期刊
ACS APPLIED MATERIALS & INTERFACES
卷 6, 期 24, 页码 22830-22837出版社
AMER CHEMICAL SOC
DOI: 10.1021/am506999p
关键词
solar; hydrogen; photocathode; protective layer; failure mechanism; alkaline electrolyte
资金
- National Science Foundation (NSF) through the Center for Sustainable Materials Chemistry [CHE-1102637]
- W.M Keck Foundation
- M.J. Murdock Charitable Trust
- ONAMI
- Air Force Research Laboratory [FA8650-05-1-5041]
- NSF [0923577, 0421086]
- University of Oregon
- Research Corporation for Science Advancement
- Division Of Chemistry
- Direct For Mathematical & Physical Scien [1102637] Funding Source: National Science Foundation
Protecting Si photocathodes from corrosion is important for developing tandem water-splitting devices operating in basic media. We show that textured commercial Si-pn(+) photovoltaics protected by solution-processed semiconducting/conducting oxides (plausibly suitable for scalable manufacturing) and coupled to thin layers of Ir yield high-performance H-2-evolving photocathodes in base. They also serve as excellent test structures to understand corrosion mechanisms and optimize interfacial electrical contacts between various functional layers. Solution-deposited TiO2 protects Si-pn(+) junctions from corrosion for similar to 24 h in base, whereas junctions protected by F:SnO2 fail after only 1 h of electrochemical cycling. Interface layers consisting of Ti metal and/or the highly doped F:SnO2 between the Si and TiO2 reduce Si-emitter/oxide/catalyst contact resistance and thus increase fill factor and efficiency. Controlling the oxide thickness led to record photocurrents near 35 mA cm(-2) at 0 V vs RHE and photocathode efficiencies up to 10.9% in the best cells. Degradation, however, was not completely suppressed. We demonstrate that performance degrades by two mechanisms, (1) deposition of impurities onto the thin catalyst layers, even from high-purity base, and (2) catastrophic failure via pinholes in the oxide layers after several days of operation. These results provide insight into the design of hydrogen-evolving photoelectrodes in basic conditions, and highlight challenges.
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