Electrochemical Water Splitting Coupled with Organic Compound Oxidation: The Role of Active Chlorine Species
Abstract
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.
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.Attached Files
Supplemental Material - jp810331w_si_001.pdf
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Additional details
- Eprint ID
- 59183
- DOI
- 10.1021/jp810331w
- Resolver ID
- CaltechAUTHORS:20150804-121741191
- Hydrogen Energy Research and Development Center
- 21st Century Frontier Research and Development Program, Ministry of Science and Technology of Korea
- Created
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2015-08-05Created from EPrint's datestamp field
- Updated
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2021-11-10Created from EPrint's last_modified field