A promising biomass carbon material,manufactured by the carbonation of Physalis peruviana L.calyx at 700℃,is presented in this wo rk.Morphology characterization shows that the carbon material possesses long microtubu...A promising biomass carbon material,manufactured by the carbonation of Physalis peruviana L.calyx at 700℃,is presented in this wo rk.Morphology characterization shows that the carbon material possesses long microtubule bundling and above 30%natural O-atom component on the surface.After KOH chemical etching,the materials maintain the oxygen content but exhibit more micropores and higher specific surface area up to 1732.6 m^2/g.Using as an electrode material for supercapacitor,the active carbon material exhibits high specific capacitance up to 339.7 F/g at 0.5 A/g in 3 mol/L KOH aqueous solution through three-electrode system.The active carbon material also exhibits excellent cycling stability(97%retention)by 10,000 cycles at 10 A/g.The outstanding electrochemical performances are attributing to the unique long microtubule bundling with much more pores and the abundant Oelement on the surface.This biomass carbon material with excellent electrochemical properties could be a useful material for multiple applications.展开更多
High performances of Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)solar cells are heavily influenced by the quality of heterojunctions.Herein,an oxygen(O)doping of CZTSSe/CdS heterojunction is performed to suppress the formation of th...High performances of Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)solar cells are heavily influenced by the quality of heterojunctions.Herein,an oxygen(O)doping of CZTSSe/CdS heterojunction is performed to suppress the formation of the defects by an ultraviolet ozone(UV-O_(3))treatment for the efficient flexible CZTSSe solar cells.The introduction of O reduces the non-radiative recombination and increases the carrier concentration of the CdS films.Furthermore,the defect density of the CdS film has been reduced from 8.24×10^(16)to2.91×10^(16)cm^(-3)by the O-doping.The results indicate that the electron transport is effectively promoted due to the decreased conduction band offset(CBO)at the heterojunction interface.As a result,the champion flexible CZTSSe solar cell achieves a power conversion efficiency(PCE)of 11.21%,with a significantly improved short circuit current density.The study for improving the CZTSSe/CdS heterojunction through O-doping treatment provides a new insight for enhancing the PCE of the flexible CZTSSe solar cells.展开更多
Calcium aluminate clinkers doped with Na2O were synthesized using analytically pure reagents CaCO3, Al2O3, SiO2 and Na2CO3. The effects of Na2O-doping on the formation mechanism of calcium aluminate compounds and the ...Calcium aluminate clinkers doped with Na2O were synthesized using analytically pure reagents CaCO3, Al2O3, SiO2 and Na2CO3. The effects of Na2O-doping on the formation mechanism of calcium aluminate compounds and the crystal property of 12CaO·7Al2O3 (C12A7) cell were studied. The results show that the minerals containing Na2O mainly include 2Na2O·3CaO·5Al2O3 and Na2O·Al2O3, when the Na2O content in clinkers is less than 4.26% (mass fraction). The rest of Na2O is mainly doped in 12CaO·7Al2O3, which results in the decrease of the crystallinity of 12CaO·7Al2O3. The crystallinity of 2Na2O·3CaO·5Al2O3 is also inversely proportional to the Na2O content in clinkers. The formation processes of 2Na2O·3CaO·5Al2O3 and 12CaO·7Al2O3 can be divided into two ways, which are the direct reactions of raw materials and the transformation of CaO·Al2O3, respectively. The simulation shows that the covalency of O-Na bond in Na2O-doped 12CaO·7Al2O3 cell is weaker than those of O-Ca and O-Al bonds. The free energy of the unit cell increases because of Na2O doping, which results in the improvement of chemical activity of 12CaO·7Al2O3. The leaching efficiency of Al2O3 in clinker is improved from 34.81% to 88.17% when the Na2O content in clinkers increases from 0 to 4.26%.展开更多
Based on the first-principles of density functional theory, the structural stability,electronic and magnetic properties of the O-doped monolayer C_2N are investigated. In details, the lattice parameters, band structur...Based on the first-principles of density functional theory, the structural stability,electronic and magnetic properties of the O-doped monolayer C_2N are investigated. In details, the lattice parameters, band structures, density of states and phonon dispersions of O-doped monolayer C_2N are obtained and analyzed. Our results show that the introduction of oxygen dopants can cause a significant local lattice distortion. The band structure indicates that monolayer C_2N is a semiconductor with a direct band gap of 1.631 eV. The electronic properties of monolayer C_2N can be regulated by oxygen dopant atoms with different numbers. However, doping nonmetal oxygen element in monolayer C_2N does not affect its magnetic properties. In other words, the pure and O-doped systems are all nonmagnetic. The phonon dispersions of all the O-doped cases are found to have not any imaginary frequencies, which indicates that the structures of these O-doped systems have good structural stability.展开更多
