71-47-6Relevant articles and documents
Flowing afterglow study of the gas phase nucleophilic reactions of some formyl, acetyl and cyclic esters
Frink, Brian T.,Hadad, Christopher M.
, p. 2397 - 2407 (1999)
A variety of nucleophiles have been investigated for their reactions with formyl and acetyl esters in the gas phase in our flowing afterglow. The reactions that are permitted in the gas phase are more varied than those seen in the condensed phase. The rates of reactions of methyl and ethyl esters as well as various lactones have been undertaken with various nucleophiles: H2N-, HO-, CH3O, NCCH2-, F-, CH3C(=O)CH2-, CH3S- and O2NCH2-. For example, the reaction rate of NCCH2- + HCO2CH2CH3 has been found to be (1.3 ± 0.2) x 10-10 cm3 molecule-1 s-1 and the only product is HC(O-)=CHCN which results from nucleophilic acyl substitution (BAC2) followed by a proton transfer within the ion-molecule complex. Other reaction mechanisms that have been observed include β-elimination (E2), bimolecular nucleophilic substitution at the alkyl group (BAL2), and the Riveros reaction (elimination of CO). A mechanism for the F- + HCO2CH3 reaction has been determined at the B3LYP/6-31 + G(d) level. Most notably, channels were determined computationally (6AL2 and Riveros), and these channels are also observed experimentally. Furthermore, the BAC2 pathway which proceeds via nucleophilic attack on the carbonyl group also leads to the Riveros products, F-(CH3OH) and CO.
Nanoconfinement Engineering over Hollow Multi-Shell Structured Copper towards Efficient Electrocatalytical C?C coupling
Li, Jiawei,Liu, Chunxiao,Xia, Chuan,Xue, Weiqing,Zeng, Jie,Zhang, Menglu,Zheng, Tingting
supporting information, (2021/12/06)
Nanoconfinement provides a promising solution to promote electrocatalytic C?C coupling, by dramatically altering the diffusion kinetics to ensure a high local concentration of C1 intermediates for carbon dimerization. Herein, under the guidance of finite-element method simulations results, a series of Cu2O hollow multi-shell structures (HoMSs) with tunable shell numbers were synthesized via Ostwald ripening. When applied in CO2 electroreduction (CO2RR), the in situ formed Cu HoMSs showed a positive correlation between shell numbers and selectivity for C2+ products, reaching a maximum C2+ Faradaic efficiency of 77.0±0.3 % at a conversion rate of 513.7±0.7 mA cm?2 in a neutral electrolyte. Mechanistic studies clarified the confinement effect of HoMSs that superposition of Cu shells leads to a higher coverage of localized CO adsorbate inside the cavity for enhanced dimerization. This work provides valuable insights for the delicate design of efficient C?C coupling catalysts.
Symmetry-Broken Au–Cu Heterostructures and their Tandem Catalysis Process in Electrochemical CO2 Reduction
Jia, Henglei,Yang, Yuanyuan,Chow, Tsz Him,Zhang, Han,Liu, Xiyue,Wang, Jianfang,Zhang, Chun-yang
, (2021/04/27)
Symmetry-breaking synthesis of colloidal nanocrystals with desired structures and properties has aroused widespread interest in various fields, but the lack of robust synthetic protocols and the complex growth kinetics limit their practical applications. Herein, a general strategy is developed to synthesize the Au–Cu Janus nanocrystals (JNCs) through the site-selective growth of Cu nanodomains on Au nanocrystals, which is directed by the substantial lattice mismatch between them, with the assistance of judicious manipulation of the growth kinetics. This strategy can work on Au nanocrystals with different architectures for the achievement of diverse asymmetric Au–Cu hybrid nanostructures. Of particular note, the obtained Au nanobipyramids (Au NBPs)-based JNCs facilitate the conversion of CO2 to C2 hydrocarbon production during electrocatalysis, with the Faradaic efficiency and maximum partial current density being 4.1-fold and 6.4-fold higher than those of their monometallic Cu counterparts, respectively. The excellent electrocatalytic performances benefit from the special design of the Au–Cu Janus architectures and their tandem catalysis mechanism as well as the high-index facets on Au nanocrystals. This research provides a new approach to synthesize various hybrid Janus nanostructures, facilitating the study of structure-function relationship in the catalytic process and the rational design of efficient heterogeneous electrocatalysts.
Ru catalyzed hydrogenation of CO2 to formate under basic and acidic conditions
Cannon, Austin T.,Saouma, Caroline T.
, (2021/08/03)
The hydrogenation of CO2 to MeOH is pertinent to advance future energy schemes. Towards this end, phosophine-ligated Ru catalysts have been shown to achieve this transformation under either acidic or basic conditions. In this manuscript, we screen catalytic conditions for a novel tris(phosphine) ligand with Ru to see if it can facilitate the conversion of CO2 to MeOH under both acidic and basic conditions. With both sets of conditions, we observe hydrogenation of CO2 to formate. This work shows that the same catalytic system can function under both reaction types but is limited to formate production.
