Electrochemical investigation of TiO2-nanotubes formation and its application on energy convertion nanostructured systems

• Grant number: 10/05555-2
• Support type: Scholarships in Brazil - Post-Doctorate
• Effective date (Start): December 01, 2010
• Effective date (End): November 30, 2013
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Physical-Chemistry
• Principal researcher: Ernesto Chaves Pereira de Souza
• Grantee: Renato Garcia de Freitas Sobrinho
• Home Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

The production of nanostructured electrochemical devices energy converters has shown significant results, due to its intrinsic properties of low dimensionality. The nature of the semiconductor TiO2 nanotubes makes it a promising candidate for electrolysis of water, energy converter device, and photocatalytic self-cleaning applications. Therefore, this project proposes to evaluate the electrochemical formation of TiO2-nanotubes (TiO2NT) and its application as electrodes for oxidation of small molecules in fuel cells. The manufacture of TiO2NT was first reported by Zwilling et al. in 1999. The first generation of TiO2NT synthesized using an electrochemical route, was limited to nanotubes with short lengths of up to 600nm. The second generation of TiO2NT, in which aqueous electrolytes were replaced by organic medium, led to new morphologies. In this sense, the use of glycerol allowed to obtain the TiO2NT with walls of low roughness and length of about 7.0 micrometers. Finally, the third generation of TiO2NT materials were obtained in ionic liquids medium and these resulted in TiO2NT with double walls.TiO2 nanotubes present as main crystalline phases a mixture of rutile and anatase phases. Several factors influenced the morphology and microstructure, such as: pH and electrolyte composition, concentration of F-, the existence of convective flow in the solution, initial state of the metal to be anodized, anodizing temperature, voltage (when anodizing at constant potential), water content in the electrolyte, temperature and atmosphere of heat treatment after the electrochemical synthesis. The efficiency of photo-electrocatalytic TiO2NT is associated with recombination rate of e-/h+ once that the photocurrent magnitude is related to the efficiency of transport agent through the base of the nanotubes, and h+ on the TiO2-electrolyte interface. Thus, thick-walled nanotubes had lower rates of recombination and e-/h+ and, consequently, an increase in photocatalytic activity. Moreover, TiO2NT with larger diameters allow better diffusion of small organic molecules such as methanol and ethanol inside the tubes to be eletrooxidized.Another approach, already used, was the electrodeposition of Pt inside the nanotubes which affects significantly the electrocatalytic performance of these materials. In this sense, one of the goals of this project is to understand precisely the effect of metal nanoparticles, for example, Pt and PtRu alloy on the mechanism of electrooxidation using in situ FTIR electrochemical. This technique allows analyzing the vibrational modes of the species in solution and/or adsorbed on the surface of TiO2NT and identifies the intermediate and final products of reaction. It is clear that a thorough knowledge of electrochemical properties of the electrode, considering its structure is also necessary to achieve this goal. For this reason, a second objective of this project is to use impedance spectroscopy to study this behaviour. As it is a porous electrode, it is already discussed in the literature the necessity to describe the system using models of transmission lines, which will be also used in this project. The methods proposed, using in situ FTIR and electrochemical impedance spectroscopy were rarely used in the literature. Thus, this project is proposed to contribute to the elucidation of mechanistic processes, which directly affect the phenomena related to energy conversion. (AU)

Scientific publications

(13)

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

SILVA, C. D.; MORAIS, L. H.; GONCALVES, R.; MATOS, R.; SOUZA, G. L. C.; FREITAS, R. G.; PEREIRA, E. C. The methanol and CO electro-oxidation onto Pt-pc/Co/Pt metallic multilayer nanostructured electrodes: An experimental and theoretical approach. Electrochimica Acta, v. 280, p. 197-205, AUG 1 2018. Web of Science Citations: 2.

SANTANNA, M. A.; MENEZES, W. T.; SANTANA, Y. V. B.; FERRER, M. M.; GOUVEIA, A. F.; FACETO, A. D.; TEREZO, A. J.; OLIVEIRA, A. J. A.; LONGO, E.; FREITAS, R. G.; PEREIRA, E. C. The effect of TiO2 nanotube morphological engineering and ZnS quantum dots on the water splitting reaction: A theoretical and experimental study. INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, v. 43, n. 14, p. 6838-6850, APR 5 2018. Web of Science Citations: 3.