We provides a novel approach to generate low-temperature atomic oxygen anions （O-） emission using the cesium oxide-doped 12CaO.7Al2O3 （Cs2O-doped C12A7）. The maximal emission intensity of O- from the Cs2O-doped C1...We provides a novel approach to generate low-temperature atomic oxygen anions （O-） emission using the cesium oxide-doped 12CaO.7Al2O3 （Cs2O-doped C12A7）. The maximal emission intensity of O- from the Cs2O-doped C12A7 at 700℃ and 800 V/cm reached about 0.54μA/cm2, which was about two times as strong as that from the un-doped C12A7 （0.23 μA/cm2） under the same condition. The initiative temperature of the O- emission from the Cs2O-doped C12A7 was about 500 ℃, which was also much lower than the initiative temperature from the un-doped C12A7 （570 ℃） in the given field of 800 V/cm. High pure O- emission close to 100% could be obtained from the Cs2O-doped C12A7 under the lower temperature （〈550℃）. The emission features of the Cs2O-doped C12A7, including the emission distribution, temperature effect, and emission branching ratio have been investigated in detail and compared with the un-doped C12A7. The structure and storage characteristics of the resulting material were also investigated via X-ray diffraction and electron paramagnetic resonance. It was found that doping Cs2Oto C12A7 will lower the initiative emission temperature and enhance the emission intensity展开更多
Potassium ion capacitors(PICs)are regarded as promising large-scale aqueous energy storage systems.However,due to the poor K^(+)transport kinetics and the structural instability of the cathode materials,the key issues...Potassium ion capacitors(PICs)are regarded as promising large-scale aqueous energy storage systems.However,due to the poor K^(+)transport kinetics and the structural instability of the cathode materials,the key issues of limited energy density and poor cyclic stability are obstacles to the in-depth growth of PICs.Herein,a novel O-doped perovskite fluoride is demonstrated via an in-situ electrochemical oxidation strategy as the cathode for PICs,introducing additional defects that improve the capacitance and facilitate the reaction kinetics of the electrode.During the electrochemical oxidation process,it is discovered that the perovskite fluoride crystal tends to transform into disordered O-doped KMnF 3(K_(x)MnF_(y)O_(z)),realizing a structural reconstruction at the electrode material/electrolyte interface.The First-principles calculations based on density functional theory(DFT)are performed to confirm that the improved electrical conduc-tivity and low ionic adsorption energy may be ascribed to the substitution of oxygen for fluorine.The obtained K_(1.14)MnF_(1.17)O_(1.26) cathode achieves a high specific capacitance of 694 F g^(-1) at 1 A g^(-1),as well as high capacitance retention of 91.3%after 10,000 charge/discharge cycles in mild K_(2)SO_(4) electrolyte.This study provides an effective strategy to improve the capacitive performance of perovskite fluoride cathode materials in electrochemical energy storage.展开更多
Highly active N,O-doped hierarchical porous carbons(NOCs)are fabricated through the in-situ polymerization and pyrolysis of o-tolidine and p-benzoquinone.As-prepared NOCs have a variety of faradaic-active species(N-6,...Highly active N,O-doped hierarchical porous carbons(NOCs)are fabricated through the in-situ polymerization and pyrolysis of o-tolidine and p-benzoquinone.As-prepared NOCs have a variety of faradaic-active species(N-6,N-5 and O-I),high ion-accessible platform(1799 m^2/g)and hierarchically micro-meso-macro porous architecture.Consequently,the resultant NOC electrode delivers an advantageous specific capacitance(311 F/g),with a pseudocapacitive contribution of 37%in a threeelectrode configuration,and an enhanced energy output of 18.0 Wh/kg@350 W/kg owing to the enlarged faradaic effect in an aqueous redox-active cell.Besides,a competitive energy density(74.9 Wh/kg)and high-potential durability(87.8%)are achieved in an ionic liquid(EMIMB F4)-assembled device.This study sheds light on a straightforward avenue to optimize the faradaic activity and nanoarchitecture for advanced supercapacitors.展开更多
