Photocatalytic synthesis of hydrogen peroxide has gradually become a promising method for in-situ pro-duction of hydrogen peroxide,which relies on sustainable solar energy.However,the commonly used photocatalyst,i.e.,...Photocatalytic synthesis of hydrogen peroxide has gradually become a promising method for in-situ pro-duction of hydrogen peroxide,which relies on sustainable solar energy.However,the commonly used photocatalyst,i.e.,carbon nitride(CN),still suffers from the drawbacks of narrow light absorption range and fast charge recombination.Here,we report a facile method to introduce nitrogen defects into carbon nitride together with sodium ion.By adjusting the ratio of sodium dicyandiamide,the band gap of carbon nitride can be controlled,while the carrier separation and transfer ability of carbon nitride is improved.The modified CN with sodium doping and nitrogen defect(SD-CN)demonstrates outstanding H_(2)O_(2)pro-duction performance(H_(2)O_(2)yield rate of 297.2μmol L^(−1)h^(−1))under visible light irradiation,which is approximately 9.8 times higher than that of pristine CN.This work deepens the understanding of the coordinated effect of structural defect and element doping of carbon nitride on the photocatalytic H_(2)O_(2)production performance,and provides new insight into the design of photocatalytic system for efficient production of H_(2)O_(2).展开更多
Defect construction and heteroatom doping are effective strategies for improving photocatalytic activity of carbon nitride(g-C_(3)N_(4)).In this work,N defects were successfully prepared via cold plasma.High-energy el...Defect construction and heteroatom doping are effective strategies for improving photocatalytic activity of carbon nitride(g-C_(3)N_(4)).In this work,N defects were successfully prepared via cold plasma.High-energy electrons generated by plasma can produce N defects and embed sulfur atoms into g-C_(3)N_(4).The N defects obviously promoted photocatalytic degradation performance that was 7.5 times higher than that of pure g-C_(3)N_(4).The concentration of N defects can be tuned by different power and time of plasma.With the increase in N defects,the photocatalytic activity showed a volcanic trend.The g-C_(3)N_(4)with moderate concentration of N defects exhibited the highest photocatalytic activity.S-doped g-C_(3)N_(4)exhibited 11.25 times higher photocatalytic activity than pure g-C_(3)N_(4).It provided extra active sites for photocatalytic reaction and improved stability of N defects.The N vacancy-enriched and S-doped g-C_(3)N_(4)are beneficial for widening absorption edge and improving the separation efficiency of electron and holes.展开更多
One of the major obstacles to the application of potassium-ion batteries in large-scale energy storage is the lack of safe and effective electrolytes.KNH_(2),a new potassium-ion solid electrolyte has been developed in...One of the major obstacles to the application of potassium-ion batteries in large-scale energy storage is the lack of safe and effective electrolytes.KNH_(2),a new potassium-ion solid electrolyte has been developed in this study.Its ionic conductivity reaches 4.84×10^(-5)S cm^(-1)at 150°C and can reach3.56×10^(-4)S cm^(-1)after mechanochemical treatment.The result from electron paramagnetic resonance(EPR) measurement shows that the increment of ionic conductivity is dependent on the concentration of nitrogen defects in the KNH_(2) electrolyte.To the best of our knowledge,this is the first report that adopts inorganic amide as an electrolyte for potassium-ion battery and initiates the search for a new amidebased solid electrolyte for an all-solid-state potassium-ion battery.展开更多
Incorporating nitrogen(N)atom in graphene is considered a key technique for tuning its electrical properties.However,this is still a great challenge,and it is unclear how to build N-graphene with desired nitrogen conf...Incorporating nitrogen(N)atom in graphene is considered a key technique for tuning its electrical properties.However,this is still a great challenge,and it is unclear how to build N-graphene with desired nitrogen configurations.There is a lack of experimental evidence to explain the influence and mechanism of structural defects for nitrogen incorporation into graphene compared to the derived DFT theories.Herein,this gap is bridged