Repassivation of the damage generated by cavitation on UNS N08031 in a LiBr solution by means of electrochemical techniques and Confocal Laser Scanning Microscopy

The objective of this work is to study the influence of cavitation on the corrosion behaviour of Alloy 31, a highly-alloyed austenitic stainless steel (UNS N08031), in a LiBr heavy brine solution (992 g/L) at 25 °C. The presence of cavitation shifted the OCP value towards the active direction by 708 mVAg/AgCl, increased anodic current densities and passivation current density, ip, and reduced the pitting potential, Ep. Repassivation behaviour of Alloy 31 has been investigated by using potentiostatic tests at different potentials. The current density transient obtained after interrupting cavitation was used to obtain the repassivation index, n, provided by the slope of the log i(t) vs. log t representation. The value of n decreased as the applied potential was increased, reaching values near zero for potentials close to the pitting potential. The damage generated during the potentiostatic tests has been quantified by means of Confocal Laser Scanning Microscopy

Effect of Temperature on Thermogalvanic Coupling of Alloy 31 in Libr Solutions Studied by Means of Imposed Potential Measurements

Corrosion resistance of Alloy 31, a highly alloyed stainless steel (UNS N08031) were studied in heavy brine LiBr solutions (400, 700 and 992 g/l) at different temperatures using electrochemical techniques. The mixed potential theory was used to evaluate thermogalvanic corrosion of Alloy 31 in the studied LiBr solutions. Potentiodynamic curves indicate that high temperatures favoured both cathodic and anodic processes, increasing passive current densities and decreasing the pitting potential. Generally, the cold electrode of the pair was the anode of the thermogalvanic cell

Thermogalvanic corrosion of Alloy 31 in different heavy brine LiBr solutions

Thermogalvanic corrosion generated between two electrodes of Alloy 31, a highly-alloyed austenitic stainless steel (UNS N08031), has been investigated imposing different temperature gradients in three deaerated LiBr solutions, under open circuit conditions by using a zero-resistance ammeter (ZRA). Besides EIS spectra were acquired in order to explain the obtained results. On the whole, cold Alloy 31 electrodes were anodic to hot Alloy 31 electrodes, since an increase in temperature favoured the cathodic behaviour of the hot electrode. Thermogalvanic corrosion of Alloy 31 in the LiBr solutions studied was not severe, although it negatively affects the corrosion resistance of the cold anode. The protective properties of the passive film formed on the anode surface were found to improve with thermogalvanic coupling time

Effects of the area of a duplex stainless steel exposed to corrosion on the cathodic and anodic reactions in a LiBr solution under static and dynamic conditions

[EN] The objective of the work was to study the influence of the exposed area of the working electrode on the corrosion behavior of a duplex stainless steel (EN 1.4462) in a 992 g/l LiBr solution under static conditions (without cavitation) and dynamic conditions (with cavitation) at 25 °C. The Potentiodynamic Cyclic curves obtained were compared and different tendencies were observed. Cavitation increased the cathodic current density when the area exposed to the solution is large (diameters 6 and 8 mm). This behavior was not observed in the tests with smaller electrode areas (diameters 1.6 and 4 mm). © 2011 by ESG.We wish to express our gratitude to Ministerio de Ciencia e Innovación (CTQ2009-07518/PPQ), to FEDER for their financial support and to Dr. M. Asunción Jaime for her translation assistance.García-García, D.; Blasco-Tamarit, E.; Garcia-Anton, J. (2011). Effects of the area of a duplex stainless steel exposed to corrosion on the cathodic and anodic reactions in a LiBr solution under static and dynamic conditions. International Journal of Electrochemical Science. 6(5):1237-1249. http://hdl.handle.net/10251/61155S123712496

Should TiO2 nanostructures doped with Li+ be used as photoanodes for photoelectrochemical water splitting applications?

