Electrochemical reduction of carbon dioxide catalyzed by Rh(diphos)2Cl

Slater, S.J.E.; Wagenknecht, J. H.

doi:10.1021/ja00330a064

Cited by 134 publications

(65 citation statements)

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“…The cyclic voltammograms (CVs) of complexes 1−5 show single reversible 2-electron reductions ( Figure 3) corresponding to the d 8 /d 10 couple, which are consistent with the electrochemistry of previously reported Rh(I) bis-diphosphine complexes. 15,22 The observed reductions are diffusion controlled, as indicated by linear plots of the peak current against the square root of the scan rate. The 2-electron nature of this couple is evident in the splitting of the cathodic and anodic peaks, which fall between the 60 mV expected for a completely reversible one-electron reduction and the 30 mV expected for a completely reversible 2-electron reduction (Table 3).…”

Section: ■ Results and Discussionmentioning

confidence: 93%

Incorporation of Pendant Bases into Rh(diphosphine)₂ Complexes: Synthesis, Thermodynamic Studies, And Catalytic CO₂ Hydrogenation Activity of [Rh(P₂N₂)₂]⁺ Complexes

et al. 2015

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A series of five [Rh(P2N2)2]+ complexes (P2N2 = 1,5-diaza-3,7-diphosphacyclooctane) have been synthesized and characterized: [Rh(PPh 2NPh 2)2]+ (1), [Rh(PPh 2NBn 2)2]+ (2), [Rh(PPh 2NPhOMe 2)2]+ (3), [Rh(PCy 2NPh 2)2]+ (4), and [Rh(PCy 2NPhOMe 2)2]+ (5). Complexes 1–5 have been structurally characterized as square planar rhodium bis-diphosphine complexes with slight tetrahedral distortions. The corresponding hydride complexes 6–10 have also been synthesized and characterized, and X-ray diffraction studies of HRh(PPh 2NBn 2)2 (7), HRh(PPh 2NPhOMe 2)2 (8) and HRh(PCy 2NPh 2)2 (9) show that the hydrides have distorted trigonal bipyramidal geometries. Equilibration of complexes 2–5 with H2 in the presence of 2,8,9-triisopropyl-2,5,8,9-tetraaza-1-phosphabicyclo[3,3,3]undecane (Verkade’s base) enabled the determination of the hydricities and estimated pK a’s of the Rh(I) hydride complexes using the appropriate thermodynamic cycles. Complexes 1–5 were active for CO2 hydrogenation under mild conditions, and their relative rates were compared to that of [Rh(depe)2]+, a nonpendant-amine-containing complex with a similar hydricity to the [Rh(P2N2)2]+ complexes. It was determined that the added steric bulk of the amine groups on the P2N2 ligands hinders catalysis and that [Rh(depe)2]+ was the most active catalyst for hydrogenation of CO2 to formate.

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Section: ■ Results and Discussionmentioning

confidence: 93%

Incorporation of Pendant Bases into Rh(diphosphine)₂ Complexes: Synthesis, Thermodynamic Studies, And Catalytic CO₂ Hydrogenation Activity of [Rh(P₂N₂)₂]⁺ Complexes

et al. 2015

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“…Previous reports have suggested that the oxygen from CO 2 is transferred to an unknown oxide acceptor (19). The oxide acceptor can be a proton that can be extracted from acetonitrile (20) or even from the supporting electrolyte via Hoffman degradation (21). More recently, evidence pointing to protons as the oxide acceptor was reported by Wong et al They showed that the catalytic current increased for the reduction of ReðbipyÞðCOÞ 3 ðpyÞðOTfÞ under CO 2 in the presence of increasing concentrations of weak Brönsted acids (22).…”

Section: Uv-vis Stopped-flow Spectroscopy: Probing the Selectivity Ofmentioning

confidence: 99%

Kinetic and structural studies, origins of selectivity, and interfacial charge transfer in the artificial photosynthesis of CO

Smieja

Benson

Kumar

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

190

235

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The effective design of an artificial photosynthetic system entails the optimization of several important interactions. Herein we report stopped-flow UV-visible (UV-vis) spectroscopy, X-ray crystallographic, density functional theory (DFT), and electrochemical kinetic studies of the Reðbipy-tBuÞðCOÞ 3 ðLÞ catalyst for the reduction of CO 2 to CO. A remarkable selectivity for CO 2 over H þ was observed by stopped-flow UV-vis spectroscopy of ½Reðbipy-tBuÞðCOÞ 3 −1 . The reaction with CO 2 is about 25 times faster than the reaction with water or methanol at the same concentrations. X-ray crystallography and DFT studies of the doubly reduced anionic species suggest that the highest occupied molecular orbital (HOMO) has mixed metal-ligand character rather than being purely doubly occupied d z 2 , which is believed to determine selectivity by favoring CO 2 (σ þ π) over H þ (σ only) binding. Electrocatalytic studies performed with the addition of Brönsted acids reveal a primary H∕D kinetic isotope effect, indicating that transfer of protons to Re-CO 2 is involved in the rate limiting step. Lastly, the effects of electrode surface modification on interfacial electron transfer between a semiconductor and catalyst were investigated and found to affect the observed current densities for catalysis more than threefold, indicating that the properties of the electrode surface need to be addressed when developing a homogeneous artificial photosynthetic system. carbon dioxide reduction | electrochemistry | kinetics | electrocatalyst T he development of artificial photosynthetic systems is of immediate concern in view of the world's dependence on fossil fuels and the increasing emissions of CO 2 . Rapid industrial growth in developing nations will significantly increase the global energy demand in coming years, and although known reserves of fuels such as natural gas and coal are sufficient for the near future, they are becoming increasingly costly to obtain. As the use of fossil fuels is fundamentally unsustainable and generates greenhouse gases and other pollutants, the development of environmentally benign energy sources is important. Solar energy is an abundant alternative but suffers from being a diffuse energy source, and its availability varies by location and time of day. If we can capture solar energy and use CO 2 as a C 1 feedstock for liquid fuels, we can envision converting our global energy economy into a nearly carbon-neutral system (1).Photosynthesis is one of the great triumphs of nature and is the cornerstone for advanced life on the planet. Mankind has yet to master nature's ability to store sunlight as chemical energy by splitting CO 2 and H 2 O to form C─C, C─H, and O─O bonds. The energy-dense liquid fuels formed by this process would have the advantage of conforming to the existing infrastructure. Photosynthesis can be divided into two parts: water splitting and reduction of carbon dioxide. Water oxidation has been reviewed extensively by others (2-4).Our laboratory is currently exploring the development of C...

