A Ni-catalyzed enantioconvergent cross-coupling between β-bromostyrenes and secondary Grignard reagents is reported. This C(sp2)–C(sp3) cross-coupling is applicable to a broad range of electrophilic and nucleophilic partners and affords the products in good to high levels of enantio-induction. Experimental mechanistic investigations revealed an unexpected binding mode of the chiral (P,N) ligand and support a radical rebound mechanism involving in-cage radicals. Kinetic experiments provide evidence for an off-cycle resting state featuring dinuclear species. Computational analyses are in line with this hypothesis and coherent with a catalytic cycle proceeding via a Ni(I)/Ni(III) manifold. They further suggest an enantio-determining radical capture event and shed light on the origin of the Dynamic Kinetic Resolution process.
{"title":"Ni-Catalyzed Enantioconvergent Kumada–Corriu Cross-Coupling between β-Bromostyrenes and Secondary Grignard Reagents: Reaction Development, Scope and Mechanistic Investigations","authors":"Kaidi Li, Baptiste Leforestier, Amalia I. Poblador-Bahamonde, Céline Besnard, Laure Guénée, Svetlana Kucher, Clément Mazet","doi":"10.1021/acscatal.4c06360","DOIUrl":"https://doi.org/10.1021/acscatal.4c06360","url":null,"abstract":"A Ni-catalyzed enantioconvergent cross-coupling between β-bromostyrenes and secondary Grignard reagents is reported. This C(sp<sup>2</sup>)–C(sp<sup>3</sup>) cross-coupling is applicable to a broad range of electrophilic and nucleophilic partners and affords the products in good to high levels of enantio-induction. Experimental mechanistic investigations revealed an unexpected binding mode of the chiral (P,N) ligand and support a radical rebound mechanism involving in-cage radicals. Kinetic experiments provide evidence for an off-cycle resting state featuring dinuclear species. Computational analyses are in line with this hypothesis and coherent with a catalytic cycle proceeding via a Ni(I)/Ni(III) manifold. They further suggest an enantio-determining radical capture event and shed light on the origin of the Dynamic Kinetic Resolution process.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"89 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142840945","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-18DOI: 10.1021/acscatal.4c05338
Pengfei Hou, Qi Yu, Feng Luo, Jin-Cheng Liu
Adsorbates can trigger surface reconstruction on metal surfaces, a common yet highly important phenomenon in heterogeneous catalysis that has not been fully explored. Here, we develop a reliable Cu–C–O machine learning force field (MLFF) with ab initio accuracy, providing insights into the reconstruction mechanism and distribution of active sites on the Cu surface under a CO atmosphere through state-of-the-art deep potential molecular dynamics (DPMD). Combining statistical cluster analysis with microkinetic modeling, we establish a strategy to quantitatively assess the turnover frequency (TOF) of catalyst surfaces during the dynamic catalytic process. Our findings reveal that edge Cu atoms undergo rearrangement, ejection, diffusion, and aggregation under a CO atmosphere, leading to the formation of cluster active sites. These small clusters in dynamic equilibrium are identified as the origin of the high catalytic activity of Cu-based catalysts for a low-temperature water–gas shift reaction (WGSR). This work not only elucidates intrinsic activity in metal catalysis and the dynamic catalysis theory but also offers valuable insights for computational catalysis methods to identify effective catalysts for practical applications.
