The employment of spin polarization under an external magnetic field holds great potential for the improvements of photocatalytic performance.However,owing to the huge difference in dielectric properties between ferro...The employment of spin polarization under an external magnetic field holds great potential for the improvements of photocatalytic performance.However,owing to the huge difference in dielectric properties between ferromagnetic oxide and polymers,the photogenerated excitons with spin states are often limited to the ferromagnetic oxide wells,which leads to unsatisfactory activity.In this paper,a single-atom Co-doped C_(3)N_(4)photocatalyst is successfully synthesized for photocatalytic water splitting and simultaneous oxidation of benzylamine.Under a tiny external magnetic field(24.5 mT),the hydrogen production rate could reach at 3979.0μmol·g^(-1)·h^(-1),which is about 340 times that of C_(3)N_(4).Experimental results and theoretical calculations indicate that the interaction of Co d and N p orbital changes the symmetry center of C_(3)N_(4),resulting in an increase in dielectric constant and spin polarization.Moreover,magnetic fields further promote parallel electron spin,and the increased number of charges with the parallel spin-down state is likely to dissociate under the action of an external magnetic field.On the other hand,the Co-N bond provides a huge built-in electric field and active site for strengthening the charge transfer and surface reaction.This work not only deepens the understanding of spin polarization,but also enriches methods to accelerate electron-hole separation.展开更多
The simultaneous accumulation of photo-holes and the specific activation of substrates present a significant challenge in photo-oxidation.Herein,we propose a dual-channel collaborative catalytic platform based on holl...The simultaneous accumulation of photo-holes and the specific activation of substrates present a significant challenge in photo-oxidation.Herein,we propose a dual-channel collaborative catalytic platform based on hollow TiO_(2) microspheres,using Cu single-atom(SA)catalysts and a composite polymer chain,to create separating pathways for unidirectional photogenerated electron/hole extraction.Ferrocene-functionalized graphene quantum dots are incorporated within the polymer chain for driving benzylamine(BA)oxidation.Quasi in situ transient photovoltage and femtosecond transient absorption tests reveal that leveraging the ultrafast charge separation capability of Cu SAs(0.44 ps)not only accelerates hole transport kinetics but also induces requisite Lewis acidity for the adsorption and activation of BA.In an air atmosphere,the rate of imine production reaches 4.81 mmol g^(−1) h^(−1)(selectivity of 98%).This study demonstrates the rational design of an SA/polymer chain dual-driven catalytic platform for optimizing kinetics and precisely controlling photocatalytic transformations in organic chemistry.展开更多
Selective oxidation of amines to imines through electrocatalysis is an attractive and efficient way for the chemical industry to produce nitrile compounds,but it is limited by the difficulty of designing efficient cat...Selective oxidation of amines to imines through electrocatalysis is an attractive and efficient way for the chemical industry to produce nitrile compounds,but it is limited by the difficulty of designing efficient catalysts and lack of understanding the mechanism of catalysis.Herein,we demonstrate a novel strategy by generation of oxyhydroxide layers on two-dimensional iron-doped layered nickel phosphorus trisulfides(Ni1-xFexPS_(3))during the oxidation of benzylamine(BA).In-depth structural and surface chemical characterizations during the electrocatalytic process combined with theoretical calculations reveal that Ni(1-x)FexPS_(3) undergoes surface reconstruction under alkaline conditions to form the metal oxyhydroxide/phosphorus trichalcogenide(NiFeOOH/Ni1-xFexPS_(3))heterostructure.Interestingly,the generated heterointerface facilitates BA oxidation with a low onset potential of 1.39 V and Faradaic efficiency of 53%for benzonitrile(BN)synthesis.Theoretical calculations further indicate that the as-formed NiFeOOH/Ni1-xFexPS_(3) heterostructure could offer optimum free energy for BA adsorption and BN desorption,resulting in promising BN synthesis.展开更多
