A new catalyst for splitting water into molecular oxygen
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A New Catalyst for Splitting Water into Molecular Oxygen. James M. Krier UC-Berkeley. Unique challenges ahead. Energy = N (GDP/N)(E/GDP).

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A New Catalyst for Splitting Water into Molecular Oxygen

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A new catalyst for splitting water into molecular oxygen

A New Catalyst for Splitting Water into Molecular Oxygen

James M. Krier

UC-Berkeley


Unique challenges ahead

Unique challenges ahead

Energy = N (GDP/N)(E/GDP)

Even with optimistic technological and conservation forecasts, the rapid economic growth in developing nations is predicted to double global energy needs by 2050

Per person GDP

Energy intensity

N. S. Lewis, D. G. Nocera, Proc. Natl. Acad. Sci. U.S.A. 103, 15729 (2006).


Power from the sun

Power from the sun

2 H2(g) + O2(g) → 2 H2O(l)

∆H = -286 kJ/mol

  • Enough solar energy strikes the globe in one hour (4.3 x 1020 J) to power all human activity for one year (4.1 x 1020 J)

  • Photosynthesis by plants is an example of splitting water for energy storage

bcs.whfreeman.com/lehninger

N. S. Lewis, D. G. Nocera, Proc. Natl. Acad. Sci. U.S.A. 103, 15729 (2006).


The artificial plant

The artificial plant

The oxygen reaction is tricky in both systems

N. S. Lewis, D. G. Nocera, Proc. Natl. Acad. Sci. U.S.A. 103, 15729 (2006).


Recent breakthrough

Recent breakthrough

e-

e-

+

-

1.29 V

Conducting glass, such as indium tin oxide

0.5 mM Co(NO3)2

0.1 M KPi (potassium phosphate)

SEM image

Film is 2:1 as Co:Pi

Alternative:

Kanan, M. W. & Nocera, D. G. Science 321, 1072–1075 (2008).


Key features

Key features

  • Self-repair mechanism, in situ formation

    • Co2+, Co3+, Co4+ species likely responsible for balancing different oxidation steps

    • Co2+-HPO42- (aq)  Co3+-HPO42- (on electrode surface)

  • Composed of earth-abundant materials

  • Long lasting O2 production at low overpotential, neutral pH, room temperature/pressure

  • Drawbacks: large initial overpotential, not effective at high current

Kanan, M. W. & Nocera, D. G. Science 321, 1072–1075 (2008).


Your new house

Your new house?

web.mit.edu/newsoffice/2008/oxygen-0731.html

Kanan, M. W. & Nocera, D. G. Science 321, 1072–1075 (2008).


Links to additional reading

Links to additional reading…

  • nature.com/nmat/journal/v7/n10/full/nmat2284.html

  • rsc.org/ej/CS/2009/b802262n.pdf

  • sciencemag.org/cgi/reprint/321/5892/1072.pdf

  • www.web.mit.edu/newsoffice/2008/oxygen-0731.html

  • www.pnas.org/content/103/43/15729.abstract


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