{"title":"Reactant-Induced Dynamic Active Sites on Cu Catalysts during the Water–Gas Shift Reaction","authors":"Pengfei Hou, Qi Yu, Feng Luo, Jin-Cheng Liu","doi":"10.1021/acscatal.4c05338","DOIUrl":"https://doi.org/10.1021/acscatal.4c05338","url":null,"abstract":"Adsorbates can trigger surface reconstruction on metal surfaces, a common yet highly important phenomenon in heterogeneous catalysis that has not been fully explored. Here, we develop a reliable Cu–C–O machine learning force field (MLFF) with ab initio accuracy, providing insights into the reconstruction mechanism and distribution of active sites on the Cu surface under a CO atmosphere through state-of-the-art deep potential molecular dynamics (DPMD). Combining statistical cluster analysis with microkinetic modeling, we establish a strategy to quantitatively assess the turnover frequency (TOF) of catalyst surfaces during the dynamic catalytic process. Our findings reveal that edge Cu atoms undergo rearrangement, ejection, diffusion, and aggregation under a CO atmosphere, leading to the formation of cluster active sites. These small clusters in dynamic equilibrium are identified as the origin of the high catalytic activity of Cu-based catalysts for a low-temperature water–gas shift reaction (WGSR). This work not only elucidates intrinsic activity in metal catalysis and the dynamic catalysis theory but also offers valuable insights for computational catalysis methods to identify effective catalysts for practical applications.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"17 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142840941","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Manganese oxides have emerged as promising catalysts for the low-temperature activation of molecular oxygen (O2), crucial for the catalytic oxidation and removal of gaseous pollutants. However, the undesired Jahn–Teller (J-T) effects associated with the Mniv/Mniii redox couple, particularly under SO2 poisoning, led to the effectiveness of Mn oxides in applications. Herein, we construct a highly covalent Seiv-O-Mniii structure via the introduction of selenium into α-MnO2. Such a structure features high-valence Seiv anchored on the oxygen-terminated (110) plane of α-MnO2, facilitates the generation of more active oxygen species, and maintains the continuous cycling of oxygen-linked Mniv/Mniii. Such dynamics are pivotal for stabilizing manganese activation and mitigating the J-T effect. Through a combination of experimental investigations and theoretical calculations, we demonstrate that the Seiv-O-Mniii configuration, characterized by a high degree of Mn–O hybridization, significantly enhances CO oxidation, NH3 oxidation, and elemental mercury (Hg0) removal performances, and exhibits resistance to SO2. This study paves the way for the development of efficient low-temperature O2 activation processes for the removal of gaseous pollutants in real-world applications.
{"title":"Revealing the Jahn–Teller Mitigating Complexity of Se-Anchored Mn Oxides for Superior SO2 Resistance in Gaseous Molecular Oxygen Activation","authors":"Haomiao Xu, Qinyuan Hong, Jia’nan Wang, Jun Lei, Mingming Wang, Jiaxing Li, Zhisong Liu, Mingze Jiao, Wenjun Huang, Zan Qu, Naiqiang Yan","doi":"10.1021/acscatal.4c06268","DOIUrl":"https://doi.org/10.1021/acscatal.4c06268","url":null,"abstract":"Manganese oxides have emerged as promising catalysts for the low-temperature activation of molecular oxygen (O<sub>2</sub>), crucial for the catalytic oxidation and removal of gaseous pollutants. However, the undesired Jahn–Teller (J-T) effects associated with the Mn<sup>iv</sup>/Mn<sup>iii</sup> redox couple, particularly under SO<sub>2</sub> poisoning, led to the effectiveness of Mn oxides in applications. Herein, we construct a highly covalent Se<sup>iv</sup>-O-Mn<sup>iii</sup> structure via the introduction of selenium into α-MnO<sub>2</sub>. Such a structure features high-valence Se<sup>iv</sup> anchored on the oxygen-terminated (110) plane of α-MnO<sub>2</sub>, facilitates the generation of more active oxygen species, and maintains the continuous cycling of oxygen-linked Mn<sup>iv</sup>/Mn<sup>iii</sup>. Such dynamics are pivotal for stabilizing manganese activation and mitigating the J-T effect. Through a combination of experimental investigations and theoretical calculations, we demonstrate that the Se<sup>iv</sup>-O-Mn<sup>iii</sup> configuration, characterized by a high degree of Mn–O hybridization, significantly enhances CO oxidation, NH<sub>3</sub> oxidation, and elemental mercury (Hg<sup>0</sup>) removal performances, and exhibits resistance to SO<sub>2</sub>. This study paves the way for the development of efficient low-temperature O<sub>2</sub> activation processes for the removal of gaseous pollutants in real-world applications.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"27 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142840943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-18DOI: 10.1021/acscatal.4c05324
Georgina Rai, Lee J. Edwards, Rebecca L. Greenaway, Philip W. Miller, Katherine M. P. Wheelhouse, Mark R. Crimmin
Aryl aldehydes are key synthetic intermediates in the manufacturing of active pharmaceutical ingredients. They are generated on scale (>1000 kg) through the palladium-catalyzed formylation of aryl bromides using syngas (CO/H2). The best-in-class catalyst system for this reaction employs di-1-adamantyl-n-butylphosphine (cataCXium A), palladium(II) acetate, and tetramethylethylenediamine. Despite nearly 20 years since its initial report, a mechanistic understanding of this system remains incomplete. Here, we use automation, kinetic analysis, and DFT calculations to develop a mechanistic model for this best-in-class catalyst. We suggest that a combination of the migratory insertion step and dihydrogen activation step is likely involved in the turnover-limiting sequence. The reaction kinetics are responsive to the nature of the substrate, with electron-rich aryl bromides reacting faster and more selectively than their electron-poor counterparts due to the influence of electronics in the migratory insertion step. Our findings add additional insight into the proposed mechanism of palladium-catalyzed formylation of aryl bromides.
