Theoretical investigation on the interaction between RhIII octaethylporphyrin and a graphite basal surface: a comparison study of DFT, DFT-D, and AFM. Issue 30 (23rd July 2018)

• Record Type: Journal Article
• Authors: Tada, Kohei; Maeda, Yasushi; Ozaki, Hiroyuki; Tanaka, Shingo; Yamazaki, Shin-ichi
• Is Part Of: Physical chemistry chemical physics. Volume 20:Issue 30(2018)
• Page Start: 20235
• Page End: 20246
• Publication Date: 2018-07-23
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c8cp02923g
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Using density functional theory based calculations and atomic-force-microscopy observations, we investigated the interaction between [Rh III (OEP)(Cl)] (OEP = octaethylporphyrin) and a graphite basal surface, and the electronic structure of [Rh III (OEP)(Cl)]/graphite. Abstract : Using density functional theory based calculations and atomic-force-microscopy observations, we investigated the interaction between [Rh III (OEP)(Cl)] (OEP = octaethylporphyrin) and a graphite basal surface, and the electronic structure of [Rh III (OEP)(Cl)]/graphite. The [Rh III (OEP)(Cl)] complex has an electronic structure effective for CO activation, possessing a closed singlet structure as its ground state; hence, both σ-donation from the CO molecule (anode-reaction reactant) to Rh III, and π-back-donation from Rh III to CO, occur, because the [Rh III (OEP)(Cl)] complex does not have a singlet occupied molecular orbital on the porphyrin ring, the π–π stacking interaction between porphyrin and graphite is not present and their interaction is dominated by dispersion forces. The [Rh III (OEP)(Cl)] complex easily diffused on the graphite basal surface, and an aggregated structure of [Rh III (OEP)(Cl)] was observed by atomic force microscopy. The difference of the electronic structures of [Rh III (OEP)(Cl)] before and after its adsorption is very small, the dispersion force being the dominant force for the adsorption. However, the lowest unoccupied molecular orbital of [Rh III (OEP)(Cl)]/graphite is a σ bonding orbital between Rh III and graphite that will cause fast electron transfer from [Rh III (OEP)(Cl)] to graphite during the CO electro-oxidation; this would be a reason why the carbon-supported [Rh III (OEP)(Cl)] has high catalytic activity for CO electro-oxidation.