Different TiO2 nanostructures, nanotubes and nanosponges, were obtained by anodization of Ti under stagnant and hydrodynamic conditions. Samples were doped with Li+ before and after annealing at 450 °C during 1 h. The nanostructures were characterized by different microscopy techniques: Field Emission Scanning Electron Microscopy (FE-SEM) and Raman Confocal Laser Microscopy. Additionally, Incident Photon-to-electron Conversion Efficiency (IPCE), photoelectrochemical water splitting and stability measurements were also performed. According to the results, TiO2 nanostructures doped before annealing present the worst photocurrent response, even if compared with undoped samples. On the other hand, this study reveals that Li+-doped TiO2 nanostructures doped after annealing can be used as durable and stable photoanodes for photoelectrochemical water splitting applications

Passivity Breakdown of Titanium in LiBr solutions

The passive behavior of titanium and its susceptibility to undergo localized attack in different LiBr solutions at 25 degrees C have been investigated using different electrochemical techniques: potentiodynamic polarization curves, potentiostatic passivation tests, EIS measurements and Mott-Schottky analysis. In low and moderately concentrated LiBr solutions, the breakdown potential E-b decreased with increasing bromide concentrations, while in highly concentrated LiBr solutions, E-b increased with increasing LiBr concentration. In the most concentrated LiBr solution (11.42M) Ti did not undergo passivity breakdown even at 9 V-Ag/AgCl. This observation can be explained by a a decrease in the activity of water in highly concentrated LiBr solutions. (C) 2013 The Electrochemical Society.We wish express our gratitude to the Ministerio de Ciencia e Innovacion (Project CTQ2009-07518), and to Dr. M. Asuncion Jaime. for her translation assistance.Fernández Domene, RM.; Blasco-Tamarit, E.; García-García, D.; García Antón, J. (2014). Passivity Breakdown of Titanium in LiBr solutions. Journal of The Electrochemical Society. 161(1):25-35. https://doi.org/10.1149/2.035401jesS25351611Been J. Grauman J. S. , in: Uhlig's Corrosion Handbook, 2nd ed., Winston Revie R. (ed.), 863-885, Wiley Interscience, New York (2000).Blasco-Tamarit, E., Igual-Muñoz, A., García Antón, J., & García-García, D. (2007). Corrosion behaviour and galvanic coupling of titanium and welded titanium in LiBr solutions. Corrosion Science, 49(3), 1000-1026. doi:10.1016/j.corsci.2006.07.007Huang, Y. Z., & Blackwood, D. J. (2005). Characterisation of titanium oxide film grown in 0.9% NaCl at different sweep rates. Electrochimica Acta, 51(6), 1099-1107. doi:10.1016/j.electacta.2005.05.051Pan, J., Thierry, D., & Leygraf, C. (1996). Electrochemical impedance spectroscopy study of the passive oxide film on titanium for implant application. Electrochimica Acta, 41(7-8), 1143-1153. doi:10.1016/0013-4686(95)00465-3Assis, S. L. de, Wolynec, S., & Costa, I. (2006). Corrosion characterization of titanium alloys by electrochemical techniques. Electrochimica Acta, 51(8-9), 1815-1819. doi:10.1016/j.electacta.2005.02.121Birch, J. R., & Burleigh, T. D. (2000). Oxides Formed on Titanium by Polishing, Etching, Anodizing, or Thermal Oxidizing. CORROSION, 56(12), 1233-1241. doi:10.5006/1.3280511Peláez-Abellán, E., Rocha-Sousa, L., Müller, W.-D., & Guastaldi, A. C. (2007). Electrochemical stability of anodic titanium oxide films grown at potentials higher than 3V in a simulated physiological solution. Corrosion Science, 49(3), 1645-1655. doi:10.1016/j.corsci.2006.08.010Azumi, K., & Seo, M. (2001). Changes in electrochemical properties of the anodic oxide film formed on titanium during potential sweep. Corrosion Science, 43(3), 533-546. doi:10.1016/s0010-938x(00)00105-0Alves, V. A., Reis, R. Q., Santos, I. C. B., Souza, D. G., de F. Gonçalves, T., Pereira-da-Silva, M. A., … da Silva, L. A. (2009). In situ impedance spectroscopy study of the electrochemical corrosion of Ti and Ti–6Al–4V in simulated body fluid at 25°C and 37°C. Corrosion Science, 51(10), 2473-2482. doi:10.1016/j.corsci.2009.06.035Schmidt, A. M., Azambuja, D. S., & Martini, E. M. A. (2006). Semiconductive properties of titanium anodic oxide films in McIlvaine buffer solution. Corrosion Science, 48(10), 2901-2912. doi:10.1016/j.corsci.2005.10.013Sellers, M. C. K., & Seebauer, E. G. (2011). Measurement method for carrier concentration in TiO2 via the Mott–Schottky approach. Thin Solid Films, 519(7), 2103-2110. doi:10.1016/j.tsf.2010.10.071Jiang, Z., Dai, X., & Middleton, H. (2011). Investigation on passivity of titanium under steady-state conditions in acidic solutions. Materials Chemistry and Physics, 126(3), 859-865. doi:10.1016/j.matchemphys.2010.12.028Kong, D.