Donor-acceptor(D-A)conjugated polymers are widely used in photovoltaic applications and heteroge-neous catalysis due to their tunable building block and pre-designable structures.Here,a series of ad-justable Donor-acc...Donor-acceptor(D-A)conjugated polymers are widely used in photovoltaic applications and heteroge-neous catalysis due to their tunable building block and pre-designable structures.Here,a series of ad-justable Donor-acceptor(D-A)benzothiodiazole-based conjugated polymers were designed and synthe-sized.The photocatalytic performance could be improved by fine-tuning the chemical structure by halo-gen substitution(F or Cl).The polymers exhibited excellent optoelectronic properties and were effective photocatalysts for the degradation of RhB and MO dyes,as well as promoting the oxidative coupling of benzylamines.Complete degradation of RhB and MO occurred in 30 min under visible light radiation,while the yield of benzylamine coupling mediated by superoxide anion was as high as 82%.Systematic characterization methods were used to gain insights on the unique photocatalytic performance of the polymers.Our findings provide further insights into the design and synthesis of benzothiadiazole-based conjugated polymers as promising organic photocatalysts for solar energy conversion.展开更多
Photocatalytic hydrogen evolution coupled with organic oxidation holds great promise for converting solar energy into high-valueadded chemicals,but it is hampered by sluggish charge dynamics and limited redox potentia...Photocatalytic hydrogen evolution coupled with organic oxidation holds great promise for converting solar energy into high-valueadded chemicals,but it is hampered by sluggish charge dynamics and limited redox potential.Herein,a porous S-doped carbon nitride(S-C_(3)N_(4−y))foam assembled from ultrathin nanosheets with rich nitrogen vacancies was synthesized using a molecular selfassembly strategy.The S dopants and N vacancies synergistically adjusted the band structure,facilitating light absorption and enhancing the oxidation ability.Moreover,the ultrathin nanosheets and porous structure provided more exposed active sites and facilitated mass and charge transfer.Consequently,S-C_(3)N_(4−y)foam exhibited enhanced photocatalytic activities for synchronous hydrogen evolution(4960μmol/(h·g))and benzylamine oxidation to N-benzylidenebenzylamine(4885μmol/(h·g))with high selectivity of>99%,which were approximately 17.6 and 72.9 times higher than those of bulk CN,respectively.The photocatalytic coupling pairing reaction promotes the water splitting by consuming H2O2,thereby improving the hydrogen evolution efficiency and achieving the production of high value-added imines.This study provides an effective route for regulating the morphology and band structure of carbon nitride for synthesizing highly valuable chemicals.展开更多
Replacing the challenging water oxidation with thermodynamically favorable organic oxidation presents a promising strategy for the efficient simultaneous production of hydrogen and value-added chemicals.However,photoc...Replacing the challenging water oxidation with thermodynamically favorable organic oxidation presents a promising strategy for the efficient simultaneous production of hydrogen and value-added chemicals.However,photocatalytic activity is hindered by inefficient separation of photogenerated electron-hole pairs and limited redox active sites.Herein,Fe/ZnIn_(2)S_(4)/Ni(Fe/ZIS/Ni)micro heterojunctions were rationally engineered for synergistically photocatalytic hydrogen evolution and selective oxidation of benzylamine.Using Fe-based metal-organic frameworks(MIL-88A)as the self-etching morphology template and iron source,ZIS was grown in situ to obtain Fe-doped ZIS(Fe/ZIS).Then nickel was introduced into Fe/ZIS to locally construct Ni-doped ZIS(ZIS/Ni)microregion,thereby forming numerous microscopic heterojunctions(Fe/ZIS/Ni).The introduction of Fe effectively lowers the energy band(EB)position of Fe/ZIS,while the introduction of Ni elevates the EB position of ZIS/Ni microregion.Such difference in the EB structures of Fe/ZIS and ZIS/Ni promote the formation of local electric field,effectively suppresses the recombination of photogenerated carriers and enhances their efficient separation and migration.Moreover,the nanosheet assembly structure increases the availability of active sites and enhances the uptake of reactants.The optimized Fe/ZIS/Ni catalyst achieves remarkable hydrogen evolution and N-benzylidenebenzylamine(NBI)production rates of 7.9 and 6.8 mmol·g^(-1)·h^(-1),respectively.Additionally,the selectivity for the oxidation of benzylamine to NBI exceeds 95%.This work establishes a novel design paradigm for developing high-performance photocatalytic systems that integrate renewable H2 production with selective organic transformations.展开更多
