Mixed-Phase (2H and 1T) MoS2 Catalyst for a Highly Efficient and Stable Si Photocathode

We describe the direct formation of mixed-phase (1T and 2H) MoS2 layers on Si as a photocathode via atomic layer deposition (ALD) for application in the photoelectrochemical (PEC) reduction of water to hydrogen. Without typical series-metal interfaces between Si and MoS2, our p-Si/SiOx/MoS2 photocat...

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Bibliographic Details
Published inCatalysts Vol. 8; no. 12; p. 580
Main Authors Joe, Jemee, Bae, Changdeuck, Kim, Eunsoo, Ho, Thi Anh, Yang, Heejun, Park, Jong Hyeok, Shin, Hyunjung
Format Journal Article
LanguageEnglish
Published Basel MDPI AG 01.12.2018
Subjects
atomic layer deposition (ALD)
Atomic layer epitaxy
Catalysts
Charge transport
Chemical reactions
Computer architecture
Electrolytes
Heterojunctions
Homojunctions
Hydrogen evolution reactions
Light
Metals
Molybdenum disulfide
p-i-n heterojunction
P-n junctions
Photocathodes
photoelectrochemical water splitting (PEC)
pinch-off effect
Silicon
Sulfuric acid
Thin films
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Summary:We describe the direct formation of mixed-phase (1T and 2H) MoS2 layers on Si as a photocathode via atomic layer deposition (ALD) for application in the photoelectrochemical (PEC) reduction of water to hydrogen. Without typical series-metal interfaces between Si and MoS2, our p-Si/SiOx/MoS2 photocathode showed efficient and stable operation in hydrogen evolution reactions (HERs). The resulting performance could be explained by spatially genuine device architectures in three dimensions (i.e., laterally homo and vertically heterojunction structures). The ALD-grown MoS2 overlayer with the mixed-phase 1T and 2H homojunction passivates light absorber and surface states and functions as a monolithic structure for effective charge transport within MoS2. It is also beneficial in the operation of p-i-n heterojunctions with inhomogeneous barrier heights due to the presence of mixed-phase cocatalysts. The effective barrier heights reached up to 0.8 eV with optimized MoS2 thicknesses, leading to a 670 mV photovoltage enhancement without employing buried Si p-n junctions. The fast-transient behaviors via light illumination show that the mixed-phase layered chalcogenides can serve as efficient cocatalysts by depinning the Fermi levels at the interfaces. A long-term operation of ~70 h was also demonstrated in a 0.5 M H2SO4 solution.
ISSN:2073-4344
2073-4344
DOI:10.3390/catal8120580