Vapor Deposition Strategies for Copper-Based Electrocatalysts in CO₂ Reduction Applications

The advent of copper-based electrocatalysts has significantly advanced the electrochemical conversion of CO₂ into valuable multicarbon fuels and chemicals. Among various synthesis methods, vapor deposition techniques offer a facile and innovative approach to produce catalysts with high conformance and precise control of morphology, thickness, and composition. This article provides a review of the application of the main vapor deposition techniques for the development of copper-based catalysts and electrodes for tuned CO₂ reduction reaction (CO2RR). The first part introduces the CO2RR principles, electrolyzer types and components, and Cu electrocatalysts, highlighting their critical role in efficient CO2RR. Then, the principles of physical vapor deposition (PVD), chemical vapor deposition (CVD), and atomic layer deposition (ALD) are introduced, including the process variations and comparative advantages. This review highlights the most promising results obtained with Cu-based catalysts and electrodes for CO2RR via vapor deposition, with a particular focus on monometallic, bimetallic, single-atom, and modified Cu catalysts. The review concludes with our perspectives on applying vapor deposition techniques for advanced catalyst preparation. We emphasize that combining these techniques offers unique opportunities to fine tune the material properties at the nanoscale, thereby optimizing active sites for improved CO₂ conversion selectivity and activity.