Cold Plasma-Assisted Oxidation of Copper Powder: Synthesis and Characterization

Global warming driven by CO₂ emissions from carbon-based fuels, necessitates Carbon Capture, Utilization, and Storage (CCUS). Role of catalysts in carbon sequestration, especially for converting CO₂ to synthetic fuels has been critically important. Catalysts like Fe₂O₃, NiO, CeO₂, and CuO have been reported for converting CO₂ into fuels, with CuO showing the highest efficiency. While CuO synthesis methods (e.g., sputtering, thermal oxidation) exist, thermal oxidation process is common and dominates, but demands energy-intensive temperatures (>500°C). This conventional process also cannot control the preferred formation of CuO over other polymorphs such as Cu₂O, CuO₂ etc. Alternatively, plasma oxidation has emerged as a sustainable solution, enabling room-temperature CuO formation without the high energy or reactive environments of conventional methods. Additionally, plasma treatment enhances catalytic activity by increasing surface area, offering a scalable and energy-efficient solution for CCUS technologies. This study explores the glow discharge pulsed DC cold plasma oxidation of copper powder under controlled conditions, focusing on the influence of reaction time (10–80 minutes) and working pressure (0.5–2 mbar) in oxygen plasma atmosphere. XRD and Raman spectroscopy analyses demonstrated that Cu₂O was the dominant phase at lower sub-atmospheric pressures 0.5 mbar, while CuO prevailed at higher pressures 2 mbar. Prolonging the oxidation time (80 minutes) at constant pressure further enhanced CuO formation. Notably, the maximum recorded temperature during the process was 200 °C, revealing that copper oxide formation occurs at substantially lower temperatures than in conventional thermal oxidation.