Photocatalytic oxidation of organic molecules into highly value-added products is an innovative and challenging research which has gradually attracted remarkable attention of scientists.In this work,it is demonstrated...Photocatalytic oxidation of organic molecules into highly value-added products is an innovative and challenging research which has gradually attracted remarkable attention of scientists.In this work,it is demonstrated that the COF-TpPa with keto-enol tautomerism equilibrium structure shows excellent performance(yield>99%after 8 h)in the selective photocatalytic oxidative coupling of amines to imines under visible light irradiation.It is revealed that three kinds of reactive oxygen species(superoxide radical,hydroxyl radical and singlet oxygen)participate in this photocatalytic oxidation reaction.In addition,hydrogen protons cleaved from the benzyl are proven to be reduced to hydrogen in the conduction band of COF-TpPa in anaerobic atmosphere,accompanied with the formation of imines.The direct hydrogen evolution from amine provides an effective way to extract clean energy from organic molecule as well as the production of value-added chemicals.As a contrast,COF-LZU1 with similar structure and chemical composition to COF-TpPa but without keto-enol tautomerism exhibits worse optical properties and photocatalytic performance.It is also demonstrated that keto-enol tautomerism favors the adsorption of benzylamine based on the characterization results and theoretical calculations.展开更多
基金This project was financially supported by the Guizhou Provincial Science and Technology Foundation(No.ZK2021069)the National Natural Science Foundation of China(No.22268015)+1 种基金the Young Science and Technology Talents Development Project of Education Department in Guizhou Province(No.KY2022144)the Innovation Group Project of Education Department in Guizhou Province(NO.2021010).
文摘The employment of spin polarization under an external magnetic field holds great potential for the improvements of photocatalytic performance.However,owing to the huge difference in dielectric properties between ferromagnetic oxide and polymers,the photogenerated excitons with spin states are often limited to the ferromagnetic oxide wells,which leads to unsatisfactory activity.In this paper,a single-atom Co-doped C_(3)N_(4)photocatalyst is successfully synthesized for photocatalytic water splitting and simultaneous oxidation of benzylamine.Under a tiny external magnetic field(24.5 mT),the hydrogen production rate could reach at 3979.0μmol·g^(-1)·h^(-1),which is about 340 times that of C_(3)N_(4).Experimental results and theoretical calculations indicate that the interaction of Co d and N p orbital changes the symmetry center of C_(3)N_(4),resulting in an increase in dielectric constant and spin polarization.Moreover,magnetic fields further promote parallel electron spin,and the increased number of charges with the parallel spin-down state is likely to dissociate under the action of an external magnetic field.On the other hand,the Co-N bond provides a huge built-in electric field and active site for strengthening the charge transfer and surface reaction.This work not only deepens the understanding of spin polarization,but also enriches methods to accelerate electron-hole separation.
基金financial support provided by the National Natural Science Foundation of China(No.22172057).
文摘The simultaneous accumulation of photo-holes and the specific activation of substrates present a significant challenge in photo-oxidation.Herein,we propose a dual-channel collaborative catalytic platform based on hollow TiO_(2) microspheres,using Cu single-atom(SA)catalysts and a composite polymer chain,to create separating pathways for unidirectional photogenerated electron/hole extraction.Ferrocene-functionalized graphene quantum dots are incorporated within the polymer chain for driving benzylamine(BA)oxidation.Quasi in situ transient photovoltage and femtosecond transient absorption tests reveal that leveraging the ultrafast charge separation capability of Cu SAs(0.44 ps)not only accelerates hole transport kinetics but also induces requisite Lewis acidity for the adsorption and activation of BA.In an air atmosphere,the rate of imine production reaches 4.81 mmol g^(−1) h^(−1)(selectivity of 98%).This study demonstrates the rational design of an SA/polymer chain dual-driven catalytic platform for optimizing kinetics and precisely controlling photocatalytic transformations in organic chemistry.
