期刊
NANO ENERGY
卷 32, 期 -, 页码 422-432出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.nanoen.2016.12.045
关键词
Water splitting; Co-catalyst; Molybdenum sulfide; Silicon microwire array; Solar hydrogen evolution
类别
资金
- Ministry of Science and Technology [MOST 103-2112-M-003-009-MY3, MOST 104-2113-M-002-012-MY3]
- Academia Sinica [AS-103-TP-A06]
- National Taiwan University [104R7563-3]
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 sulfurterminated 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.
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