Metal hydrides serve as crucial intermediates in many chemical processes,facilitating the utilization of hydrogen resources.Traditionally,three-centre metal hydrides have been viewed as less reactive due to their mult...Metal hydrides serve as crucial intermediates in many chemical processes,facilitating the utilization of hydrogen resources.Traditionally,three-centre metal hydrides have been viewed as less reactive due to their multi-stabilization effects.However,recent discoveries show the"three-centre four-electron"(3c-4e)bridging hydride bond exhibits significant activity in boryl transition metal systems.This research employs computational techniques to explore the factors that influence the formation of the 3c-4e bridging hydride,focusing on boryl 3d non-noble transition metals ranging from chromium(Cr)to nickel(Ni).By analyzing bond distances and bond orders,the study sheds light on the electronic and structural characteristics of the B-H-M bridging hydride.It reveals a clear link between the metal centre’s redox properties and the emergence of bridging hydrides.Specifically,metal centres like Cr and Co,which have lower oxidation states and electronegativity,are more inclined to form active 3c-4e bridging hydrides.These insights,derived from computational analyses,offer valuable guidelines for the development of active 3c-4e bridging metal hydrides,thereby contributing to the advancement of new hydrogen transformation catalysts.展开更多
We consider an energy operator of four-electron system in the Impurity Hubbard model with a coupling between nearest-neighbors. The spectrum of the systems in the second triplet state in a ν-dimensional lattice is in...We consider an energy operator of four-electron system in the Impurity Hubbard model with a coupling between nearest-neighbors. The spectrum of the systems in the second triplet state in a ν-dimensional lattice is investigated. For investigation the structure of essential spectra and discrete spectrum of the energy operator of four-electron systems in an impurity Hubbard model, for which the momentum representation is convenient. In addition, we used the tensor products of Hilbert spaces and tensor products of operators in Hilbert spaces and described the structure of essential spectrum and discrete spectrum of the energy operator of four-electron systems in an impurity Hubbard model for the second triplet state of the system. The investigations show that the essential spectrum of the system consists of the union of no more than sixteen segments, and the discrete spectrum of the system consists of no more than eleven eigenvalues.展开更多
We consider the energy operator of four-electron systems in an impurity Hubbard model and investigated the structure of essential spectra and discrete spectrum of the system in the first triplet state in a one-dimensi...We consider the energy operator of four-electron systems in an impurity Hubbard model and investigated the structure of essential spectra and discrete spectrum of the system in the first triplet state in a one-dimensional lattice. For investigation the structure of essential spectra and discrete spectrum of the energy operator of four-electron systems in an impurity Hubbard model, for which the momentum representation is convenient. In addition, we used the tensor products of Hilbert spaces and tensor products of operators in Hilbert spaces and described the structure of essential spectrum and discrete spectrum of the energy operator of four-electron systems in an impurity Hubbard model. The investigations show that there are such cases: 1) the essential spectrum of the system consists of the union of no more than eight segments, and the discrete spectrum of the system consists of no more than three eigenvalues;2) the essential spectrum of the system consists of the union of no more than sixteen segments, and the discrete spectrum of the system consists of no more than eleven eigenvalues;3) the essential spectrum of the system consists of the union of no more than three segments, and the discrete spectrum of the system is the empty set. Consequently, the essential spectrum of the system consists of the union of no more than sixteen segments, and the discrete spectrum of the system consists of no more than eleven eigenvalues.展开更多
The oxygen reduction reaction(ORR)is a cornerstone inelectrochemical energy conversion and chemical synthesis,with its four-electron and two-electron transfer pathwaysserving distinct purposes:efficient fuel cell oper...The oxygen reduction reaction(ORR)is a cornerstone inelectrochemical energy conversion and chemical synthesis,with its four-electron and two-electron transfer pathwaysserving distinct purposes:efficient fuel cell operation andsustainable hydrogen peroxide production,respectively.Akey challenge in ORR is the development of low-cost andefficient electrocatalysts that can achieve selective controlover either the two-electron or four-electron pathway.Car-bonaceous materials have emerged as promising candidatesfor addressing this challenge due to their abundance,highefficiency,and versatile structural tunability.By manipulat-ing the type of heteroatoms or the configuration of defectsin the carbon materials,it is possible to effectively regulateselectivity toward distinct pathways.This review provides anoverview of recent advancements in the design and engi-neering of carbonaceous materials to regulate ORR selectivi-ty,focusing on the three strate gies of heteroatom doping,defect engineering,and their synergistic integration.In theend,we discuss the current challenges and future perspec-tives on advancing the rational design of carbonaceouscatalysts with tailored selectivity for different ORR path-ways.These insights will aid in the development of sustain-able and highly selective electrocatalysts for clean energytechnologies and other industrial applications.展开更多
Main observation and conclusion Herein,we describe a novel catalytic Pictet-Spengler-type cyclization using CO_(2) as a nontoxic and sustainable C1 feedstock with envi-ronmentally benign and non-precious-metal iron as...Main observation and conclusion Herein,we describe a novel catalytic Pictet-Spengler-type cyclization using CO_(2) as a nontoxic and sustainable C1 feedstock with envi-ronmentally benign and non-precious-metal iron as catalyst.The reaction is achieved by selective four-electron reduction of CO_(2) into methylene level intermediate through carefully tuning the reaction parameters.A variety of tetrahydro-B-carbolines and other nitro-gen-containing heterocycles can be easily obtained under mild conditions.Mechanistic studies have shown that tetrahy-dro-B-carbolines are probably obtained via spiroindolenine intermediates.展开更多
基金supported by the National Natural Science Foundation of Chian(NSFC,Nos.22373118 and 22231002)the Guangdong Basic and Applied Basic Research Foundation(No.2024B1515040025)the Fundamental Research Funds for the Central Universities.
