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Promising GeSe Nanosheet-Based Thin-Film Photocathode for Efficient and Stable Overall Solar Water Splitting

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journal contribution
posted on 04.03.2019, 00:00 by Kang Wang, Dingwang Huang, Le Yu, Kuang Feng, Lintao Li, Takashi Harada, Shigeru Ikeda, Feng Jiang
Compound semiconductor GeSe nanosheet-based thin films were systematically researched for application in solar water splitting. p-type GeSe films obtained from the rapid thermal sublimation method have a sheetlike grain structure and a homogeneous elemental distribution, which is suitable for application in photocathodes for solar hydrogen production. Deposition of a CdS layer on top of GeSe was found to be effective in enhancing the photoelectrochemical properties due to the pn junction formed at the interface of CdS/GeSe that enhances the separation rate of photoexcited carriers. Furthermore, the atomic layer deposition of the TiO2 overlayer under the CdS/GeSe photocathode not only protects the CdS from photocorrosion but also reduces surface recombination, which could generally enhance photocathode performance. The obtained Pt-TiO2/CdS/GeSe photocathode generated ∼10.5 mA/cm2 under 0 VRHE and presented an onset potential of ∼0.45 VRHE. The calculated half-cell solar-to-hydrogen (HC-STH) efficiency of the obtained Pt-TiO2/CdS/GeSe photocathode was over 1%, and the stacked photocathode exhibited an appreciable photoelectrochemical stability of more than 8 h. It was found that the relationship between H2 evolution amount and illumination time is almost linear, with more than 105 μmol of H2 accompanied by ∼54 μmol of O2 evolving throughout the detection period of 3 h under sustained solar light illumination.

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