Metal confinement catalyst Mo S_(2)/Pt@TD-6%Ti(TD,TS-1/Dendritic mesoporous silica nanoparticles composite) in dendritic hierarchical pore structures was synthesized and showed excellent sulfur-resistance performance ...Metal confinement catalyst Mo S_(2)/Pt@TD-6%Ti(TD,TS-1/Dendritic mesoporous silica nanoparticles composite) in dendritic hierarchical pore structures was synthesized and showed excellent sulfur-resistance performance and stabilities in catalytic hydrodesulfurization reactions of probe sulfide molecules.The Mo S_(2)/Pt@TD-6%Ti catalyst combines the concepts of Pt-confinement effect and hydrogen spillover of Pt noble metal.The modified micropores of Mo/Pt@TD-6%Ti only allow the migration and dissociation of small H_(2) molecules(0.289 nm),and effectively keep the sulfur-containing compounds(e.g.H_(2)S,0.362 nm) outside.Thus,the Mo S_(2)/Pt@TD-6%Ti catalyst exhibits higher DBT and 4,6-DMDBT HDS activities because of the synergistic effect of the strong H_(2) dissociation ability of Pt and desulfurization ability of Mo S_(2) with a lower catalyst cost.This new concept combining H2dissociation performance of noble metal catalyst with the desulfurization ability of transition metal sulfide Mo S_(2) can protect the noble metal catalyst avoiding deactivation and poison,and finally guarantee the higher activities for DBT and 4,6-DMDBT HDS.展开更多
Nitrogen fixation is a complex process involving the transfer of six electrons and protons.Diverging from the conventional Haber-Bosch process,which relies on hydrogen(H_(2))to provide both electrons and protons to re...Nitrogen fixation is a complex process involving the transfer of six electrons and protons.Diverging from the conventional Haber-Bosch process,which relies on hydrogen(H_(2))to provide both electrons and protons to reduce nitrogen(N_(2)),homogeneous transition metal complex-catalyzed N_(2)reduction reactions(NRR)employ an array of electron and proton donors or even electron donors combined with silanes.As the synthesis of diverse catalytic progress,the categories of donors have seen rapid expansion.However,existing literature only provides summaries regarding the metal,ligands,and mechanism.Despite the significance of electron and proton donor combinations in nitrogen reduction reactions,no literature has thoroughly reviewed this aspect.Therefore,we hereby compiled a comprehensive list of commonly used reagents in N_(2)reduction and classified them according to their specific donor combinations.This review presents clear and organized information about these combinations,along with a summary of their general performance trend in NRR with related catalysts.Finally,we conclude the discussion by highlighting key points for researchers to consider when selecting catalysts and donor combinations,with the ultimate goal of advancing the field of nitrogen fixation.展开更多
Lithium(Li)is an essential element in modern energy production and storage devices.Technology to extract Li from seawater,which contains~230 billion tons of Li,offers a solution to the widespread concern regarding qua...Lithium(Li)is an essential element in modern energy production and storage devices.Technology to extract Li from seawater,which contains~230 billion tons of Li,offers a solution to the widespread concern regarding quantitative and geographical limitations of future Li supplies.To obtain green Li from seawater,we propose an unassisted photoelectrochemical(PEC)Li extraction system based on an III-V-based triple-junction(3J)photoelectrode and a Li-ion selective membrane with only sunlight as an input.A light-harvesting/catalysis decoupling scheme yielded a 3J photoelectrode with excellent light-harvesting and catalysis reaction capabilities and superb stability over the 840 h of the extraction process.It allows the system to successfully enrich seawater Li by 4,350 times(i.e.,from 0.18 ppm to 783.56 ppm)after three extraction stages.The overall reaction of the unassisted PEC green Li extraction system achieved 2.08 mg kJ^(−1) of solar-to-Li efficiency and 3.65%of solar-to-hydrogen efficiency.展开更多
Efforts to develop organometallic complexes for catalytic nitrogen reduction have seen significant progress in recent years.However,the strategies for improving the activity of the homogenous catalysts have mainly foc...Efforts to develop organometallic complexes for catalytic nitrogen reduction have seen significant progress in recent years.However,the strategies for improving the activity of the homogenous catalysts have mainly focused on alternating ligands and metals.Herein,we report that the activity and stability of a PN_(P-Mo pincer complex(2)toward dinitrogen(N_(2))reduction were greatly enhanced through postmodification of the PN^(3)P pincer framework of its parent complex(1).A high ratio of NH_(3)/Mo(3525)was achieved in the presence of SmI_(2)as a reductant.In sharp contrast,1 only afforded an NH_(3)/Mo ratio of 21.Moreover,when supported by an anionic pincer ligand,2 furnished a high oxidation state Mo(V)-nitride complex via N_(2)cleavage as a plausible key intermediate in the catalytic process,suggesting a catalytic cycle that may involve different oxidation states(Ⅱ/Ⅴ)from those with 10-πelectron configuration in the literature.展开更多
We present the mechanistic understanding of an electrochemically-driven nickel-catalyzed coupling reaction.Computational analysis reveals that the spin density is mostly residing on the nickel(Ni)center when Ni^(II) i...We present the mechanistic understanding of an electrochemically-driven nickel-catalyzed coupling reaction.Computational analysis reveals that the spin density is mostly residing on the nickel(Ni)center when Ni^(II) is reduced to NiI.Ni-mediated halogen atom abstraction through outer-sphere electron-transfer pathway to yield coupling products under mild conditions is demonstrated.Importantly,we have elucidated the role of Ni^(I) and Ni^(0) for successive coupling of benzyl bromide and benzyl chloride derivatives,respectively,to corresponding bibenzyl products.The Ni-catalyst bearing a PN^(3) P-ligand is an effective catalyst,producing a strong ligand effect on the reactivity and selectivity for the homocoupling reactions.展开更多