With the advantages of high energy/power density,long cycling life and low cost,dual-carbon potassium ion hybrid capacitors(PIHCs)have great potential in the field of energy storage.Here,a novel bilayer-shelled N,O-do...With the advantages of high energy/power density,long cycling life and low cost,dual-carbon potassium ion hybrid capacitors(PIHCs)have great potential in the field of energy storage.Here,a novel bilayer-shelled N,O-doped hollow porous carbon microspheres(NOHPC)anode has been prepared by a self-template method,which is consisted of a dense thin shell and a hollow porous spherical core.Excitingly,the NOHPC anode possesses a high K-storage capacity of 325.9 mA h g^(−1)at 0.1 A g^(−1)and a capacity of 201.1 mAh g^(−1)at 5 A g^(−1)after 6000 cycles.In combination with ex situ characterizations and density functional theory calculations,the high reversible capacity has been demonstrated to be attributed to the co-doping of N/O heteroatoms and porous structure improved K+adsorption and intercalation capabilities,and the stable long-cycling performance originating from the bilayer-shelled hollow porous carbon sphere structure.Meanwhile,the hollow porous activated carbon microspheres(HPAC)cathode with a high specific surface area(1472.65 m^(2)g^(−1))deriving from etching NOHPC with KOH,contributing to a high electrochemical adsorption capacity of 71.2 mAh g^(−1)at 1 A g^(−1).Notably,the NOHPC//HPAC PIHC delivers a high energy density of 90.1 Wh kg^(−1)at a power density of 939.6 W kg^(−1)after 6000 consecutive charge-discharge cycles.展开更多
Porous heteroatom-doped carbon materials exhibit promising electrochemical applications because of tunable porous structure and doping heteroatom-induced charge redistribution.Nevertheless,it is still a great challeng...Porous heteroatom-doped carbon materials exhibit promising electrochemical applications because of tunable porous structure and doping heteroatom-induced charge redistribution.Nevertheless,it is still a great challenge to develop porous heteroatom-doped carbon materials with both high-content active heteroatom species and facilitated diffusion route.Herein,we report a bowl-shaped nitrogen and oxygen dual-doping carbon(N,O-doped carbon)material based on low-temperature defluorination pyrolysis and alkali-etched activation of 3-fluorophenol-3-amino-4-hydroxypyridine-formaldehyde co-condensed resin and its excellent supercapacitance.This low-temperature thermal treatment strategy ensures high-content pyrrolic nitrogen(4.6 at.%)and oxygen species(15.9 at.%)to avoid high-temperature treatment-induced heteroatom loss and undesired configuration conversion.In these processes,the defluorination pyrolysis promotes the transformation from the resin to carbon material to some extent,and KOH activation also promotes the ordered arrangement of 002 planes,which together assure the appropriate conductivity of the final microporous carbon material.More importantly,KOH-etched activation partially removes an un-stable nano/microscale domain of the intermediate carbon microspheres to form a unique bowl-shaped structure extremely facilitating the diffusion of the substitutes and/or electrolyte ions.As expected,N,O-doped carbon material displays a remarkable specific capacitance of 486.4 F g^(−1)at 1 A g^(−1)with nitro-gen/oxygen species-dependant pseudocapacitance and good electrochemical durability.展开更多
基金Hebei Natural Science Foundation(No.B2015203259)Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education),College of Chemistry,Nankai University for providing the financial support for this project。
文摘A promising biomass carbon material,manufactured by the carbonation of Physalis peruviana L.calyx at 700℃,is presented in this wo rk.Morphology characterization shows that the carbon material possesses long microtubule bundling and above 30%natural O-atom component on the surface.After KOH chemical etching,the materials maintain the oxygen content but exhibit more micropores and higher specific surface area up to 1732.6 m^2/g.Using as an electrode material for supercapacitor,the active carbon material exhibits high specific capacitance up to 339.7 F/g at 0.5 A/g in 3 mol/L KOH aqueous solution through three-electrode system.The active carbon material also exhibits excellent cycling stability(97%retention)by 10,000 cycles at 10 A/g.The outstanding electrochemical performances are attributing to the unique long microtubule bundling with much more pores and the abundant Oelement on the surface.This biomass carbon material with excellent electrochemical properties could be a useful material for multiple applications.
