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Electrochemical Water Splitting Coupled with Organic Compound Oxidation: The Role of Active Chlorine Species

Park, Hyunwoong and Vecitis, Chad D. and Hoffmann, Michael R. (2009) Electrochemical Water Splitting Coupled with Organic Compound Oxidation: The Role of Active Chlorine Species. Journal of Physical Chemistry C, 113 (18). pp. 7935-7945. ISSN 1932-7447.

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The need for alternative energy sources with minimal to no carbon footprint is growing. A solar-powered electrochemical system that produces hydrogen via water splitting using organic pollutants as sacrificial electron donors is a possible solution. The hybridization of a BiO_x−TiO_2/Ti anode with a stainless steel cathode powered by a photovoltaic (PV) array has been shown to achieve this process. The electrochemical degradation kinetics of a variety of organic substrates is investigated as a function of a background electrolyte, NaCl versus Na_2SO_4. The observed substrate (S) degradation kinetics (k_(obs)^S) are found to correlate well with the cell current (I_(cell)) and the H_2 production energy efficiency (EE) in the presence of NaCl as the background electrolyte. In the case of Na_2SO_4, no correlation is observed and the degradation rates are greatly reduced in comparison to NaCl. This suggests that the primary chemical oxidant is electrolyte-dependent. The k_(obs)^S’s are found to be proportional to the bimolecular rate constants of Cl_2^(•−) with the substrate (k_(Cl_2^(•−) + S)) and to substrate-induced ΔEEs (EE with substrate − EE without substrate) in the presence of NaCl. The ΔEE correlation arises from the active chlorine species acting as an electron shuttle, which compete with H_2 production for cathodic electrons. In the presence of the organic substrates, the active chlorine species are quenched, increasing the fraction of electrons utilized for the H_2 production.

Item Type:Article
Related URLs:
URLURL TypeDescription Information
Park, Hyunwoong0000-0002-4938-6907
Hoffmann, Michael R.0000-0001-6495-1946
Additional Information:© 2009 American Chemical Society. Received: November 24, 2008; Revised Manuscript Received: February 3, 2009. We are grateful to the Hydrogen Energy Research & Development Center, and 21st Century Frontier Research and Development Program of the Ministry of Science and Technology of Korea for research support. Supporting Information: Kinetic mass balances and steady-state concentrations of the reactive species are provided in Table S1. Reaction rate constants for Cl^• and Cl_2^(•−) reacting with the target substrates are provided in Table S2.
Funding AgencyGrant Number
Hydrogen Energy Research and Development CenterUNSPECIFIED
21st Century Frontier Research and Development Program, Ministry of Science and Technology of KoreaUNSPECIFIED
Issue or Number:18
Record Number:CaltechAUTHORS:20150804-121741191
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Official Citation:Electrochemical Water Splitting Coupled with Organic Compound Oxidation: The Role of Active Chlorine Species Hyunwoong Park, Chad D. Vecitis, and Michael R. Hoffmann The Journal of Physical Chemistry C 2009 113 (18), 7935-7945 DOI: 10.1021/jp810331w
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:59183
Deposited By: George Porter
Deposited On:05 Aug 2015 22:11
Last Modified:09 Mar 2020 13:19

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