The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Frederic Jaouen - One of the best experts on this subject based on the ideXlab platform.
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Electroreduction of CO 2 on Single-Site Copper-Nitrogen-Doped Carbon Material: Selective Formation of Ethanol and Reversible Restructuration of the Metal Sites
Angewandte Chemie International Edition, 2019Co-Authors: Dilan Karapinar, Ngoc Tran Huan, Nastaran Ranjbar sahraie, David Wakerley, Nadia Touati, Sandrine Zanna, Dario Taverna, Henrique Tizei, Andrea Zitolo, Frederic JaouenAbstract:It is generally believed that CO2 Electroreduction to multi‐carbon products such as ethanol or ethylene may be catalyzed with significant yield only on metallic copper surfaces, implying large ensembles of copper atoms. Here, we report on an inexpensive Cu‐N‐C material prepared via a simple pyrolytic route that exclusively feature single copper atoms with a CuN4 coordination environment, atomically dispersed in a nitrogen‐doped conductive carbon matrix. This material achieves aqueous CO2 Electroreduction to ethanol at a Faradaic yield of 55 % under optimized conditions (electrolyte: 0.1 m CsHCO3, potential: −1.2 V vs. RHE and gas‐phase recycling set up), as well as CO Electroreduction to C2‐products (ethanol and ethylene) with a Faradaic yield of 80 %. During electrolysis the isolated sites transiently convert into metallic copper nanoparticles, as shown by operando XAS analysis, which are likely to be the catalytically active species. Remarkably, this process is reversible and the initial material is recovered intact after electrolysis.
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o2 reduction mechanism on non noble metal catalysts for pem fuel cells part ii a porous electrode model to predict the quantity of h2o2 detected by rotating ring disk electrode
Journal of Physical Chemistry C, 2009Co-Authors: Frederic JaouenAbstract:During O2 Electroreduction, some O2 molecules are only reduced by two electrons to form H2O2 while the rest is reduced by four electrons to form water. The relative H2O2 production is quantified with the % H2O2.The latter number means that if the reduction of 100 O2 molecules yields, e.g., 20 H2O2 and 160 H2O molecules, then the % H2O2 is 20%. Here, O2 Electroreduction in a porous electrode is modeled to calculate the polarization (I−V curve) and % H2O2−voltage curves (%−V curve) for non-noble metal catalysts that are assumed to reduce O2 following either (i) 2e reduction + H2O2 disproportionation or (ii) 2e + 2e Electroreduction. Using a set of base-case parameters, a series of I−V and %−V curves has been calculated for case i upon variation of (a) porous electrode thickness, (b) electrode rotation rate, (c) rate constant of H2O2 disproportionation, and (d) rate constant of O2-to-H2O2 Electroreduction. For case ii typical I−V and %−V curves have also been modeled for one electrode thickness, one rotation...
Ziyang Lou - One of the best experts on this subject based on the ideXlab platform.
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a novel desulfurization process of gasoline via sodium metaborate Electroreduction with pulse voltage using a boron doped diamond thin film electrode
Fuel, 2013Co-Authors: Chenhua Shu, Tonghua Sun, Jinping Jia, Ziyang LouAbstract:Abstract A novel desulfurization process of gasoline was realized via sodium metaborate (NaBO 2 ) Electroreduction with pulse voltage using a boron-doped diamond (BDD) thin film electrode under mild conditions. The results of cyclic voltammetry and 11 boron (B) nuclear magnetic resonance (NMR) confirmed that NaBO 2 was converted into sodium borohydride (NaBH 4 ) by Electroreduction and the Electroreduction voltage ranged from −1.2 V to −1.8 V. The factors that influenced desulfurization efficiency were investigated and the desulfurization efficiency reached more than 95% for model gasoline and more than 97% for real gasoline. The components of model gasolines before and after desulfurization were analyzed by gas chromatography/mass spectrometer (GC/MS) and the elements content of electrolytes and digestion solution of precipitate were determined by inductively coupled plasma (ICP). Results indicated that reductive desulfurization process mainly involved the cleavage of C–S bond and the hydrogenation of C–C double bond and B recycle was realized at the same time as desulfurization. Consequently, possible desulfurization mechanism was proposed. Desulfurization kinetics showed a pseudo-first-order toward thiophene or benzothiophene. All these results indicated that the gasoline desulfurization process via sodium metaborate Electroreduction with pulse voltage using a BDD thin film electrode was feasible.
