Graduate Student Domenica Fertal

"Quantum Dots for Hydrogen Generation"

Since the effects of climate change have been recognized, scientists have been searching for ways to sustainably support our growing world. The consistent availability of the sun in most areas makes solar energy an attractive paradigm to sustain our lifestyles. While solar energy is useful, a way to store solar energy is critical for days when the sun is not shining. One way to store solar energy is in chemical bonds. Hydrogen is an attractive target to store solar energy due to its high energy per weight and environmental friendliness. Hydrogen gas can be produced through water splitting, which involves the separation of a water molecule into hydrogen gas and oxygen gas upon some type of energy input.^1 Water splitting can be achieved through electrolysis with electrons derived from sunlight or otherwise, or it can be achieved photoelectrochemically using a photosensitizer to collect solar photons and a catalyst to perform water splitting. Quantum dots are nanoscale semiconductors that are attractive targets for their photosensitizer abilities. They are capable of absorbing light and producing the electron necessary for the hydrogen reduction reaction. However, the quantum dot alone is not enough.^1 A catalyst is needed to provide an active site for the hydrogen reduction reaction. Hydrogenase is an enzyme known to perform this function but is too large to be effectively integrated with a quantum dot. Hydrogenase mimics have been developed that maintain the integrity of the active site but reduce the steric hindrance and are therefore better suited for a nanosized quantum dot.^2,3 In this seminar, I will present the photochemistry of quantum dots as it pertains to their role as photosensitizers in quantum dot-hydrogenase mimic assemblies. A metal chalcogenide combination of cadmium selenide is utilized to synthesize quantum dots with hydrogenase mimics.^4 Quantum dot assemblies can be modified to increase their efficiency for hydrogen production by adding a support to which the quantum dots may adsorb.^5 While quantum dots can be used to produce green fuels such as hydrogen, some quantum dots themselves, like the ones made from cadmium, are not all environmentally friendly. For this reason, carbon quantum dots are being explored as an alternative to traditional metal chalcogenide dots.^6,7

References
[1] Wang Q. et al. Chemical Reviews, (2020), 919-985, 120(2)
[2] Bera, D. et al. Materials, (2010), 2260-2345, 3(4)
[3] Hines D. et al. ACS Applied Materials and Interfaces. (2014), 3041-3057, 6(5)
[4] Schleusener A. et al. Journal of Physical Chemsitry Letters, (2021), 4385-4391, 12(18)
[5] Li C. et al. ACS Applied Nano Materials, (2021), 6280-6289, 4(6)
[6] Hola K. et al. ACS Catalysis, (2020), 9943-9952, 10(17)
[7] Sakdaronnarong, C. et al. Catalysts, (2020), 320, 10