基金supported by the National Natural Science Foundation of China(62474043,62074037,52372183)the Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(2021ZZ124)+1 种基金Fujian Provincial Natural Science Foundation of China(2024J09015)the Foundation of Fujian Provincial Department of Industry and Information Technology of China(82318075)。
文摘High performances of Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)solar cells are heavily influenced by the quality of heterojunctions.Herein,an oxygen(O)doping of CZTSSe/CdS heterojunction is performed to suppress the formation of the defects by an ultraviolet ozone(UV-O_(3))treatment for the efficient flexible CZTSSe solar cells.The introduction of O reduces the non-radiative recombination and increases the carrier concentration of the CdS films.Furthermore,the defect density of the CdS film has been reduced from 8.24×10^(16)to2.91×10^(16)cm^(-3)by the O-doping.The results indicate that the electron transport is effectively promoted due to the decreased conduction band offset(CBO)at the heterojunction interface.As a result,the champion flexible CZTSSe solar cell achieves a power conversion efficiency(PCE)of 11.21%,with a significantly improved short circuit current density.The study for improving the CZTSSe/CdS heterojunction through O-doping treatment provides a new insight for enhancing the PCE of the flexible CZTSSe solar cells.
基金Projects(51174054,51104041,51374065)supported by the National Natural Science Foundation of ChinaProject(N130402010)supported by the Fundamental Research Funds for the Central Universities of China
文摘Calcium aluminate clinkers doped with Na2O were synthesized using analytically pure reagents CaCO3, Al2O3, SiO2 and Na2CO3. The effects of Na2O-doping on the formation mechanism of calcium aluminate compounds and the crystal property of 12CaO·7Al2O3 (C12A7) cell were studied. The results show that the minerals containing Na2O mainly include 2Na2O·3CaO·5Al2O3 and Na2O·Al2O3, when the Na2O content in clinkers is less than 4.26% (mass fraction). The rest of Na2O is mainly doped in 12CaO·7Al2O3, which results in the decrease of the crystallinity of 12CaO·7Al2O3. The crystallinity of 2Na2O·3CaO·5Al2O3 is also inversely proportional to the Na2O content in clinkers. The formation processes of 2Na2O·3CaO·5Al2O3 and 12CaO·7Al2O3 can be divided into two ways, which are the direct reactions of raw materials and the transformation of CaO·Al2O3, respectively. The simulation shows that the covalency of O-Na bond in Na2O-doped 12CaO·7Al2O3 cell is weaker than those of O-Ca and O-Al bonds. The free energy of the unit cell increases because of Na2O doping, which results in the improvement of chemical activity of 12CaO·7Al2O3. The leaching efficiency of Al2O3 in clinker is improved from 34.81% to 88.17% when the Na2O content in clinkers increases from 0 to 4.26%.
