Thermally activated delayed fluorescent(TADF) materials capable of efficient solution-processed nondoped organic light-emitting diodes(OLEDs) are of important and practical significance for further development of OLED...Thermally activated delayed fluorescent(TADF) materials capable of efficient solution-processed nondoped organic light-emitting diodes(OLEDs) are of important and practical significance for further development of OLEDs. In this work, a new electron-donating segment, 2,7-di(9 H-carbazol-9-yl)-9,9-dimethyl-9,10-dihydroacridine(2 Cz-DMAC), was designed to develop solution-processable non-doped TADF emitters. 2 Cz-DMAC can not only simultaneously increase the solubility of compounds and suppress harmful aggregation-caused quenching, but also efficiently broaden the delocalization of the highest occupied molecular orbital and promote the reverse intersystem crossing process. Three new TADF emitters, 2-(2,7-di(9 H-carbazol-9-yl)-9,9-dimethylacridin-10(9 H)-yl)dibenzo[b,d]thiophene 5,5-dioxide(2 Cz-DMAC-BTB), 2-(2,7-di(9 H-carbazol-9-yl)-9,9-dimethylacridin-10(9 H)-yl)-9 H-thioxanthen-9-one(2 Cz-DMAC-TXO), 2-(2,7-di(9 H-carbazol-9-yl)-9,9-dimethylacridin-10(9 H)-yl)thianthrene 5,5,10,10-tetraoxide(2 Cz-DMAC-TTR), were developed by using 2 Cz-DMAC segment as the electron-donor. As anticipated, the solution-processed non-doped OLEDs employing 2 Cz-DMAC-BTB, 2 Cz-DMAC-TXO and 2 CzDMAC-TTR as the emitters respectively exhibited green, orange and red emissions with maximum external quantum efficiencies of 14.0%, 6.6% and 2.9%. These results successfully demonstrate the feasibility and convenience of developing efficient solution-processable non-doped TADF emitters based on 2 CzDMAC segment.展开更多
p-Benzoquinone(BQ)is a promising candidate for next-generation sodium-ion batteries(SIBs)because of its high theoretical specific capacity,good reaction reversibility,and high resource availability.However,practical a...p-Benzoquinone(BQ)is a promising candidate for next-generation sodium-ion batteries(SIBs)because of its high theoretical specific capacity,good reaction reversibility,and high resource availability.However,practical application of BQ faces many challenges,such as a low discharge plateau(~2.7 V)as cathode material or a high discharge plateau as anode material compared with inorganic materials for SIBs and high solubility in organic electrolytes,resulting in low power and energy densities.Here,tetrahydroxybenzoquinone tetrasodium salt(Na_(4)C_(6)O_(6))is synthesized through a simple neutralization reaction at low temperatures.The four-ONa electron-donating groups introduced on the structure of BQ greatly lower the discharge plateau by over 1.4 V from ~2.70 V to ~1.26 V,which can change BQ from cathode to anode material for SIBs.At the same time,the addition of four-ONa hydrophilic groups inhibits the dissolution of BQ in the organic electrolyte to a certain extent.As a result,Na_(4)C_(6)O_(6) as the anode displays a moderate discharge capacity and cycling performance at an average work voltage of ~1.26 V versus Na/Na^(+).When evaluated as a Na-ion full cell(NIFC),a Na_(3)V_(2)(PO_(4))_(3)||Na_(4)C_(6)O_(6) NIFC reveals a moderate discharge capacity and an average discharge plateau of ~1.4 V.This research offers a new molecular structure design strategy for reducing the discharge plateau and simultaneously restraining the dissolution of organic electrode materials.展开更多
In this study,a novel series of chiral 1,2-propanediol derivatives with different electron-donating and electron-withdrawing groups were synthesized and characterized by FT-IR and ~1H NMR.The helical twisting properti...In this study,a novel series of chiral 1,2-propanediol derivatives with different electron-donating and electron-withdrawing groups were synthesized and characterized by FT-IR and ~1H NMR.The helical twisting properties of all the chiral dopants were investigated by doping the chiral dopants into a nematic liquid crystal host（SLC-1717）.The results indicate that the donor-acceptor electron effect have a prominent influence on helical twisting property of the chiral nematic phase induced by the chiral dopants. Introducing electron-withdrawing groups into the terminal ends of chiral 1,2-propanediol can decrease the absolute values of the helical twisting power.In addition,the helix inversion temperatures of the induced chiral nematic phase are variational with the change of terminal groups.展开更多
