Nanocrystal Tandems as Improved Solar Water Splitting Photocatalysts

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PI: OsterlohProposal Number: 1133099Intellectual Merit The solar energy?]driven splitting of water into hydrogen and oxygen is promising route for the production of clean, carbon-free renewable fuel in the form of hydrogen gas (H2). Although many semiconductor materials catalyze this reaction, the solar energy conversion efficiency is still too low (1%) for commercial applications. The overall goal of this proposed research is to synthesize nanocrystal tandem photocatalysts for solar energy driven water splitting. These catalysts combine the high theoretical efficiency limit of tandem cells (24%) with the advantages of inorganic nanocrystals, including high crystallinity, short charge transport pathways, and adjustable electronic structure. Suspended in water or as deposited as a thin film, the tandem photocatalysts will be designed to achieve the difficult technical goal of splitting water at greater than 1% efficiency.The proposed research has two fundamental objectives. The first objective is to synthesize well-defined nanocrystal model systems that will allow detailed studies on light absorption, photochemical charge generation and charge transfer in tandem photocatalyst systems. These properties are central to applications of inorganic nanocrystals for solar energy conversion and photocatalysis. The second objective is to gain fundamental understanding on the photochemical and charge transfer properties of metal oxide and chalcogenide nanocrystals, and relate these properties to their electronic structure. The mechanistic insight gained here will serve as the basis for designing new water splitting photocatalysts.Broader ImpactsThe proposed activities are designed to educate students and the public on issues related to solar energy and climate change, with examples derived from the proposed research. Towards this end, a module on the photocatalytic properties of inorganic nanoparticles will be incorporated into a graduate level class on catalysis in the Chemistry Department at the University of California at Davis (UC-Davis), and an experimental module on synthesis and testing of metal oxide gels for photocatalytic H2 production will be incorporated into the undergraduate chemistry laboratory at UC-Davis. A photocatalytic H2 demo will also be developed and incorporated into chemistry shows for the public that will be performed through the UC-Davis Chemistry Club.