-S., Lu, W.-H., Feng, Y.-Y., Yu, Z.-Y., Wu, J.-X., Fan, W.-J., & Liu, H.-Y. (2009). Studying on the Point-Defect-Conductive Property of the Semiconducting Anodic Oxide Films on Titanium. Journal of The Electrochemical Society, 156(1), C39. doi:10.1149/1.3021008Roh, B., & Macdonald, D. D. (2007). Effect of oxygen vacancies in anodic titanium oxide films on the kinetics of the oxygen electrode reaction. Russian Journal of Electrochemistry, 43(2), 125-135. doi:10.1134/s1023193507020012Sazou, D., Saltidou, K., & Pagitsas, M. (2012). Understanding the effect of bromides on the stability of titanium oxide films based on a point defect model. Electrochimica Acta, 76, 48-61. doi:10.1016/j.electacta.2012.04.158Roberge P. R. , Handbook of Corrosion Engineering, p. 756, McGraw-Hill, New York (2000).Basame, S. B., & White, H. S. (1995). Scanning electrochemical microscopy of native titanium oxide films. Mapping the potential dependence of spatially-localized electrochemical reactions. The Journal of Physical Chemistry, 99(44), 16430-16435. doi:10.1021/j100044a034Basame, S. B., & White, H. S. (2000). Pitting Corrosion of Titanium The Relationship Between Pitting Potential and Competitive Anion Adsorption at the Oxide Film/Electrolyte Interface. Journal of The Electrochemical Society, 147(4), 1376. doi:10.1149/1.1393364Dugdale, I., & Cotton, J. B. (1964). The anodic polarization of titanium in halide solutions. Corrosion Science, 4(1-4), 397-411. doi:10.1016/0010-938x(64)90041-1Virtanen, S., & Curty, C. (2004). Metastable and Stable Pitting Corrosion of Titanium in Halide Solutions. CORROSION, 60(7), 643-649. doi:10.5006/1.3287839Trompette, J. L., Massot, L., Arurault, L., & Fontorbes, S. (2011). Influence of the anion specificity on the anodic polarization of titanium. Corrosion Science, 53(4), 1262-1268. doi:10.1016/j.corsci.2010.12.021Casillas, N. (1994). Pitting Corrosion of Titanium. Journal of The Electrochemical Society, 141(3), 636. doi:10.1149/1.2054783Beck, T. R. (1973). Pitting of Titanium. Journal of The Electrochemical Society, 120(10), 1310. doi:10.1149/1.2403253Huo, S., & Meng, X. (1990). The states of bromide on titanium surface prior to pit initiation. Corrosion Science, 31, 281-286. doi:10.1016/0010-938x(90)90120-tFernández-Domene, R. M., Blasco-Tamarit, E., García-García, D. M., & García-Antón, J. (2011). Cavitation corrosion and repassivation kinetics of titanium in a heavy brine LiBr solution evaluated by using electrochemical techniques and Confocal Laser Scanning Microscopy. Electrochimica Acta, 58, 264-275. doi:10.1016/j.electacta.2011.09.034Srikhirin, P., Aphornratana, S., & Chungpaibulpatana, S. (2001). A review of absorption refrigeration technologies. Renewable and Sustainable Energy Reviews, 5(4), 343-372. doi:10.1016/s1364-0321(01)00003-xLee R. J. DiGuilio R. M. Jeter S. M. Teja A. S. , ASHRAE Tran., 96(1), (1990).Guiñon, J. L., Garcia-Anton, J., Pérez-Herranz, V., & Lacoste, G. (1994). Corrosion of Carbon Steels, Stainless Steels, and Titanium in Aqueous Lithium Bromide Solution. CORROSION, 50(3), 240-246. doi:10.5006/1.3293516Florides, G. A., Kalogirou, S. A., Tassou, S. A., & Wrobel, L. C. (2003). Design and construction of a LiBr–water absorption machine. Energy Conversion and Management, 44(15), 2483-2508. doi:10.1016/s0196-8904(03)00006-2Misra, R. D., Sahoo, P. K., & Gupta, A. (2005). Thermoeconomic evaluation and optimization of a double-effect H2O/LiBr vapour-absorption refrigeration system. International Journal of Refrigeration, 28(3), 331-343. doi:10.1016/j.ijrefrig.2004.09.006Hamer, W. J., & Wu, Y. (1972). Osmotic Coefficients and Mean Activity Coefficients of Uni‐univalent Electrolytes