through a systematic study of different nitrogen-containing gaseous plasma post-treatments on graphene nanowalls(CNWs)to produce N-CNWs with incorporated and substituted nitrogen.The structural and morphological analyses describe a remarkable difference in the plasma–surface interaction,nitrogen concentration and nitrogen incorporation mechanism in CNWs by using different nitrogen-containing plasma.Electrical conductivity measurements revealed that the conductivity of the N-graphene is strongly influenced by the position and concentration of C–N bonding configurations.These findings open up a new pathway for the synthesis of N-graphene using plasma post-treatment to control the concentration and configuration of incorporated nitrogen for application-specific properties.展开更多
Despite the challenges that remain,the synergistic adjustment of various microstructures and photochemical parameters of graphitic carbon nitride(g-C_(3)N_(4))in photocatalytic reactions holds promises for improving c...Despite the challenges that remain,the synergistic adjustment of various microstructures and photochemical parameters of graphitic carbon nitride(g-C_(3)N_(4))in photocatalytic reactions holds promises for improving catalytic efficiency and reducing energy consumption.Herein,sulfur-doped and nitrogen-defective g-C_(3)N_(4)(n-SC_(3)N_(x))nanosheets were designed and elaborately synthesized.The resultant n-SC_(3)N_(x)possessed a precisely defined 2D layer structure with extensive porosity and incremental specific surface area.Enhanced photoinduced electron transfer-reversible addition-fragmentation chain transfer(PET-RAFT)polymerization of vinyl monomers with low dispersity,excellent temporal control and high chain-end fidelity was achieved under mild blue light irradiation in a nondegassed system.Owing to their ultrathin nanostructures with nitrogen defects and sulfur dopants,n-SC_(3)N_(x)was capable of catalyzing RAFT polymerization in aqueous solutions at significantly accelerated rates,which were nearly 8 times faster compared to bulk g-C_(3)N_(4).The ease of separation and efficient reusability in subsequent polymerizations was enabled by the heterogeneous nature of n-SC_(3)N_(x).The appeal of this approach was illustrated by the fact that utilizing a reusable and metal-free photocatalyst in aqueous environments allowed for the synthesis of polymers with molecular weight up to 300 kg mol^(-1) and a dispersity of 1.32.展开更多
Defective electrocatalysts,especially for intrinsic defective carbon,have aroused a wide concern owing to high spin and charge densities.However,the designated nitrogen species favorable for creating defects by the re...Defective electrocatalysts,especially for intrinsic defective carbon,have aroused a wide concern owing to high spin and charge densities.However,the designated nitrogen species favorable for creating defects by the removal of nitrogen,and the influence of defects for the coordination structure of active site and oxygen reduction reaction(ORR)activity have not been elucidated.Herein,we designed and synthesized a pair of electrocatalysts,denoted as Fe-N/C and Fe-ND/C for coordination sites of atomic iron-nitrogen and iron-nitrogen/defect configuration embedded in hollow carbon spheres,respectively,through direct pyrolysis of their corresponding hollow carbon spheres adsorbed with Fe(acac)3.The nitrogen defects were fabricated via the evaporation of pyrrolic-N on nitrogen doped hollow carbon spheres.Results of comparative experiments between Fe-N/C and Fe-ND/C reveal that Fe-ND/C shows superior ORR activity with an onset potential of 30 mV higher than that of Fe-N/C.Fe-ND sites are more favorable for the enhancement of ORR activity.Density functional theory(DFT)calculation demonstrates that Fe-ND/C with proposed coordination structure of FeN_(4-x)(0<x<4)anchored by OH as axial ligand during ORR,weakens the strong binding of OH^(*)intermediate and promotes the desorption of OH^(*)as rate-determining step for ORR in alkaline electrolyte.Thus,Fe-ND/C electrocatalysts present much better ORR activity compared with that of Fe-N/C with proposed coordination structure of FeN_(4).展开更多
基金supported by the National Natural Science Foundation of China(No.22376159)the Fundamental Research Funds for the Central Universities(No.2022-4-ZD-08).
