(Invited) Corrosion of Semiconductors at the Solution Interface in Integrated Solar Fuel Devices: Challenges and Perspectives

Tuesday, 30 May 2017: 12:20
Churchill C2 (Hilton New Orleans Riverside)
K. Sun (California Institute of Technology), C. Xiang (Caltech), and N. S. Lewis (California Institute of Technology)
Corrosion of technologically important small band-gap (EG<2 eV) semiconductors is a common behavioral response to the photoelectrochemical environment such as illumination condition, potential, pH, buffer ions, and etc. Importantly, this corrosion process of semiconductors is generally recognized as the leading failure mechanism in integrated solar fuel devices. Therefore, understanding the corrosion reaction is critical to the development of stabilization strategies toward the realization of efficient and stable solar fuel conversion devices. Depending on the materials behavior in response to the corrosive environment and electrochemical stress, the corrosion process can be categorized into dissolution and passivation corrosion depending on the dissolution rate of the thermodynamically decomposed products at the semiconductor solution interface. In this work, photo-passivation and -corrosion processes of two representative semiconductors under working conditions have been identified. Functions of the decomposed product that remains at the semiconductor interface have been investigated including effects to the interfacial energetics and co-stabilization. For the semiconductor that involves dissolution corrosion under operation, two effective new designs that are promising in maintaining the functionalities of the integrated photoelectrodes have been experimentally studied. Challenges and future research directions will be also discussed.