Advanced oxygen carrier plays a pivotal role in various chemical looping processes,such as CO_(2)splitting.However,oxygen carriers have been restricted by deactivation and inferior oxygen transferability at low temper...Advanced oxygen carrier plays a pivotal role in various chemical looping processes,such as CO_(2)splitting.However,oxygen carriers have been restricted by deactivation and inferior oxygen transferability at low temperatures.Herein,we design an Fe-Ov-Ce-triggered phase-reversible CeO_(2)−x·Fe·CaO↔CeO_(2)·Ca_(2)Fe_(2)O_(5)oxygen carrier with strong electron-donating ability,which activates CO_(2)at low temperatures and promotes oxygen transformation.Results reveal that the maximum CO_(2)conversion and CO yield obtained with 50 mol%CeO_(2)−x·Fe·CaO are,respectively,426%and 53.6 times higher than those of Fe·CaO at 700℃.This unique multiphase material also retains exceptional redox durability,with no obvious deactivation after 100 splitting cycles.The addition of Ce promotes the formation of the Fe-Ov-Ce structure,which acts as an activator,triggers CO_(2)splitting,and lowers the energy barrier of C═O dissociation.The metallic Fe plays a role in consuming O_(2)−lattice transformed from Fe-Ov-Ce,whereas CaO acts as a structure promoter that enables phase-reversible Fe0↔Fe3+looping.展开更多
The adsorption kinetics for model pollutants on activated carbon fiber(ACF)by polarization was investigated in this work.Kinetics data obtained for the adsorption of these model pollutants at open-circuit,400 mV,and−4...The adsorption kinetics for model pollutants on activated carbon fiber(ACF)by polarization was investigated in this work.Kinetics data obtained for the adsorption of these model pollutants at open-circuit,400 mV,and−400 mV polarization were applied to the Lagergren equation,and adsorption rate constants(Ka)were determined.With the anodic polarization of 400 mV,the capacity of sodium phenoxide was increased from 0.0083 mmol/g at open-circuit to 0.18 mmol/g,and a 17-fold enhancement was achieved;however,the capacity of p-nitrophenol was decreased from 2.93 mmol/g at open-circuit to 2.65 mmol/g.With the cathodal polarization of−400 mV,the capacity of aniline was improved from 3.60 mmol/g at open-circuit to 3.88 mmol/g;however,the capacity of sodium dodecylben-zene sulfonate was reduced from 2.20 mmol/g at open-circuit to 1.59 mmol/g.The enhancement for electrosorption changed with dif ferent groups substituting.Anodic polarization enhances the adsorption of benzene with the electron-donating group.But whether anodic or not,cathodal polariza-tion had less effect on the adsorption of electron-accepting aromatic compounds,and decreased the adsorption capacity of benzene-bearing donor-conjugate bridge-acceptor,while increasing its adsorption rate.Electrostatic interaction played a very important role in the electrosorption of ion-pollutants.展开更多
Microplastics have attracted global concern.The environmental-weathering processes control their fate,transport,transformation,and toxicity to wildlife and human health,but their impacts on biogeochemical redox proces...Microplastics have attracted global concern.The environmental-weathering processes control their fate,transport,transformation,and toxicity to wildlife and human health,but their impacts on biogeochemical redox processes remain largely unknown.Herein,multiple spectroscopic and electrochemical approaches in concert with wet-chemistry analyses were employed to characterize the redox properties of weathered microplastics.The spectroscopic results indicated that weathering of phenol-formaldehyde resins(PFs)by hydrogen peroxide(H2O2)led to a slight decrease in the content of phenol functional groups,accompanied by an increase in semiquinone radicals,quinone,and carboxylic groups.Electrochemical and wet-chemistry quantifications,coupled with microbial-chemical characterizations,demonstrated that the PFs exhibited appreciable electron-donating capacity(0.264-1.15 mmol e-g^(-1))and electron-accepting capacity(0.120-0.300 mmol e-g^(-1)).Specifically,the phenol groups and semiquinone radicals were responsible