Bandgap engineering of NiWO4/CdS solid Z-scheme system via an ion-exchange reaction

Mingjie Li, Shun Yokoyama, Hideyuki Takahashi, Kazuyuki Tohji

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


Energy band alignment is essential for efficient charge transfer and solar light utilization in the solid Z-scheme system (SZSS). Here, we propose a strategy to fabricate the NiWO4/CdS composition as SZSS with an additional feature of a tunable bandgap via an ion-exchange reaction between the NiWO4 precursor and Cd2+/S2–, which is confirmed with SEM-EDS and Raman spectroscopy. UV–vis DRS and photoluminescence spectrometry determine the bandgap structures. Photosystem II is constructed from NiWO4, while the structure of photosystem I (PSI) depends on the S content in the composition. As the S content increases from 0 to 45 at%, the bandgap decreases from 2.62 to 1.86 eV for PSI. Moreover, the photoluminescence spectra and photocatalytic H2 generation experiments demonstrate that the introduction of S provides the proper band alignment for efficient charge transfer and H2 generation. Bandgap engineering in SZSS by adjusting the S content in the NiWO4/CdS composition can be also extended to other metal tungstate and metal sulfide composites (MWO4/MS).

Original languageEnglish
Pages (from-to)284-291
Number of pages8
JournalApplied Catalysis B: Environmental
Publication statusPublished - 2019 Feb


  • Bandgap engineering
  • Hydrogen generation
  • NiWO/CdS
  • Z-scheme system

ASJC Scopus subject areas

  • Catalysis
  • Environmental Science(all)
  • Process Chemistry and Technology


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