Pub Date : 2026-01-26DOI: 10.1021/acscatal.5c08083
Harie Goli, , , Umut Kilic, , , Stefan Grimme, , , Zheng-Wang Qu*, , and , Andreas Gansäuer*,
We describe a titanocene-catalyzed hydrosilylation of oxetanes to yield primary alcohols in high yields, under robust conditions and with low catalyst loading, via ET from the catalyst to the oxetane and ensuing highly efficient HAT to the radical formed from the Ti–H bond. PhSiH3 or the inexpensive industrial waste product polymethylhydrosiloxane (PMHS) can be used as terminal reductant. The reactions are more selective and proceed under more efficient reaction conditions than titanocene-catalyzed epoxide hydrosilylations. The reasons for the high selectivity are outlined with the aid of DFT calculations and are compared with the reactions of epoxides.
{"title":"Titanocene-Catalyzed Hydrosilylation of Oxetanes─are Oxetanes the Better Epoxides?","authors":"Harie Goli, , , Umut Kilic, , , Stefan Grimme, , , Zheng-Wang Qu*, , and , Andreas Gansäuer*, ","doi":"10.1021/acscatal.5c08083","DOIUrl":"10.1021/acscatal.5c08083","url":null,"abstract":"<p >We describe a titanocene-catalyzed hydrosilylation of oxetanes to yield primary alcohols in high yields, under robust conditions and with low catalyst loading, via ET from the catalyst to the oxetane and ensuing highly efficient HAT to the radical formed from the Ti–H bond. PhSiH<sub>3</sub> or the inexpensive industrial waste product polymethylhydrosiloxane (PMHS) can be used as terminal reductant. The reactions are more selective and proceed under more efficient reaction conditions than titanocene-catalyzed epoxide hydrosilylations. The reasons for the high selectivity are outlined with the aid of DFT calculations and are compared with the reactions of epoxides.</p>","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"16 3","pages":"2628–2635"},"PeriodicalIF":13.1,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146044984","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}
Conformationally inflexible medium-sized azacycles may be stable chiral molecules even when lacking conventional chiral elements, offering significant potential applications in chiral recognition and asymmetric synthesis. Herein, an efficient kinetic resolution of inherently chiral 10-vinyltribenzo[b,d,f]azocines through chiral phosphoric-acid-catalyzed (CPA) asymmetric transfer hydrogenation of the pending alkenyl moiety has been developed. Although the chirality in the hydrogenated products, 10-alkyltribenzo[b,d,f]azocines, is acid-labile, the recovered enantioenriched 10-vinyltribenzo[b,d,f]azocines are optically stable under both acidic and thermal conditions. This approach features mild reaction conditions, good functional group tolerance, good yields, and high enantioselectivity (up to 99% ee). Density functional theory (DFT) calculations reveal the reason for optical lability of the hydrogenated products in acid.
{"title":"Kinetic Resolution of Inherently Chiral Eight-Membered Azacycles via Chiral Phosphoric Acid-Catalyzed Asymmetric Transfer Hydrogenation of the Pending Alkenes","authors":"Tao Zhang, , , Meiling Chen, , , Yu Luo, , , Jingyi Wang, , , Shuang Luo*, , and , Qiang Zhu*, ","doi":"10.1021/acscatal.5c08663","DOIUrl":"10.1021/acscatal.5c08663","url":null,"abstract":"<p >Conformationally inflexible medium-sized azacycles may be stable chiral molecules even when lacking conventional chiral elements, offering significant potential applications in chiral recognition and asymmetric synthesis. Herein, an efficient kinetic resolution of inherently chiral 10-vinyltribenzo[<i>b,d,f</i>]azocines through chiral phosphoric-acid-catalyzed (CPA) asymmetric transfer hydrogenation of the pending alkenyl moiety has been developed. Although the chirality in the hydrogenated products, 10-alkyltribenzo[<i>b,d,f</i>]azocines, is acid-labile, the recovered enantioenriched 10-vinyltribenzo[<i>b,d,f</i>]azocines are optically stable under both acidic and thermal conditions. This approach features mild reaction conditions, good functional group tolerance, good yields, and high enantioselectivity (up to 99% ee). Density functional theory (DFT) calculations reveal the reason for optical lability of the hydrogenated products in acid.</p>","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"16 3","pages":"1944–1950"},"PeriodicalIF":13.1,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146048309","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}
We describe a titanocene-catalyzed hydrosilylation of oxetanes to yield primary alcohols in high yields, under robust conditions and with low catalyst loading, via ET from the catalyst to the oxetane and ensuing highly efficient HAT to the radical formed from the Ti–H bond. PhSiH3 or the inexpensive industrial waste product polymethylhydrosiloxane (PMHS) can be used as terminal reductant. The reactions are more selective and proceed under more efficient reaction conditions than titanocene-catalyzed epoxide hydrosilylations. The reasons for the high selectivity are outlined with the aid of DFT calculations and are compared with the reactions of epoxides.
