Enhanced hydrogen generation from formic acid by a biomimetic ruthenium complex with a covalently bonded phosphine ligand

Mei Hua Chen, Jia Hoa Lin, Chuen Ru Li, Jacek Gliniak, Chin Hao Chang, Chun Sheng Peng, Yi Ting Chen, Jen-Shiang Yu, Tung-Kung Wu*

*Corresponding author for this work

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

A series of [Ru 2 (CO) 5 (μ-SCH 2 CH 2 CH 2 S)PXS] complexes (Ru 2 -S 2 -PXS, X = phosphine ligands, S = 1–8) have been synthesized and evaluated for their photocatalytic H 2 generation efficiencies from formic acid decomposition. The [Ru 2 (CO) 5 (μ-SCH 2 CH 2 CH 2 S)P(o-C 6 H 4 CH 3 ) 3 ] (Ru 2 -S 2 -PX4) catalyst + P(CH 3 ) 3 ligand exhibited a high turnover frequency of 15,840 h −1 and turnover number of 24,536. A mechanistic investigation of the Ru 2 -S 2 -PX4 + FA/TEA catalyzed photocatalytic H 2 generation reaction using ATR-IR, EI-MS, and NMR techniques suggested that when Ru 2 -S 2 -PX4 was photoirradiated, the P(o-C 6 H 4 CH 3 ) 3 was dissociated from the complex to form a new species, [Ru 2 (CO) 5 (μ-SCH 2 CH 2 CH 2 S)]* (I). The free P(o-C 6 H 4 CH 3 ) 3 then attacks a second molecule of Ru 2 -S 2 -PX4 to form Ru 2 -S 2 -(PX4) 2 and release of free CO, which is then combined with species I to form Ru 2 -S 2 . Subsequent attachment of formate ion to species Ru 2 -S 2 -PX4, Ru 2 -S 2 , and Ru 2 -S 2 -(PX4) 2 to form [Ru 2 (CO) 5 (μ-SCH 2 CH 2 CH 2 S)]-HCOO (II), Ru 2 -S 2 -HCOO (II′) and Ru 2 -S 2 -PX4-HCOO (II″), respectively. Rearrangement of complex II (or II′ or II″) and evolution of CO 2 generate a transient complex [Ru 2 (CO) 5 (μ-SCH 2 CH 2 CH 2 S)H] (III), which then undergoes a protonation process to yield complex [Ru 2 (CO) 5 (μ-SCH 2 CH 2 CH 2 S)H 2 ] (IV). Release of H 2 and re-incorporation of the formate anion as well as evolution of CO 2 regenerates the active complex III and the cycle begins again.

Original languageEnglish
Pages (from-to)9784-9794
Number of pages11
JournalInternational Journal of Hydrogen Energy
Volume42
Issue number15
DOIs
StatePublished - 13 Apr 2017

Keywords

  • Biomimetic photocatalyst
  • Hydrogen generation
  • Ruthenium H-cluster

Fingerprint Dive into the research topics of 'Enhanced hydrogen generation from formic acid by a biomimetic ruthenium complex with a covalently bonded phosphine ligand'. Together they form a unique fingerprint.

  • Cite this