in Water at 25°C. Journal of Physical and Chemical Reference Data, 1(4), 1047-1100. doi:10.1063/1.3253108Prausnitz J. M. Lichtenthaler R. N. Azevedo E. G. , Molecular Thermodynamics of Fluid-Phase Equilibria, p. 517, Prentice Hall, Upper Saddle River, NJ (1999).Blandamer, M. J., Engberts, J. B. F. N., Gleeson, P. T., & Reis, J. C. R. (2005). Activity of water in aqueous systems; A frequently neglected property. Chemical Society Reviews, 34(5), 440. doi:10.1039/b400473fSelcuk, H., Sene, J. J., Zanoni, M. V. B., Sarikaya, H. Z., & Anderson, M. A. (2004). Behavior of bromide in the photoelectrocatalytic process and bromine generation using nanoporous titanium dioxide thin-film electrodes. Chemosphere, 54(7), 969-974. doi:10.1016/j.chemosphere.2003.09.016Muñoz, A. I., Antón, J. G., Guiñón, J. L., & Herranz, V. P. (2003). Corrosion Behavior and Galvanic Coupling of Stainless Steels, Titanium, and Alloy 33 in Lithium Bromide Solutions. CORROSION, 59(7), 606-615. doi:10.5006/1.3277591Muñoz-Portero, M. J., García-Antón, J., Guiñón, J. L., & Leiva-García, R. (2011). Pourbaix diagrams for titanium in concentrated aqueous lithium bromide solutions at 25°C. Corrosion Science, 53(4), 1440-1450. doi:10.1016/j.corsci.2011.01.013Davydov, A. . (2001). Breakdown of valve metal passivity induced by aggressive anions. Electrochimica Acta, 46(24-25), 3777-3781. doi:10.1016/s0013-4686(01)00664-8Lin, L. F. (1981). A Point Defect Model for Anodic Passive Films. Journal of The Electrochemical Society, 128(6), 1194. doi:10.1149/1.2127592Haruna, T. (1997). Theoretical Prediction of the Scan Rate Dependencies of the Pitting Potential and the Probability Distribution in the Induction Time. Journal of The Electrochemical Society, 144(5), 1574. doi:10.1149/1.1837643Macdonald, D. D. (1992). The Point Defect Model for the Passive State. Journal of The Electrochemical Society, 139(12), 3434. doi:10.1149/1.2069096Macdonald, D. D. (1999). Passivity–the key to our metals-based civilization. Pure and Applied Chemistry, 71(6), 951-978. doi:10.1351/pac199971060951Macdonald, D. D. (2011). The history of the Point Defect Model for the passive state: A brief review of film growth aspects. Electrochimica Acta, 56(4), 1761-1772. doi:10.1016/j.electacta.2010.11.005Macdonald, D. D., & Sun, A. (2006). An electrochemical impedance spectroscopic study of the passive state on Alloy-22. Electrochimica Acta, 51(8-9), 1767-1779. doi:10.1016/j.electacta.2005.02.103Park, K., Ahn, S., & Kwon, H. (2011). Effects of solution temperature on the kinetic nature of passive film on Ni. Electrochimica Acta, 56(3), 1662-1669. doi:10.1016/j.electacta.2010.09.077Macdonald, D. D. (2008). On the tenuous nature of passivity and its role in the isolation of HLNW. Journal of Nuclear Materials, 379(1-3), 24-32. doi:10.1016/j.jnucmat.2008.06.004Paola, A. D. (1989). Semiconducting properties of passive films on stainless steels. Electrochimica Acta, 34(2), 203-210. doi:10.1016/0013-4686(89)87086-0Gomes, W. P., & Vanmaekelbergh, D. (1996). Impedance spectroscopy at semiconductor electrodes: Review and recent developments. Electrochimica Acta, 41(7-8), 967-973. doi:10.1016/0013-4686(95)00427-0Da Cunha Belo, M., Hakiki, N. ., & Ferreira, M. G. . (1999). Semiconducting properties of passive films formed on nickel–base alloys type Alloy 600: influence of the alloying elements. Electrochimica Acta, 44(14), 2473-2481. doi:10.1016/s0013-4686(98)00372-7Hakiki, N. B., Boudin, S., Rondot, B., & Da Cunha Belo, M. (1995). The electronic structure of passive films formed on stainless steels. Corrosion Science, 37(11), 1809-1822. doi:10.1016/0010-938x(95)00084-wHamadou, L., Kadri, A., & Benbrahim, N. (2005). Characterisation of passive films formed on low carbon steel in borate buffer solution (pH 9.2) by electrochemical impedance spectroscopy. Applied Surface Science, 252(5), 1510-1519. doi:10.1016/j.apsusc.2005.02.135Wijesinghe, T. L. S. L., & Blackwood, D. J. (2008). Photocurrent and capacitance investigations into the nature of the passive films on austenitic stainless steels. Corrosion Science, 50(1), 23-34. doi:10.1016/j.corsci.2007.06.009Amri, J., Souier, T., Malki, B., & Baroux, B. (2008). Effect of the final annealing