{"title":"Titanocene-Catalyzed Hydrosilylation of Oxetanes─are Oxetanes the Better Epoxides?","authors":"Harie Goli,Umut Kilic,Stefan Grimme,Zheng-Wang Qu,Andreas Gansäuer","doi":"10.1021/acscatal.5c08083","DOIUrl":"https://doi.org/10.1021/acscatal.5c08083","url":null,"abstract":"We describe a titanocene-catalyzed hydrosilylation of oxetanes to yield primary alcohols in high yields, under robust conditions and with low catalyst loading, via ET from the catalyst to the oxetane and ensuing highly efficient HAT to the radical formed from the Ti–H bond. PhSiH3 or the inexpensive industrial waste product polymethylhydrosiloxane (PMHS) can be used as terminal reductant. The reactions are more selective and proceed under more efficient reaction conditions than titanocene-catalyzed epoxide hydrosilylations. The reasons for the high selectivity are outlined with the aid of DFT calculations and are compared with the reactions of epoxides.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"40 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146045003","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}
Highly robust Ir complexes were developed for the additive-free dehydrogenation of formic acid (FA) in water under harsh reaction conditions. Phenanthroline as the core unit of the ligand with amino groups as substituents enhanced both catalytic activity and durability with a negligible amount of CO formed as a contaminant (below 0.5 ppm). Notably, when a 20 M FA solution was continuously supplied to the Ir phenanthroline complex with two pyrrolidino-substituents (0.2 μmol) in 8 M FA (100 mL) under reflux conditions, a maximum turnover frequency of 245,000 h–1 was maintained for 14 h, and a turnover number of up to 14 million was achieved. Additionally, the iridium-bound formato intermediate was characterized in situ using 1H and 13C NMR, as well as electrospray ionization-mass spectrometry.
制备了高鲁棒性Ir配合物,用于甲酸在水中的无添加剂脱氢反应。邻菲罗啉作为配体的核心单元,氨基作为取代基,在污染物(低于0.5 ppm)中形成的CO量可以忽略不计的情况下,增强了催化活性和耐久性。值得注意的是,在回流条件下,将20 μmol FA溶液以8 M FA (100 mL)连续提供给含有两个吡咯烷二取代基的Ir -菲罗啉配合物(0.2 μmol),最大周转频率保持在245,000 h - 1,周转数可达1400万。此外,利用1H和13C NMR以及电喷雾电离质谱法对铱结合的甲醛中间体进行了原位表征。
{"title":"Highly Robust Diamino-Substituted Phenanthroline-Based Iridium Catalysts for Dehydrogenation of Formic Acid in Water with Mechanistic Insights","authors":"Babulal Maji,Srinivas Chandrasekaran,Takuji Hirose,Naoya Onishi,Yuichiro Himeda","doi":"10.1021/acscatal.5c07546","DOIUrl":"https://doi.org/10.1021/acscatal.5c07546","url":null,"abstract":"Highly robust Ir complexes were developed for the additive-free dehydrogenation of formic acid (FA) in water under harsh reaction conditions. Phenanthroline as the core unit of the ligand with amino groups as substituents enhanced both catalytic activity and durability with a negligible amount of CO formed as a contaminant (below 0.5 ppm). Notably, when a 20 M FA solution was continuously supplied to the Ir phenanthroline complex with two pyrrolidino-substituents (0.2 μmol) in 8 M FA (100 mL) under reflux conditions, a maximum turnover frequency of 245,000 h–1 was maintained for 14 h, and a turnover number of up to 14 million was achieved. Additionally, the iridium-bound formato intermediate was characterized in situ using 1H and 13C NMR, as well as electrospray ionization-mass spectrometry.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"179 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146045009","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}
We describe a titanocene-catalyzed hydrosilylation of oxetanes to yield primary alcohols in high yields, under robust conditions and with low catalyst loading, via ET from the catalyst to the oxetane and ensuing highly efficient HAT to the radical formed from the Ti–H bond. PhSiH3 or the inexpensive industrial waste product polymethylhydrosiloxane (PMHS) can be used as terminal reductant. The reactions are more selective and proceed under more efficient reaction conditions than titanocene-catalyzed epoxide hydrosilylations. The reasons for the high selectivity are outlined with the aid of DFT calculations and are compared with the reactions of epoxides.