文摘Photocatalytic synthesis of hydrogen peroxide has gradually become a promising method for in-situ pro-duction of hydrogen peroxide,which relies on sustainable solar energy.However,the commonly used photocatalyst,i.e.,carbon nitride(CN),still suffers from the drawbacks of narrow light absorption range and fast charge recombination.Here,we report a facile method to introduce nitrogen defects into carbon nitride together with sodium ion.By adjusting the ratio of sodium dicyandiamide,the band gap of carbon nitride can be controlled,while the carrier separation and transfer ability of carbon nitride is improved.The modified CN with sodium doping and nitrogen defect(SD-CN)demonstrates outstanding H_(2)O_(2)pro-duction performance(H_(2)O_(2)yield rate of 297.2μmol L^(−1)h^(−1))under visible light irradiation,which is approximately 9.8 times higher than that of pristine CN.This work deepens the understanding of the coordinated effect of structural defect and element doping of carbon nitride on the photocatalytic H_(2)O_(2)production performance,and provides new insight into the design of photocatalytic system for efficient production of H_(2)O_(2).
基金supported by the National Natural Science Foundation of China(Grant Nos.21878214 and 21938009).
文摘Defect construction and heteroatom doping are effective strategies for improving photocatalytic activity of carbon nitride(g-C_(3)N_(4)).In this work,N defects were successfully prepared via cold plasma.High-energy electrons generated by plasma can produce N defects and embed sulfur atoms into g-C_(3)N_(4).The N defects obviously promoted photocatalytic degradation performance that was 7.5 times higher than that of pure g-C_(3)N_(4).The concentration of N defects can be tuned by different power and time of plasma.With the increase in N defects,the photocatalytic activity showed a volcanic trend.The g-C_(3)N_(4)with moderate concentration of N defects exhibited the highest photocatalytic activity.S-doped g-C_(3)N_(4)exhibited 11.25 times higher photocatalytic activity than pure g-C_(3)N_(4).It provided extra active sites for photocatalytic reaction and improved stability of N defects.The N vacancy-enriched and S-doped g-C_(3)N_(4)are beneficial for widening absorption edge and improving the separation efficiency of electron and holes.
基金supported by the Key R&D Program of Shandong Province China (2020CXGC010402)the National Natural Science Foundation of China (51801197)+3 种基金the Youth Innovation Promotion Association CAS (2019189)the Liaoning Revitalization Talents Program (XLYC2002076)the Dalian High-level Talents Program (2019RD09)the K.C. Wong Education Foundation (GJTD2018-06)。
文摘One of the major obstacles to the application of potassium-ion batteries in large-scale energy storage is the lack of safe and effective electrolytes.KNH_(2),a new potassium-ion solid electrolyte has been developed in this study.Its ionic conductivity reaches 4.84×10^(-5)S cm^(-1)at 150°C and can reach3.56×10^(-4)S cm^(-1)after mechanochemical treatment.The result from electron paramagnetic resonance(EPR) measurement shows that the increment of ionic conductivity is dependent on the concentration of nitrogen defects in the KNH_(2) electrolyte.To the best of our knowledge,this is the first report that adopts inorganic amide as an electrolyte for potassium-ion battery and initiates the search for a new amidebased solid electrolyte for an all-solid-state potassium-ion battery.
基金funded by the European Union’s Horizon Research and Innovation Program under Grant agreement No. 766894partially supported also by JSPS, MESS and ARRS under the Japan-Slovenia Research Cooperative Program grants to U.C., M.H. and H.Kthe allocation of synchrotron radiation beam time at Bessy II via projects 17205612ST/R, 17206156ST, 18106986ST, 19107892-ST/R and 191-08281 ST/R as well as Calypso
文摘Incorporating nitrogen(N)atom in graphene is considered a key technique for tuning its electrical properties.However,this is still a great challenge,and it is unclear how to build N-graphene with desired nitrogen configurations.There is a lack of experimental evidence to explain the influence and mechanism of structural defects for nitrogen incorporation into graphene compared to the derived DFT theories.Herein,this gap is bridged through a systematic study of different nitrogen-containing gaseous plasma post-treatments on graphene nanowalls(CNWs)to produce N-CNWs with incorporated and substituted nitrogen.The structural and morphological analyses describe a remarkable difference in the plasma–surface interaction,nitrogen concentration and nitrogen incorporation mechanism in CNWs by using different nitrogen-containing plasma.Electrical conductivity measurements revealed that the conductivity of the N-graphene is strongly influenced by the position and concentration of C–N bonding configurations.These findings open up a new pathway for the synthesis of N-graphene using plasma post-treatment to control the concentration and configuration of incorporated nitrogen for application-specific properties.
