Enhanced Charge Carrier Separation in WO3/BiVO4Photoanodes Achieved via Light Absorption in the BiVO4Layer

Ivan Grigioni, Annalisa Polo, Maria Vittoria Dozzi, Kevin G. Stamplecoskie, Danilo H. Jara, Prashant V. Kamat, Elena Selli

Research output: Contribution to journalArticlepeer-review

Abstract

Photoelectrochemical (PEC) water splitting converts solar light and water into oxygen and energy-rich hydrogen. WO3/BiVO4 heterojunction photoanodes perform much better than the separate oxide components, though internal charge recombination undermines their PEC performance when both oxides absorb light. Here we exploit the BiVO4 layer to sensitize WO3 to visible light and shield it from direct photoexcitation to overcome this efficiency loss. PEC experiments and ultrafast transient absorption spectroscopy performed by frontside (through BiVO4) or backside (through WO3) irradiating photoanodes with different BiVO4 layer thickness demonstrate that irradiation through BiVO4 is beneficial for charge separation. Optimized electrodes irradiated through BiVO4 show 40% higher photocurrent density compared to backside irradiation.

Original languageEnglish
JournalACS Applied Energy Materials
DOIs
StateAccepted/In press - 2022
Externally publishedYes

Keywords

  • filter effect
  • heterojunction
  • photoactive layer thickness
  • solar water oxidation
  • ultrafast transient absorption

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