{"title":"Titanocene-Catalyzed Hydrosilylation of Oxetanes─are Oxetanes the Better Epoxides?","authors":"Harie Goli,Umut Kilic,Stefan Grimme,Zheng-Wang Qu,Andreas Gansäuer","doi":"10.1021/acscatal.5c08083","DOIUrl":"https://doi.org/10.1021/acscatal.5c08083","url":null,"abstract":"We describe a titanocene-catalyzed hydrosilylation of oxetanes to yield primary alcohols in high yields, under robust conditions and with low catalyst loading, via ET from the catalyst to the oxetane and ensuing highly efficient HAT to the radical formed from the Ti–H bond. PhSiH3 or the inexpensive industrial waste product polymethylhydrosiloxane (PMHS) can be used as terminal reductant. The reactions are more selective and proceed under more efficient reaction conditions than titanocene-catalyzed epoxide hydrosilylations. The reasons for the high selectivity are outlined with the aid of DFT calculations and are compared with the reactions of epoxides.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"51 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146045002","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 : 2026-01-25DOI: 10.1021/acscatal.5c05049
Peipei Zhang, , , Chenxi Guo*, , and , P. Hu*,
Among the proposed mechanisms of the electrocatalytic CO2 reduction reaction (eCO2RR) to convert CO2 into valuable C2 chemicals and fuels, *CO–*CO coupling is a key C–C bond formation step. However, static density functional theory (DFT) calculations often struggle to accurately describe this process at the liquid–solid interface. In this work, we employed ab initio molecular dynamics with umbrella sampling to calculate the free energy changes of *CO–*CO coupling on Cu(111) in the presence of water. Through detailed and rigorous analysis, the bridge/hollow–bridge/hollow (*OC–CO) configuration was identified as the most favorable transition state structure at the interface, offering valuable insight into ongoing debates over the true nature of reaction sites. This preference is supported by a larger orbital-overlap integral between *C 2p and Cu 3d orbitals and enhanced charge transfer from *OC–CO to the surface. Importantly, we demonstrate that the *CO–*CO coupling barrier, despite being a thermally driven (non-electrochemical) step, is sensitive to electrode potential. A barrier reduction of ∼0.11 eV per 1.0 V negative shift was observed, potentially enhancing reaction rates by an order of magnitude. These findings underscore the dynamic nature of interfacial environments and highlight the need to reconsider the interplay between electrochemical and thermally driven steps in the eCO2RR under varying electrode potentials.
