. Compared to untreated Cu 2 O, the laser‐etched electrode reached 72% in C 2 + selectivity and 900 mA cm −2 current density. The superhydrophobic structure is still intact after 50 h of working. This work establishes a framework for tailoring gas diffusion electrode architectures to directionally modulate the CO 2 RR microenvironment, offering new routes to enhance selectivity and activity.
Liu et al. (Mon,) studied this question.