An Analysis of the Electrolyte Resistivity Effect on the Pore Diameter and Pore Density of Anodic Aluminium Oxide (AAO) Films Produced by Single-Step Anodization

Nanoporous anodic aluminum oxide (AAO) layers were successfully fabricated on aluminum foil through an anodizing process in oxalic acid and mixed electrolytes of sulfuric and oxalic acid. The effect of electrolyte resistivity on the morphology of nanoporous AAO, such as pore diameter and pore density, was investigated. The nanoporous AAO layers‘bmorphology was examined using field emission scanning electron microscopy (FE-SEM) and analyzed using image analysis software. The results showed that anodizing in mixed electrolytes (sulfuric and oxalic acid) produced a much smaller pore diameter and a much higher pore density at lower voltage compared to anodizing in a single oxalic acid. For the anodizing process in oxalic acid, the pore diameters ranged from 14 to 52 nm, and the pore density ranged from 34?106 pores in 500×500 nm2. The anodizing process in the mixed electrolytes resulted in pore diameters within the range of 7?14 nm, and the pore densities were within the range of 211?779 pores in 500×500 nm2. Overall, increasing the electrolyte resistivity within the same solution leads to decreased pore diameter.

Anodic Aluminum Oxide; Electrolyte resistivity; Mixed electrolytes; Oxalic acid; Pores

Nanoporous AAO was successfully fabricated on aluminum foil through an anodizing process in oxalic acid and a mixed electrolyte of sulfuric and oxalic acids. Generally, the type of electrolyte and its resistivity can control pore diameter and density. For the anodizing process in oxalic acid, the measured pore diameter was in the range of 14.3±2.3 to 52.9±5.5 nm, and the pore density was in the range of 34±1.2 to 106±2.4 pores in 500×500 nm2. The higher the oxalic acid concentration, the wider the pore diameter and the lower the pore density produced. Adding 3 M sulfuric acid to oxalic acid electrolyte produced much smaller pore diameters and much higher pore densities at lower voltage compared to anodizing in a single oxalic acid. This mixed electrolyte produced a pore morphology as small as 7.2±1.2 nm in diameter and a density of 779.3±17.5 pores per 500×500 nm2. The significant difference in the diameter was attributed to the electrolyte’s acidity, which affects the electrolyte’s resistivity. Increasing the electrolyte resistivity within the same type of solution led to decreasing the pore diameter.

Aerts, T., De Graeve, I., Terryn, H., 2009. Control of the Electrode Temperature for Electrochemical Studies: A New Approach Illustrated on Porous Anodizing of Aluminium. Electrochemistry Communications, Volume 11(12), pp. 2292–2295

Aerts, T., Jorcin, J.-B., Graeve, I.D., Terryn, H., 2010. Comparison between the Influence of Applied Electrode and Electrolyte Temperatures on Porous Anodizing of Aluminium. Electrochimica Acta, Volume 55(12), pp. 3957–3965

Bartolomé, M.J., Lopez, V., Escudero, E., Caruana, G., Gonzales, J.A., 2006. Changes in the Specific Surface Area of Porous Aluminium Oxide Films during Sealing. Surface and Coatings Technology, Volume 200(14–15), pp. 4530–4537

Belwalkar, A., Grasing, E., Geertruyden,W.V., Huang, Z., Misiolek, W.Z., 2008. Effect of Processing Parameters on Pore Structure and Thickness of Anodic Aluminum Oxide (AAO) Tubular Membranes. Journal of Membrane Science, Volume 319(1–2), pp. 192–198

Benenson, W., Harris, J.W., Stocker, H., Lutz, H., 2002. Handbook of Physics (1st ed.). New York, NY: Springer-Verlag New York

Bensalah, W., Feki, M., Wery, M., Ayedi, H.F., 2011. Chemical Dissolution Resistance of Anodic Oxide Layers Formed on Aluminum. Transactions of Nonferrous Metals Society of China (English Edition), Volume 21(7), pp. 1673–1679