基金National Natural Science Foundation of China,Grant/Award Number:22179029Fundamental Research Funds for the Central Universities,Grant/Award Number:buctrc202324+2 种基金Young Elite Scientists Sponsorship Program by BAST,Grant/Award Number:BYESS2023093Ministero dell'Istruzione,dell'Universitàe della Ricerca,Grant/Award Number:2022FNL89YKempestiftelserna。
文摘Selective oxidation of amines to imines through electrocatalysis is an attractive and efficient way for the chemical industry to produce nitrile compounds,but it is limited by the difficulty of designing efficient catalysts and lack of understanding the mechanism of catalysis.Herein,we demonstrate a novel strategy by generation of oxyhydroxide layers on two-dimensional iron-doped layered nickel phosphorus trisulfides(Ni1-xFexPS_(3))during the oxidation of benzylamine(BA).In-depth structural and surface chemical characterizations during the electrocatalytic process combined with theoretical calculations reveal that Ni(1-x)FexPS_(3) undergoes surface reconstruction under alkaline conditions to form the metal oxyhydroxide/phosphorus trichalcogenide(NiFeOOH/Ni1-xFexPS_(3))heterostructure.Interestingly,the generated heterointerface facilitates BA oxidation with a low onset potential of 1.39 V and Faradaic efficiency of 53%for benzonitrile(BN)synthesis.Theoretical calculations further indicate that the as-formed NiFeOOH/Ni1-xFexPS_(3) heterostructure could offer optimum free energy for BA adsorption and BN desorption,resulting in promising BN synthesis.
基金financially supported by National Natural Science Foundation of China(No.52173099)the Science and Technology Department of Jiangxi Province(No.20192BBEL50025)+1 种基金Nanchang Hangkong University(No.EA201902288)the Special Fund for Graduate Innovation(No.YC2020-011).
文摘Donor-acceptor(D-A)conjugated polymers are widely used in photovoltaic applications and heteroge-neous catalysis due to their tunable building block and pre-designable structures.Here,a series of ad-justable Donor-acceptor(D-A)benzothiodiazole-based conjugated polymers were designed and synthe-sized.The photocatalytic performance could be improved by fine-tuning the chemical structure by halo-gen substitution(F or Cl).The polymers exhibited excellent optoelectronic properties and were effective photocatalysts for the degradation of RhB and MO dyes,as well as promoting the oxidative coupling of benzylamines.Complete degradation of RhB and MO occurred in 30 min under visible light radiation,while the yield of benzylamine coupling mediated by superoxide anion was as high as 82%.Systematic characterization methods were used to gain insights on the unique photocatalytic performance of the polymers.Our findings provide further insights into the design and synthesis of benzothiadiazole-based conjugated polymers as promising organic photocatalysts for solar energy conversion.
基金the National Key Research and Development Program of China(No.2022YFA1503003)the National Natural Science Foundation of China(Nos.U20A20250 and 22271081)+1 种基金the Natural Science Foundation of Heilongjiang Province(No.ZD2021B003)the University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province(No.UNPYSCT-2020004).
文摘Photocatalytic hydrogen evolution coupled with organic oxidation holds great promise for converting solar energy into high-valueadded chemicals,but it is hampered by sluggish charge dynamics and limited redox potential.Herein,a porous S-doped carbon nitride(S-C_(3)N_(4−y))foam assembled from ultrathin nanosheets with rich nitrogen vacancies was synthesized using a molecular selfassembly strategy.The S dopants and N vacancies synergistically adjusted the band structure,facilitating light absorption and enhancing the oxidation ability.Moreover,the ultrathin nanosheets and porous structure provided more exposed active sites and facilitated mass and charge transfer.Consequently,S-C_(3)N_(4−y)foam exhibited enhanced photocatalytic activities for synchronous hydrogen evolution(4960μmol/(h·g))and benzylamine oxidation to N-benzylidenebenzylamine(4885μmol/(h·g))with high selectivity of>99%,which were approximately 17.6 and 72.9 times higher than those of bulk CN,respectively.The photocatalytic coupling pairing reaction promotes the water splitting by consuming H2O2,thereby improving the hydrogen evolution efficiency and achieving the production of high value-added imines.This study provides an effective route for regulating the morphology and band structure of carbon nitride for synthesizing highly valuable chemicals.