基金supported by the National Natural Science Foundation of China(51773156)the Shenzhen Science and Technology Program(JCYJ20220530140607016)。
文摘Despite the challenges that remain,the synergistic adjustment of various microstructures and photochemical parameters of graphitic carbon nitride(g-C_(3)N_(4))in photocatalytic reactions holds promises for improving catalytic efficiency and reducing energy consumption.Herein,sulfur-doped and nitrogen-defective g-C_(3)N_(4)(n-SC_(3)N_(x))nanosheets were designed and elaborately synthesized.The resultant n-SC_(3)N_(x)possessed a precisely defined 2D layer structure with extensive porosity and incremental specific surface area.Enhanced photoinduced electron transfer-reversible addition-fragmentation chain transfer(PET-RAFT)polymerization of vinyl monomers with low dispersity,excellent temporal control and high chain-end fidelity was achieved under mild blue light irradiation in a nondegassed system.Owing to their ultrathin nanostructures with nitrogen defects and sulfur dopants,n-SC_(3)N_(x)was capable of catalyzing RAFT polymerization in aqueous solutions at significantly accelerated rates,which were nearly 8 times faster compared to bulk g-C_(3)N_(4).The ease of separation and efficient reusability in subsequent polymerizations was enabled by the heterogeneous nature of n-SC_(3)N_(x).The appeal of this approach was illustrated by the fact that utilizing a reusable and metal-free photocatalyst in aqueous environments allowed for the synthesis of polymers with molecular weight up to 300 kg mol^(-1) and a dispersity of 1.32.
基金the National Natural Science Foundation of China(Nos.21905271,21701168)Liaoning Natural Science Foundation(Nos.20180510029,20180510043,20180510050)+2 种基金the Dalian National Laboratory for Clean Energy(DNL)CAS,DNL Cooperation Fund,CAS(No.DNL180402)Australian Research Council(No.DP180100568).For XAFS measurement,we gratefully acknowledge 1W1B beamline of Beijing Synchrotron Radiation Facility(BSRF)Beijing,China for providing the beam time.
文摘Defective electrocatalysts,especially for intrinsic defective carbon,have aroused a wide concern owing to high spin and charge densities.However,the designated nitrogen species favorable for creating defects by the removal of nitrogen,and the influence of defects for the coordination structure of active site and oxygen reduction reaction(ORR)activity have not been elucidated.Herein,we designed and synthesized a pair of electrocatalysts,denoted as Fe-N/C and Fe-ND/C for coordination sites of atomic iron-nitrogen and iron-nitrogen/defect configuration embedded in hollow carbon spheres,respectively,through direct pyrolysis of their corresponding hollow carbon spheres adsorbed with Fe(acac)3.The nitrogen defects were fabricated via the evaporation of pyrrolic-N on nitrogen doped hollow carbon spheres.Results of comparative experiments between Fe-N/C and Fe-ND/C reveal that Fe-ND/C shows superior ORR activity with an onset potential of 30 mV higher than that of Fe-N/C.Fe-ND sites are more favorable for the enhancement of ORR activity.Density functional theory(DFT)calculation demonstrates that Fe-ND/C with proposed coordination structure of FeN_(4-x)(0<x<4)anchored by OH as axial ligand during ORR,weakens the strong binding of OH^(*)intermediate and promotes the desorption of OH^(*)as rate-determining step for ORR in alkaline electrolyte.Thus,Fe-ND/C electrocatalysts present much better ORR activity compared with that of Fe-N/C with proposed coordination structure of FeN_(4).