{"title":"Combined Kinetic and Computational Analysis of the Palladium-Catalyzed Formylation of Aryl Bromides","authors":"Georgina Rai, Lee J. Edwards, Rebecca L. Greenaway, Philip W. Miller, Katherine M. P. Wheelhouse, Mark R. Crimmin","doi":"10.1021/acscatal.4c05324","DOIUrl":"https://doi.org/10.1021/acscatal.4c05324","url":null,"abstract":"Aryl aldehydes are key synthetic intermediates in the manufacturing of active pharmaceutical ingredients. They are generated on scale (>1000 kg) through the palladium-catalyzed formylation of aryl bromides using syngas (CO/H<sub>2</sub>). The best-in-class catalyst system for this reaction employs di-1-adamantyl-<i>n</i>-butylphosphine (cata<i>CX</i>ium A), palladium(II) acetate, and tetramethylethylenediamine. Despite nearly 20 years since its initial report, a mechanistic understanding of this system remains incomplete. Here, we use automation, kinetic analysis, and DFT calculations to develop a mechanistic model for this best-in-class catalyst. We suggest that a combination of the migratory insertion step and dihydrogen activation step is likely involved in the turnover-limiting sequence. The reaction kinetics are responsive to the nature of the substrate, with electron-rich aryl bromides reacting faster and more selectively than their electron-poor counterparts due to the influence of electronics in the migratory insertion step. Our findings add additional insight into the proposed mechanism of palladium-catalyzed formylation of aryl bromides.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"37 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142840939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The M1M2–N–C (where, M represents elements such as Mn, Fe, Co, Ni, Cu, and Zn) bimetallic electrocatalysts have garnered significant attention for their applications in the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). However, the design of catalytic sites remains unclear, which limits further advancements. In this study, we employed high-throughput first-principles calculations to demonstrate that the ORR/OER catalytic activity of M1M2–N–C can be regulated through organizational and mechanistic modulation. A systematic comparison of the ORR/OER activities of nearly 100 catalytic sites in FeNi–N–C revealed that bridged and unbridged bimetallic atoms exhibit distinct ORR/OER catalytic performances. Specifically, the bimetallic bridged configurations follow associative or dissociative reaction pathways, whereas the unbridged configurations adhere solely to the dissociative path. Bridging enhances the ORR/OER catalytic activity of FeNi–N–C. Additionally, atomic substitution can effectively control the reaction pathway of bridged configurations and allow them to follow the dissociative mechanism. Notably, replacing Ni with Co can reduce the theoretical ORR/OER overpotentials of the bridged configuration under the dissociative mechanism to 0.11/0.13 V, which makes it a bifunctional catalyst. Furthermore, the integrated crystal orbital Hamilton population is proposed as an electronic descriptor that characterizes the selectivity of the ORR/OER reaction mechanism and the performance of M1M2–N–C. This work provides insights into the ORR/OER activity of M1M2–N–C catalysts and paves the way for future designs and catalytic improvements.