{"title":"Transition State Characterization and Electrode Potential Effects on Thermally Driven *CO–*CO Coupling in the Free Energy Landscape","authors":"Peipei Zhang, , , Chenxi Guo*, , and , P. Hu*, ","doi":"10.1021/acscatal.5c05049","DOIUrl":"10.1021/acscatal.5c05049","url":null,"abstract":"<p >Among the proposed mechanisms of the electrocatalytic CO<sub>2</sub> reduction reaction (eCO<sub>2</sub>RR) to convert CO<sub>2</sub> into valuable C<sub>2</sub> chemicals and fuels, *CO–*CO coupling is a key C–C bond formation step. However, static density functional theory (DFT) calculations often struggle to accurately describe this process at the liquid–solid interface. In this work, we employed ab initio molecular dynamics with umbrella sampling to calculate the free energy changes of *CO–*CO coupling on Cu(111) in the presence of water. Through detailed and rigorous analysis, the bridge/hollow–bridge/hollow (*OC–CO) configuration was identified as the most favorable transition state structure at the interface, offering valuable insight into ongoing debates over the true nature of reaction sites. This preference is supported by a larger orbital-overlap integral between *C 2p and Cu 3d orbitals and enhanced charge transfer from *OC–CO to the surface. Importantly, we demonstrate that the *CO–*CO coupling barrier, despite being a thermally driven (non-electrochemical) step, is sensitive to electrode potential. A barrier reduction of ∼0.11 eV per 1.0 V negative shift was observed, potentially enhancing reaction rates by an order of magnitude. These findings underscore the dynamic nature of interfacial environments and highlight the need to reconsider the interplay between electrochemical and thermally driven steps in the eCO<sub>2</sub>RR under varying electrode potentials.</p>","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"16 3","pages":"1966–1977"},"PeriodicalIF":13.1,"publicationDate":"2026-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146044985","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}
Remote stereocontrol in catalytic reactions is challenging due to the weakened influence of the catalyst arising from the long distance and conformational flexibility of the linear transition state. Herein, we report the bifunctional thiourea-N-heterocyclic carbene (NHC)-catalyzed remote ε-Michael addition of trienolate intermediates to nitroalkenes, with biomass-derived platform compounds 5-(chloromethyl)furfural (CMF) and 5-(hydroxymethyl)furfural (HMF) derivatives serving as the trienolate precursors. A wide range of high-value-added N-containing chiral products was afforded in good yields with high enantioselectivities. In this protocol, the macrocyclic transition state enabled high levels of remote enantiocontrol through a dual H-bonding network linking the trienolate intermediate and the nitroalkene. Detailed control experiments and density functional theory (DFT) calculations confirmed the significance of the bifunctional thiourea-NHC catalyst.
由于线性过渡态的长距离和构象柔韧性导致催化剂的影响减弱,因此催化反应的远程立体控制具有挑战性。本文报道了以5-(氯甲基)糠醛(CMF)和5-(羟甲基)糠醛(HMF)衍生物为平台化合物,以双功能硫脲- n -杂环碳(NHC)催化三烯酸酯中间体在硝基烯烃上的远端ε-Michael加成反应。研究结果表明,含氮手性产品产率高,对映选择性高,具有广泛的高附加值。在该方案中,大环过渡态通过连接三烯酸酯中间体和硝基烯的双氢键网络实现了高水平的远程对映体控制。详细的控制实验和密度泛函理论(DFT)计算证实了双功能硫脲- nhc催化剂的意义。
