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🤝 Collaborative Paper

Restricting Copper Reconstruction with Ultrathin Polydopamine for Selective and Stable Electrochemical CO₂ Reduction Reaction to C₂ Products

Adv. Energy Sustainability Res., e202500354 (2025) (Wiley-VCH) | DOI: 10.1002/aesr.202500354
Authors：Omran Moradlou, Mohammad Qorbani, Amr Sabbah, Varad Modak, Mengstu Etay Ashebir, Osama Nasr, Chih-Yang Huang, Fadila Arum Ramadani, Chen-Hao Wang, Heng-Liang Wu, Li-Chyong Chen, and Kuei-Hsien Chen*

📄 Abstract

A strategy is presented to mitigate copper surface reconstruction during electrochemical CO₂ reduction reaction (EC-CO₂RR) by conformally coating copper microcubes (CuMCs) with an ultrathin (2 nm) polydopamine (PDA) layer. The formation of nanocubes (30–50 nm in size) at the surface of microcubes at the early stages of the EC-CO₂RR contributes to suppressed surface reconstruction and sustained Faradaic efficiency (FE) for C₂ products. Furthermore, PDA coating effectively stabilizes adsorbed COatop and CObridge intermediates and promotes C─C coupling. As a result, the FE for C₂ products increases from 52.0 ± 4.0% for unmodified CuMCs to 81.6 ± 2.8% for PDA-coated CuMCs at −1.18 V versus reversible hydrogen electrode (VRHE). The PDA coating effectively slows down the surface evolution process of the catalyst during electrolysis. After 18 h of continuous operation at −0.88 VRHE, the CuMCs retain their original framework owing to a tightly adhered PDA layer that effectively stabilizes the surface and enhances catalyst durability. In situ surface-enhanced infrared absorption spectroscopy confirms the presence of adsorbed COatop, CObridge, and *OCCOH intermediates on PDA/CuMCs surface, which are believed to boost C─C coupling. This work highlights the potential of polymer film to stabilize the catalyst surface and steer product distribution in CO₂ electroreduction.

🔬 Five Key Findings

1
Ultrathin (2 nm) PDA Protective Coating: Conformal polydopamine coating suppresses copper surface reconstruction during EC-CO₂RR, preserving catalyst structural integrity.
2
C₂ FE Boost from 52% to 81.6%: At −1.18 VRHE, PDA/CuMCs achieves significantly higher C₂ product Faradaic efficiency compared to unmodified CuMCs (52.0 ± 4.0%).
3
18-Hour Durability: CuMCs retain original framework after 18 h of continuous electrolysis at −0.88 VRHE, far superior to rapidly degrading unmodified samples.
4
Stabilization of COatop, CObridge, and *OCCOH Intermediates: In situ SEIRAS confirms PDA coating stabilizes key C─C coupling precursors, promoting multicarbon product selectivity.
5
Microcube-to-Nanobox Evolution: CuMCs transform into cage-like nanobox structures (30–50 nm); the PDA coating acts as a protective skeleton preventing structural collapse during EC-CO₂RR.

📊 Key Figures

Figure 1: Schematic representation of the CuMCs catalyst preparation process and the membrane electrode assembly configuration for CO₂ electroreduction.
Figure 2: High-resolution XPS spectra of C 1s, O 1s, and Cu 2p regions for PDA, GDE, and CuMCs/PDA/GDE, confirming successful catalyst integration.