Water Compatible Silicon Quantum Dots for Photocatalytic Water-splitting

Undergraduate #201
Discipline: Chemistry and Chemical Sciences
Subcategory: Nanoscience

Aaleyah J. Joe - Mary Baldwin University
Co-Author(s): Mersedeh Saniepay, Rajib Mandal, Rebecca Anthony, and Remi Beaulac, Michigan State University, East Lansing, MI

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Current fuel sources involve burning hydrocarbons, which are raw materials we cannot afford to waste. From an environmental sustainability perspective, the rapid depletion of costly nonrenewable fuels is driving research on alternative sources of energy, such as hydrogen fuel production. Photocatalytic water-splitting is a carbon neutral approach to this issue because it requires only water, photons, and a catalyst to produce hydrogen fuel. Water splitting is an artificial photosynthetic process that is inexpensive and produces clean renewable energy (H2) without the production of harmful greenhouse gases that current oil and nonrenewable fuels produce. In the present work, we researched a green chemistry approach to the synthesis of water-soluble silicon quantum dots that could potentially be coupled with a catalyst to facilitate water-splitting (i.e., the formation of O2 and H2). The challenges to overcome include functionalizing the silicon quantum dots with a water-soluble ligand and finding ways to make the particles stable in water. In experiments, hydrogen-terminated silicon quantum dots (5 nm diam.) obtained from a plasma reactor were functionalized with a water-soluble ligand. We studied the surface chemistry,morphology and size of the modified silicon quantum dots using nuclear magnetic resonance spectroscopy (NMR), transmission electron microscopy (TEM), and x-ray powder diffraction (XRD). We will report results from these studies. Understanding the fundamental processes that enable Si quantum dot stablility in water would help enable the proposed solar-to-hydrogen fuel pathway, which has potential to decrease the substantial amount of precious raw materials we waste each year.

Funder Acknowledgement(s): Funding for this research was provided by the “REU Site: Cross-Disciplinary Training in Sustainable Chemistry and Chemical Processes” under award number CHE-1358842.

Faculty Advisor: Remi Beaulac, beaulacr@chemistry.msu.edu

Role: The ultimate goal for my research was to synthesize water-compatible silicon quantum dots for photocatalytic splitting of water. I obtained hydrogen capped silicon quatum dots from a plasma generator and re-functionalized the surface of the particles. I used various characterization methods to analyze my results.