{"title":"Organizational and Mechanistic Modulation of ORR/OER Activity in M1M2–N–C Bimetallic Catalysts","authors":"Xinge Wu, Zhaoying Yang, Chao Li, Shuai Shao, Gaowu Qin, Xiangying Meng","doi":"10.1021/acscatal.4c06280","DOIUrl":"https://doi.org/10.1021/acscatal.4c06280","url":null,"abstract":"The M<sub>1</sub>M<sub>2</sub>–N–C (where, M represents elements such as Mn, Fe, Co, Ni, Cu, and Zn) bimetallic electrocatalysts have garnered significant attention for their applications in the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). However, the design of catalytic sites remains unclear, which limits further advancements. In this study, we employed high-throughput first-principles calculations to demonstrate that the ORR/OER catalytic activity of M<sub>1</sub>M<sub>2</sub>–N–C can be regulated through organizational and mechanistic modulation. A systematic comparison of the ORR/OER activities of nearly 100 catalytic sites in FeNi–N–C revealed that bridged and unbridged bimetallic atoms exhibit distinct ORR/OER catalytic performances. Specifically, the bimetallic bridged configurations follow associative or dissociative reaction pathways, whereas the unbridged configurations adhere solely to the dissociative path. Bridging enhances the ORR/OER catalytic activity of FeNi–N–C. Additionally, atomic substitution can effectively control the reaction pathway of bridged configurations and allow them to follow the dissociative mechanism. Notably, replacing Ni with Co can reduce the theoretical ORR/OER overpotentials of the bridged configuration under the dissociative mechanism to 0.11/0.13 V, which makes it a bifunctional catalyst. Furthermore, the integrated crystal orbital Hamilton population is proposed as an electronic descriptor that characterizes the selectivity of the ORR/OER reaction mechanism and the performance of M<sub>1</sub>M<sub>2</sub>–N–C. This work provides insights into the ORR/OER activity of M<sub>1</sub>M<sub>2</sub>–N–C catalysts and paves the way for future designs and catalytic improvements.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"28 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142849837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-18DOI: 10.1021/acscatal.4c06895
Mattis Damrath, Tarek Scheele, Daniel Duvinage, Tim Neudecker, Boris J. Nachtsheim
Herein, we present the synthesis of chiral triazole-based diaryliodonium salts and their application as monodentate asymmetric iodine(III) derivates in halogen bond (XB) catalyzed reactions. These potential Lewis acids were successfully benchmarked in the vinylogous Mannich reaction of cyanomethyl coumarin with isatin-derived ketimine to obtain the addition product in up to 99% yield and >99:1 e.r. Furthermore, these halogen bond catalysts allowed an efficient functionalization of ketimines with various alcohols toward N,O-acetals in up to 99% yield and 90:10 e.r. Additionally, we studied the origin of the enantioselectivity based on density functional theory (DFT) and the catalyst crystal structure. These unveiled an approach of asymmetric induction facilitated by using σ-hole stabilized chiral moieties in iodine(III)-based catalysts, predominantly predicated upon XB activation.