基金supported by the National Natural Science Foundation of China(No.21576208)
文摘Based on the first-principles of density functional theory, the structural stability,electronic and magnetic properties of the O-doped monolayer C_2N are investigated. In details, the lattice parameters, band structures, density of states and phonon dispersions of O-doped monolayer C_2N are obtained and analyzed. Our results show that the introduction of oxygen dopants can cause a significant local lattice distortion. The band structure indicates that monolayer C_2N is a semiconductor with a direct band gap of 1.631 eV. The electronic properties of monolayer C_2N can be regulated by oxygen dopant atoms with different numbers. However, doping nonmetal oxygen element in monolayer C_2N does not affect its magnetic properties. In other words, the pure and O-doped systems are all nonmagnetic. The phonon dispersions of all the O-doped cases are found to have not any imaginary frequencies, which indicates that the structures of these O-doped systems have good structural stability.
基金This work is supported by the National Natural Science Foundation of China （No.50772107）, the National High Tech Research and Development Program （No.2009AA05Z435）, and the National Basic Research Program of the Ministry of Science and Technology of China （No.2007CB210206）.
文摘We provides a novel approach to generate low-temperature atomic oxygen anions （O-） emission using the cesium oxide-doped 12CaO.7Al2O3 （Cs2O-doped C12A7）. The maximal emission intensity of O- from the Cs2O-doped C12A7 at 700℃ and 800 V/cm reached about 0.54μA/cm2, which was about two times as strong as that from the un-doped C12A7 （0.23 μA/cm2） under the same condition. The initiative temperature of the O- emission from the Cs2O-doped C12A7 was about 500 ℃, which was also much lower than the initiative temperature from the un-doped C12A7 （570 ℃） in the given field of 800 V/cm. High pure O- emission close to 100% could be obtained from the Cs2O-doped C12A7 under the lower temperature （〈550℃）. The emission features of the Cs2O-doped C12A7, including the emission distribution, temperature effect, and emission branching ratio have been investigated in detail and compared with the un-doped C12A7. The structure and storage characteristics of the resulting material were also investigated via X-ray diffraction and electron paramagnetic resonance. It was found that doping Cs2Oto C12A7 will lower the initiative emission temperature and enhance the emission intensity
基金the financial support from Liaoning Sci-ence and Technology Development Foundation Guided by Cen-tral Government(No.2021JH6/10500139)the Fundamental Research Funds for the Central Universities(No.N2205003)+2 种基金the financial support from the National Natural Science Foundation of China(No.52003007)Nat-ural Science Foundation of Hebei Province(No.E2019409063)Langfang top-notch talent(No.LFBJ202004).
文摘Potassium ion capacitors(PICs)are regarded as promising large-scale aqueous energy storage systems.However,due to the poor K^(+)transport kinetics and the structural instability of the cathode materials,the key issues of limited energy density and poor cyclic stability are obstacles to the in-depth growth of PICs.Herein,a novel O-doped perovskite fluoride is demonstrated via an in-situ electrochemical oxidation strategy as the cathode for PICs,introducing additional defects that improve the capacitance and facilitate the reaction kinetics of the electrode.During the electrochemical oxidation process,it is discovered that the perovskite fluoride crystal tends to transform into disordered O-doped KMnF 3(K_(x)MnF_(y)O_(z)),realizing a structural reconstruction at the electrode material/electrolyte interface.The First-principles calculations based on density functional theory(DFT)are performed to confirm that the improved electrical conduc-tivity and low ionic adsorption energy may be ascribed to the substitution of oxygen for fluorine.The obtained K_(1.14)MnF_(1.17)O_(1.26) cathode achieves a high specific capacitance of 694 F g^(-1) at 1 A g^(-1),as well as high capacitance retention of 91.3%after 10,000 charge/discharge cycles in mild K_(2)SO_(4) electrolyte.This study provides an effective strategy to improve the capacitive performance of perovskite fluoride cathode materials in electrochemical energy storage.
