Biomimetic Design of “Trunk‐Branch‐Leaf” Metallene Electrode for Efficient CO ₂ Electroreduction

ABSTRACT Controllable synthesis of ultrathin metallene nanosheets and rational design of their spatial arrangement in favor of electrochemical catalysis are critical for their renewable energy applications. Here, a biomimetic design of “Trunk‐Branch‐Leaf” strategy is proposed to prepare the ultrathin edge‐riched Zn‐ene “leaves” with a thickness of ~2.5 nm, adjacent Zn‐ene cross‐linked with each other, which are supported by copper nanoneedle “branches” on copper mesh “trunks,” named as Zn‐ene/Cu‐CM. The resulting superstructure enables the formation of an interconnected network and multiple channels, which can be used as an electrocatalytic CO ₂ reduction reaction (CO ₂ RR) electrode to allow a fast charge and mass transfer as well as a large electrolyte reservoir. By virtue of the distinctive structure, the obtained Zn‐ene/Cu‐CM electrode exhibits excellent selectivity and activity toward CO production with a maximum Faradaic efficiency of 91.3% and incredible partial current density up to 40 mA cm ⁻² , outperforming most of the state‐of‐the‐art Zn‐based electrodes for CO ₂ reduction. The phenolphthalein color probe combined with in situ attenuated total reflection‐infrared spectroscopy uncovered the formation of the localized pseudo‐alkaline microenvironment at the interface of the Zn‐ene/Cu‐CM electrode. Theoretical calculations confirmed that the localized pH as the origin is responsible for the adsorption of CO ₂ at the interface and the generation of *COOH and *CO intermediates. This study offers valuable insights into developing efficient electrodes through synergistic regulation of reaction microenvironments and active sites, thereby facilitating the electrolysis of practical CO ₂ conversion.