Synthesis of stable main-group element-based radicals represents one of the most interesting topics in contemporary organometallic chem- istry, because of their vital roles in organic, inorganic and biological chemist...Synthesis of stable main-group element-based radicals represents one of the most interesting topics in contemporary organometallic chem- istry, because of their vital roles in organic, inorganic and biological chemistry as well as materials science. However, the access of stable main-group element-based radicals is highly challenging owing to the lack of energetically accessible orbitals in the main-group elements. During the last decades, several synthetic strategies have been developed in obtaining these reactive species. Among them, utilizing the stericaliy demanding substituents and x-conjugated ligands has proven to be an effective approach. Weakly coordinating ions （WCAs） have also been found to be exceptionally practical in synthesizing radical cations of main-group elements. By introducing these stabilization methods, we have successfully prepared a variety of radical ions of p-block elements in the crystalline forms, and investigated their properties by different experimental and quantum chemical calculation methods. According to the investigations, magnetic stability was observed, resulting from the intramolecular electron-exchange interaction. Furthermore, we also found that the singlet-triptet energy gaps of the bis（triarylamine） diradical dications can be tunable by varying the temperature. These investigations open new avenues of the main-group element-based radicals for a large variety of applications.展开更多
Exploring novel superconductors is a crucial topic in condensed matter physics.There are few reports on the superconductivity of fluorine due to the extremely high pressures required for its metallization.Here,metalli...Exploring novel superconductors is a crucial topic in condensed matter physics.There are few reports on the superconductivity of fluorine due to the extremely high pressures required for its metallization.Here,metallization and superconductivity of fluorine were achieved in MgF_(5)at 120 GPa by exploiting the high-pressure s-d transition of doped Mg.The unexpected Mg-F covalent bonding induced by Mg-d and F-p orbital interactions led to fluorine metallization and the formation of an F skeleton similar to a H-cage.The high density of states(DOS)from the F skeleton and phonon softening from strong Fermi surface nesting contribute to a high superconducting transition temperature(Tc).The Tc of Pmmm-MgF_(5)at 120 GPa is 14.02 K,with strong electron-phonon coupling(λ=0.84),which is close to that of Li_(6)P at 270 GPa(λ=1.01).This is the first observation of superconductivity in main-group metal fluorides.Additionally,two near-monatomic F atoms exist in the interstitial region of MgF_(5),significantly enhancing electron-phonon coupling.This work challenges the traditional view of main-group metal fluorides and provides deeper insights into the superconductivity and physicochemical properties of fluorine.展开更多
Single-atom Fe catalysts show significant promise in the electrocatalytic reduction of CO_(2)(CO_(2)RR),while their performance remains inferior to that of precious metal catalysts due to the overly strong binding of^...Single-atom Fe catalysts show significant promise in the electrocatalytic reduction of CO_(2)(CO_(2)RR),while their performance remains inferior to that of precious metal catalysts due to the overly strong binding of^(*)CO intermediates.Although the introduction of heteroatoms or transition metal sites can modulate the binding strength of^(*)CO on Fe sites,these regulators often induce competitive hydrogen evolution reaction(HER)with reduced Faraday efficiency(FE).In this work,we employ HER-inert Sn as a regulator to tune the electronic structure of Fe,weakening^(*)CO adsorption and enhancing CO_(2)RR performance.Diatomic Fe-Sn pairs supported on N-doped carbon(Fe-Sn/NC)were synthesized,achieving FE for CO exceeding 90%over a broad potential range from−0.4 to−0.9 V versus the reversible hydrogen electrode.Fe-Sn/NC shows a high turnover frequency of 1.5×10^(4)h^(-1),much higher than that of Fe/NC.Characterization results and theoretical calculations demonstrate that bonding Sn site to Fe generates electron-rich Fe centers,effectively reducing the adsorption strength of^(*)CO without triggering HER.Additionally,Fe-Sn/NC exhibits exceptional activity in hydrazine oxidation performance(HzOR).The HzOR-assisted CO_(2)RR system using Fe-Sn/NC as electrodes reduces energy consumption by 38%compared with the conventional CO_(2)RR coupled oxygen evolution reaction system.展开更多
基金We thank the National Key R＆D Program of China （Grant 2016YFA0300404, X.W.） and the National Natural Science Foundation of China （Grants 21525102, 21690062, X.W. and 21601082, G.T.） for financial support. Dr. Li Zhang is acknowledged for proofreading the manuscript.