of cold rolled stainless steels sheets on the electronic properties and pit nucleation resistance of passive films. Corrosion Science, 50(2), 431-435. doi:10.1016/j.corsci.2007.08.013Li, D. G., Wang, J. D., & Chen, D. R. (2012). Influence of potentiostatic aging, temperature and pH on the diffusivity of a point defect in the passive film on Nb in an HCl solution. Electrochimica Acta, 60, 134-146. doi:10.1016/j.electacta.2011.11.024Fernández-Domene, R. M., Blasco-Tamarit, E., García-García, D. M., & García-Antón, J. (2013). Passive and transpassive behaviour of Alloy 31 in a heavy brine LiBr solution. Electrochimica Acta, 95, 1-11. doi:10.1016/j.electacta.2013.02.024Urquidi-Macdonald, M. (1989). Theoretical Analysis of the Effects of Alloying Elements on Distribution Functions of Passivity Breakdown. Journal of The Electrochemical Society, 136(4), 961. doi:10.1149/1.2096894Schmidt, A. M., & Azambuja, D. S. (2006). Electrochemical behavior of Ti and Ti6Al4V in aqueous solutions of citric acid containing halides. Materials Research, 9(4), 387-392. doi:10.1590/s1516-14392006000400008Brug, G. J., van den Eeden, A. L. G., Sluyters-Rehbach, M., & Sluyters, J. H. (1984). The analysis of electrode impedances complicated by the presence of a constant phase element. Journal of Electroanalytical Chemistry and Interfacial Electrochemistry, 176(1-2), 275-295. doi:10.1016/s0022-0728(84)80324-1Valero Vidal, C., & Igual Muñoz, A. (2010). Study of the adsorption process of bovine serum albumin on passivated surfaces of CoCrMo biomedical alloy. Electrochimica Acta, 55(28), 8445-8452. doi:10.1016/j.electacta.2010.07.028Smart, N. G., & Bockris, J. O. (1992). Effect of Water Activity on Corrosion. CORROSION, 48(4), 277-280. doi:10.5006/1.3315933Frankel, G. S. (1998). Pitting Corrosion of Metals. Journal of The Electrochemical Society, 145(6), 2186. doi:10.1149/1.1838615Blasco-Tamarit, E., Igual-Muñoz, A., & García-Antón, J. (2007). Galvanic corrosion of high alloyed austenitic stainless steel welds in LiBr systems. Corrosion Science, 49(12), 4452-4471. doi:10.1016/j.corsci.2007.05.020Crozier, P. S., & Rowley, R. L. (2002). Activity coefficient prediction by osmotic molecular dynamics. Fluid Phase Equilibria, 193(1-2), 53-73. doi:10.1016/s0378-3812(01)00734-8Burstein, G. T. (1989). The Dissolution and Repassivation of New Titanium Surfaces in Alkaline Methanolic Solution. Journal of The Electrochemical Society, 136(5), 1313. doi:10.1149/1.2096913Banaś, J., Stypuła, B., Banaś, K., Światowska-Mrowiecka, J., Starowicz, M., & Lelek-Borkowska, U. (2008). Corrosion and passivity of metals in methanol solutions of electrolytes. Journal of Solid State Electrochemistry, 13(11), 1669-1679. doi:10.1007/s10008-008-0649-5Beck K. O. , Titanium anodizing process, US Patent 2,949, 411 (1960).Delplancke, J.-L., Degrez, M., Fontana, A., & Winand, R. (1982). Self-colour anodizing of titanium. Surface Technology, 16(2), 153-162. doi:10.1016/0376-4583(82)90033-4Gaul, E. (1993). Coloring titanium and related metals by electrochemical oxidation. Journal of Chemical Education, 70(3), 176. doi:10.1021/ed070p176Sul, Y.-T., Johansson, C. B., Jeong, Y., & Albrektsson, T. (2001). The electrochemical oxide growth behaviour on titanium in acid and alkaline electrolytes. Medical Engineering & Physics, 23(5), 329-346. doi:10.1016/s1350-4533(01)00050-9Yan, Z.  M., Guo, T.  W., Pan, H.  B., & Yu, J.  J. (2002). Influences of Electrolyzing Voltage on Chromatics of Anodized Titanium Dentures. MATERIALS TRANSACTIONS, 43(12), 3142-3145. doi:10.2320/matertrans.43.3142Chen, C., Chen, J., Chao, C., & Say, W. C. (2005). Electrochemical characteristics of surface of titanium formed by electrolytic polishing and anodizing. Journal of Materials Science, 40(15), 4053-4059. doi:10.1007/s10853-005-2802-1Diamanti, M. V., Del Curto, B., & Pedeferri, M. (2008). Interference colors of thin oxide layers on titanium. Color Research & Application, 33(3), 221-228. doi:10.1002/col.20403Karambakhsh, A., Afshar, A., Ghahramani, S., & Malekinejad, P. (2011). Pure Commercial Titanium Color Anodizing and Corrosion Resistance. Journal of Materials Engineering and Performance, 20(9), 1690-1696. doi:10.1007/s11665-011-9860-

