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Double-Layer Graphene Outperforming Monolayer as Catalyst on Silicon Photocathode for Hydrogen Production

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Authors
Sim, Uk; Moon, Joonhee; Lee, Joohee; An, Junghyun; Ahn, Hyo-Yong; Kim, Dong Jin; Jo, Insu; Jeon, Cheolho; Han, Seungwu; Hong, Byung Hee; Nam, Ki Tae
Issue Date
2017-02
Citation
ACS Applied Materials and Interfaces, Vol.9 No.4, pp.3570-3580
Keywords
silicongraphenehydrogen evolution reaction (HER)metal free catalystphotoelectrochemical cell
Abstract
Photoelectrochemical cells are used to split hydrogen and oxygen from water molecules to generate chemical fuels to satisfy our ever-increasing energy demands. However, it is a major challenge to design efficient catalysts to use in the photoelectochemical process. Recently, research has focused on carbon-based catalysts, as they are nonprecious and environmentally benign. Interesting advances have also been made in controlling nanostructure interfaces and in introducing new materials as catalysts in the photoelectrochemical cell. However, these catalysts have as yet unresolved issues involving kinetics and light-transmittance. In this work, we introduce high-transmittance graphene onto a planar p-Si photocathode to produce a hydrogen evolution reaction to dramatically enhance photon-to-current efficiency. Interestingly, double-layer graphene/Si exhibits noticeably improved photon-to-current efficiency and modifies the band structure of the graphene/Si photocathode. On the basis of in-depth electrochemical and electrical analyses, the band structure of graphene/Si was shown to result in a much lower work function than Si, accelerating the electron-to-hydrogen production potential. Specifically, plasma-treated double-layer graphene exhibited the best performance and the lowest work function. We electrochemically analyzed the mechanism at work in the graphene-assisted photoelectrode. Atomistic calculations based on the density functional theory were also carried out to more fully understand our experimental observations. We believe that investigation of the underlying mechanism in this high-performance electrode is an important contribution to efforts to develop high-efficiency metal-free carbon-based catalysts for photoelectrochemical cell hydrogen production.
ISSN
1944-8244
URI
https://hdl.handle.net/10371/172117
DOI
https://doi.org/10.1021/acsami.6b11750
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College of Natural Sciences (자연과학대학)Dept. of Chemistry (화학부)Journal Papers (저널논문_화학부)
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