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Multiple band gap devices for solar water splitting

Multiple band gap devices for solar water splitting. Tfy-56.5141 Special Course in Advanced Energy Technologies Priit Jaanson. C ontents. Direct PV ( photovoltaic ) electrolysis vs PEC ( photo electrochemical cell ) electrolysis PEC challenges Biasing the PEC Examples.

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Multiple band gap devices for solar water splitting

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

  2. Contents • Direct PV (photovoltaic) electrolysisvsPEC (photoelectrochemicalcell) electrolysis • PEC challenges • Biasing the PEC • Examples

  3. Direct PV electrolysisvs PEC electrolysis • Direct PV electrolysis • Expensive? • Highcurrentdensities -> overpotential -> lowerefficiency • Not compact? • PEC electrolysis • Lowercurrentdensities -> higherelectrolysisefficency • All in onepackage: cheap, compact. L. Minggu et al. An overview of photocells and photoreactors for photoelectrochemicalwatersplitting, International Journal of Hydrogen Energy, Vol. 35, 11, 2010 5233-5244.

  4. PEC challenges • Visiblelight absorption • Stabilityagainstphotocorrosion • Metaloxides: Chargetransferkinetics > anodicdecompositionrate • Non-oxides: thinoxidelayerformation, dissolving. • Suitablebandgap and bandedgeenergies.

  5. Bandgapmatching • Oxidationcovered • Reductionchallenging • Need for externalbias Solarhydrogenproduction with nanostructuredmetaloxides, Roelvan de Krol , YongqiLiang and JoopSchoonman, J. Mater. Chem., 2008,18, 2311-2320

  6. Biasing • Grid biased • Fossilfuels • pH biased • Moreconsumables • PV or DSSC biased • Internalbiased L. Minggu et al. An overview of photocells and photoreactors for photoelectrochemicalwatersplitting, International Journal of Hydrogen Energy, Vol. 35, 11, 2010 5233-5244.

  7. Internal-biasedsystems - PV/PEC • Solar to hydrogenefficiency 0.7 % • Estimated to beimproved to ~10 % with thickeroxidelayer Eric L. Miller, DanielaPaluselli, BjornMarsen, Richard E. Rocheleau, Development of reactivelysputteredmetaloxidefilms for hydrogen-producinghybridmultijunctionphotoelectrodes, Solar Energy Materials and SolarCells, Volume 88, Issue 2, 15 July 2005, Pages 131-144.

  8. Internal-biasedsystems - PV/PV • STH efficiency 16.5% • STE efficiency 28.5% O. Khaselev, A. Bansal, J.A. Turner, High-efficiencyintegratedmultijunctionphotovoltaic/electrolysissystems for hydrogenproduction, International Journal of Hydrogen Energy, Volume 26, Issue 2, February 2001, Pages 127-132,

  9. Internal-biasedsystems - PV/PV • STH efficiency7.8% • STE efficiency9%

  10. Internal-biasedsystems - PEC/PEC • Efficiency 5% • Glasssheet • Aqueouselectrolyte • Meseporousoxidefilm • TCO (transparentconductingoxide) • Electricalconnection • Dyesensitizedmeseoporous TiO2 • Electrolyte • CE • Same as 2) • Catalyticcathode • Glassfrit Gratzel, M. and Augustynski, J. 2005. Tandem cell for water cleavage by visible light. Patent no. US 6936143.

  11. Conclusions • Highest STH efficiencyachieved is 18.3 % with a multibandgap PV/PV PEC • Theoreticallyover 30% possible. Future: • Emerginghybridthermalelectricalsystemsutilizingwiderrange of solarspectrumpromiseup to 50% efficiency.

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