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mild process for reductive desulfurization of diesel fuel using sodium borohydride in situ generated via sodium metaborate Electroreduction
Industrial & Engineering Chemistry Research, 2013Co-Authors: Chenhua Shu, Tonghua Sun, Jinping Jia, Ziyang LouAbstract:A novel integrated process was proposed for reductive desulfurization of diesel fuel, in which the reductant sodium borohydride (NaBH4) was in situ generated via sodium metaborate (NaBO2) Electroreduction. In order to improve the conversion rate of BO2– into BH4–, NaBO2 Electroreduction was fulfilled by applying pulse voltage and using a boron-doped diamond (BDD) thin film electrode. The NaBO2 Electroreduction process was analyzed by cyclic voltammetry and 11boron nuclear magnetic resonance (11B NMR) and the factors that influenced desulfurization efficiency were investigated. Under the optimal conditions desulfurization efficiency reached more than 93% for model diesel fuel. The components of model diesel fuel after desulfurization were analyzed by gas chromatography/mass spectrometry (GC/MS) and the electrolyte and digestion solution of precipitate were analyzed by inductively coupled plasma (ICP). Results indicated that B recycle was realized at the same time as desulfurization. Finally, the desulfuriz...
Chenhua Shu - One of the best experts on this subject based on the ideXlab platform.
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a novel desulfurization process of gasoline via sodium metaborate Electroreduction with pulse voltage using a boron doped diamond thin film electrode
Fuel, 2013Co-Authors: Chenhua Shu, Tonghua Sun, Jinping Jia, Ziyang LouAbstract:Abstract A novel desulfurization process of gasoline was realized via sodium metaborate (NaBO 2 ) Electroreduction with pulse voltage using a boron-doped diamond (BDD) thin film electrode under mild conditions. The results of cyclic voltammetry and 11 boron (B) nuclear magnetic resonance (NMR) confirmed that NaBO 2 was converted into sodium borohydride (NaBH 4 ) by Electroreduction and the Electroreduction voltage ranged from −1.2 V to −1.8 V. The factors that influenced desulfurization efficiency were investigated and the desulfurization efficiency reached more than 95% for model gasoline and more than 97% for real gasoline. The components of model gasolines before and after desulfurization were analyzed by gas chromatography/mass spectrometer (GC/MS) and the elements content of electrolytes and digestion solution of precipitate were determined by inductively coupled plasma (ICP). Results indicated that reductive desulfurization process mainly involved the cleavage of C–S bond and the hydrogenation of C–C double bond and B recycle was realized at the same time as desulfurization. Consequently, possible desulfurization mechanism was proposed. Desulfurization kinetics showed a pseudo-first-order toward thiophene or benzothiophene. All these results indicated that the gasoline desulfurization process via sodium metaborate Electroreduction with pulse voltage using a BDD thin film electrode was feasible.
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mild process for reductive desulfurization of diesel fuel using sodium borohydride in situ generated via sodium metaborate Electroreduction
Industrial & Engineering Chemistry Research, 2013Co-Authors: Chenhua Shu, Tonghua Sun, Jinping Jia, Ziyang LouAbstract:A novel integrated process was proposed for reductive desulfurization of diesel fuel, in which the reductant sodium borohydride (NaBH4) was in situ generated via sodium metaborate (NaBO2) Electroreduction. In order to improve the conversion rate of BO2– into BH4–, NaBO2 Electroreduction was fulfilled by applying pulse voltage and using a boron-doped diamond (BDD) thin film electrode. The NaBO2 Electroreduction process was analyzed by cyclic voltammetry and 11boron nuclear magnetic resonance (11B NMR) and the factors that influenced desulfurization efficiency were investigated. Under the optimal conditions desulfurization efficiency reached more than 93% for model diesel fuel. The components of model diesel fuel after desulfurization were analyzed by gas chromatography/mass spectrometry (GC/MS) and the electrolyte and digestion solution of precipitate were analyzed by inductively coupled plasma (ICP). Results indicated that B recycle was realized at the same time as desulfurization. Finally, the desulfuriz...
Jolanta Nieszporek - One of the best experts on this subject based on the ideXlab platform.
