Silicon microwire arrays decorated with amorphous heterometal-doped molybdenum sulfide for water photoelectrolysis

Chih Jung Chen, Kai Chih Yang, Chi Wei Liu, Ying Rui Lu, Chung Li Dong, Da Hua Wei*, Shu Fen Hu, Ru Shi Liu

*此作品的通信作者

研究成果: 雜誌貢獻期刊論文同行評審

41 引文 斯高帕斯(Scopus)

摘要

Silicon is a promising photocathode material for solar hydrogen evolution because of its small band gap, negative conduction band position, and ideal theoretical current density. In this study, p-type Si microwire (p-Si MW) arrays were prepared as photocathodes because of the large surface area and high light-harvesting capability. However, Si MWs suffered from low photocatalytic activity because of slow photo-induced carriers during driving of water-splitting reaction. Therefore, molybdenum sulfide (MoS2) with appropriate band alignment with p-Si material was employed for surface modification to function as a co-catalyst for collecting photo-generated minority carriers and reducing recombination possibility. The onset potential and current density at 0 V versus reversible hydrogen electrode (RHE) of Si@MoS2 MWs were +0.122 V and −8.41 mA cm−2. Heterometal atoms were employed to dope MoS2 co-catalyst and expose more sulfur-terminated active sites to further boost photoelectrochemical performance. Optimal activity of Si@MMoSx (M = Fe, Co, Ni) was achieved by doping Co heteroatoms, and its turn-on voltage and photocurrent density at 0 V (vs. RHE) were respectively increased to +0.192 V and −17.2 mA cm−2. X-ray absorption spectroscopy was applied to demonstrate that Fe ions of FeMoSx were dichalcogenide materials, forming a composite with MoS2 and contributing better photoelectrolytic efficiency. By contrast, two-valent heteroatoms of CoMoSx and NiMoSx substituted the Mo4+ ions in MoS2. For charge compensation, more defects and edges were revealed as active sites of solar hydrogen production by adding Co or Ni dopants in MoS2 co-catalyst, which led to lower overpotential.

原文英語
頁(從 - 到)422-432
頁數11
期刊Nano Energy
32
DOIs
出版狀態已發佈 - 2017 二月 1

ASJC Scopus subject areas

  • 可再生能源、永續發展與環境
  • 材料科學(全部)
  • 電氣與電子工程

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