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

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)422-432
Number of pages11
JournalNano Energy
Volume32
DOIs
Publication statusPublished - 2017 Feb 1

Fingerprint

Silicon
Molybdenum
Hydrogen
Photocathodes
Catalysts
Water
Current density
Doping (additives)
Ions
Electrodes
X ray absorption spectroscopy
Hydrogen production
Conduction bands
Photocurrents
Sulfur
Surface treatment
Energy gap
Atoms
Defects
Composite materials

Keywords

  • Co-catalyst
  • Molybdenum sulfide
  • Silicon microwire array
  • Solar hydrogen evolution
  • Water splitting

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)
  • Electrical and Electronic Engineering

Cite this

Chen, C. J., Yang, K. C., Liu, C. W., Lu, Y. R., Dong, C. L., Wei, D. H., ... Liu, R. S. (2017). Silicon microwire arrays decorated with amorphous heterometal-doped molybdenum sulfide for water photoelectrolysis. Nano Energy, 32, 422-432. https://doi.org/10.1016/j.nanoen.2016.12.045

Silicon microwire arrays decorated with amorphous heterometal-doped molybdenum sulfide for water photoelectrolysis. / Chen, Chih Jung; Yang, Kai Chih; Liu, Chi Wei; Lu, Ying Rui; Dong, Chung Li; Wei, Da Hua; Hu, Shu Fen; Liu, Ru Shi.

In: Nano Energy, Vol. 32, 01.02.2017, p. 422-432.

Research output: Contribution to journalArticle

Chen, Chih Jung ; Yang, Kai Chih ; Liu, Chi Wei ; Lu, Ying Rui ; Dong, Chung Li ; Wei, Da Hua ; Hu, Shu Fen ; Liu, Ru Shi. / Silicon microwire arrays decorated with amorphous heterometal-doped molybdenum sulfide for water photoelectrolysis. In: Nano Energy. 2017 ; Vol. 32. pp. 422-432.
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