{"title":"Remote Stereocontrol via Macrocyclic Transition State in Thiourea-NHC-Catalyzed ε-Michael Addition of Biomass-Derived Furfurals","authors":"Xu Han,Lei Dai,Yuan-Yuan Xu,Zhao-Fei Zhang,Zhong-Hua Gao,Song Ye,Xu Han,Lei Dai,Yuan-Yuan Xu,Zhao-Fei Zhang,Zhong-Hua Gao,Song Ye","doi":"10.1021/acscatal.5c07756","DOIUrl":"https://doi.org/10.1021/acscatal.5c07756","url":null,"abstract":"Remote stereocontrol in catalytic reactions is challenging due to the weakened influence of the catalyst arising from the long distance and conformational flexibility of the linear transition state. Herein, we report the bifunctional thiourea-N-heterocyclic carbene (NHC)-catalyzed remote ε-Michael addition of trienolate intermediates to nitroalkenes, with biomass-derived platform compounds 5-(chloromethyl)furfural (CMF) and 5-(hydroxymethyl)furfural (HMF) derivatives serving as the trienolate precursors. A wide range of high-value-added N-containing chiral products was afforded in good yields with high enantioselectivities. In this protocol, the macrocyclic transition state enabled high levels of remote enantiocontrol through a dual H-bonding network linking the trienolate intermediate and the nitroalkene. Detailed control experiments and density functional theory (DFT) calculations confirmed the significance of the bifunctional thiourea-NHC catalyst.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"1 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2026-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146045005","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}
Atomically dispersed non-noble metal–nitrogen-carbon electrocatalysts could derive a four-electron oxygen reduction reaction (ORR) described via a typical adsorbate evolution mechanism (AEM), but their kinetics are limited by the linear scaling relationship (LSR) between the *OOH and *OH. Herein, we reported heteronuclear dual-site FeN6–CoN4 materials obtained via integrating Fe3+ and Co2+ into pyrrole-functionalized g-C3N4 nanosheets. Such electrocatalysts broke the conventional LSR through a shifted oxygen dissociation mechanism (ODM: *O2 → *O + *OH → 2 *OH). Density functional theory calculations confirmed the strongest and weakest adsorption strengths of key ORR intermediates in the CoN4 and FeN6 sites with a conventional AEM pathway. Under the synergistic effect of dual-site strong-weak adsorption, FeN6–CoN4 switched from ORR pathways to the ODM observed via in situ infrared spectroscopy for the rate-determining step (*O2 → *O + *OH) with the decreased overpotentials of 0.41 V (FeN6) and 0.50 V (CoN4), enhancing intrinsic ORR kinetics. A Zn–air battery based on FeN6–CoN4 demonstrated an open-circuit voltage of 1.65 V approaching the theoretical 1.68 V, high-power density of 314 mW cm–2, and durable discharge at 500 mA cm–2. This work provides fundamental insights into dual-site synergy for regulating ORR pathways, offering a strategy for designing efficient atomic catalysts.
原子分散的非贵金属-氮-碳电催化剂可以通过典型的吸附质演化机制(AEM)进行四电子氧还原反应(ORR),但其动力学受到*OOH和*OH之间的线性结垢关系(LSR)的限制。本文报道了通过将Fe3+和Co2+整合到吡咯官能化的g-C3N4纳米片中获得的异核双位点FeN6-CoN4材料。这种电催化剂通过移位氧解离机制(ODM: *O2→*O + *OH→2 *OH)打破了传统的LSR。密度泛函理论计算证实了常规AEM途径中关键ORR中间体在CoN4和FeN6位点的吸附强度最强和最弱。在双位点强弱吸附的协同作用下,原位红外光谱观察到,FeN6 - CoN4从ORR途径切换到ODM,在决定速率的步骤(*O2→*O + *OH)中,过电位降低了0.41 V (FeN6)和0.50 V (CoN4),增强了本征ORR动力学。基于FeN6-CoN4的锌空气电池的开路电压为1.65 V,接近理论值1.68 V,功率密度为314 mW cm-2,放电强度为500 mA cm-2。这项工作为调控ORR通路的双位点协同提供了基本见解,为设计高效的原子催化剂提供了策略。
{"title":"Synergistic Strong-Weak Adsorption Coupling in the FeN6–CoN4 Dual-Site Modulates Oxygen Reduction Pathways via Oxygen Adsorbate Evolution-to-Dissociation Transition","authors":"Min Jie Wang*, , , Rumeng Ji, , , Chao Huang, , , Xiaodan Huang, , , Li Wang, , , Bingjie Zhou, , , Shaojie Lu, , , Zehui Liu, , , Yongjun Han, , , Qingbin Li, , , Lishan Peng*, , , Qingfei Liu, , , Jing Li, , , Liwei Mi*, , , Yonghui Deng*, , and , Zidong Wei, ","doi":"10.1021/acscatal.5c08495","DOIUrl":"10.1021/acscatal.5c08495","url":null,"abstract":"<p >Atomically dispersed non-noble metal–nitrogen-carbon electrocatalysts could derive a four-electron oxygen reduction reaction (ORR) described via a typical adsorbate evolution mechanism (AEM), but their kinetics are limited by the linear scaling relationship (LSR) between the *OOH and *OH. Herein, we reported heteronuclear dual-site FeN<sub>6</sub>–CoN<sub>4</sub> materials obtained via integrating