Multimetallic Systems for the Photocatalytic Production of Fuels from Abundant Sources

Technical Report · Sun Apr 01 00:00:00 EDT 2018

DOI:https://doi.org/10.2172/1430648· OSTI ID:1430648

Dunbar, Kim R. ^[1]; Turro, Claudia ^[2]

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1. Texas A & M Univ., College Station, TX (United States)
2. The Ohio State Univ., Columbus, OH (United States)

The reported findings herein are a result of a collaboration between the groups of Claudia Turro at The Ohio State University (DE-SC0010542) and Kim R. Dunbar at Texas A&M University (DE-SC0010721). The Turro and Dunbar groups jointly discovered that cationic d⁷–d⁷ Rh₂(II,II) complexes bridged by electron-donating formamidinate (form) ligands possess redox-active excited states that are relatively long-lived and can engage in charge transfer reactions. As part of the present grant we designed new complexes that exhibit strong absorption from the UV to ~800 nm. The Rh₂(II,II) complexes under investigation are poised to undergo catalytic reduction of substrates because they are robust to changes in metal oxidation state, the two metals and the two diimine ligands, together with the non-innocent bridges, can be used to store redox equivalents, making these complexes capable of coupling one-electron events with multi-electron transformations. We discovered the electrocatalytic reduction of H⁺ and CO₂ by complexes that are able to electrocatalytically reduce H⁺ to H₂ with high turnover frequencies (TOFs) and overpotentials, η, of ~0.5 V,8 as well as to reduce CO₂ to HCOOH. We now have experimental evidence that both the production of H² from H⁺ and HCOOH. The molecular catalysts are stable after the acid and/or CO₂ is consumed since electrocatalysis is restored at the same rate upon the addition of substrate to the cell.8,9 Moreover, we showed that the catalysis is not a result of a decomposition product deposited on the electrode, since placing an electrode from an active electrocatalytic solution into one that does not contain catalyst completely shuts down the reactivity. We are currently exploring the reactivity of these complexes in hydride transfer reactions with other substrates and in the presence of CO₂ and reducing agents, as well as attempting to grow single crystals for x-ray diffraction.

• Research Organization: Texas A & M Univ., College Station, TX (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Contributing Organization: Texas A&M University and The Oho State University
• DOE Contract Number: SC0010721
• OSTI ID: 1430648
• Report Number(s): DOE_TexasA&M0010721
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
Solar energy
carbon dioxide reduction
hydrogen production
electrocatalytic reduction of H+ and CO2