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Abstract Time‐dependent density functional theory (TDDFT) was applied to gain insights into the electronic and vibrational spectroscopic properties of an important electron transport mediator, methyl viologen (MV2+). An organic dication, MV2+has numerous applications in electrochemistry that include energy conversion and storage, environmental remediation, and chemical sensing and electrosynthesis. MV2+is easily reduced by a single electron transfer to form a radical cation species (MV•+), which has an intense UV–visible absorption near 600 nm. The redox properties of the MV2+/MV•+couple and light‐sensitivity of MV•+have made the system appealing for photo‐electrochemical energy conversion (e.g., solar hydrogen generation from water) and the study of photo‐induced charge transfer processes through electronic absorption and resonance Raman spectroscopic measurements. The reported work applies leading TDDFT approaches to investigate the electronic and vibrational spectroscopic properties of MV2+and MV•+. Using a conventional hybrid exchange functional (B3‐LYP) and a long‐range corrected hybrid exchange functional (ωB97X‐D3), including with a conductor‐like polarizable continuum model to account for solvation, the electronic absorption and resonance Raman spectra predicted are in good agreement with experiment. Also analyzed are the charge transfer character and natural transition orbitals derived from the TDDFT vertical excitations calculated. The findings and models developed further the understanding of the electronic properties of viologens and related organic redox mediators important in renewable energy applications and serve as a reference for guiding the interpretation of electronic absorption and Raman spectra of the ions.
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This content will become publicly available on May 22, 2026
Mechanism of Charge Transport in Mixed-Valence 2D Layered Hybrid Organic–Inorganic Bronze Materials
Two-dimensional layered hybrid organic–inorganic bronze (HOIB) materials are a new class of mixed-valence hybrid metal-oxides that demonstrate great potential as advanced functional materials for next-generation electronics. Recently, new hybrid vanadium bronze materials, (EV)V8O20 and (MV)V8O20, EV = ethyl viologen and MV = methyl viologen, have been introduced, with EV having ≈3 orders of magnitude higher electrical conductivity than the MV system. Given their stoichiometrically similar inorganic V–O layers and close reduction potentials, the observed significant difference in electrical conductivities is puzzling. Here, through accurate first-principles electronic structure calculations coupled with MACE machine learning molecular dynamics (MD) simulations validated by accurate ab initio MD data, we provide mechanistic molecular-level insights into dominant charge transport and electrical conductivity pathways in these materials. Our detailed structural and electronic properties data identify factors contributing to this significant difference in the electrical conductivity of these materials. Our findings in this work offer clues and provide valuable insights into improving the electrical conductivity of hybrid bronze and similar materials, suggesting new ways to guide the design of next-generation materials with enhanced properties for electronic and energy conversion applications.
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- Award ID(s):
- 2302618
- PAR ID:
- 10623754
- Publisher / Repository:
- American Chemical Society (ACS)
- Date Published:
- Journal Name:
- The Journal of Physical Chemistry C
- Volume:
- 129
- Issue:
- 20
- ISSN:
- 1932-7447
- Page Range / eLocation ID:
- 9518 to 9528
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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