Selectivity Control of Cu Nanocrystals in a Gas-Fed Flow Cell through CO2Pulsed Electroreduction
Jeon, Hyo Sang,Timoshenko, Janis,Rettenmaier, Clara,Herzog, Antonia,Yoon, Aram,Chee, See Wee,Oener, Sebastian,Hejral, Uta,Haase, Felix T.,Roldan Cuenya, Beatriz
supporting information, p. 7578 - 7587 (2021/05/26)
In this study, we have taken advantage of a pulsed CO2 electroreduction reaction (CO2RR) approach to tune the product distribution at industrially relevant current densities in a gas-fed flow cell. We compared the CO2RR selectivity of Cu catalysts subjected to either potentiostatic conditions (fixed applied potential of -0.7 VRHE) or pulsed electrolysis conditions (1 s pulses at oxidative potentials ranging from Ean = 0.6 to 1.5 VRHE, followed by 1 s pulses at -0.7 VRHE) and identified the main parameters responsible for the enhanced product selectivity observed in the latter case. Herein, two distinct regimes were observed: (i) for Ean = 0.9 VRHE we obtained 10% enhanced C2 product selectivity (FEC2H4 = 43.6% and FEC2H5OH = 19.8%) in comparison to the potentiostatic CO2RR at -0.7 VRHE (FEC2H4 = 40.9% and FEC2H5OH = 11%), (ii) while for Ean = 1.2 VRHE, high CH4 selectivity (FECH4 = 48.3% vs 0.1% at constant -0.7 VRHE) was observed. Operando spectroscopy (XAS, SERS) and ex situ microscopy (SEM and TEM) measurements revealed that these differences in catalyst selectivity can be ascribed to structural modifications and local pH effects. The morphological reconstruction of the catalyst observed after pulsed electrolysis with Ean = 0.9 VRHE, including the presence of highly defective interfaces and grain boundaries, was found to play a key role in the enhancement of the C2 product formation. In turn, pulsed electrolysis with Ean = 1.2 VRHE caused the consumption of OH- species near the catalyst surface, leading to an OH-poor environment favorable for CH4 production.
Operando Investigation of Ag-Decorated Cu2O Nanocube Catalysts with Enhanced CO2 Electroreduction toward Liquid Products
Herzog, Antonia,Bergmann, Arno,Jeon, Hyo Sang,Timoshenko, Janis,Kühl, Stefanie,Rettenmaier, Clara,Lopez Luna, Mauricio,Haase, Felix T.,Roldan Cuenya, Beatriz
supporting information, p. 7426 - 7435 (2021/02/26)
Direct conversion of carbon dioxide into multicarbon liquid fuels by the CO2 electrochemical reduction reaction (CO2RR) can contribute to the decarbonization of the global economy. Here, well-defined Cu2O nanocubes (NCs, 35 nm) uniformly covered with Ag nanoparticles (5 nm) were synthesized. When compared to bare Cu2O NCs, the catalyst with 5 at % Ag on Cu2O NCs displayed a two-fold increase in the Faradaic efficiency for C2+ liquid products (30 % at ?1.0 VRHE), including ethanol, 1-propanol, and acetaldehyde, while formate and hydrogen were suppressed. Operando X-ray absorption spectroscopy revealed the partial reduction of Cu2O during CO2RR, accompanied by a reaction-driven redispersion of Ag on the CuOx NCs. Data from operando surface-enhanced Raman spectroscopy further uncovered significant variations in the CO binding to Cu, which were assigned to Ag?Cu sites formed during CO2RR that appear crucial for the C?C coupling and the enhanced yield of liquid products.
Hydrogen and chemicals from alcohols through electrochemical reforming by Pd-CeO2/C electrocatalyst
Bellini, Marco,Pagliaro, Maria V.,Marchionni, Andrea,Filippi, Jonathan,Miller, Hamish A.,Bevilacqua, Manuela,Lavacchi, Alessandro,Oberhauser, Werner,Mahmoudian, Jafar,Innocenti, Massimo,Fornasiero, Paolo,Vizza, Francesco
, (2021/01/25)
The development of low-cost and sustainable hydrogen production is of primary importance for a future transition to sustainable energy. In this work, the selective and simultaneous production of pure hydrogen and chemicals from renewable alcohols is achieved using an anion exchange membrane electrolysis cell (electrochemical reforming) employing a nanostructured Pd-CeO2/C anode. The catalyst exhibits high activity for alcohol electrooxidation (e.g. 474 mA cm?2 with EtOH at 60 °C) and the electrolysis cell produces high volumes of hydrogen (1.73 l min?1 m?2) at low electrical energy input (Ecost = 6 kWh kgH2?1 with formate as substrate). A complete analysis of the alcohol oxidation products from several alcohols (methanol, ethanol, 1,2-propandiol, ethylene glycol, glycerol and 1,4-butanediol) shows high selectivity in the formation of valuable chemicals such as acetate from ethanol (100%) and lactate from 1,2-propandiol (84%). Importantly for industrial application, in batch experiments the Pd-CeO2/C catalyst achieves conversion efficiencies above 80% for both formate and methanol, and 95% for ethanol.