{"title":"Chiral Triazole-Substituted Iodonium Salts in Enantioselective Halogen Bond Catalysis","authors":"Mattis Damrath, Tarek Scheele, Daniel Duvinage, Tim Neudecker, Boris J. Nachtsheim","doi":"10.1021/acscatal.4c06895","DOIUrl":"https://doi.org/10.1021/acscatal.4c06895","url":null,"abstract":"Herein, we present the synthesis of chiral triazole-based diaryliodonium salts and their application as monodentate asymmetric iodine(III) derivates in halogen bond (XB) catalyzed reactions. These potential Lewis acids were successfully benchmarked in the vinylogous Mannich reaction of cyanomethyl coumarin with isatin-derived ketimine to obtain the addition product in up to 99% yield and >99:1 e.r. Furthermore, these halogen bond catalysts allowed an efficient functionalization of ketimines with various alcohols toward <i>N,O</i>-acetals in up to 99% yield and 90:10 e.r. Additionally, we studied the origin of the enantioselectivity based on density functional theory (DFT) and the catalyst crystal structure. These unveiled an approach of asymmetric induction facilitated by using σ-hole stabilized chiral moieties in iodine(III)-based catalysts, predominantly predicated upon XB activation.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"271 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142849840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-17DOI: 10.1021/acscatal.4c05134
Georgios Giannakakis, Marc Eduard Usteri, Aram Bugaev, Andrea Ruiz-Ferrando, Dario Faust Akl, Núria López, Serena Fantasia, Kurt Püntener, Javier Pérez-Ramírez, Sharon Mitchell
Buchwald–Hartwig (BH) aminations are crucial for synthesizing arylamine motifs in numerous bioactive molecules and fine chemicals. While homogeneous palladium complexes can be effective catalysts, their high costs and environmental impact motivate the search for alternative approaches. Heterogeneous palladium single-atom catalysts (SAC) offer promising recoverable alternatives in C–C cross-couplings. Yet their use in C–N couplings remains unexplored, and mechanistic insights into amine coupling with aryl halides over solid surfaces that could guide catalyst design are lacking. Here, we demonstrate that palladium atoms coordinated to well-defined heptazinic cavities of graphitic carbon nitride (Pd1@C3N4) deliver practically relevant yields for BH couplings across various aryl halides and amines, exhibiting persistent activity and negligible leaching over several cycles. Notably, Pd1@C3N4 shows comparable or superior activity with certain aryl chlorides to bromides, alongside high chemoselectivity for amines over amides. In situ X-ray absorption spectroscopy analyses supported by density functional theory simulations identify the concerted role of the ligand and the C3N4 host in determining the performance, with a Pd(II) nominal oxidation state observed under all coupling conditions. Complementary structural and kinetic studies highlight a distinct reaction mechanism than that typically reported for homogeneous catalysts. These findings offer key insights for designing recyclable SAC for BH coupling, setting the basis for extending the scope toward more complex industrial targets.
{"title":"Reactivity and Mechanism of Recoverable Pd1@C3N4 Single-Atom Catalyst in Buchwald–Hartwig Aminations","authors":"Georgios Giannakakis, Marc Eduard Usteri, Aram Bugaev, Andrea Ruiz-Ferrando, Dario Faust Akl, Núria López, Serena Fantasia, Kurt Püntener, Javier Pérez-Ramírez, Sharon Mitchell","doi":"10.1021/acscatal.4c05134","DOIUrl":"https://doi.org/10.1021/acscatal.4c05134","url":null,"abstract":"Buchwald–Hartwig (BH) aminations are crucial for synthesizing arylamine motifs in numerous bioactive molecules and fine chemicals. While homogeneous palladium complexes can be effective catalysts, their high costs and environmental impact motivate the search for alternative approaches. Heterogeneous palladium single-atom catalysts (SAC) offer promising recoverable alternatives in C–C cross-couplings. Yet their use in C–N couplings remains unexplored, and mechanistic insights into amine coupling with aryl halides over solid surfaces that could guide catalyst design are lacking. Here, we demonstrate that palladium atoms coordinated to well-defined heptazinic cavities of graphitic carbon nitride (Pd<sub>1</sub>@C<sub>3</sub>N<sub>4</sub>) deliver practically relevant yields for BH couplings across various aryl halides and amines, exhibiting persistent activity and negligible leaching over several cycles. Notably, Pd<sub>1</sub>@C<sub>3</sub>N<sub>4</sub> shows comparable or superior activity with certain aryl chlorides to bromides, alongside high chemoselectivity for amines over amides. In situ X-ray absorption spectroscopy analyses supported by density functional theory simulations identify the concerted role of the ligand and the C<sub>3</sub>N<sub>4</sub> host in determining the performance, with a Pd(II) nominal oxidation state observed under all coupling conditions. Complementary structural and kinetic studies highlight a distinct reaction mechanism than that typically reported for homogeneous catalysts. These findings offer key insights for designing recyclable SAC for BH coupling, setting the basis for extending the scope toward more complex industrial targets.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"19 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142840955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-17DOI: 10.1021/acscatal.4c05289
