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Multiple band gap devices for solar water splitting Tfy-56.5141 Special Course in Advanced Energy Technologies Priit Jaanson.

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Presentation on theme: "Multiple band gap devices for solar water splitting Tfy-56.5141 Special Course in Advanced Energy Technologies Priit Jaanson."— Presentation transcript:

1 Multiple band gap devices for solar water splitting Tfy Special Course in Advanced Energy Technologies Priit Jaanson

2 Contents Direct PV (photovoltaic) electrolysis vs PEC (photo electrochemical cell) electrolysis PEC challenges Biasing the PEC Examples

3 Direct PV electrolysis vs PEC electrolysis Direct PV electrolysis – Expensive? – High current densities -> overpotential -> lower efficiency – Not compact? PEC electrolysis – Lower current densities -> higher electrolysis efficency – All in one package: cheap, compact. L. Minggu et al. An overview of photocells and photoreactors for photoelectrochemical water splitting, International Journal of Hydrogen Energy, Vol. 35, 11,

4 PEC challenges Visible light absorption Stability against photocorrosion – Metal oxides: Charge transfer kinetics > anodic decomposition rate – Non-oxides: thin oxide layer formation, dissolving. Suitable band gap and band edge energies.

5 Bandgap matching Oxidation covered Reduction challenging Need for external bias Solar hydrogen production with nanostructured metal oxides, Roel van de Krol, Yongqi Liang and Joop Schoonman, J. Mater. Chem., 2008,18,

6 Biasing Grid biased – Fossil fuels pH biased – More consumables PV or DSSC biased Internal biased L. Minggu et al. An overview of photocells and photoreactors for photoelectrochemical water splitting, International Journal of Hydrogen Energy, Vol. 35, 11,

7 Internal-biased systems - PV/PEC Eric L. Miller, Daniela Paluselli, Bjorn Marsen, Richard E. Rocheleau, Development of reactively sputtered metal oxide films for hydrogen-producing hybrid multijunction photoelectrodes, Solar Energy Materials and Solar Cells, Volume 88, Issue 2, 15 July 2005, Pages Solar to hydrogen efficiency 0.7 % Estimated to be improved to ~10 % with thicker oxide layer

8 Internal-biased systems - PV/PV STH efficiency 16.5% STE efficiency 28.5% O. Khaselev, A. Bansal, J.A. Turner, High-efficiency integrated multijunction photovoltaic/electrolysis systems for hydrogen production, International Journal of Hydrogen Energy, Volume 26, Issue 2, February 2001, Pages ,

9 Internal-biased systems - PV/PV STH efficiency 7.8% STE efficiency 9%

10 Internal-biased systems - PEC/PEC Efficiency 5% 1)Glass sheet 2)Aqueous electrolyte 3)Meseporous oxide film 4)TCO (transparent conducting oxide) 5)Electrical connection 6)Dye sensitized meseoporous TiO2 7)Electrolyte 8)CE 9)Same as 2) 10)Catalytic cathode 11)Glass frit Gratzel, M. and Augustynski, J Tandem cell for water cleavage by visible light. Patent no. US

11 Conclusions Highest STH efficiency achieved is 18.3 % with a multi bandgap PV/PV PEC Theoretically over 30% possible. Future: Emerging hybrid thermal electrical systems utilizing wider range of solar spectrum promise up to 50% efficiency.


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