Fe<sup>3+</sup> and Co<sup>2+</sup> into pyrrole-functionalized g-C<sub>3</sub>N<sub>4</sub> nanosheets. Such electrocatalysts broke the conventional LSR through a shifted oxygen dissociation mechanism (ODM: *O<sub>2</sub> → *O + *OH → 2 *OH). Density functional theory calculations confirmed the strongest and weakest adsorption strengths of key ORR intermediates in the CoN<sub>4</sub> and FeN<sub>6</sub> sites with a conventional AEM pathway. Under the synergistic effect of dual-site strong-weak adsorption, FeN<sub>6</sub>–CoN<sub>4</sub> switched from ORR pathways to the ODM observed via in situ infrared spectroscopy for the rate-determining step (*O<sub>2</sub> → *O + *OH) with the decreased overpotentials of 0.41 V (FeN<sub>6</sub>) and 0.50 V (CoN<sub>4</sub>), enhancing intrinsic ORR kinetics. A Zn–air battery based on FeN<sub>6</sub>–CoN<sub>4</sub> demonstrated an open-circuit voltage of 1.65 V approaching the theoretical 1.68 V, high-power density of 314 mW cm<sup>–2</sup>, and durable discharge at 500 mA cm<sup>–2</sup>. This work provides fundamental insights into dual-site synergy for regulating ORR pathways, offering a strategy for designing efficient atomic catalysts.</p>","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"16 3","pages":"2800–2813"},"PeriodicalIF":13.1,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146034110","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 : 2026-01-23DOI: 10.1021/acscatal.5c05991
Fang Fang, , , Hui Guo, , , Hong Zhu, , and , Zhao-Xu Chen*,
Hydrogen is a high-density and clean energy source, and ammonia is a hydrogen carrier. Catalytic ammonia decomposition (AD), as a means of hydrogen generation, has received much attention. High-entropy alloy (HEA) has been studied as a promising catalyst for AD. Despite many studies, the reaction network and mechanism of AD on HEA surfaces are still not well understood. Herein, we combine density functional theory calculations with microkinetic modeling to investigate the network of the AD process, including both dehydrogenation and N-containing species coupling on the two sites (site 1 and site 2), which refer to small areas centered on the two most favorable positions for NH3 adsorption at the (111) surface of CoIrNiRhRu HEA, a catalyst showing good performance for AD at high temperatures experimentally. It is found that site 2 is much less active than site 1. On site 1, the adsorption energy of atomic N is the catalytic activity descriptor, with the rate-controlling step being N* + N* = N2* + * and the dominant pathway being NH3* → NH2* → NH* → N*→ N2*. N2 is selectively produced on both sites beyond 700 K. The (111) surface of CoIrNiRhRu HEA has many different sites that are composed of different element combinations and feature different adsorption and kinetic properties. Linear Ridge Regression (RR) machine learning models were constructed to correlate well the site composition with the N1 species’ adsorption energies. Analysis indicates that the impact of an element on the adsorption energy and reaction kinetics can be both positive and negative depending on the position. Transition state scaling (TSS) relations were also established for the dehydrogenation and coupling reactions, and their extensibility, as well as that of the Ridge Regression models, was tested. A more active site or local structure on the CoIrNiRhRu HEA (111) surface was designed based on the RR models and the TSS relations. The activity of this designed site is 71(3840) times as high as that of site 1(site 2) at 773 K. The present paper not only presents a comprehensive understanding of AD on CoIrNiRhRu HEA surfaces but also provides a theoretical scheme to optimize and design low-temperature, highly active HEA catalysts for AD reaction, which deserves generalization for solving similar problems.