基金financially supported by the National Natural Science Foundation of China(Nos.21905207,21875165,51772216,and 21703161)the Science and Technology Commission of Shanghai Municipality,China(No.14DZ2261100)+1 种基金the Natural Foundation of Hubei Province of China(No.2014CFB782)the Fundamental Research Funds for the Central Universities。
文摘Highly active N,O-doped hierarchical porous carbons(NOCs)are fabricated through the in-situ polymerization and pyrolysis of o-tolidine and p-benzoquinone.As-prepared NOCs have a variety of faradaic-active species(N-6,N-5 and O-I),high ion-accessible platform(1799 m^2/g)and hierarchically micro-meso-macro porous architecture.Consequently,the resultant NOC electrode delivers an advantageous specific capacitance(311 F/g),with a pseudocapacitive contribution of 37%in a threeelectrode configuration,and an enhanced energy output of 18.0 Wh/kg@350 W/kg owing to the enlarged faradaic effect in an aqueous redox-active cell.Besides,a competitive energy density(74.9 Wh/kg)and high-potential durability(87.8%)are achieved in an ionic liquid(EMIMB F4)-assembled device.This study sheds light on a straightforward avenue to optimize the faradaic activity and nanoarchitecture for advanced supercapacitors.
基金supported by the National Natural Science Foundation of China(Nos.21701163,21671181,21831006,and 22075268)the Fundamental Research Funds for the Central Universities(No.WK5290000003)Innovation Key Fund Project of University of Science and Technology of China(YD2060002023).
文摘With the advantages of high energy/power density,long cycling life and low cost,dual-carbon potassium ion hybrid capacitors(PIHCs)have great potential in the field of energy storage.Here,a novel bilayer-shelled N,O-doped hollow porous carbon microspheres(NOHPC)anode has been prepared by a self-template method,which is consisted of a dense thin shell and a hollow porous spherical core.Excitingly,the NOHPC anode possesses a high K-storage capacity of 325.9 mA h g^(−1)at 0.1 A g^(−1)and a capacity of 201.1 mAh g^(−1)at 5 A g^(−1)after 6000 cycles.In combination with ex situ characterizations and density functional theory calculations,the high reversible capacity has been demonstrated to be attributed to the co-doping of N/O heteroatoms and porous structure improved K+adsorption and intercalation capabilities,and the stable long-cycling performance originating from the bilayer-shelled hollow porous carbon sphere structure.Meanwhile,the hollow porous activated carbon microspheres(HPAC)cathode with a high specific surface area(1472.65 m^(2)g^(−1))deriving from etching NOHPC with KOH,contributing to a high electrochemical adsorption capacity of 71.2 mAh g^(−1)at 1 A g^(−1).Notably,the NOHPC//HPAC PIHC delivers a high energy density of 90.1 Wh kg^(−1)at a power density of 939.6 W kg^(−1)after 6000 consecutive charge-discharge cycles.
基金the National Natural Science Foundation of China(No.52202048)the Hebei Natural Science Foundation(Nos.E2022203082 and B2021203012)the Department of Education of Hebei Province(No.QN2021140).
文摘Porous heteroatom-doped carbon materials exhibit promising electrochemical applications because of tunable porous structure and doping heteroatom-induced charge redistribution.Nevertheless,it is still a great challenge to develop porous heteroatom-doped carbon materials with both high-content active heteroatom species and facilitated diffusion route.Herein,we report a bowl-shaped nitrogen and oxygen dual-doping carbon(N,O-doped carbon)material based on low-temperature defluorination pyrolysis and alkali-etched activation of 3-fluorophenol-3-amino-4-hydroxypyridine-formaldehyde co-condensed resin and its excellent supercapacitance.This low-temperature thermal treatment strategy ensures high-content pyrrolic nitrogen(4.6 at.%)and oxygen species(15.9 at.%)to avoid high-temperature treatment-induced heteroatom loss and undesired configuration conversion.In these processes,the defluorination pyrolysis promotes the transformation from the resin to carbon material to some extent,and KOH activation also promotes the ordered arrangement of 002 planes,which together assure the appropriate conductivity of the final microporous carbon material.More importantly,KOH-etched activation partially removes an un-stable nano/microscale domain of the intermediate carbon microspheres to form a unique bowl-shaped structure extremely facilitating the diffusion of the substitutes and/or electrolyte ions.As expected,N,O-doped carbon material displays a remarkable specific capacitance of 486.4 F g^(−1)at 1 A g^(−1)with nitro-gen/oxygen species-dependant pseudocapacitance and good electrochemical durability.