Study of the effect of temperature on the galvanic corrosion between Alloy 31 base metal and its weld in polluted phosphoric acid

This work studies the influence of the solution temperature on the corrosion resistance of a high alloyed austenitic stainless steel (UNS N08031) used as Base Metal (BM), the Heat Affected Zone (HAZ) and the Weld Metal (WM) obtained by the Gas Tungsten Arc Welding technique using a Nickel-base alloy (UNS N06059) as filler metal (GTAW). Electrochemical tests were carried out in a 5.5 M polluted phosphoric acid solution with 0.03 wt% (380 ppm) of chloride ions and 2 wt% of H2SO4 at 25, 40, 60 and 80 degrees C. The potentiodynamic curves of the materials were registered in each condition under study and electrochemical parameters such as E-corr, i(corr), E-b and i(p) were obtained. The galvanic corrosion generated between the BM-HAZ and HAZ-WM pairs was also analysed by means of the Mixed Potential Theory. The lower E-b and (E-b-E-corr) values and higher ip values obtained at higher temperatures indicate that the properties of the passive film formed degraded with temperature. The welding process modifies the characteristics of the passive film, deteriorating them and favouring the loss of passivity of the WM with respect to the BM, as shown by the lowest E-b values and highest i(p) values of the WM.Blasco-Tamarit, E.; García-García, D.; Garcia-Anton, J.; Guenbour, A. (2011). Study of the effect of temperature on the galvanic corrosion between Alloy 31 base metal and its weld in polluted phosphoric acid. International Journal of Electrochemical Science. 6(12):6244-6260. http://hdl.handle.net/10251/61160S6244626061