Chung, C.K., Liao, M.W., Chang, H.C., Lee, C.T., 2011. Effects of Temperature and Voltage Mode on Nanoporous Anodic Aluminum Oxide Films by One-step Anodization. Thin Solid Films, Volume 520(5), pp. 1554–1558

Chung, C.K., Li, C.H., Hsieh, Y.Y., Wang, Z.W., 2017. Microstructure and Photoluminescence of Sputtered Silicon-rich-nitride on Anodic Aluminum Oxide Annealed at Low Temperature. Journal of Alloys and Compounds, Volume 709, pp. 658–662

Dhaneswara, D., Sofyan, E., 2016. Effect of Different Pluronic P123 Triblock Copolymer Surfactant Concentrations on SBA-15 Pore Formation. International Journal of Technology, Volume 7(6), pp. 1009–1015

Gao, L., Wang, P., Wu, X., Yang, S., Song, X., 2008. A New Method Detaching Porous Anodic Alumina Films from Aluminum Substrates. Journal of Electroceramics, Volume 21(1–4), pp. 791–794

Gering, K.L., 2017. Prediction of Electrolyte Conductivity: Results from a Generalized Molecular Model based on Ion Solvation and a Chemical Physics Framework. Electrochimica Acta, No. 225, pp. 175–189

Hao, Q., Qiu, T., Chu, P.K., 2012. Surfaced-enhanced Cellular Fluorescence Imaging. Progress in Surface Science, Volume 87(1–4), pp. 23–45

Ingham, C.J., ter Maat, J., de Vos, W.M., 2012. Where Bio Meets Nano: The Many Uses for Nanoporous Aluminum Oxide in Biotechnology. Biotechnology Advances, Volume 30(5), pp. 1089–1099

Kang, H.-J., Kim, D.J., Park, S.-J., Yoo, J.-B., Ryu, Y.S., 2007. Controlled Drug Release Using Nanoporous Anodic Aluminum Oxide on Stent. Thin Solid Films, Volume 515(12), pp. 5184–5187

Kao, T.T., Chang, Y.C., 2014. Influence of Anodization Parameters on the Volume Expansion of Anodic Aluminum Oxide Formed in Mixed Solution of Phosphoric and Oxalic Acids. Applied Surface Science, Volume 288, pp. 654–659

Keshavarz, A., Parang, Z., Nasseri, A., 2013. The Effect of Sulfuric Acid, Oxalic Acid, and Their Combination on the Size and Regularity of the Porous Alumina by Anodization. Journal of Nanostructure in Chemistry, Volume 3(34), https://doi.org/10.1186/2193-8865-3-34

Kikuchi, T., Yamamoto, T., Natsui, S., Suzuki, R.O., 2014. Fabrication of Anodic Porous Alumina by Squaric Acid Anodizing. Electrochimica Acta, No. 123, pp. 14–22

Lee, J., Jung, U., Kim, W., Chung, W., 2013. Effects of Residual Water in the Pores of Aluminum Anodic Oxide Layers Prior to Sealing on Corrosion Resistance. Applied Surface Science, Volume 283, pp. 941–946 

Prihandana, G.S., Sriani, T., Mahardika, M., 2015. Review of Surface Modification of Nanoporous Polyethersulfone Membrane as a Dialysis Membrane. International Journal of Technology, Volume 6(6), pp. 1025–1030

Nguyen, V.H., Sichanugrist, P.,Kato, S., Usami, N., 2017. Impact of Anodic Aluminum Oxide Fabrication and Post-deposition Anneal on the Effective Carrier Lifetime of Vertical Silicon Nanowires. Solar Energy Materials and Solar Cells, Volume 166, pp. 39–44

Rizkia, V., Munir, B., Soedarsono, J.W., Suharno, B., Rustandi, A., 2014. Growth of Porous Alumina Layer and Cerium Sealing of Al7xxx/SiC Composite for Structural Lightweight Alloy Corrosion Resistant Application. Advanced Materials Research, Volume 911, pp. 55–59