for the electron-donating capacity,whereas the quinone groups dominated the electron-accepting capacity.The reversible redox peaks in the cyclic voltammograms and the enhanced electron-donating capacity after accepting electrons from microbial reduction demonstrated the reversibility of the electron-donating and-accepting reactions.More importantly,the electron-donating phenol groups and weathering-induced semiquinone radicals were found to mediate the production of H2O2 from oxygen for arsenite oxidation.In addition to the H2O2-weathered PFs,the ozone-aged PF and polystyrene were also found to have electron-donating and arsenite-oxidation capacity.This study reports important redox properties of microplastics and their effect in mediating contaminant transformation.These findings will help to better understand the fate,transformation,and biogeochemical roles of microplastics on element cycling and contaminant fate.展开更多
A burgeoning hydrogen technology utilizing anion exchange membranes(AEMs)has attracted increasing interest owing to its potential for cost-effective commercial values.Nonetheless,there are still challenges pertaining ...A burgeoning hydrogen technology utilizing anion exchange membranes(AEMs)has attracted increasing interest owing to its potential for cost-effective commercial values.Nonetheless,there are still challenges pertaining to conductivity and persistent stability.Herein,an innovative approach has been introduced to enhance the alkaline resistance and conductivity of AEMs viaπ-πinteractions.The synergisticπ-stacking networks in the polymer backbone induce long-range cation aggregation through directed self-assembly,generating ionic cluster microdomains.These nanoconfined environments elevate local hydroxide concentration,leading to the increased density of accessible ion hopping sites within the localized regions.Furthermore,the electron-donating effects of pyrene effectively reduce the electrostatic potential of theβ-H adjacent to quaternary ammonium cations,thus increasing the energy barrier for OH^(-)nucleophilic attack.The obtained AEMs demonstrate exceptional performance,exhibiting both high conductivity(160 mS/cm)and excellent alkaline stability(merely 0.35%conductivity degradation after 1950 h in 2 M KOH at 80℃).These good properties enable the membrane electrode assembly(MEA)to achieve the current density of 2.58 A/cm^(2) at 1.8 V,while maintaining stable operation for over 700 h in durability testing.展开更多
基金supported by the National Natural Science Foundation of China (Nos.51773029,52073040 and 51821002)the Fundamental Research Funds for the Central Universities (No.ZYGX2016Z010)the International Cooperation and Exchange Project of Science and Technology Department of Sichuan Province (No.2019YFH0057)。
文摘Thermally activated delayed fluorescent(TADF) materials capable of efficient solution-processed nondoped organic light-emitting diodes(OLEDs) are of important and practical significance for further development of OLEDs. In this work, a new electron-donating segment, 2,7-di(9 H-carbazol-9-yl)-9,9-dimethyl-9,10-dihydroacridine(2 Cz-DMAC), was designed to develop solution-processable non-doped TADF emitters. 2 Cz-DMAC can not only simultaneously increase the solubility of compounds and suppress harmful aggregation-caused quenching, but also efficiently broaden the delocalization of the highest occupied molecular orbital and promote the reverse intersystem crossing process. Three new TADF emitters, 2-(2,7-di(9 H-carbazol-9-yl)-9,9-dimethylacridin-10(9 H)-yl)dibenzo[b,d]thiophene 5,5-dioxide(2 Cz-DMAC-BTB), 2-(2,7-di(9 H-carbazol-9-yl)-9,9-dimethylacridin-10(9 H)-yl)-9 H-thioxanthen-9-one(2 Cz-DMAC-TXO), 2-(2,7-di(9 H-carbazol-9-yl)-9,9-dimethylacridin-10(9 H)-yl)thianthrene 5,5,10,10-tetraoxide(2 Cz-DMAC-TTR), were developed by using 2 Cz-DMAC segment as the electron-donor. As anticipated, the solution-processed non-doped OLEDs employing 2 Cz-DMAC-BTB, 2 Cz-DMAC-TXO and 2 CzDMAC-TTR as the emitters respectively exhibited green, orange and red emissions with maximum external quantum efficiencies of 14.0%, 6.6% and 2.9%. These results successfully demonstrate the feasibility and convenience of developing efficient solution-processable non-doped TADF emitters based on 2 CzDMAC segment.