{"title":"A First-Principles Study and Microkinetic Simulation of Ammonia Decomposition on CoIrNiRhRu High-Entropy Alloy Surfaces","authors":"Fang Fang, , , Hui Guo, , , Hong Zhu, , and , Zhao-Xu Chen*, ","doi":"10.1021/acscatal.5c05991","DOIUrl":"10.1021/acscatal.5c05991","url":null,"abstract":"<p >Hydrogen is a high-density and clean energy source, and ammonia is a hydrogen carrier. Catalytic ammonia decomposition (AD), as a means of hydrogen generation, has received much attention. High-entropy alloy (HEA) has been studied as a promising catalyst for AD. Despite many studies, the reaction network and mechanism of AD on HEA surfaces are still not well understood. Herein, we combine density functional theory calculations with microkinetic modeling to investigate the network of the AD process, including both dehydrogenation and N-containing species coupling on the two sites (site 1 and site 2), which refer to small areas centered on the two most favorable positions for NH<sub>3</sub> adsorption at the (111) surface of CoIrNiRhRu HEA, a catalyst showing good performance for AD at high temperatures experimentally. It is found that site 2 is much less active than site 1. On site 1, the adsorption energy of atomic N is the catalytic activity descriptor, with the rate-controlling step being N* + N* = N<sub>2</sub>* + * and the dominant pathway being NH<sub>3</sub>* → NH<sub>2</sub>* → NH* → N*→ N<sub>2</sub>*. N<sub>2</sub> is selectively produced on both sites beyond 700 K. The (111) surface of CoIrNiRhRu HEA has many different sites that are composed of different element combinations and feature different adsorption and kinetic properties. Linear Ridge Regression (RR) machine learning models were constructed to correlate well the site composition with the N1 species’ adsorption energies. Analysis indicates that the impact of an element on the adsorption energy and reaction kinetics can be both positive and negative depending on the position. Transition state scaling (TSS) relations were also established for the dehydrogenation and coupling reactions, and their extensibility, as well as that of the Ridge Regression models, was tested. A more active site or local structure on the CoIrNiRhRu HEA (111) surface was designed based on the RR models and the TSS relations. The activity of this designed site is 71(3840) times as high as that of site 1(site 2) at 773 K. The present paper not only presents a comprehensive understanding of AD on CoIrNiRhRu HEA surfaces but also provides a theoretical scheme to optimize and design low-temperature, highly active HEA catalysts for AD reaction, which deserves generalization for solving similar problems.</p>","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"16 3","pages":"2050–2064"},"PeriodicalIF":13.1,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146021803","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 : 2026-01-23DOI: 10.1021/acscatal.5c08164
Konlarat Phirom-on, , , Khanh-Trang Vu-Le, , , Leander Sützl, , , Benedikt Lehner, , , David Whelan, , , Lucile Guerent, , , Irene Pasini, , , Marc Schuh, , , Anita de Ruiter, , , Markus Blaukopf, , , Dietmar Haltrich, , , Chris Oostenbrink, , and , Thu-Ha Nguyen*,
β-Galactosidases catalyze the transgalactosylation of lactose to produce prebiotic galacto-oligosaccharides (GOS), key fortificants in infant formulas. A β-galactosidase from the infant isolate Bifidobacterium breve DSM20213 (Bbreβgal-III), which belongs to the glycoside hydrolase (GH) family 42, exhibits limited transgalactosylation activity, resulting in a low yield of GOS with the predominant formation of β-(1→6)-linked GOS. Structural analysis revealed a hydrophobic-rich active site and the presence of a water tunnel connecting the deeply buried active site to the exterior environment. The highly conserved hydrophilic Arg121 residue, which is adjacent to the catalytic acid/base residue Glu160, was found to play a crucial role in the hydrolytic activity of Bbreβgal-III. The guanidino group of the Arg121 side chain forms a network of hydrogen bonds involving the catalytic Glu160 and a water molecule in the water tunnel. This influences the coordination environment of the active site, resulting in a preference for hydrolysis over transgalactosylation in Bbreβgal-III. Site-saturation mutagenesis at Arg121 revealed that all variants enhanced the transgalactosylation activity. Among these, Bbreβgal-III-R121C exhibited the highest GOS yield, reaching 34% mass of total sugars in the transgalactosylation reaction compared to 17% by the wild-type enzyme. Bbreβgal-III-R121C not only enhanced transgalactosylation but also displayed distinct changes in the main GOS components synthesized, including a shift from 6′-galactosyllactose, which is formed predominantly by wild-type Bbreβgal-III, to 3′-galactosyllactose and a notable increase in the formation of β-(1→2)-linked GOS. These results suggest that Arg121 acts as a key switch for transgalactosylation/hydrolysis activity in GH42 β-galactosidases. Furthermore, water tunnel engineering, i.e., modification of the active-site access pathway, using alanine scanning also increased the transgalactosylation activity. Disrupting the movement of water molecules within the tunnel resulted in higher transgalactosylation activity. Understanding the catalytic importance of amino acids involved in transgalactosylation and rational mutagenesis of active-site residues provided further insights into the structure−function relationships of β-galactosidases within the GH42 family.
