2024-03-29T00:59:07Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/1640802018-06-08T12:15:55Zcom_10261_101com_10261_5col_10261_858
00925njm 22002777a 4500
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Tapia, Cristina
author
2017
Water splitting to form hydrogen (H2) and oxygen (O2) is considered a sustainable process for
energy conversion. The integration of light-harvesting, multistep transfer of electrons and protons and
chemical conversion processes, using water as an electron source and sunlight as an energy source, to
synthesize biofuels is the principle of photosynthesis. The global aim of this thesis is the development
of inorganic/biological hybrid systems for the artificial photosynthesis of H2 and O2 from water.
The first approach of this thesis for H2 electrochemical photoproduction was to combine two
biological catalysts, photosystem I (PSI) from spinach’s thylakoids as light absorber able to donate high
energy electrons, and the [NiFe] hydrogenase from Desulfovibrio gigas, with two hydrogels containing
different inorganic redox complexes. This combined photocatalytic system was developed on a gold
electrode, which allowed the electron transfer from the electrode to the PSI and then from the PSI to
the Hase for H2 evolution. At the same time, the photocurrents derived from the illumination of the
system with visible light could be monitored.
The aim of the second approach for H2 evolution was based on the combination of In2S3, an
inorganic semiconductor able to absorb in the visible light spectral range, with the [NiFeSe]
Hydrogenase from Desulfovibrio vulgaris Hildenborough for protons’ reduction. In2S3 was synthesized
and characterized for this purpose. This hybrid photocatalytic system was developed by mixing both
components in solution and measuring the H2 photoproduction by mass spectrometry.
The last approach of this thesis was the photoelectrochemical evolution of O2 from water by a
hybrid system combining the In2S3 semiconductor with the Trametes hirsuta Laccase, a biocatalyst able
to oxidize water to O2. In this case a Fluorine-doped tin oxide (FTO) coated glass was used as electrode
substrate, which was drop-coated with In2S3, and the laccase was covalently bound to it. The O2
photoproduction and faradaic yield were estimated according to the registered photocurrents on the
electrode and the response of an O2 microsensor placed near to the electrode.
http://hdl.handle.net/10261/164080
Photocatalytic production of H2 and O2 from water based on hybrid enzyme / inorganic semiconductor systems