基金the National Natural Science Foundation of China(No.21875076)the Science and Technology Planning Project of Guangdong Province(No.2018A05050677)+1 种基金the Undergraduates’Innovating Experimentation Project of Guangdong Province(No.S202110574025)the Undergraduates’Innovating Experimentation Project of China(No.202010574034)for financial support.
文摘p-Benzoquinone(BQ)is a promising candidate for next-generation sodium-ion batteries(SIBs)because of its high theoretical specific capacity,good reaction reversibility,and high resource availability.However,practical application of BQ faces many challenges,such as a low discharge plateau(~2.7 V)as cathode material or a high discharge plateau as anode material compared with inorganic materials for SIBs and high solubility in organic electrolytes,resulting in low power and energy densities.Here,tetrahydroxybenzoquinone tetrasodium salt(Na_(4)C_(6)O_(6))is synthesized through a simple neutralization reaction at low temperatures.The four-ONa electron-donating groups introduced on the structure of BQ greatly lower the discharge plateau by over 1.4 V from ~2.70 V to ~1.26 V,which can change BQ from cathode to anode material for SIBs.At the same time,the addition of four-ONa hydrophilic groups inhibits the dissolution of BQ in the organic electrolyte to a certain extent.As a result,Na_(4)C_(6)O_(6) as the anode displays a moderate discharge capacity and cycling performance at an average work voltage of ~1.26 V versus Na/Na^(+).When evaluated as a Na-ion full cell(NIFC),a Na_(3)V_(2)(PO_(4))_(3)||Na_(4)C_(6)O_(6) NIFC reveals a moderate discharge capacity and an average discharge plateau of ~1.4 V.This research offers a new molecular structure design strategy for reducing the discharge plateau and simultaneously restraining the dissolution of organic electrode materials.
基金supported in part by the National Natural Science Foundation of China(No.51173155)the Hebei Province Science Foundation of China(No.E2010001182)
文摘In this study,a novel series of chiral 1,2-propanediol derivatives with different electron-donating and electron-withdrawing groups were synthesized and characterized by FT-IR and ~1H NMR.The helical twisting properties of all the chiral dopants were investigated by doping the chiral dopants into a nematic liquid crystal host（SLC-1717）.The results indicate that the donor-acceptor electron effect have a prominent influence on helical twisting property of the chiral nematic phase induced by the chiral dopants. Introducing electron-withdrawing groups into the terminal ends of chiral 1,2-propanediol can decrease the absolute values of the helical twisting power.In addition,the helix inversion temperatures of the induced chiral nematic phase are variational with the change of terminal groups.
基金supported by the National Key R&D Program of China(2022YFE0105900)the National Natural Science Foundation of China(52436006,52476144,52311530339,42441835)the Innovation-Driven Project of Central South University(2023ZZTS0721).
文摘Advanced oxygen carrier plays a pivotal role in various chemical looping processes,such as CO_(2)splitting.However,oxygen carriers have been restricted by deactivation and inferior oxygen transferability at low temperatures.Herein,we design an Fe-Ov-Ce-triggered phase-reversible CeO_(2)−x·Fe·CaO↔CeO_(2)·Ca_(2)Fe_(2)O_(5)oxygen carrier with strong electron-donating ability,which activates CO_(2)at low temperatures and promotes oxygen transformation.Results reveal that the maximum CO_(2)conversion and CO yield obtained with 50 mol%CeO_(2)−x·Fe·CaO are,respectively,426%and 53.6 times higher than those of Fe·CaO at 700℃.This unique multiphase material also retains exceptional redox durability,with no obvious deactivation after 100 splitting cycles.The addition of Ce promotes the formation of the Fe-Ov-Ce structure,which acts as an activator,triggers CO_(2)splitting,and lowers the energy barrier of C═O dissociation.The metallic Fe plays a role in consuming O_(2)−lattice transformed from Fe-Ov-Ce,whereas CaO acts as a structure promoter that enables phase-reversible Fe0↔Fe3+looping.
基金This work was supported by the National Key Basic Research and Development(973)Program of China(Grant No.2003CB415006).