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“…9,23,24 Mechanistic insights have been gained recently too with Re, [28][29][30] Mn 31,32 and Ni 33-36 based catalysts through electrochemical and spectroscopic analysis, and quantum chemistry calculations. The reduction of carbon dioxide into formate has been more rarely observed using molecular catalysts, in electrochemical conditions with Fe, Ni, Co, Ru, Rh or Ir based catalysts [37][38][39][40][41][42][43][44][45][46][47][48][49] (see also tables 2 and 3 in reference 7) and in photochemical conditions 13,14,[50][51][52][53] with Re, Ru, Ir main-2 ly and very recently Mn complexes. 53 Mechanistic studies have accordingly been scarce.…”

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confidence: 99%

Molecular Catalysis of the Electrochemical and Photochemical Reduction of CO₂ with Earth-Abundant Metal Complexes. Selective Production of CO vs HCOOH by Switching of the Metal Center

et al. 2015

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Molecular catalysis of carbon dioxide reduction using earth-abundant metal complexes as catalysts is a key challenge related to the production of useful products--the "solar fuels"--in which solar energy would be stored. A direct approach using sunlight energy as well as an indirect approach where sunlight is first converted into electricity could be used. A Co(II) complex and a Fe(III) complex, both bearing the same pentadentate N5 ligand (2,13-dimethyl-3,6,9,12,18-pentaazabicyclo[12.3.1]octadeca-1(18),2,12,14,16-pentaene), were synthesized, and their catalytic activity toward CO2 reduction was investigated. Carbon monoxide was formed with the cobalt complex, while formic acid was obtained with the iron-based catalyst, thus showing that the catalysis product can be switched by changing the metal center. Selective CO2 reduction occurs under electrochemical conditions as well as photochemical conditions when using a photosensitizer under visible light excitation (λ > 460 nm, solvent acetonitrile) with the Co catalyst. In the case of the Fe catalyst, selective HCOOH production occurs at low overpotential. Sustained catalytic activity over long periods of time and high turnover numbers were observed in both cases. A catalytic mechanism is suggested on the basis of experimental results and preliminary quantum chemistry calculations.

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Electrochemical reduction of carbon dioxide catalyzed by Rh(diphos)2Cl

Cited by 134 publications

References 0 publications

Incorporation of Pendant Bases into Rh(diphosphine)₂ Complexes: Synthesis, Thermodynamic Studies, And Catalytic CO₂ Hydrogenation Activity of [Rh(P₂N₂)₂]⁺ Complexes

Incorporation of Pendant Bases into Rh(diphosphine)₂ Complexes: Synthesis, Thermodynamic Studies, And Catalytic CO₂ Hydrogenation Activity of [Rh(P₂N₂)₂]⁺ Complexes

Kinetic and structural studies, origins of selectivity, and interfacial charge transfer in the artificial photosynthesis of CO

Molecular Catalysis of the Electrochemical and Photochemical Reduction of CO₂ with Earth-Abundant Metal Complexes. Selective Production of CO vs HCOOH by Switching of the Metal Center

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Electrochemical reduction of carbon dioxide catalyzed by Rh(diphos)2Cl

Cited by 134 publications

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Incorporation of Pendant Bases into Rh(diphosphine)2 Complexes: Synthesis, Thermodynamic Studies, And Catalytic CO2 Hydrogenation Activity of [Rh(P2N2)2]+ Complexes

Incorporation of Pendant Bases into Rh(diphosphine)2 Complexes: Synthesis, Thermodynamic Studies, And Catalytic CO2 Hydrogenation Activity of [Rh(P2N2)2]+ Complexes

Kinetic and structural studies, origins of selectivity, and interfacial charge transfer in the artificial photosynthesis of CO

Molecular Catalysis of the Electrochemical and Photochemical Reduction of CO2 with Earth-Abundant Metal Complexes. Selective Production of CO vs HCOOH by Switching of the Metal Center

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Incorporation of Pendant Bases into Rh(diphosphine)₂ Complexes: Synthesis, Thermodynamic Studies, And Catalytic CO₂ Hydrogenation Activity of [Rh(P₂N₂)₂]⁺ Complexes

Incorporation of Pendant Bases into Rh(diphosphine)₂ Complexes: Synthesis, Thermodynamic Studies, And Catalytic CO₂ Hydrogenation Activity of [Rh(P₂N₂)₂]⁺ Complexes

Molecular Catalysis of the Electrochemical and Photochemical Reduction of CO₂ with Earth-Abundant Metal Complexes. Selective Production of CO vs HCOOH by Switching of the Metal Center