<p>Nanocarbon materials have attracted attention due to their unique properties and wide range of applications; however, their production requires high temperatures and pressures. This study provides a novel method for electrodeposition of carbon nanoparticles onto an Ag substrate from CO₂ using a potential-step application in P₂₂₂₅-TFSI at room temperature and medium pressure. Potential-step electrolysis, where − 3.0, − 0.40, and − 1.0&#xa0;V (vs. Ag⁺/Ag) were applied for 1&#xa0;min each, was conducted to reduce CO₂ to silver carbonyl ions, which were then electrochemically reduced to carbon nanoparticles. The SEM images and XRD analysis of the electrodeposited material revealed that the carbon nanoparticles formed near the three-phase interface under an 8.0&#xa0;atm CO₂ atmosphere consist of graphite with a defective structure and ca. 13.7&#xa0;nm in size. As the CO₂ pressure increased from 1.0 to 8.0&#xa0;atm, the size of carbon nanoparticles decreased. Raman spectroscopy revealed that as the CO₂ pressure increased, the crystallinity of carbon improved near the three-phase interface of Ag/P₂₂₂₅-TFSI/CO₂. Moreover, in electrodeposited carbon obtained at 8.0&#xa0;atm CO₂ atmosphere, the crystallinity difference of approximately 0.1 in the I_D/I_G ratio was observed between at the three-phase interface and at the two-phase interface of Ag/P₂₂₂₅-TFSI. The reported data demonstrate that nanocarbon can be electrodeposited by injecting medium-pressure CO₂ at room temperature, which is&#xa0;expected to broaden the options for nanocarbon production methods and enable the production of functional carbon materials as a new CO₂ recycling technology.</p> Graphical Abstract <p></p>