Boosting Unassisted Alkaline Solar Water Splitting Using Silicon Photocathode with TiO2 Nanorods Decorated by Edge‐Rich MoS2 Nanoplates

To construct a highly efficient photoelectrochemical tandem device with silicon photocathode operating in alkaline conditions, it is desirable to develop stable and active catalysts which enable the photocathode to reliably perform under an alkaline environment. With nanostructured passivation layer...

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Published in:Small (Weinheim an der Bergstrasse, Germany) Germany), 2021-10, Vol.17 (39), p.e2103457-n/a
Main Authors: Jun, Sang Eon, Hong, Seung‐Pyo, Choi, Seokhoon, Kim, Changyeon, Ji, Su Geun, Park, Ik Jae, Lee, Sol A, Yang, Jin Wook, Lee, Tae Hyung, Sohn, Woonbae, Kim, Jin Young, Jang, Ho Won
Format: Article
Language:English
Subjects:
Catalysts
Energy bands
hydrogen evolution
Hydrogen evolution reactions
Interfacial energy
Molybdenum disulfide
Nanorods
Nanotechnology
Perovskites
Photocathodes
Photoelectric effect
photoelectrochemical water splitting
Photovoltaic cells
Silicon
tandem device
Titanium dioxide
Transition metals
Water splitting
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Summary:To construct a highly efficient photoelectrochemical tandem device with silicon photocathode operating in alkaline conditions, it is desirable to develop stable and active catalysts which enable the photocathode to reliably perform under an alkaline environment. With nanostructured passivation layer and edge‐exposed transition metal disulfides, silicon photocathode provides new opportunities for achieving unbiased alkaline solar water splitting. Here, the TiO2 nanorod arrays decorated by edge‐rich MoS2 nanoplates are elaborately synthesized and deposited on p‐Si. The vertically aligned TiO2 nanorods fully stabilize the Si surface and improve anti‐reflectance. Moreover, MoS2 nanoplates with exposed edge sites provide catalytically active regions resulting in the kinetically favored hydrogen evolution under an alkaline environment. Interfacial energy band bending between p‐Si and catalyst layers facilitates the transport of photogenerated electrons under steady‐state illumination. Consequently, the MoS2 nanoplates/TiO2 nanorods/p‐Si photocathode exhibits significantly improved photoelectrochemical‐hydrogen evolution reaction (PEC‐HER) performance in alkaline media with a high photocurrent density of 10 mA cm−2 at 0 V versus RHE and high stability. By integrating rationally designed photocathode with earth‐abundant Fe60(NiCo)30Cr10 anode and perovskite/Si tandem photovoltaic cell, an unassisted alkaline solar water splitting is accomplished with a current density of 5.4 mA cm−2 corresponding to 6.6% solar‐to‐hydrogen efficiency, which is the highest among p‐Si photocathodes. TiO2 nanorods decorated by edge‐exposed MoS2 nanoplates are successfully deposited on silicon photocathode using hydrothermal method. The device shows remarkable photoelectrochemical performance under alkaline environment due to enhanced anti‐reflectance, edge‐rich active sites, and energetically favorable photogenerated electron transfer. Based on as‐fabricated photocathode, photoelectrochemical‐photovoltaic tandem device is constructed for unbiased alkaline solar water splitting, exhibiting 6.6% solar‐to‐hydrogen efficiency.
ISSN:1613-6810
1613-6829
DOI:10.1002/smll.202103457