Stability and Protective Coatings of Semiconductor Electrodes for Solar Fuel Devices

Author: Buabthong, Pakpoom (Pai)

Year: 2021

Degree: Dissertation (Ph.D.)

Advisor: Lewis, Nathan Saul

Committee Members: Gray, Harry B.; Faber, Katherine T.; Goddard, William A., III; Lewis, Nathan Saul

Option: Materials Science; Computer Science

DOI: 10.7907/dx7s-fh20

Abstract

Climate change and increasing global energy consumption drive the need for clean and renewable alternatives to fossil fuels. Photoelectrochemical solar fuel devices offer a potential solution to capture and store clean and renewable solar energy in chemical bonds. Nevertheless, degradation of semiconductor electrodes is one of the major impediments to the implementation of practical stable solar fuels systems.

erein, we investigate the corrosion mechanisms and the corrosion kinetics of CdTe and ZnTe cathodes under the conditions for hydrogen-evolution reaction in strong acid and strong alkaline media. The effects of catalyst over-layer on CdTe’s and ZnTe’s corrosion pathways are discussed as well as potential protective coatings for ZnTe cathodes. Then, we address the original physical pinhole defects in amorphous a TiO₂ grown by atomic-layer deposition (ALD) on GaAs anodes. In addition, we explore new pinhole formation during electrochemical experiments and provide simulation for the propagation of the corroding GaAs substrate after new exposure to the electrolyte through microscopic pinholes. Finally, we develop a fabrication procedure for GaAs micro-island structures to provide defect isolation on the a TiO₂ film. The micro-island structures combined with dissolution measurements of the ALD a TiO₂ films were used to study the distribution and the evolution of pinholes from pre-existing defect spots in the protective coatings.

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