Zhongyao Zhang, Feiting Zhang, Zhongxin Song, Lei Zhang
Metal-free carbon materials functionalized with pyridinic nitrogen groups exhibit promising electrocatalytic activity for the oxygen reduction reaction (ORR). However, not all pyridinic nitrogen groups are equally active for the ORR, which remains ambiguous and requires rigorous quantification and differentiation by their basicity. Here, we introduce the potentiometric titration method for identifying and quantifying nitrogen-containing groups on carbon materials by their Lewis basicity and reactivity in characteristic tests. Various carbon materials are functionalized with nitrogen heteroatoms. Potentiometric titration, X-ray photoelectron spectroscopy (XPS), and elemental analysis suggest that a significant amount of pyridinic nitrogen groups are buried within the bulk structures and cannot be accessed by protons and oxygen molecules. Besides, pyridinic nitrogen functions located adjacent to other nitrogen atoms exhibit weaker basicity due to strong inductive or resonance effects, resulting in a negligible contribution to the ORR activity. ORR measurements under alkaline conditions suggest that the titratable pyridinic nitrogen groups are essential for the active site (or site pair), and kinetic current density is directly proportional to the density of titratable pyridinic nitrogen groups. Furthermore, the turnover frequency for the ORR increases with the Lewis basicity of the pyridinic nitrogen groups for all investigated carbon materials in alkaline and acidic conditions. Density functional theory (DFT) calculations suggest that the ORR occurs on the carbon atoms adjacent to pyridinic nitrogen groups. Pyridinic nitrogen with a higher Lewis basicity can affect adjacent carbon atoms more efficiently, which stabilizes the key intermediates for the ORR and decreases the activation barrier. This work provides an informative and convenient way for characterizing nitrogen-containing groups on carbon materials, especially in quantifying the active pyridinic nitrogen sites for the ORR.
{"title":"Oxygen Reduction Reaction on Pyridinic Nitrogen-Functionalized Carbon: Active Site Quantification and Effects of Lewis Basicity","authors":"Zhongyao Zhang, Feiting Zhang, Zhongxin Song, Lei Zhang","doi":"10.1021/acscatal.4c05289","DOIUrl":"https://doi.org/10.1021/acscatal.4c05289","url":null,"abstract":"Metal-free carbon materials functionalized with pyridinic nitrogen groups exhibit promising electrocatalytic activity for the oxygen reduction reaction (ORR). However, not all pyridinic nitrogen groups are equally active for the ORR, which remains ambiguous and requires rigorous quantification and differentiation by their basicity. Here, we introduce the potentiometric titration method for identifying and quantifying nitrogen-containing groups on carbon materials by their Lewis basicity and reactivity in characteristic tests. Various carbon materials are functionalized with nitrogen heteroatoms. Potentiometric titration, X-ray photoelectron spectroscopy (XPS), and elemental analysis suggest that a significant amount of pyridinic nitrogen groups are buried within the bulk structures and cannot be accessed by protons and oxygen molecules. Besides, pyridinic nitrogen functions located adjacent to other nitrogen atoms exhibit weaker basicity due to strong inductive or resonance effects, resulting in a negligible contribution to the ORR activity. ORR measurements under alkaline conditions suggest that the titratable pyridinic nitrogen groups are essential for the active site (or site pair), and kinetic current density is directly proportional to the density of titratable pyridinic nitrogen groups. Furthermore, the turnover frequency for the ORR increases with the Lewis basicity of the pyridinic nitrogen groups for all investigated carbon materials in alkaline and acidic conditions. Density functional theory (DFT) calculations suggest that the ORR occurs on the carbon atoms adjacent to pyridinic nitrogen groups. Pyridinic nitrogen with a higher Lewis basicity can affect adjacent carbon atoms more efficiently, which stabilizes the key intermediates for the ORR and decreases the activation barrier. This work provides an informative and convenient way for characterizing nitrogen-containing groups on carbon materials, especially in quantifying the active pyridinic nitrogen sites for the ORR.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"64 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142840946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-17DOI: 10.1021/acscatal.4c05268