基金supported by the National Key R&D Program of China(No.2022YFA1503003)the National Natural Science Foundation of China(No.22271081)+2 种基金the Postdoctoral Science Foundation of Heilongjiang Province(No.LBH-Z22240)the Basic Research Fund of Heilongjiang University in Heilongjiang Province(No.2022-KYYWF-1060)the Heilongjiang University Excellent Youth Foundation.
文摘Replacing the challenging water oxidation with thermodynamically favorable organic oxidation presents a promising strategy for the efficient simultaneous production of hydrogen and value-added chemicals.However,photocatalytic activity is hindered by inefficient separation of photogenerated electron-hole pairs and limited redox active sites.Herein,Fe/ZnIn_(2)S_(4)/Ni(Fe/ZIS/Ni)micro heterojunctions were rationally engineered for synergistically photocatalytic hydrogen evolution and selective oxidation of benzylamine.Using Fe-based metal-organic frameworks(MIL-88A)as the self-etching morphology template and iron source,ZIS was grown in situ to obtain Fe-doped ZIS(Fe/ZIS).Then nickel was introduced into Fe/ZIS to locally construct Ni-doped ZIS(ZIS/Ni)microregion,thereby forming numerous microscopic heterojunctions(Fe/ZIS/Ni).The introduction of Fe effectively lowers the energy band(EB)position of Fe/ZIS,while the introduction of Ni elevates the EB position of ZIS/Ni microregion.Such difference in the EB structures of Fe/ZIS and ZIS/Ni promote the formation of local electric field,effectively suppresses the recombination of photogenerated carriers and enhances their efficient separation and migration.Moreover,the nanosheet assembly structure increases the availability of active sites and enhances the uptake of reactants.The optimized Fe/ZIS/Ni catalyst achieves remarkable hydrogen evolution and N-benzylidenebenzylamine(NBI)production rates of 7.9 and 6.8 mmol·g^(-1)·h^(-1),respectively.Additionally,the selectivity for the oxidation of benzylamine to NBI exceeds 95%.This work establishes a novel design paradigm for developing high-performance photocatalytic systems that integrate renewable H2 production with selective organic transformations.
基金supported by the National Natural Science Foundation of China (51802015, 51972024)the Fundamental Research Funds for the Central Universities (FRF-TP-20-005A3)the Interdisciplinary Research Project for Young Teachers of USTB (Fundamental Research Funds for the Central Universities) (FRF-IDRY-19-020)。
文摘Photocatalytic oxidation of organic molecules into highly value-added products is an innovative and challenging research which has gradually attracted remarkable attention of scientists.In this work,it is demonstrated that the COF-TpPa with keto-enol tautomerism equilibrium structure shows excellent performance(yield>99%after 8 h)in the selective photocatalytic oxidative coupling of amines to imines under visible light irradiation.It is revealed that three kinds of reactive oxygen species(superoxide radical,hydroxyl radical and singlet oxygen)participate in this photocatalytic oxidation reaction.In addition,hydrogen protons cleaved from the benzyl are proven to be reduced to hydrogen in the conduction band of COF-TpPa in anaerobic atmosphere,accompanied with the formation of imines.The direct hydrogen evolution from amine provides an effective way to extract clean energy from organic molecule as well as the production of value-added chemicals.As a contrast,COF-LZU1 with similar structure and chemical composition to COF-TpPa but without keto-enol tautomerism exhibits worse optical properties and photocatalytic performance.It is also demonstrated that keto-enol tautomerism favors the adsorption of benzylamine based on the characterization results and theoretical calculations.
