2007 Progress Report: Tunneled Titanate Photocatalysts for Environmental Remediation and Hydrogen Generation

EPA Grant Number: X832541C008
Subproject: this is subproject number 008 , established and managed by the Center Director under grant X832541
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: Center for Environmental and Energy Research (CEER)
Center Director: Earl, David A.
Title: Tunneled Titanate Photocatalysts for Environmental Remediation and Hydrogen Generation
Investigators: Edwards, Doreen , Misture, Scott
Institution: Alfred University
EPA Project Officer: Lasat, Mitch
Project Period: September 1, 2006 through February 28, 2008
Project Period Covered by this Report: September 1, 2006 through February 28, 2007
RFA: Targeted Research Center (2006) Recipients Lists
Research Category: Targeted Research

Objective:

Photocatalytic processes are being used for environmental remediation and have shown promise for the production of clean-burning hydrogen fuel. The continued development of these technologies, particularly those which use solar energy for photoexcitation, will require new and improved photocatalysts. The objective of this project is to determine the relationships between the composition, structure, and photocatalytic properties of tunneled titanate materials. In studies of BaTi4O9 and M2Ti6O13 (M = Na, K and Rb), other researchers have suggested that structural features such as a distorted TiO6 octahedra and tunnel sites may be responsible for enhanced photocatalytic activity. By preparing and examining different tunneled materials with systematic variations in chemistry and structure, we will be able to further test the validity of this hypothesis and identify factors that influence photocatalytic activity.

Progress Summary:

Six tunneled titanates (listed in the table below) were prepared using solid-state synthesis. The powders were characterized using X-ray diffraction to confirm phase purity, scanning electron microscopy to investigate particle morphology, and diffuse reflectance spectroscopy to measure optical properties. Particle size and surface area of the powders were also measured.

Table I. List of tunneled titanates

Composition

Average Particle Size (μm)

Surface Area (m2/g)

Bandgap (eV)

Na0.7Ga4.7Ti0.3O8

1

1.58 ± 0.01

3.03

Na0.8Ga4.8Ti1.2O10

9

0.57 ± 0.02

3.01

Na0.2Ga4.2Ti2.8O12

7

0.40 ± 0.02

2.98

K1.5Ga1.5Ti6.5O16

25

0.64 ± 0.01

---

K1Ga17Ti15O56

13

0.54 ± 0.02

2.97

BaTi4O9

2

1.33 ± 0.02

2.89

The photocatalytic activity of the titanates towards decomposition of a model compound, methylene blue, was evaluated using optical spectroscopy and compared to Degussa P25, a commercial titanium-oxide photocatalyst. Approximately 0.1 gram of the sample powers was placed in 125 mls of a 20 μM methylene blue solution and irradiated with a 100 W xenon lamp for up to eight hours. At periodic intervals, a small portion of the solution was removed and analyzed using optical spectroscopy. Figure 1 shows that all of but one of titanates, Na0.7Ga4.7Ti0.3O8, show some degree of photocatalytic activity towards the methylene blue decomposition, but none were as effective as the commercial photocatalyst. However, it is important to note that the surface area of the photocatalyst was ~ 50 greater than any of the tunnel titanates produced in this study, which is expected to have a dramatic effect on activity.

Figure 1.

Future Activities:

The photocatalytic activity towards hydrolysis is currently being studied.

Journal Articles:

No journal articles submitted with this report: View all 1 publications for this subproject

Supplemental Keywords:

photocatalysis, titanates, titanium dioxide, hydrogen production, solar technologies,

Relevant Websites:

http://ceer.alfred.edu/news/news.html Exit

Progress and Final Reports:

Original Abstract
  • Final

  • Main Center Abstract and Reports:

    X832541    Center for Environmental and Energy Research (CEER)

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
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    X832541C003 The Fining Behavior of Selectively Batched Commercial Glasses
    X832541C004 The Use of Fly Ash in the Production of SiAlON based Structural Ceramics
    X832541C005 Separation and Purification of Hydrogen From Mixed Gas Streams Using Hollow Glass Microspheres
    X832541C006 Magnesium Rich Coatings for Corrosion Control of Reactive Metal Alloys
    X832541C008 Tunneled Titanate Photocatalysts for Environmental Remediation and Hydrogen Generation
    X832541C009 Material and Environmental Sustainability in Ceramic Processing
    X832541C010 Robust, Spectrally Selective Ceramic Coatings for Recycled Solar Power Tubes
    X832541C011 Recycling of Silicon-Wafers Production Wastes to SiAlON Based Ceramics with Improved Mechanical Properties
    X832541C012 Emissions Reduction of Commercial Glassmaking Using Selective Batching