基金supported by the National Natural Science Foundation of China(No.21808079,21878330 and 21676298)Key Research and Development Program of Shandong Province(No.2019GSF109115)+2 种基金the National Science and Technology Major Project,the CNPC Key Research Project(2016E-0707)the King Abdullah University of Science and Technology(KAUST) Office of Sponsored Research(OSR) under Award(No.OSR-2019-CPF-4103.2)the Project of National Key R&D Program of China(2019YFC1907700)。
文摘Metal confinement catalyst Mo S_(2)/Pt@TD-6%Ti(TD,TS-1/Dendritic mesoporous silica nanoparticles composite) in dendritic hierarchical pore structures was synthesized and showed excellent sulfur-resistance performance and stabilities in catalytic hydrodesulfurization reactions of probe sulfide molecules.The Mo S_(2)/Pt@TD-6%Ti catalyst combines the concepts of Pt-confinement effect and hydrogen spillover of Pt noble metal.The modified micropores of Mo/Pt@TD-6%Ti only allow the migration and dissociation of small H_(2) molecules(0.289 nm),and effectively keep the sulfur-containing compounds(e.g.H_(2)S,0.362 nm) outside.Thus,the Mo S_(2)/Pt@TD-6%Ti catalyst exhibits higher DBT and 4,6-DMDBT HDS activities because of the synergistic effect of the strong H_(2) dissociation ability of Pt and desulfurization ability of Mo S_(2) with a lower catalyst cost.This new concept combining H2dissociation performance of noble metal catalyst with the desulfurization ability of transition metal sulfide Mo S_(2) can protect the noble metal catalyst avoiding deactivation and poison,and finally guarantee the higher activities for DBT and 4,6-DMDBT HDS.
基金supported by the King Abdullah University of Science and Technologysupported by Agency for Science,Technology,and Research(SC22/23-82301U,SC22/23-82801U)。
文摘Nitrogen fixation is a complex process involving the transfer of six electrons and protons.Diverging from the conventional Haber-Bosch process,which relies on hydrogen(H_(2))to provide both electrons and protons to reduce nitrogen(N_(2)),homogeneous transition metal complex-catalyzed N_(2)reduction reactions(NRR)employ an array of electron and proton donors or even electron donors combined with silanes.As the synthesis of diverse catalytic progress,the categories of donors have seen rapid expansion.However,existing literature only provides summaries regarding the metal,ligands,and mechanism.Despite the significance of electron and proton donor combinations in nitrogen reduction reactions,no literature has thoroughly reviewed this aspect.Therefore,we hereby compiled a comprehensive list of commonly used reagents in N_(2)reduction and classified them according to their specific donor combinations.This review presents clear and organized information about these combinations,along with a summary of their general performance trend in NRR with related catalysts.Finally,we conclude the discussion by highlighting key points for researchers to consider when selecting catalysts and donor combinations,with the ultimate goal of advancing the field of nitrogen fixation.
基金City University of Hong Kong funding(No.9380107).
文摘Lithium(Li)is an essential element in modern energy production and storage devices.Technology to extract Li from seawater,which contains~230 billion tons of Li,offers a solution to the widespread concern regarding quantitative and geographical limitations of future Li supplies.To obtain green Li from seawater,we propose an unassisted photoelectrochemical(PEC)Li extraction system based on an III-V-based triple-junction(3J)photoelectrode and a Li-ion selective membrane with only sunlight as an input.A light-harvesting/catalysis decoupling scheme yielded a 3J photoelectrode with excellent light-harvesting and catalysis reaction capabilities and superb stability over the 840 h of the extraction process.It allows the system to successfully enrich seawater Li by 4,350 times(i.e.,from 0.18 ppm to 783.56 ppm)after three extraction stages.The overall reaction of the unassisted PEC green Li extraction system achieved 2.08 mg kJ^(−1) of solar-to-Li efficiency and 3.65%of solar-to-hydrogen efficiency.
文摘Efforts to develop organometallic complexes for catalytic nitrogen reduction have seen significant progress in recent years.However,the strategies for improving the activity of the homogenous catalysts have mainly focused on alternating ligands and metals.Herein,we report that the activity and stability of a PN_(P-Mo pincer complex(2)toward dinitrogen(N_(2))reduction were greatly enhanced through postmodification of the PN^(3)P pincer framework of its parent complex(1).A high ratio of NH_(3)/Mo(3525)was achieved in the presence of SmI_(2)as a reductant.In sharp contrast,1 only afforded an NH_(3)/Mo ratio of 21.Moreover,when supported by an anionic pincer ligand,2 furnished a high oxidation state Mo(V)-nitride complex via N_(2)cleavage as a plausible key intermediate in the catalytic process,suggesting a catalytic cycle that may involve different oxidation states(Ⅱ/Ⅴ)from those with 10-πelectron configuration in the literature.
文摘We present the mechanistic understanding of an electrochemically-driven nickel-catalyzed coupling reaction.Computational analysis reveals that the spin density is mostly residing on the nickel(Ni)center when Ni^(II) is reduced to NiI.Ni-mediated halogen atom abstraction through outer-sphere electron-transfer pathway to yield coupling products under mild conditions is demonstrated.Importantly,we have elucidated the role of Ni^(I) and Ni^(0) for successive coupling of benzyl bromide and benzyl chloride derivatives,respectively,to corresponding bibenzyl products.The Ni-catalyst bearing a PN^(3) P-ligand is an effective catalyst,producing a strong ligand effect on the reactivity and selectivity for the homocoupling reactions.
