Molten Salt Reduction of CO₂ to Graphite

Scientific Achievement

• Researchers in the MINES Program determined that Carbon-adsorbed peroxide intermediate facilitates graphite formation from CO₂ in molten salt
• Operando Raman revealed a transient but essential intermediate for the first time

Significance and Impact

• Resolves long-standing mechanistic ambiguity in molten-carbonate CO_₂-to-carbon electrolysis
• Peroxide intermediate common across four electrode materials

Research Details

• New high-temperature operando Raman spectro-electrochemical cell
• Two-step, two-electron reaction mechanism:
  • 2CO_₃^²⁻ + 2e⁻ ⇌ 2C(s) + 3O_₂^²⁻(ads)
  • O_₂^²⁻(ads) + 2e⁻ → 2O^²⁻

Publication Details

S. Ratso, M. L. Whittaker, K. Kaare, R. O. Scarlat,  Nature Communications (2026).

DOI: 10.1038/s41467-026-70977-0

Work was performed at Lawrence Berkeley National Laboratory.