文摘Metal hydrides serve as crucial intermediates in many chemical processes,facilitating the utilization of hydrogen resources.Traditionally,three-centre metal hydrides have been viewed as less reactive due to their multi-stabilization effects.However,recent discoveries show the"three-centre four-electron"(3c-4e)bridging hydride bond exhibits significant activity in boryl transition metal systems.This research employs computational techniques to explore the factors that influence the formation of the 3c-4e bridging hydride,focusing on boryl 3d non-noble transition metals ranging from chromium(Cr)to nickel(Ni).By analyzing bond distances and bond orders,the study sheds light on the electronic and structural characteristics of the B-H-M bridging hydride.It reveals a clear link between the metal centre’s redox properties and the emergence of bridging hydrides.Specifically,metal centres like Cr and Co,which have lower oxidation states and electronegativity,are more inclined to form active 3c-4e bridging hydrides.These insights,derived from computational analyses,offer valuable guidelines for the development of active 3c-4e bridging metal hydrides,thereby contributing to the advancement of new hydrogen transformation catalysts.
文摘We consider an energy operator of four-electron system in the Impurity Hubbard model with a coupling between nearest-neighbors. The spectrum of the systems in the second triplet state in a ν-dimensional lattice is investigated. For investigation the structure of essential spectra and discrete spectrum of the energy operator of four-electron systems in an impurity Hubbard model, for which the momentum representation is convenient. In addition, we used the tensor products of Hilbert spaces and tensor products of operators in Hilbert spaces and described the structure of essential spectrum and discrete spectrum of the energy operator of four-electron systems in an impurity Hubbard model for the second triplet state of the system. The investigations show that the essential spectrum of the system consists of the union of no more than sixteen segments, and the discrete spectrum of the system consists of no more than eleven eigenvalues.
文摘We consider the energy operator of four-electron systems in an impurity Hubbard model and investigated the structure of essential spectra and discrete spectrum of the system in the first triplet state in a one-dimensional lattice. For investigation the structure of essential spectra and discrete spectrum of the energy operator of four-electron systems in an impurity Hubbard model, for which the momentum representation is convenient. In addition, we used the tensor products of Hilbert spaces and tensor products of operators in Hilbert spaces and described the structure of essential spectrum and discrete spectrum of the energy operator of four-electron systems in an impurity Hubbard model. The investigations show that there are such cases: 1) the essential spectrum of the system consists of the union of no more than eight segments, and the discrete spectrum of the system consists of no more than three eigenvalues;2) the essential spectrum of the system consists of the union of no more than sixteen segments, and the discrete spectrum of the system consists of no more than eleven eigenvalues;3) the essential spectrum of the system consists of the union of no more than three segments, and the discrete spectrum of the system is the empty set. Consequently, the essential spectrum of the system consists of the union of no more than sixteen segments, and the discrete spectrum of the system consists of no more than eleven eigenvalues.
基金supported by the National Natural ScienceFoundation of china(grant nos.22405066,22375o67,21925104,922612o4,and 224310o5)the National Key Researchand Development Program of China(grant nos.2022YFA1504703and 2o22YFB4002204)+3 种基金Hubei Provincial Science and TechnologyInnovation Team Project(2o22)the Innovational Fund for Sci-entific and Technological Personnel of Hainan Province(grant no.KJRC2o23C1o)the Princess Nourah bint Abdulrahman Uni-versity Researchers Supporting Project number(grant no.PNURSP2025R398)Princess Nourah bint Abdulrahman Univer-sity,Riyadh,Saudi Arabia.
文摘The oxygen reduction reaction(ORR)is a cornerstone inelectrochemical energy conversion and chemical synthesis,with its four-electron and two-electron transfer pathwaysserving distinct purposes:efficient fuel cell operation andsustainable hydrogen peroxide production,respectively.Akey challenge in ORR is the development of low-cost andefficient electrocatalysts that can achieve selective controlover either the two-electron or four-electron pathway.Car-bonaceous materials have emerged as promising candidatesfor addressing this challenge due to their abundance,highefficiency,and versatile structural tunability.By manipulat-ing the type of heteroatoms or the configuration of defectsin the carbon materials,it is possible to effectively regulateselectivity toward distinct pathways.This review provides anoverview of recent advancements in the design and engi-neering of carbonaceous materials to regulate ORR selectivi-ty,focusing on the three strate gies of heteroatom doping,defect engineering,and their synergistic integration.In theend,we discuss the current challenges and future perspec-tives on advancing the rational design of carbonaceouscatalysts with tailored selectivity for different ORR path-ways.These insights will aid in the development of sustain-able and highly selective electrocatalysts for clean energytechnologies and other industrial applications.
基金We are grateful to the financial support from NSFC(Nos.21772208,21702212,21602230)the Key Research Program of Frontier Sciences of CAS(No.QYZDJSSW-SLH051).
文摘Main observation and conclusion Herein,we describe a novel catalytic Pictet-Spengler-type cyclization using CO_(2) as a nontoxic and sustainable C1 feedstock with envi-ronmentally benign and non-precious-metal iron as catalyst.The reaction is achieved by selective four-electron reduction of CO_(2) into methylene level intermediate through carefully tuning the reaction parameters.A variety of tetrahydro-B-carbolines and other nitro-gen-containing heterocycles can be easily obtained under mild conditions.Mechanistic studies have shown that tetrahy-dro-B-carbolines are probably obtained via spiroindolenine intermediates.