TiO2 Nanostructures for Photoelectrocatalytic Degradation of Acetaminophen

Advanced oxidation processes driven by renewable energy sources are gaining attention in degrading organic pollutants in waste waters in an efficient and sustainable way. The present work is focused on a study of TiO2 nanotubes as photocatalysts for photoelectrocatalytic (PEC) degradation of acetaminophen (AMP) at different pH (3, 7, and 9). In particular, different TiO2 photocatalysts were synthetized by stirring the electrode at different Reynolds numbers (Res) during electrochemical anodization. The morphology of the photocatalysts and their crystalline structure were evaluated by field emission scanning electron microscopy (FESEM) and Raman confocal laser microscopy (RCLM). These analyses revealed that anatase TiO2 nanotubes were obtained after anodization. In addition, photocurrent densities versus potential curves were performed in order to characterize the electrochemical properties of the photocatalysts. These results showed that increasing the Re during anodization led to an enhancement in the obtained photocurrents, since under hydrodynamic conditions part of the initiation layer formed over the tubes was removed. PEC degradation of acetaminophen was followed by ultraviolet-visible absorbance measurements and chemical oxygen demand tests. As drug mineralization was the most important issue, total organic carbon measurements were also carried out. The statistical significance analysis established that acetaminophen PEC degradation improved as hydrodynamic conditions linearly increased in the studied range (Re from 0 to 600). Additionally, acetaminophen conversion had a quadratic behavior with respect to the reaction pH, where the maximum conversion value was reached at pH 3. However, in this case, the diversity of the byproducts increased due to a different PEC degradation mechanism

Original Approach to Synthesize TiO2/ZnO Hybrid nanosponges used as photoanodes for photoelectrochemical applications