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The mechanism and kinetics of Zn2+ Electroreduction in the presence of octyltrimethylammonium bromide
Journal of Electroanalytical Chemistry, 2013Co-Authors: Jolanta NieszporekAbstract:Abstract Zn 2+ Electroreduction in the presence of octyltrimethylammonium bromide at a mercury electrode has been studied by voltammetric and impedance measurements in the range of 288–308 K. Kinetic data showed a two-step character of the electrode process and an inhibiting influence of octyltrimethylammonium bromide on Zn 2+ Electroreduction rate. Analysis of Tafel plots showed a change of Electroreduction mechanism at a certain octyltrimethylammonium bromide concentration. Four models of Electroreduction mechanisms were applied: two consecutive electron transfers (EE), ion transfer step followed by electron transfer (IE), ion transfer followed by adsorption (IA), and chemical step followed by electron transfer (CE). The results of investigations of Zn 2+ reduction mechanism were combined with studies concerning activation energy for diffusion, standard reaction entropy, and activation enthalpy.
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Accelerating Effect of Tetramethylthiourea on the Kinetics of Zn2+ Electroreduction
Electroanalysis, 2012Co-Authors: Jolanta NieszporekAbstract:The results of kinetic measurements of Zn2+ Electroreduction on mercury electrode in the presence of tetramethylthiourea showed the two-step character of the electrode process. The acquisition of nonlinear wide potential range Tafel plots was found to offer a good opportunity to examine the Zn2+ Electroreduction mechanism. Three mechanisms including the ion transfer step followed by the electron exchange step (IE mechanism), the adsorption step (IA mechanism) and the chemical step followed by electron transfer (CE) were applied. The accelerating influence of tetramethylthiourea on Zn2+ Electroreduction was found to result from possible complexes formation in the diffuse layer. The ion transport step is probably combined with the loss or exchange of a ligand. The second step probably consists in the electron transfer or adsorption process connected with partial charge transfer.
Feng Jiao - One of the best experts on this subject based on the ideXlab platform.
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The impact of nitrogen oxides on electrochemical carbon dioxide reduction.
Nature Communications, 2020Co-Authors: Bjorn Hasa, Haeun Shin, Emily Jeng, Sean Overa, Wilson Chen, Feng JiaoAbstract:The Electroreduction of carbon dioxide offers a promising avenue to produce valuable fuels and chemicals using greenhouse gas carbon dioxide as the carbon feedstock. Because industrial carbon dioxide point sources often contain numerous contaminants, such as nitrogen oxides, understanding the potential impact of contaminants on carbon dioxide electrolysis is crucial for practical applications. Herein, we investigate the impact of various nitrogen oxides, including nitric oxide, nitrogen dioxide, and nitrous oxide, on carbon dioxide Electroreduction on three model electrocatalysts (i.e., copper, silver, and tin). We demonstrate that the presence of nitrogen oxides (up to 0.83%) in the carbon dioxide feed leads to a considerable Faradaic efficiency loss in carbon dioxide Electroreduction, which is caused by the preferential Electroreduction of nitrogen oxides over carbon dioxide. The primary products of nitrogen oxides Electroreduction include nitrous oxide, nitrogen, hydroxylamine, and ammonia. Despite the loss in Faradaic efficiency, the electrocatalysts exhibit similar carbon dioxide reduction performances once a pure carbon dioxide feed is restored, indicating a negligible long-term impact of nitrogen oxides on the catalytic properties of the model catalysts.
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formation of carbon nitrogen bonds in carbon monoxide electrolysis
Nature Chemistry, 2019Co-Authors: Matthew Jouny, Jingjing Lv, Tao Cheng, Byung Hee Ko, William A Goddard, Feng JiaoAbstract:The Electroreduction of CO2 is a promising technology for carbon utilization. Although electrolysis of CO2 or CO2-derived CO can generate important industrial multicarbon feedstocks such as ethylene, ethanol, n-propanol and acetate, most efforts have been devoted to promoting C–C bond formation. Here, we demonstrate that C–N bonds can be formed through co-electrolysis of CO and NH3 with acetamide selectivity of nearly 40% at industrially relevant reaction rates. Full-solvent quantum mechanical calculations show that acetamide forms through nucleophilic addition of NH3 to a surface-bound ketene intermediate, a step that is in competition with OH– addition, which leads to acetate. The C–N formation mechanism was successfully extended to a series of amide products through amine nucleophilic attack on the ketene intermediate. This strategy enables us to form carbon–heteroatom bonds through the Electroreduction of CO, expanding the scope of products available from CO2 reduction. The Electroreduction of CO2-derived CO is a promising technology for the sustainable production of value-added chemicals. Now, it is shown how C–N bonds can be formed electrochemically through CO Electroreduction on a Cu surface in the presence of amines. The formation of acetamides is observed through nucleophilic addition to a ketene intermediate.
