The scale of renewable energy challenge not only calls for highly efficient technologies but also abundant, inexpensive, and robust materials.  Nanomaterials can help to mitigate the poor properties of earth-abundant semiconductors to enhance solar energy conversion. I will first discuss a new growth mechanism of one-dimensional (1D) nanowires, in which screw dislocation defects provide the self-perpetuating steps to enable anisotropic crystal growth. Dislocations can further drive the spontaneous formation of nanotubes, 2D plates, and other nanomaterial morphologies for many different materials synthesized via various methods.  Our discovery and understanding of the crystal growth theory have enabled the low-cost synthesis of nanomaterials for large scale renewable energy applications.  For example, we have developed rational synthesis of nanomaterials of earth-abundant semiconductors, such as hematite (a-Fe2O3) and pyrite (FeS2), and investigated their photoelectrochemical (PEC) and photovoltaic (PV) properties.  Investigation of the surface of pyrite nanomaterials using electrochemical and transport measurements is shedding critical insights on how to enable pyrite for high performance solar applications. Furthermore, by controlling the nanostructures and polymorphs of two-dimensional (2D) layered MX2 (M = Mo, W; X = S, Se) materials, we have significant enhanced their catalytic activity in hydrogen evolution reaction for PEC water splitting.  We will also show that other earth-abundant metal sulfides and their nanostructures are highly efficient hydrogen evolution catalysts.

Solar energy conversion and hydrogen evolution catalysis using earth-abundant nanomaterials

247th National Meeting (2014)

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