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Synthesis and Stabilization of Blue-Black TiO_2 Nanotube Arrays for Electrochemical Oxidant Generation and Wastewater Treatment

Yang, Yang and Hoffmann, Michael R. (2016) Synthesis and Stabilization of Blue-Black TiO_2 Nanotube Arrays for Electrochemical Oxidant Generation and Wastewater Treatment. Environmental Science and Technology, 50 (21). pp. 11888-11894. ISSN 0013-936X. http://resolver.caltech.edu/CaltechAUTHORS:20161017-102746361

[img] PDF (BNTA characterizations such as cyclic voltammeties, and FESEM images. Results of electrochemical BA degradation, the electrolysis of 30 mM NaCl solution, and wastewater are also enclosed. The SI text includes a calculation of the band structure, width of ) - Supplemental Material
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Abstract

Efficient, inexpensive, and stable electrode materials are key components of commercially viable electrochemical wastewater treatment system. In this study, blue-black TiO_2 nanotube array (BNTA) electrodes are prepared by electrochemical self-doping. The 1-D structure, donor state density, and Fermi energy level position are critical for maintaining the semimetallic functionality of the BNTA. The structural strength of the BNTA is enhanced by surface crack minimization, reinforcement of the BNTA-Ti metal interface, and stabilized by a protective overcoating with nanoparticulate TiO_2 (Ti/EBNTA). Ti/EBNTA electrodes are employed as both anodes and cathodes with polarity switching at a set frequency. Oxidants are generated at the anode, while the doping levels are regenerated along with byproduct reduction at the cathode. The estimated maximum electrode lifetime is 16 895 h. Ti/EBNTA has comparable hydroxyl radical production activity (6.6 × 10^(–14) M) with boron-doped diamond (BDD, 7.4 × 10^(–14) M) electrodes. The chlorine production rate follows a trend with respective to electrode type of Ti/EBNTA > BDD > IrO_2. Ti/EBNTA electrodes operated in a bipolar mode have a minimum energy consumption of 62 kWh/kg COD, reduced foam formation due to less gas bubble production, minimum scale formation, and lower chlorate production levels (6 mM vs 18 mM for BDD) during electrolytic wastewater treatment.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/acs.est.6b03540DOIArticle
http://pubs.acs.org/doi/abs/10.1021/acs.est.6b03540PublisherArticle
http://pubs.acs.org/doi/suppl/10.1021/acs.est.6b03540PublisherSupporting Information
ORCID:
AuthorORCID
Hoffmann, Michael R.0000-0002-0432-6564
Additional Information:© 2016 American Chemical Society. Received: July 14, 2016; Revised: September 13, 2016; Accepted: September 20, 2016. We gratefully acknowledge the financial support of Bill and Melinda Gates Foundation (BMGF-RTTC Grant, OPP1111246). The authors declare no competing financial interest.
Funders:
Funding AgencyGrant Number
Bill and Melinda Gates FoundationOPP1111246
Record Number:CaltechAUTHORS:20161017-102746361
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20161017-102746361
Official Citation:Synthesis and Stabilization of Blue-Black TiO2 Nanotube Arrays for Electrochemical Oxidant Generation and Wastewater Treatment Yang Yang and Michael R. Hoffmann Environmental Science & Technology 2016 50 (21), 11888-11894 DOI: 10.1021/acs.est.6b03540
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:71153
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:17 Oct 2016 17:43
Last Modified:07 Nov 2016 18:03

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