ECN publication
Prestatiemetingen aan een foto-elektrochemische reactor
Published by: Publication date:
ECN Energy Efficiency in Industry 1-2-2001
ECN report number: Document type:
ECN-I--01-004 Other
Number of pages: Full text:
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Results of a project aimed at proofing the technical possibility ofdirectly splitting water with a photo-electrochemical reactor (PEC-reactor) are presented. The PEC-reactor under study consists of a combination of a photovoltaic cell based on TiO2 and an electrochemical cell within one device. Proofing the working principle is seen as the first important step in the development of the PEC-reactor. Improving efficiency, decreasing costs, extending lifetime, etc., are steps which follow the 'proof-of-principle'. A PEC-reactor is constructed based on a photoanode made of titanium coated with a pure TiO2-layer as a photocatalyst and an electrocathode made of carbon cloth with platinum as an electrocatalyst. The two electrodes are connected to and separated by a proton conductor Nafion. Water is fed to the photoanode which under illumination of an artificial sun results in splitting of water in oxygen and protons. The protons diffuse through the Nafion layer and recombine to hydrogen at the electrocathode. Measurements were carried out on the photocurrent and the production of oxygen. Using a light intensity of 1000 W/m2, a photocurrent of 0.08 mA/cm2 has been measured. The resulting oxygen production is 0.032 /h.m2 . Applying a bias of 1.5 Volt to the PEC-reactor increases the photocurrent and oxygen production to 0.17 mA/cm2 and 0.052 l/h.m2 respectively. The unbiased results correspond to an Incident Photon to Current Efficiency (IPCE) of 0.11% based on photocurrent and a cell efficiency of 0.02% based on oxygen production. The conclusion of this work is that it is indeed possible to directly split water in a photo-electrochemical reactor using sunlight. The efficiency of the device however is quite low and should be improved significantly in further development phases. 2 refs.

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