Steering electrons and holes in the right direction

Project description:

One of science biggest dreams is to be able to use energy of the sun to efficiently convert H2O and CO2 into fuels. Photocatalysis is considered one of the most promising techniques able to do this [1, 2]. In photocatalysis, a semiconductor material absorbs the energy of a photon, generating an electron/hole pair. Both the excited electron and the hole are used for chemical half-reactions. For example, electrons can be used to produce the fuel hydrogen out of water, whereas holes are then used to produce oxygen.

Alas, photocatalysis faces two major problems preventing highly efficient photocatalysis. First, most active stable semiconductors have a relatively low visible light sensitivity. Second, electrons and holes tend to recombine before they can be used for photoconversion. This means that the electrons and holes need to be separated efficiently before being able to recombine. This project addresses the latter problem.

Some methods are already investigated for efficient separation of electrons and holes. For example, one can think of depositing cocatalysts on the semiconductor surface. These cocatalysts act as beacons for either electrons or holes. Ohno et al. showed by photodeposition of Pt and PbO2 that there is also a preferred movement direction of the charge carriers themselves in titanium dioxide [3]. We are investigating if this is also the case for other semiconductor materials. Furthermore, we study the photodeposition of other (transition) metals on the semiconductor materials. Also, we explore the effect of plasmon resonance to create more efficient photocatalysts.

[1] S. C. Roy et al.; Toward Solar Fuels: Photocatalytic Conversion of Carbon Dioxide to Hydrocarbons; ASCNano 2010, Vol. 4, No. 3, 1259-1278

[2] X. Chen et al.; Semiconductor-bases Photocatalytic Hydrogen Generation; Chem. Rev. 2010, 110, 6503-6570

[3] T. Ohno et al.; Crystal faces of rutile and anatase TiO2 particles and their roles in photocatalytic reactions; New J. Chem. 2002, 26, 1167-1170

Figure 1 – Using sunlight CO2 and H2O can be converted into hydrocarbon fuels [1].

Figure 2 – SEM image of a rutile particle with Pt and PbO2 deposits. Pt is mostly deposited at the (110)-facet, whereas PbO2 is mostly deposited at the (011)-facet [3].

Biography:

Kasper Wenderich (born in 11-11-1987, Hengelo, The Netherlands) received his BSc and MSc in Applied Physics in 2009 and 2011 respectively at the University of Twente, Enschede, The Netherlands. He graduated for his MSc on the topic “Realization and testing of a single-emitter excitation spectroscopy setup”. On December 1st Kasper started as a PhD-student in the PhotoCatalytic Synthesis (PCS) Group of prof. G. Mul on the project ‘Steering electrons and holes in the right direction.’

Scientific interests:

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Photocatalysis

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Semiconductor science

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Spectroscopic techniques

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Quantum mechanics

Personal interests:

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Listening music

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Playing piano/guitar

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Running

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Cycling (as recreation activity)

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Walking (as recreation activity)

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Watching movies

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Hanging out with friends