Rizkia, V., Munir, B., Soedarsono, J.W., Suharno, B., 2015. Corrosion Resistance Enhancement of an Anodic Layer on an Aluminum Matrix Composite by Cerium Sealing. International Journal of Technology, Volume 6(7), pp. 1191–1197

Stêpniowski, W.J., Norek, M., Michalska-Domanska, M., Bombalska, A., Nowak-Stepniowska, A., Kwasny, M., Bojar, Z., 2012. Fabrication of Anodic Aluminum Oxide with Incorporated Chromate Ions. Applied Surface Science, Volume 259, pp. 324–330

St?pniowski, W.J., Forbot, D., Norek, M., Michalska-Domanska, M., Krol, A., 2014. The Impact of Viscosity of the Electrolyte on the Formation of Nanoporous Anodic Aluminum Oxide. Electrochimica Acta, Volume 133, pp. 57–64

Stepniowski, W.J., Zasada, D., Bojar, Z., 2011. First Step of Anodization Influences the Final Nanopore Arrangement in Anodized Alumina. Surface & Coatings Technologys, Volume 206, pp. 1416–1422

Sulka, G.D., 2008. Highly Ordered Anodic Porous Alumina Formation by Self Organized Anodizing A. Eftekhari, ed., Weinheim: Wiley-VCH Verlag GmbH & Co

Sulka, G.D., Parko?a, K.G., 2007. Temperature Influence on Well-ordered Nanopore Structures Grown by Anodization of Aluminium in Sulphuric Acid. Electrochimica Acta, Volume 52(5), pp. 1880–1888

Tamburrano, A., Vivo, B.D., Hoijer, M., Arurault, L., Tucci, V., Fontorbes, S., Lamberti, P., Vilar, V., Daffos, B., Sarto, M.S., 2011. Effect of Electric Field Polarization and Temperature on the Effective Permittivity and Conductivity of Porous Anodic Aluminium Oxide Membranes. Microelectronic Engineering, Volume 88(11), pp. 3338–3346

Theohari, S., Kontogeorgou, C., 2013. Effect of Temperature on the Anodizing Process of Aluminum Alloy AA 5052. Applied Surface Science, Volume 284, pp. 611–618

Voon, C.H., Derman, M.N., Hashim, U., Ahmad, K.R., Foo, K.L., 2013. Effect of Temperature of Oxalic Acid on the Fabrication of Porous Anodic Alumina from Al-Mn Alloys. Journal of Nanomaterials, Volume 2013, pp. 1–8

Vrublevsky, I., Parkoun, V., Schreckenbach, J., Goedel, W.A., 2006. Dissolution Behaviour of the Barrier Layer of Porous Oxide Films on Aluminum Formed in Phosphoric Acid Studied by a Re-anodizing Technique. Applied Surface Science, Volume 252(14), pp. 5100–5108

Vrublevsky, I., Chernyakova, K., Bund, A., Ispas, A., Schmidt, U., 2012. Effect of Anodizing Voltage on the Sorption of Water Molecules on Porous Alumina. Applied Surface Science, Volume 258(14), pp. 5394–5398

Wang, Y., Kuo, H.H., Kia, S., 2006. Effect of Alloy Types on the Anodizing Process of Aluminum. Surface & Coatings Technology, Volume 200, pp. 2634–2641

Wu, C., Sun, H., Li, Y., Liu, X., Du, X., Wang, X., Xu, P., 2015. Biosensor based on Glucose Oxidase-nanoporous Gold Co-catalysis for Glucose Detection. Biosensors and Bioelectronics, Volume 66, pp. 350–355 

Zahariev, A., Kanazirski, I., Girginov, A., 2008. Anodic Alumina Films Formed in Sulfamic Acid Solution. Inorganica Chimica Acta, Volume 361(6), pp. 1789–1792

Zaraska, L., Stepniowski, W.J., Ciepiela, E., Sulka, G.D., 2013. The Effect of Anodizing Temperature on Structural Features and Hexagonal Arrangement of Nanopores in Alumina Synthesized by Two-step Anodizing in Oxalic Acid. Thin Solid Films, Volume 534, pp. 155–161