文摘Synthesis of stable main-group element-based radicals represents one of the most interesting topics in contemporary organometallic chem- istry, because of their vital roles in organic, inorganic and biological chemistry as well as materials science. However, the access of stable main-group element-based radicals is highly challenging owing to the lack of energetically accessible orbitals in the main-group elements. During the last decades, several synthetic strategies have been developed in obtaining these reactive species. Among them, utilizing the stericaliy demanding substituents and x-conjugated ligands has proven to be an effective approach. Weakly coordinating ions （WCAs） have also been found to be exceptionally practical in synthesizing radical cations of main-group elements. By introducing these stabilization methods, we have successfully prepared a variety of radical ions of p-block elements in the crystalline forms, and investigated their properties by different experimental and quantum chemical calculation methods. According to the investigations, magnetic stability was observed, resulting from the intramolecular electron-exchange interaction. Furthermore, we also found that the singlet-triptet energy gaps of the bis（triarylamine） diradical dications can be tunable by varying the temperature. These investigations open new avenues of the main-group element-based radicals for a large variety of applications.
基金supported by the National Natural Science Foundation of China(Nos.12374004 and 12174141)the National Key R&D Program of China(No.2023YFA1406200)。
文摘Exploring novel superconductors is a crucial topic in condensed matter physics.There are few reports on the superconductivity of fluorine due to the extremely high pressures required for its metallization.Here,metallization and superconductivity of fluorine were achieved in MgF_(5)at 120 GPa by exploiting the high-pressure s-d transition of doped Mg.The unexpected Mg-F covalent bonding induced by Mg-d and F-p orbital interactions led to fluorine metallization and the formation of an F skeleton similar to a H-cage.The high density of states(DOS)from the F skeleton and phonon softening from strong Fermi surface nesting contribute to a high superconducting transition temperature(Tc).The Tc of Pmmm-MgF_(5)at 120 GPa is 14.02 K,with strong electron-phonon coupling(λ=0.84),which is close to that of Li_(6)P at 270 GPa(λ=1.01).This is the first observation of superconductivity in main-group metal fluorides.Additionally,two near-monatomic F atoms exist in the interstitial region of MgF_(5),significantly enhancing electron-phonon coupling.This work challenges the traditional view of main-group metal fluorides and provides deeper insights into the superconductivity and physicochemical properties of fluorine.
文摘Single-atom Fe catalysts show significant promise in the electrocatalytic reduction of CO_(2)(CO_(2)RR),while their performance remains inferior to that of precious metal catalysts due to the overly strong binding of^(*)CO intermediates.Although the introduction of heteroatoms or transition metal sites can modulate the binding strength of^(*)CO on Fe sites,these regulators often induce competitive hydrogen evolution reaction(HER)with reduced Faraday efficiency(FE).In this work,we employ HER-inert Sn as a regulator to tune the electronic structure of Fe,weakening^(*)CO adsorption and enhancing CO_(2)RR performance.Diatomic Fe-Sn pairs supported on N-doped carbon(Fe-Sn/NC)were synthesized,achieving FE for CO exceeding 90%over a broad potential range from−0.4 to−0.9 V versus the reversible hydrogen electrode.Fe-Sn/NC shows a high turnover frequency of 1.5×10^(4)h^(-1),much higher than that of Fe/NC.Characterization results and theoretical calculations demonstrate that bonding Sn site to Fe generates electron-rich Fe centers,effectively reducing the adsorption strength of^(*)CO without triggering HER.Additionally,Fe-Sn/NC exhibits exceptional activity in hydrazine oxidation performance(HzOR).The HzOR-assisted CO_(2)RR system using Fe-Sn/NC as electrodes reduces energy consumption by 38%compared with the conventional CO_(2)RR coupled oxygen evolution reaction system.