文摘The adsorption kinetics for model pollutants on activated carbon fiber(ACF)by polarization was investigated in this work.Kinetics data obtained for the adsorption of these model pollutants at open-circuit,400 mV,and−400 mV polarization were applied to the Lagergren equation,and adsorption rate constants(Ka)were determined.With the anodic polarization of 400 mV,the capacity of sodium phenoxide was increased from 0.0083 mmol/g at open-circuit to 0.18 mmol/g,and a 17-fold enhancement was achieved;however,the capacity of p-nitrophenol was decreased from 2.93 mmol/g at open-circuit to 2.65 mmol/g.With the cathodal polarization of−400 mV,the capacity of aniline was improved from 3.60 mmol/g at open-circuit to 3.88 mmol/g;however,the capacity of sodium dodecylben-zene sulfonate was reduced from 2.20 mmol/g at open-circuit to 1.59 mmol/g.The enhancement for electrosorption changed with dif ferent groups substituting.Anodic polarization enhances the adsorption of benzene with the electron-donating group.But whether anodic or not,cathodal polariza-tion had less effect on the adsorption of electron-accepting aromatic compounds,and decreased the adsorption capacity of benzene-bearing donor-conjugate bridge-acceptor,while increasing its adsorption rate.Electrostatic interaction played a very important role in the electrosorption of ion-pollutants.
基金the National Natural Science Foundation of China(4197310)the Alabama Agricultural Experiment Station,and the Hatch Program of the National Institute of Food and Agriculture,U.S.Department of Agriculture(ALA016-1-19123).
文摘Microplastics have attracted global concern.The environmental-weathering processes control their fate,transport,transformation,and toxicity to wildlife and human health,but their impacts on biogeochemical redox processes remain largely unknown.Herein,multiple spectroscopic and electrochemical approaches in concert with wet-chemistry analyses were employed to characterize the redox properties of weathered microplastics.The spectroscopic results indicated that weathering of phenol-formaldehyde resins(PFs)by hydrogen peroxide(H2O2)led to a slight decrease in the content of phenol functional groups,accompanied by an increase in semiquinone radicals,quinone,and carboxylic groups.Electrochemical and wet-chemistry quantifications,coupled with microbial-chemical characterizations,demonstrated that the PFs exhibited appreciable electron-donating capacity(0.264-1.15 mmol e-g^(-1))and electron-accepting capacity(0.120-0.300 mmol e-g^(-1)).Specifically,the phenol groups and semiquinone radicals were responsible for the electron-donating capacity,whereas the quinone groups dominated the electron-accepting capacity.The reversible redox peaks in the cyclic voltammograms and the enhanced electron-donating capacity after accepting electrons from microbial reduction demonstrated the reversibility of the electron-donating and-accepting reactions.More importantly,the electron-donating phenol groups and weathering-induced semiquinone radicals were found to mediate the production of H2O2 from oxygen for arsenite oxidation.In addition to the H2O2-weathered PFs,the ozone-aged PF and polystyrene were also found to have electron-donating and arsenite-oxidation capacity.This study reports important redox properties of microplastics and their effect in mediating contaminant transformation.These findings will help to better understand the fate,transformation,and biogeochemical roles of microplastics on element cycling and contaminant fate.
基金supported by the National Key R&D Program of China (2022YFA1504003)the National Natural Science Foundation of China (22322811, 22278388, 223B2804, and 22438012)the University Synergy Innovation Program of Anhui Province (GXXT-2022027)。
文摘A burgeoning hydrogen technology utilizing anion exchange membranes(AEMs)has attracted increasing interest owing to its potential for cost-effective commercial values.Nonetheless,there are still challenges pertaining to conductivity and persistent stability.Herein,an innovative approach has been introduced to enhance the alkaline resistance and conductivity of AEMs viaπ-πinteractions.The synergisticπ-stacking networks in the polymer backbone induce long-range cation aggregation through directed self-assembly,generating ionic cluster microdomains.These nanoconfined environments elevate local hydroxide concentration,leading to the increased density of accessible ion hopping sites within the localized regions.Furthermore,the electron-donating effects of pyrene effectively reduce the electrostatic potential of theβ-H adjacent to quaternary ammonium cations,thus increasing the energy barrier for OH^(-)nucleophilic attack.The obtained AEMs demonstrate exceptional performance,exhibiting both high conductivity(160 mS/cm)and excellent alkaline stability(merely 0.35%conductivity degradation after 1950 h in 2 M KOH at 80℃).These good properties enable the membrane electrode assembly(MEA)to achieve the current density of 2.58 A/cm^(2) at 1.8 V,while maintaining stable operation for over 700 h in durability testing.
