Enhanced Photocatalytic Alcohol Oxidation at the Interface of RuC-Coated TiO2Nanorod Arrays

Shuya Li, Eric Wolfgang Shuler, Debora Willinger, Hai Tien Nguyen, Saerona Kim, Hyeong Cheol Kang, Jae Joon Lee, Weiwei Zheng, Chang Geun Yoo, Benjamin D. Sherman, Gyu Leem

Research output: Contribution to journalReview articlepeer-review

16 Scopus citations

Abstract

Visible-light-driven organic oxidations carried out under mild conditions offer a sustainable approach to performing chemical transformations important to the chemical industry. This work reports an efficient photocatalytic benzyl alcohol oxidation process using one-dimensional (1D) TiO2nanorod (NR)-based photoanodes with surface-adsorbed ruthenium polypyridyl photocatalysts at room temperature. The photocatalyst bis(2,2′-bipyridine)(4,4′-dicarboxy-2,2′-bipyridine)Ru(II) (RuC) was covalently anchored onto TiO2nanorod arrays grown on fluorine-doped tin oxide (FTO) electrode surfaces (FTO|t-TiO2|RuC, t = the thickness of TiO2NR). Under aerobic conditions, the photophysical and photocatalytic properties of FTO|t-TiO2|RuC (t = 1, 2, or 3.5 μm) photoanodes were investigated in a solution containing a hydrogen atom transfer mediator (4-acetamido-2,2,6,6-tetramethylpiperidine-N-oxyl, ACT) as cocatalyst. Dye-sensitized photoelectrochemical cells (DSPECs) using the FTO|t-TiO2|RuC (t = 1, 2, or 3.5 μm) photoanodes and ACT-containing electrolyte were investigated for carrying out photocatalytic oxidation of a lignin model compound containing a benzylic alcohol functional group. The best-performing anode surface, FTO|1-TiO2|RuC (shortest NR length), oxidized the 2° alcohol of the lignin model compound to the Cα-ketone form with a > 99% yield over a 4 h photocatalytic experiment with a Faradaic efficiency of 88%. The length of TiO2NR arrays (TiO2NRAs) on the FTO substrate influenced the photocatalytic performance with longer NRAs underperforming compared to the shorter arrays. The influence of the NR length is hypothesized to affect the homogeneity of the RuC coating and accessibility of the ACT mediator to the RuC-coated TiO2surface. The efficient photocatalytic alcohol oxidation with visible light at room temperature as demonstrated in this study is important to the development of sustainable approaches for lignin depolymerization and biomass conversion.

Original languageEnglish (US)
Pages (from-to)22799-22809
Number of pages11
JournalACS Applied Materials and Interfaces
Volume14
Issue number20
DOIs
StatePublished - May 25 2022

Keywords

  • TiOnanorods
  • alcohol dehydrogenation
  • dye-sensitized photoelectrosynthesis cell
  • lignin conversion
  • mild conditions
  • photo-oxidation

ASJC Scopus subject areas

  • General Materials Science

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