Biomimetic Design of “Trunk-Branch-Leaf” Metallene Electrode for Efficient CO₂ 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 CO₂ reduction reaction (CO₂RR) 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 CO₂ 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 CO₂ 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 CO₂ conversion.

Keywords

carbon dioxide reduction / local pH / metallene / reaction microenvironment / trunk-branch-leaf

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2025 The Author(s). Carbon Energy published by Wenzhou University and John Wiley & Sons Australia, Ltd.