? Nanoparticle-Based Catalysts for Photochemical Water Splitting
     
 
Photochemical Water Splitting 
 
 
Background 

 

At a power level of 1000 W/m2, the solar energy incident on the earth's surface is theoretically sufficient to cover all human energy needs. Using suitable catalysts, this solar energy can be used to convert water into hydrogen and oxygen - the fuels of a hydrogen-based energy economy.

 

H2O --> 0.5 O2 (g) + H2 (g) ?G = +237 kJ/mol
    (1. 3 eV/e, ?min = 1100 nm)

 

The goal of this project is to assemble catalysts in solution phase from inorganic nanoparticles with proven efficiencies for light absorption, water reduction and oxidation. Advantages of this modular approach are that:

 

(1) sensitive semiconductors can be protected from photochemical corrosion by using metal and metal oxide nanoparticles as separate sites for reduction and oxidation of waterelectrodes to create devices that can be integrated into existing technology.

 

(2) light absorbance and redox catalysis can be independently optimized by varying nanoparticle components (sizes and materials).

 

(3) electron-hole separation and charge transfer can be optimized with rectifying Schottky barriers between the particles.

 

Nanoparticles are essential building blocks for these catalyst because their mass and charge transfer is fast, and because they exhibit increased light absorption and reduced light scattering. The final catalyst particles will be micrometer sized, and can be suspended in the reaction medium (water or methanol) or they can be mounted on electrodes to create devices that can be integrated into existing technology.

 

References
  1. Nathan S. Lewis and Daniel G. Nocera, Powering the Planet: Chemical challenges in solar energy utilization, Proc. Nat. Acad. Sci., 2006, 103, 15729-15735. http://www.pnas.org/cgi/content/abstract/103/43/15729  
 
Publications
       
  » Charge Separation in a Niobate Nanosheet Photocatalyst Studied with Photochemical Labeling, Erwin M. Sabio, Miaofang Chi, Nigel D. Browning, and Frank E. Osterloh, Langmuir, In Press DOI: 10.1021//la904377f. Download Local Copy 
       
  » Evolution of physical and photocatalytic properties in the layered titanates A2Ti4O9 (A=K, H) and in nanosheets derived by chemical exfoliation, Mark Allen, Arthur Thibert, Erwin M. Sabio, Nigel Browning, Delmar S. Larsen, and Frank E. Osterloh, Chem. Mater., (Materials Chemistry of Energy Conversion Special Issue) 2010, 22 (3), 1220-1228. DOI: 10.1021/cm902695r. Download Local Copy 
       
  » Unique LaTaO4 Polymorph for Multiple Energy Applications, May Nyman, Mark A. Rodriguez, Lauren E. S. Rohwer, James E. Martin, Mollie Waller, and Frank E. Osterloh, Chem. Mater., 2009, 211 (19), 4731-4737. DOI: 10.1021/cm9020645. Download Local Copy 
       
  » Osterloh, F. E., Nanoparticle-Assembled Water Splitting Catalysts, In Solar Hydrogen & Nanotechnology, Vayssieres, L., Ed, In Press, Wiley VCH. 
       
  » Niobate Nanosheets as catalysts for Photochemical Water Splitting into Hydrogen and Hydrogen Peroxide, Owen C. Compton and Frank E. Osterloh, J. Phys. Chem. C, 2009, 113 (1), 479-485. DOI: 10.1021/jp807839b. Download Local Copy 
       
  » K4Nb6O17-derived Photocatalysts for Hydrogen Evolution from Water: Nanoscrolls versus Nanosheets, Michael C. Sarahan; Elizabeth C. Carroll; Delmar S. Larsen; Nigel D. Browning; and Frank E. Osterloh, J. Solid State Chem, 2008, 181 (7), 1681-1686. DOI: 10.1016/j.jssc.2008.06.021. Download Local Copy 
       
  » First Demonstration of CdSe as a Photocatalyst for Hydrogen Evolution from Water under UV and visible light, F. Andrew Frame; Elizabeth C. Carroll; Delmar S. Larsen; Michael Sarahan; Nigel D. Browning; Frank E. Osterloh, Chem. Comm., 2008, 2206-2208. DOI: 10.1039/b718796c. Download Local Copy 
       
  » A Building Block Approach towards Photochemical Water Splitting Catalysts based on Niobate Nanosheets, Owen C. Compton; Cory H. Mullet; Shirley Chiang; Frank E. Osterloh, J. Phys. Chem. C, 2008, 112(15), 6202-6208. DOI: 10.1021/jp711589z. Download Local Copy 
       
  » Ultrafast Carrier Dynamics in Exfoliated and Functionalized Calcium Niobate Nanosheets in Water and Methanol, Elizabeth C. Carroll, Owen C. Compton, Dorte Madsen, Frank E. Osterloh, Delmar S. Larsen, J. Phys. Chem. C, 2008, 112(7), 2394-2403. DOI: 10.1021/jp077427d. Download Local Copy
       
  » Inorganic Materials as Catalysts for Photochemical Splitting of Water, Frank E. Osterloh, Chem. Mater., 2008, 20(1), 35-54. DOI: 10.1021/cm7024203. Download Local Copy 
       
  » Calcium Niobate Semiconductor Nanosheets at Catalysts for Photochemical Hydrogen Evolution from Water, Owen C. Compton, Elizabeth C. Carroll, Jin Y. Kim, Delmar Larsen, Frank E. Osterloh, J. Phys. Chem. C, 2007, 111(40), 14589-14592. DOI: 10.1021/jp0751155 Download Local Copy
       
  » Planar Polarized Light Emission From CdSe Nanoparticle Clusters, Jin Young Kim, Hiroki Hiramatsu, Frank E. Osterloh, J. Am. Chem. Soc., 2005, 127(44), 15556-15561. DOI: 10.1021/ja0541377 Download Local Copy
       
  » ZnO-CdSe Nanoparticle Clusters as Directional Photoemitters with Tunable Wavelength, Jin Young Kim, Frank E. Osterloh, J. Am. Chem. Soc, 2005, 127 (29), 10152-10153. DOI: 10.1021/ja052735f Download Local Copy
       
       
    This project is supported by grant #0829142 from the National Science Foundation.
 
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