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Electrolysis of urea and urine for solar hydrogen

Kim, Jungwon and Choi, Won Joon K. and Choi, Jina and Hoffmann, Michael R. and Park, Hyunwoong (2013) Electrolysis of urea and urine for solar hydrogen. Catalysis Today, 199 . pp. 2-7. ISSN 0920-5861. doi:10.1016/j.cattod.2012.02.009.

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Hybrid photovoltaic (PV) arrays-electrochemical systems have been envisaged as an alternative technology that co-manages an energy–water nexus, yet improving the technical viability and applicability of the hybrids remains a challenge. With this in mind, we studied the hybrid electrochemical system for urea and urine treatment and simultaneous H_2 production using BiO_x–TiO_2 anode and stainless steel cathode couples with different electrolytes (NaCl vs. LiClO_4 vs. Na_2SO_4). In the presence of NaCl, urea electrolysis was found to enhance the cathodic H_2 production by a maximum of ca. 20% at low urea concentrations, yet reduce the H_2 production at high urea concentrations as compared to water electrolysis. Varying degrees of the synergistic H_2 production were attributed to competitive reactions between active chlorine species and urea/urea intermediates for protons and electrons. The synergistic effect by the urea electrolysis disappeared when LiClO_4 and Na_2SO_4 were used as electrolytes indicating the crucial role of chlorine species in the hybrid reactions. In addition, the electrolysis of actual urine was found to successfully operate along with simultaneous generation of H_2 even in the absence of externally added electrolytes. This electrolyteless-hybrid electrolysis resulted from the large amounts of chloride and other ionic species originally included in the actual urine sample. A detailed reaction mechanism of urea electrolysis and its application potential in terms of solar hydrogen were discussed.

Item Type:Article
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URLURL TypeDescription
Hoffmann, Michael R.0000-0001-6495-1946
Park, Hyunwoong0000-0002-4938-6907
Additional Information:© 2012 Elsevier B.V. Received 18 October 2011. Received in revised form 27 January 2012. Accepted 5 February 2012. Available online 3 March 2012. This research was supported by the Basic Science Research Programs (No. 2009-0071350, 2009-0089904, 2010-0002674, and 2011-0021148) and by the Korea Center for Artificial Photosynthesis (NRF-2009-C1AAA001-2009-0093879) through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science, and Technology.
Funding AgencyGrant Number
Basic Science Research Program2009-0071350
Basic Science Research Program2009-0089904
Basic Science Research Program2010-0002674
Basic Science Research Program2011-0021148
National Research Foundation of KoreaNRF-2009-C1AAA001-2009-0093879
Ministry of Education, Science, and Technology (Korea)UNSPECIFIED
Subject Keywords:Solar hydrogen; Electrolysis; Hybrid; Water treatment; Energy–water nexus
Record Number:CaltechAUTHORS:20130104-131246841
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Official Citation:Jungwon Kim, Won Joon K. Choi, Jina Choi, Michael R. Hoffmann, Hyunwoong Park, Electrolysis of urea and urine for solar hydrogen, Catalysis Today, Volume 199, 1 January 2013, Pages 2-7, ISSN 0920-5861, 10.1016/j.cattod.2012.02.009. (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:36173
Deposited By: Ruth Sustaita
Deposited On:04 Jan 2013 21:36
Last Modified:09 Nov 2021 23:20

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