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Electrocatalytic arsenite oxidation in bicarbonate solutions combined with CO₂ reduction to formate

Choi, Wonjung and Kim, Minju and Kim, Byeong-ju and Park, Yiseul and Han, Dong Suk and Hoffmann, Michael R. and Park, Hyunwoong (2020) Electrocatalytic arsenite oxidation in bicarbonate solutions combined with CO₂ reduction to formate. Applied Catalysis B, 265 . Art. No. 118607. ISSN 0926-3373. doi:10.1016/j.apcatb.2020.118607.

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Sunlight-driven water-energy nexus technologies are receiving increasing attention. This study presents a hybrid electrochemical system that catalyzes the oxidation of As(III) to As(V) with a nanoparticulate TiO₂ electrocatalyst (Ti/Ir_(1-x)Ta_xO_y/TiO₂; denoted as an n-TEC) while simultaneously converting CO₂ to formate on a Bi electrode in aqueous bicarbonate solutions at circum-neutral pH. Linear sweep voltammograms of n-TEC exhibit a specific As(III) oxidation peak (E_(p,As)), at which the Faradaic efficiency (FE) of As(V) production is ∼100%. However, the application of a potential higher than the peak (E > E_(p,As)) leads to a significant decrease in the FE due to water oxidation. Upon the addition of chloride, the oxidation of water and chloride occur competitively, producing reactive chlorine species responsible for mediating the oxidation of As(III). The Bi electrodes synthesized via the electrodeposition of Bi³⁺ typically show high FEs of >80% for formate production in bicarbonate solution purged with CO₂. The addition of chloride significantly enhances the current while maintaining the FE. The n-TEC catalyst and Bi electrodes are paired in a single device equipped with a membrane, and significant effort is made to achieve the same FEs in both the anodic and cathodic reactions as in their half-reactions. Finally, the optimized n-TEC/Bi pair is coupled with a low-cost, commercially available photovoltaic (PV). Various technical factors that drive the overall reactions with the PV are considered, and maximum FEs of ∼95% are achieved for the production of both As(V) and formate.

Item Type:Article
Related URLs:
URLURL TypeDescription
Kim, Byeong-ju0000-0002-0807-4878
Park, Yiseul0000-0003-3256-1032
Han, Dong Suk0000-0002-4804-5369
Hoffmann, Michael R.0000-0001-6495-1946
Park, Hyunwoong0000-0002-4938-6907
Additional Information:© 2020 Elsevier B.V. Received 3 September 2019, Revised 21 November 2019, Accepted 6 January 2020, Available online 7 January 2020. This research was partly supported by the National Research Foundation of Korea (2019R1A2C2002602, 2018R1A6A1A03024962, and 2019M1A2A2065616). This publication was made possible by a grant from the Qatar National Research Fund under its National Priorities Research Program (NPRP 10-1210-160019). The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. CRediT authorship contribution statement: Wonjung Choi: Methodology, Validation, Formal analysis, Investigation. Minju Kim: Methodology, Validation, Formal analysis, Investigation. Byeong-ju Kim: Formal analysis. Yiseul Park: Resources, Funding acquisition. Dong Suk Han: Funding acquisition. Michael R. Hoffmann: Resources. Hyunwoong Park: Conceptualization, Methodology, Validation, Formal analysis, Resources, Writing - original draft, Writing - review & editing, Visualization, Supervision, Project administration, Funding acquisition.
Funding AgencyGrant Number
National Research Foundation of Korea2019R1A2C2002602
National Research Foundation of Korea2018R1A6A1A03024962
National Research Foundation of Korea2019M1A2A2065616
Qatar National Research FundNPRP 10-1210-160019
Subject Keywords:Redox reactions; Electrocatalysis; Water treatment; Solar fuels; Water-energy nexus
Record Number:CaltechAUTHORS:20200107-145010832
Persistent URL:
Official Citation:Wonjung Choi, Minju Kim, Byeong-ju Kim, Yiseul Park, Dong Suk Han, Michael R. Hoffmann, Hyunwoong Park, Electrocatalytic arsenite oxidation in bicarbonate solutions combined with CO2 reduction to formate, Applied Catalysis B: Environmental, Volume 265, 2020, 118607, ISSN 0926-3373,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:100544
Deposited By: Tony Diaz
Deposited On:08 Jan 2020 15:50
Last Modified:06 May 2022 22:49

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