Charitomeni Angeli, Sara Atienza-Sanz, Simon Schröder, Annika Hein, Yongxin Li, Alexander Argyrou, Angelina Osipyan, Henrik Terholsen, Sandy Schmidt
The biological formation of nitrogen–nitrogen (N–N) bonds represents intriguing reactions that have attracted much attention in the past decade. This interest has led to an increasing number of N–N bond-containing natural products (NPs) and related enzymes that catalyze their formation (referred to in this review as NNzymes) being elucidated and studied in greater detail. While more detailed information on the biosynthesis of N–N bond-containing NPs, which has only become available in recent years, provides an unprecedented source of biosynthetic enzymes, their potential for biocatalytic applications has been minimally explored. With this review, we aim not only to provide a comprehensive overview of both characterized NNzymes and hypothetical biocatalysts with putative N–N bond forming activity, but also to highlight the potential of NNzymes from a biocatalytic perspective. We also present and compare conventional synthetic approaches to linear and cyclic hydrazines, hydrazides, diazo- and nitroso-groups, triazenes, and triazoles to allow comparison with enzymatic routes via NNzymes to these N–N bond-containing functional groups. Moreover, the biosynthetic pathways as well as the diversity and reaction mechanisms of NNzymes are presented according to the direct functional groups currently accessible to these enzymes.
{"title":"Recent Developments and Challenges in the Enzymatic Formation of Nitrogen–Nitrogen Bonds","authors":"Charitomeni Angeli, Sara Atienza-Sanz, Simon Schröder, Annika Hein, Yongxin Li, Alexander Argyrou, Angelina Osipyan, Henrik Terholsen, Sandy Schmidt","doi":"10.1021/acscatal.4c05268","DOIUrl":"https://doi.org/10.1021/acscatal.4c05268","url":null,"abstract":"The biological formation of nitrogen–nitrogen (N–N) bonds represents intriguing reactions that have attracted much attention in the past decade. This interest has led to an increasing number of N–N bond-containing natural products (NPs) and related enzymes that catalyze their formation (referred to in this review as NNzymes) being elucidated and studied in greater detail. While more detailed information on the biosynthesis of N–N bond-containing NPs, which has only become available in recent years, provides an unprecedented source of biosynthetic enzymes, their potential for biocatalytic applications has been minimally explored. With this review, we aim not only to provide a comprehensive overview of both characterized NNzymes and hypothetical biocatalysts with putative N–N bond forming activity, but also to highlight the potential of NNzymes from a biocatalytic perspective. We also present and compare conventional synthetic approaches to linear and cyclic hydrazines, hydrazides, diazo- and nitroso-groups, triazenes, and triazoles to allow comparison with enzymatic routes via NNzymes to these N–N bond-containing functional groups. Moreover, the biosynthetic pathways as well as the diversity and reaction mechanisms of NNzymes are presented according to the direct functional groups currently accessible to these enzymes.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"30 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142840947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-17DOI: 10.1021/acscatal.4c04777
Lu Liu, Liam P. Twight, Shibo Xi, Yingqing Ou, Shannon W. Boettcher
Iron plays a central and critical role in the water oxidation mechanism and the activity of transition-metal oxides and (oxy)hydroxides. Tracking Fe dynamics (deposition/dissolution/electrolyte transport) and unraveling the chemistries of various Fe active sites under oxygen-evolution reaction (OER) conditions are important for catalyst design, particularly for applications in alkaline electrolysis. Here, we use CoOxHy thin films as a platform to investigate Fe transport and reactivity at the catalyst-electrolyte interface and its impact on OER activity. We find that the deposition/dissolution of the surface-absorbed Fe species is governed by the transport of soluble Fe species and applied potential. Soluble Fe species in the electrolyte adsorb on CoOxHy under stirred electrolyte conditions. Accelerated Fe desorption is observed with a more-positive OER potential. The surface-localized Fe sites generated by absorption from soluble Fe species have a higher OER turnover frequency (TOFFe) compared to Fe in codeposited CoFeOxHy films. Operando X-ray absorption spectroscopy shows structural similarity between reference Fe oxyhydroxides and surface Fe sites on CoOxHy, contrasting with Fe sites within the CoOxHy structure made by codeposition, where Fe shows a different apparent X-ray absorption edge energy. The OER activity of the surface-absorbed Fe decreased by Fe desorption but was recoverable by redepositing Fe species under non-OER conditions.
