期刊
ACS APPLIED MATERIALS & INTERFACES
卷 12, 期 49, 页码 54671-54682出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsami.0c15905
关键词
silicon micropillars; molybdenum tungsten disulfide; sulfur vacancies; electronic unoccupied states; photoelectrochemical hydrogen production
资金
- Ministry of Science and Technology [MOST 109-2112-M-003-011, MOST 109-2113-M-002-020-MY3, MOST 107-2113-M-002-008-MY3, MOST 106-2112-M-003-007-MY3]
Hydrogen energy is a promising alternative for fossil fuels because of its high energy density and carbon-free emission. Si is an ideal light absorber used in solar water splitting to produce H-2 gas because of its small band gap, appropriate conduction band position, and high theoretical photocurrent. However, the overpotential required to drive the photo-electrochemical (PEC) hydrogen evolution reaction (HER) on bare Si electrodes is severely high owing to its sluggish kinetics. Herein, a molybdenum tungsten disulfide (MoS2-WS2) composite decorated on a Si photoabsorber is used as a cocatalyst to accelerate HER kinetics and enhance PEC performance. This MoS2-WS2 hybrid showed superior catalytic activity compared with pristine MoS2 or WS2. The optimal MoS2-WS2/Si electrode delivered a photocurrent of -25.9 mA/cm(2) at 0 V (vs reversible hydrogen electrode). X-ray absorption spectroscopy demonstrated that MoS2-WS2 possessed a high hole concentration of unoccupied electronic states in the MoS2 component, which could promote to accept large amounts of carriers from the Si photoabsorber. Moreover, a large number of sulfur vacancies are generated in the MoS(2 )constituent of this hybrid cocatalyst. These sulfur defects served as HER active sites to boost the catalytic efficiency. Besides, the TiO2-protective MoS2-WS2/Si photocathode maintained a current density of -15.0 mA/cm(2) after 16 h of the photocatalytic stability measurement.
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