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Substrate Oxidation Enhances the Electrochemical Production of Hydrogen Peroxide

Lim, Jonghun and Hoffmann, Michael R. (2019) Substrate Oxidation Enhances the Electrochemical Production of Hydrogen Peroxide. Chemical Engineering Journal, 374 . pp. 958-964. ISSN 1385-8947. PMCID PMC6686209.

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Hydrogen peroxide (H_2O_2) is electrochemically produced via oxygen (O_2) reduction on a carbon cathode surface. In order to enhance the production of H_2O_2, anodic loss pathways, which significantly reduce the overall H_2O_2 production rate, should be inhibited. In this study, we investigate the effects of organic electron donors (i.e., typical chemical contaminants) on the anodic loss pathways of H_2O_2 in a single-cell electrochemical reactor that employs an anode composed of TiO_2 over-coated on a mixed-metal oxide ohmic contact catalyst, Ir_(0.7)Ta_(0.3)O_2, deposited on a Ti-metal that is coupled with a graphite rod cathode in a sodium sulfate (Na_2SO_4) electrolyte that is saturated with oxygen (O_2). Organic electron donors are shown to enhance the electrochemical production of H_2O_2, while simultaneously undergoing oxidative degradation. The observed positive effect of organic electron donors on the electrochemical production of H_2O_2 is due in part to a preferential adsorption of organic substrates on the TiO_2 outer layer of the anode. The sorption of the organic electron donors inhibits the formation of surficial titanium hydroperoxo species ( Ti-OOH) on the anode surface. The organic sorbates also act as scavengers of surface-bound hydroxyl radical Ti-OH. As a result, the decomposition of H_2O_2 on the anode surface is significantly reduced. The cathodic production rate of H_2O_2 at low pH is enhanced due to proton coupled electron transfer (PCET) to O_2, while the anodic decomposition of H_2O_2 is inhibited due to electrostatic interactions between negatively-charged organic substrates and a positively-charged outer surface of the anode (TiO_2 pH_(zpc) = 5.8) at low pH.

Item Type:Article
Related URLs:
URLURL TypeDescription CentralArticle
Lim, Jonghun0000-0002-2943-1846
Hoffmann, Michael R.0000-0001-6495-1946
Additional Information:© 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license ( Received 6 February 2019, Revised 22 May 2019, Accepted 24 May 2019, Available online 25 May 2019. This research was supported by the Bill and Melinda Gates Foundation (OPP1149755).
Funding AgencyGrant Number
Bill and Melinda Gates FoundationOPP1149755
Subject Keywords:electrocatalysis; hydrogen peroxide; anodic decomposition of H2O2; organic electron donors
PubMed Central ID:PMC6686209
Record Number:CaltechAUTHORS:20190528-104654913
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Official Citation:Jonghun Lim, Michael R. Hoffmann, Substrate oxidation enhances the electrochemical production of hydrogen peroxide, Chemical Engineering Journal, Volume 374, 2019, Pages 958-964, ISSN 1385-8947, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:95812
Deposited By: Tony Diaz
Deposited On:28 May 2019 20:17
Last Modified:09 Mar 2020 13:19

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