铁在水氧化机制以及过渡金属氧化物和（氧）氢氧化物的活性中发挥着核心和关键作用。跟踪铁的动态（沉积/溶解/电解质迁移）并揭示氧进化反应（OER）条件下各种铁活性位点的化学性质对于催化剂的设计，尤其是碱性电解中的应用非常重要。在此，我们以 CoOxHy 薄膜为平台，研究铁在催化剂-电解质界面上的迁移和反应性及其对 OER 活性的影响。我们发现，表面吸收的铁元素的沉积/溶解受可溶性铁元素的迁移和应用电势的影响。在搅拌电解质条件下，电解质中的可溶性铁会吸附在 CoOxHy 上。随着 OER 电位越来越正，铁的解吸速度也越来越快。与共沉积 CoFeOxHy 薄膜中的铁相比，由可溶性铁吸收产生的表面定位铁位点具有更高的 OER 转换频率 (TOFFe)。运算 X 射线吸收光谱显示，CoOxHy 上的参考铁氧氢氧化物和表面铁位点之间存在结构相似性，这与共沉积 CoOxHy 结构中的铁位点形成鲜明对比，在共沉积 CoOxHy 结构中，铁显示出不同的表观 X 射线吸收边缘能量。表面吸收的铁的 OER 活性因铁的解吸而降低，但在非 OER 条件下通过重新沉积铁物种可以恢复。
{"title":"Dynamics of Fe Adsorption and Desorption from CoOxHy During Oxygen Evolution Reaction Electrocatalysis","authors":"Lu Liu, Liam P. Twight, Shibo Xi, Yingqing Ou, Shannon W. Boettcher","doi":"10.1021/acscatal.4c04777","DOIUrl":"https://doi.org/10.1021/acscatal.4c04777","url":null,"abstract":"Iron plays a central and critical role in the water oxidation mechanism and the activity of transition-metal oxides and (oxy)hydroxides. Tracking Fe dynamics (deposition/dissolution/electrolyte transport) and unraveling the chemistries of various Fe active sites under oxygen-evolution reaction (OER) conditions are important for catalyst design, particularly for applications in alkaline electrolysis. Here, we use CoO<i><sub>x</sub></i>H<i><sub>y</sub></i> thin films as a platform to investigate Fe transport and reactivity at the catalyst-electrolyte interface and its impact on OER activity. We find that the deposition/dissolution of the surface-absorbed Fe species is governed by the transport of soluble Fe species and applied potential. Soluble Fe species in the electrolyte adsorb on CoO<i><sub>x</sub></i>H<i><sub>y</sub></i> under stirred electrolyte conditions. Accelerated Fe desorption is observed with a more-positive OER potential. The surface-localized Fe sites generated by absorption from soluble Fe species have a higher OER turnover frequency (TOF<sub>Fe</sub>) compared to Fe in codeposited CoFeO<i><sub>x</sub></i>H<i><sub>y</sub></i> films. <i>Operando</i> X-ray absorption spectroscopy shows structural similarity between reference Fe oxyhydroxides and surface Fe sites on CoO<i><sub>x</sub></i>H<i><sub>y</sub></i>, contrasting with Fe sites within the CoO<i><sub>x</sub></i>H<i><sub>y</sub></i> structure made by codeposition, where Fe shows a different apparent X-ray absorption edge energy. The OER activity of the surface-absorbed Fe decreased by Fe desorption but was recoverable by redepositing Fe species under non-OER conditions.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"1 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142832583","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：