{"title":"Unveiling the Transgalactosylation Switch of a GH42 β-Galactosidase from the Infant Isolate Bifidobacterium breve DSM20213","authors":"Konlarat Phirom-on, , , Khanh-Trang Vu-Le, , , Leander Sützl, , , Benedikt Lehner, , , David Whelan, , , Lucile Guerent, , , Irene Pasini, , , Marc Schuh, , , Anita de Ruiter, , , Markus Blaukopf, , , Dietmar Haltrich, , , Chris Oostenbrink, , and , Thu-Ha Nguyen*, ","doi":"10.1021/acscatal.5c08164","DOIUrl":"10.1021/acscatal.5c08164","url":null,"abstract":"<p >β-Galactosidases catalyze the transgalactosylation of lactose to produce prebiotic galacto-oligosaccharides (GOS), key fortificants in infant formulas. A β-galactosidase from the infant isolate <i>Bifidobacterium breve</i> DSM20213 (<i>Bbre</i>βgal-III), which belongs to the glycoside hydrolase (GH) family 42, exhibits limited transgalactosylation activity, resulting in a low yield of GOS with the predominant formation of β-(1→6)-linked GOS. Structural analysis revealed a hydrophobic-rich active site and the presence of a water tunnel connecting the deeply buried active site to the exterior environment. The highly conserved hydrophilic Arg121 residue, which is adjacent to the catalytic acid/base residue Glu160, was found to play a crucial role in the hydrolytic activity of <i>Bbre</i>βgal-III. The guanidino group of the Arg121 side chain forms a network of hydrogen bonds involving the catalytic Glu160 and a water molecule in the water tunnel. This influences the coordination environment of the active site, resulting in a preference for hydrolysis over transgalactosylation in <i>Bbre</i>βgal-III. Site-saturation mutagenesis at Arg121 revealed that all variants enhanced the transgalactosylation activity. Among these, <i>Bbre</i>βgal-III-R121C exhibited the highest GOS yield, reaching 34% mass of total sugars in the transgalactosylation reaction compared to 17% by the wild-type enzyme. <i>Bbre</i>βgal-III-R121C not only enhanced transgalactosylation but also displayed distinct changes in the main GOS components synthesized, including a shift from 6′-galactosyllactose, which is formed predominantly by wild-type <i>Bbre</i>βgal-III, to 3′-galactosyllactose and a notable increase in the formation of β-(1→2)-linked GOS. These results suggest that Arg121 acts as a key switch for transgalactosylation/hydrolysis activity in GH42 β-galactosidases. Furthermore, water tunnel engineering, i.e., modification of the active-site access pathway, using alanine scanning also increased the transgalactosylation activity. Disrupting the movement of water molecules within the tunnel resulted in higher transgalactosylation activity. Understanding the catalytic importance of amino acids involved in transgalactosylation and rational mutagenesis of active-site residues provided further insights into the structure−function relationships of β-galactosidases within the GH42 family.</p>","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"16 3","pages":"2669–2686"},"PeriodicalIF":13.1,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/pdf/10.1021/acscatal.5c08164","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146021805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}