Enhanced photocatalytic H₂-production activity of WO₃/TiO₂ step-scheme heterojunction by graphene modification

Fei HE, Aiyun MENG, Bei CHENG, Wing Kei HO, Jiaguo YU

Research output: Contribution to journalArticle

Abstract

Sunlight-driven photocatalytic water-splitting for hydrogen (H₂) evolution is a desirable strategy to utilize solar energy. However, this strategy is restricted by insufficient light harvesting and high photogenerated electron–hole recombination rates of TiO₂-based photocatalysts. Here, a graphene-modified WO₃/TiO₂ step-scheme heterojunction (S-scheme heterojunction) composite photocatalyst was fabricated by a facile one-step hydrothermal method. In the ternary composite, TiO₂ and WO₃ nanoparticles adhered closely to reduced graphene oxide (rGO) and formed a novel S-scheme heterojunction. Moreover, rGO in the composite not only supplied abundant adsorption and catalytically active sites as an ideal support but also promoted electron separation and transfer from the conduction band of TiO₂ by forming a Schottky junction between TiO₂ and rGO. The positive cooperative effect of the S-scheme heterojunction formed between WO₃ and TiO₂ and the Schottky heterojunction formed between TiO₂ and graphene sheets suppressed the recombination of relatively useful electrons and holes. This effect also enhanced the light harvesting and promoted the reduction reaction at the active sites. Thus, the novel ternary WO₃/TiO₂/rGO composite demonstrated a remarkably enhanced photocatalytic H₂ evolution rate of 245.8 μmol g⁻¹h⁻¹, which was approximately 3.5-fold that of pure TiO₂. This work not only presents a low-cost graphene-based S-scheme heterojunction photocatalyst that was obtained via a feasible one-step hydrothermal approach to realize highly efficient H₂ generation without using noble metals, but also provides new insights into the design of novel heterojunction photocatalysts. Copyright © 2020 Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.
Original languageEnglish
Pages (from-to)9-20
JournalChinese Journal of Catalysis
Volume41
Issue number1
Early online dateNov 2019
DOIs
Publication statusPublished - Jan 2020

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Graphite
Graphene
Heterojunctions
Photocatalysts
Oxides
Composite materials
Hydrogen
Electrons
Precious metals
Conduction bands
Solar energy
Physics
Nanoparticles
Adsorption
Water
Costs

Citation

He, F., Meng, A., Cheng, B., Ho, W., & Yu, J. (2020). Enhanced photocatalytic H₂-production activity of WO₃/TiO₂ step-scheme heterojunction by graphene modification. Chinese Journal of Catalysis, 41(1), 9-20. doi: 10.1016/S1872-2067(19)63382-6

Keywords

  • Step-like heterojunction
  • S-scheme heterojunction
  • S heterojunction
  • Photocatalyst
  • Hydrogen generation