[EN] In the present work, TiO2/ZnO hybrid nanosponges have been synthesized for the first time. First, TiO2 nanosponges were obtained by anodization under hydrodynamic conditions in a glycerol/water/NH4F electrolyte. Next, in order to achieve the anatase phase of TiO2 and improve its photocatalytic behaviour, the samples were annealed at 450 degrees C for 1 h. Once the TiO2 nanosponges were synthesized, TiO2/ZnO hybrid nanosponges were obtained by electrodeposition of ZnO on TiO2 nanosponges using different temperatures, times, and concentrations of zinc nitrate (Zn(NO3)(2)). TiO2/ZnO hybrid nanosponges were used as photoanodes in photoelectrochemical water splitting tests. The results indicate that the photoelectrochemical response improves, in the studied range, by increasing the temperature and the Zn(NO3)(2) concentration during the electrodeposition process, obtaining an increase in the photoelectrochemical response of 141% for the TiO2/ZnO hybrid nanosponges electrodeposited at 75 degrees C with 10 mM Zn(NO3)(2) for 15 min. Furthermore, morphological, chemical, and structural characterization was performed by Field Emission Scanning Electron Microscopy (FE-SEM) with Energy Dispersive X-Ray spectroscopy (EDX), Raman Confocal Laser Spectroscopy, X-Ray Photoelectron Spectroscopy (XPS), and Grazing Incidence X-Ray Diffraction (GIXRD).The authors would like to express their gratitude for the financial support of the ¿Agencia Estatal de Investigación (PID2019-105844RB-I00/MCIN/AEI/10.13039/501100011033)¿, for the co-finance by the European Social Fund, and for its help in the ¿Laser Raman Microscope acquisition (UPOV08-3E-012) ¿. Pedro José Navarro Gázquez also thanks the Grant PEJ2018-003596-A-AR funded by MCIN/AEI/10.13039/501100011033 and by ¿ESF Investing in your future¿.Navarro-Gázquez, PJ.; Muñoz-Portero, M.; Blasco-Tamarit, E.; Sánchez-Tovar, R.; Fernández-Domene, RM.; Garcia-Anton, J. (2021). Original Approach to Synthesize TiO2/ZnO Hybrid nanosponges used as photoanodes for photoelectrochemical applications. Materials. 14(21):1-21. https://doi.org/10.3390/ma14216441S121142

Temperature Effect on the Corrosion Behaviour of Alloy 31 in polluted H3PO4 and Analysis of the Corrosion Products by Laser Raman Microscope

[EN] Electrochemical behaviour of Alloy 31, a highly alloyed austenitic stainless steel (UNS N08031), in a 40 wt.% H3PO4 solution polluted with 2 wt.% H2SO4, 0.06 wt.% KCl and 0.6 wt.% HF was evaluated by cyclic potentiodinamic curves at different temperatures (20, 40, 60 and 80 degrees C). Temperature was found to favour both cathodic and anodic reactions. The corrosion products forming on the surface of Alloy 31 were indentified in situ by Laser Raman microscope. Corrosion products were mainly iron and chromium oxides, although phosphates were also included as a corrosion product on the surface of Alloy 31.Authors express their gratitude to the MAEC of Spain (PCI Mediterráneo C/8196/07, C/018046/08, D/023608/09 and D/030177/10), to Programa de Apoyo a la Investigación y Desarrollo de la UPV (PAID-06-09) and to the Generalitat Valenciana (GV/2011/093) for the financial support, to Ministerio de Ciencia e Innovación for its help in the Laser Raman Microscope acquisition (UPOV08-3E-012) and to Dra. Asunción Jaime for her translation assistance.Escrivá Cerdán, C.; Blasco-Tamarit, E.; García-García, D.; Garcia-Anton, J.; Ben-Bachir, A. (2012). Temperature Effect on the Corrosion Behaviour of Alloy 31 in polluted H3PO4 and Analysis of the Corrosion Products by Laser Raman Microscope. International Journal of Electrochemical Science. 7(7):5754-5764. http://hdl.handle.net/10251/61165S575457647