FREITAS, R. G.; LUCAS, F. W. S.; SANTANNA, M. A.; MENDES, R. A.; TEREZO, A. J.; DE SOUZA, G. L. C.; MASCARO, L. H.; PEREIRA, E. C. An experimental and theoretical study on the electronic and structural properties of CdSe@TiO2 nanotube arrays. Physical Chemistry Chemical Physics, v. 18, n. 38, p. 26885-26893, OCT 14 2016. Web of Science Citations: 5.

NAGAO, RAPHAEL; FREITAS, RENATO G.; SILVA, CAMILA D.; VARELA, HAMILTON; PEREIRA, ERNESTO C. Oscillatory Electro-oxidation of Methanol on Nanoarchitectured Pt-pc/Rh/Pt Metallic Multilayer. ACS CATALYSIS, v. 5, n. 2, p. 1045-1052, FEB 2015. Web of Science Citations: 7.

FREITAS, R. G.; SANTANNA, M. A.; PEREIRA, E. C. Preparation and Characterization of TiO2 Nanotube Arrays in Ionic Liquid for Water Splitting. Electrochimica Acta, v. 136, p. 404-411, AUG 1 2014. Web of Science Citations: 22.

FREITAS, R. G.; SANTANNA, M. A.; PEREIRA, E. C. Dependence of TiO2 nanotube microstructural and electronic properties on water splitting. Journal of Power Sources, v. 251, p. 178-186, APR 1 2014. Web of Science Citations: 17.

FREITAS, R. G.; JUSTO, S. G.; PEREIRA, E. C. The influence of self-ordered TiO2 nanotubes microstructure towards Li+ intercalation. Journal of Power Sources, v. 243, p. 569-572, DEC 1 2013. Web of Science Citations: 7.

PEREIRA, R.; MARCHESI, L. F.; FREITAS, R. G.; MATOS, R.; PEREIRA, E. C. A low-cost platinum film deposited direct on glass substrate for electrochemical counter electrodes. Journal of Power Sources, v. 232, p. 254-257, JUN 15 2013. Web of Science Citations: 8.

FREITAS, R. G.; ANTUNES, E. P.; CHRISTENSEN, P. A.; PEREIRA, E. C. The influence of Ir and Pt1Ir1 structure in metallic multilayers nanoarchitectured electrodes towards ethylene glycol electro-oxidation. Journal of Power Sources, v. 214, p. 351-357, SEP 15 2012. Web of Science Citations: 6.

FREITAS, RENATO G.; PEREIRA, ERNESTO C.; CHRISTENSEN, PAUL A. The selective oxidation of ethanol to CO2 at Pt-pc/Ir/Pt metallic multilayer nanostructured electrodes. Electrochemistry Communications, v. 13, n. 10, p. 1147-1150, OCT 2011. Web of Science Citations: 15.

FREITAS, R. G.; MARCHESI, L. F. Q. P.; FORIM, M. R.; BULHOES, L. O. S.; PEREIRA, E. C.; SANTOS, M. C.; OLIVEIRA, R. T. S. Ethanol Electrooxidation using Ti/(RuO2)((x)) Pt(1-x) Electrodes Prepared by the Polymeric Precursor Method. Journal of the Brazilian Chemical Society, v. 22, n. 9, p. 1709-1717, SEP 2011. Web of Science Citations: 10.

FREITAS, RENATO GARCIA; BATISTA, EVELINE CRISTINE; CASTRO, MARCELA PORTES; OLIVEIRA, ROBSON T. S.; SANTOS, MAURO COELHO; PEREIRA, ERNESTO CHAVES. Ethanol Electrooxidation on Bi Submonolayers Deposited on a Pt Electrode. ELECTROCATALYSIS, v. 2, n. 3, p. 224-230, SEP 2011. Web of Science Citations: 4.

R. G FREITAS; L. F. Q. P MARCHESI; M. R FORIM; L. O. S BULHÕES; E. C PEREIRA; M. C SANTOS; R. T. S OLIVEIRA. Ethanol electrooxidation using Ti/(RuO2)(x) Pt(1-x) electrodes prepared by the polymeric precursor method. Journal of the Brazilian Chemical Society, v. 22, n. 9, p. -, Set. 2011.