Erratum: Thermodynamic Analysis of Metal-Ligand Cooperativity of PNP Ru Complexes: Implications for CO2Hydrogenation to Methanol and Catalyst Inhibition (J. Am. Chem. Soc. (2019) 141:36 (14317-14328) DOI: 10.1021/jacs.9b06760)
Ardon, Yotam,Geary, Jackson,Mathis, Cheryl L.,Philliber, Mallory A.,Reese, Maxwell S.,Saouma, Caroline T.,Vanderlinden, Ryan T.
supporting information, p. 11274 - 11274 (2021/08/03)
Equation 13 in the Supporting Information contained a sign error, resulting in the incorrect pKa values reported for (PNP)Ru-CO2and PNP. The pKa of (PNP)Ru-CO2should be 26.1 ± 0.4 (not 24.6 ± 0.4). The pKa of PNP should be 29.0 ± 0.4 (not 28.6 ± 0.4). The same incorrect pKa values are reported on page 14322, in the left column, last paragraph for PNP, and in the right column, first paragraph for (PNP)Ru-CO2), and on page 14323, in Table 2, as well as in the SI (Table S3 and Figure S12 caption). Also in the Supporting Information, Figures S15 and S17 have the wrong functions plotted. The slope of the correct function was used in extrapolating thermochemical parameters derived from Figure S17. The slope of Figure S15 was used to extrapolate thermochemical parameters, which resulted in our reporting incorrect values. The value of K8,Cl should be 0.004 ± 0.0016 (not 2.5 × 10-7). The value of K5,Cl should be 2.0(±0.8) × 10-31(not 1.3 × 10-34), and hence the corresponding pKa should be >29.7 ± 0.2 (not >33.9 ± 0.4). The value of K6,Clshould be 1.0(±0.6) × 10-7(not 6.3 × 10-12), and hence the corresponding ΔG6,Cl should be 9.5 ± 0.3 kcalmol-1(not 15.3 ± 0.5 kcalmol-1). A corrected Supporting Information file is provided that has revised versions of eq 13, Figure S12 caption, Figure S15, Figure S17, and Table S3. The corrected Table 2 is shown below. None of these errors impact the discussion and conclusions drawn. We regret these errors and apologize for any confusion that may have resulted.
Reconstructing two-dimensional defects in CuO nanowires for efficient CO2electroreduction to ethylene
Li, Zhengyuan,Wang, Yan,Wu, Jingjie,Wu, Yucheng,Xia, Shuai,Zhang, Jianfang,Zhang, Tianyu
supporting information, p. 8276 - 8279 (2021/08/25)
Here we report that in situ reconstructed Cu two-dimensional (2D) defects in CuO nanowires during CO2RR lead to significantly enhanced activity and selectivity of C2H4 compared to the CuO nanoplatelets. Specifically, the CuO nanowires achieve high faradaic efficiency of 62% for C2H4 and a partial current density of 324 mA cm-2 yet at a low potential of -0.56 V versus a reversible hydrogen electrode. Structural evolution characterization and in situ Raman spectra reveal that the high yield of C2H4 on CuO nanowires is attributed to the in situ reduction of CuO to Cu followed by structural reconstruction to form 2D defects, e.g., stacking faults and twin boundaries, which improve the CO production rate and ?CO adsorption strength. This finding may provide a paradigm for the rational design of nanostructured catalysts for efficient CO2 electroreduction to C2H4.
A bioinspired molybdenum-copper molecular catalyst for CO2electroreduction
Dey, Subal,Fontecave, Marc,Mouchfiq, Ahmed,Mougel, Victor,Todorova, Tanya K.
, p. 5503 - 5510 (2020/06/10)
Non-noble metal molecular catalysts mediating the electrocatalytic reduction of carbon dioxide are still scarce. This work reports the electrochemical reduction of CO2to formate catalyzed by the bimetallic complex [(bdt)MoVI(O)S2CuICN]2?(bdt = benzenedithiolate), a mimic of the active site of the Mo-Cu carbon monoxide dehydrogenase enzyme (CODH2). Infrared spectroelectrochemical (IR-SEC) studies coupled with density functional theory (DFT) computations revealed that the complex is only a pre-catalyst, the active catalyst being generated upon reduction in the presence of CO2. We found that the two-electron reduction of [(bdt)MoVI(O)S2CuICN]2?triggers the transfer of the oxo moiety to CO2forming CO32?and the complex [(bdt)MoIVS2CuICN]2?and that a further one-electron reduction is needed to generate the active catalyst. Its protonation yields a reactive MoVH hydride intermediate which reacts with CO2to produce formate. These findings are particularly relevant to the design of catalysts from metal oxo precursors.
