Wide Range pH-Tolerable Silicon@Pyrite Cobalt Dichalcogenide Microwire Array Photoelectrodes for Solar Hydrogen Evolution

详细信息    查看全文

• 作者：Chih-Jung Chen ; Kai-Chih Yang ; Mrinmoyee Basu ; Tzu-Hsiang Lu ; Ying-Rui Lu ; Chung-Li Dong ; Shu-Fen Hu ; Ru-Shi Liu
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：March 2, 2016
• 年：2016
• 卷：8
• 期：8
• 页码：5400-5407
• 全文大小：482K
• ISSN：1944-8252

文摘

This study employed silicon@cobalt dichalcogenide microwires (MWs) as wide range pH-tolerable photocathode material for solar water splitting. Silicon microwire arrays were fabricated through lithography and dry etching technologies. Si@Co(OH)₂ MWs were utilized as precursors to synthesize Si@CoX₂ (X = S or Se) photocathodes. Si@CoS₂ and Si@CoSe₂ MWs were subsequently prepared by thermal sulfidation and hydrothermal selenization reaction of Si@Co(OH)₂, respectively. The CoX₂ outer shell served as cocatalyst to accelerate the kinetics of photogenerated electrons from the underlying Si MWs and reduce the recombination. Moreover, the CoX₂ layer completely deposited on the Si surface functioned as a passivation layer by decreasing the oxide formation on Si MWs during solar hydrogen evolution. Si@CoS₂ photocathode showed a photocurrent density of −3.22 mA cm^–2 at 0 V (vs RHE) in 0.5 M sulfuric acid electrolyte, and Si@CoSe₂ MWs revealed moderate photocurrent density of −2.55 mA cm^–2. However, Si@CoSe₂ presented high charge transfer efficiency in neutral and alkaline electrolytes. Continuous chronoamperometry in acid, neutral, and alkaline solutions was conducted at 0 V (vs RHE) to evaluate the photoelectrochemical durability of Si@CoX₂ MWs. Si@CoS₂ electrode showed no photoresponse after the chronoamperometry test because it was etched through the electrolyte. By contrast, the photocurrent density of Si@CoSe₂ MWs gradually increased to −5 mA cm^–2 after chronoamperometry characterization owing to the amorphous structure generation.