Novel cinnamon carbon dots: amplifying aluminum’s mechanical properties and corrosion resistance in hydrochloric acid

• S. El-Housseiny¹, B.A. Abd-El-Nabey², A. Abdelrahman^2,3 and M.A. Abd-El-Fatah⁴

¹ Faculty of Sciences, Physics Department, Jouf University, Sakakah, Saudi Arabia
² Faculty of Science, Chemistry Department, Alexandria University, Alexandria, Egypt
³ EPROM-MIDOR Refinery, Laboratory Department, Alexandria, Egypt
⁴ Faculty of Education, Alexandria University, Alexandria, Egypt

Abstract: This study introduces cinnamon-derived carbon quantum dots (CCQDs) as a sustainable, high-efficiency anti-corrosion agent for aluminum in a 1.0 M hydrochloric acid solution. Comprehensive testing revealed outstanding inhibition efficiency of 95.7% at 400 mg/L. Polarization data indicated a dual-mode inhibition process with predominantly anodic inhibition. Surface analysis (XRD, EDX, XPS) confirmed strong adsorption of CCQDs onto aluminum, displacing chloride ions and reducing corrosive Al₂O₃ layer formation. The adsorption process was consistent with the Langmuir isotherm. A ΔG⁰_ads value of −26.6 kJ/mol was obtained, which points toward a cooperative physical adsorption mechanism. Furthermore, adding 400 mg/L CCQDs significantly enhanced the mechanical properties of aluminum; hardness increased from 3 to 8 GPa and tensile strength from 45 to 65 MPa. This improvement is assigned to the replacement of adsorbed chlorides by protective CCQD films. The adsorption of CCQDs, correlating with these mechanical gains, also followed Langmuir behavior, yielding ΔG⁰_ads values of −23.9 kJ/mol (for hardness) and −20.7 kJ/mol (for tensile strength), pointing to a physisorption-dominated process.

Keywords: carbon quantum dots, cinnamon, aluminum, corrosion inhibition, mechanical properties, HCl solution

Int. J. Corros. Scale Inhib., 2026, 15, no. 4, 197-229
doi: 10.17675/2305-6894-2026-15-4-8

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