The efficacy of the oxygen reduction reaction(ORR) in fuel cells can be significantly enhanced by optimizing cobalt-based catalysts,which provide a more stable alternative to iron-based catalysts.However,their perform...The efficacy of the oxygen reduction reaction(ORR) in fuel cells can be significantly enhanced by optimizing cobalt-based catalysts,which provide a more stable alternative to iron-based catalysts.However,their performance is often impeded by weak adsorption of oxygen species,leading to a 2e^(-)pathway that negatively affects fuel cell discharge efficiency.Here,we engineered a high-density cobalt active center catalyst,coordinated with nitrogen and sulfur atoms on a porous carbon substrate.Both experimental and theoretical analyses highlighted the role of sulfur atoms as electron donors,disrupting the charge symmetry of the original Co active center and promoting enhanced interaction with Co 3d orbitals.This modification improves the adsorption of oxygen and reaction intermediates during ORR,significantly reducing the production of hydrogen peroxide(H_(2)O_(2)).Remarkably,the optimized catalyst demonstrated superior fuel cell performance,with peak power densities of 1.32 W cm^(-2) in oxygen and 0.61 W cm^(-2) in air environments,respectively.A significant decrease in H_(2)O_(2) by-product accumulation was observed during the reaction process,reducing catalyst and membrane damage and consequently improving fuel cell durability.This study emphasizes the critical role of coordination symmetry in Co/N/C catalysts and proposes an effective strategy to enhance fuel cell performance.展开更多
One-dimensional ultrathin nanowires(NWs)offer a great deal of promising properties for electrochemical energy storage and conversion due to their nanoscale confinement effect and high surface-to-volume ratios.It is hi...One-dimensional ultrathin nanowires(NWs)offer a great deal of promising properties for electrochemical energy storage and conversion due to their nanoscale confinement effect and high surface-to-volume ratios.It is highly desirable to precisely design and synthesize ultrathin Ti_(3)C_(2)NWs in the aspect of size,crystalline structure and composition.Here,we report a simple alkalization strategy to design the ultrathin Ti_(3)C_(2)NWs for hydrogen evolution reaction(HER)by modulating the surface-active sites.The design principle can well improve the amount of the defect sites and ion accessibility to increase the interactions between Ti_(3)C_(2)NWs and H^(*).The optimized Ti_(3)C_(2)NWs achieve an overpotential of 476 mV at the current density of 10 mA/cm^(2)and a Tafel slope of 129 mV/dec for HER catalysis,which are superior to that of Ti_(3)C_(2)nanosheets and m-Ti_(3)C_(2).It paves an avenue for the rational transformation of MXene bulks to one-dimensional NWs catalysts for HER.展开更多
In this study,TiO_(2) nanosheets(NSs)grown in situ on extremely conductive Ti_(3)C_(2)T_(x) MXene to form TiO_(2)/Ti_(3)C_(2)T_(x) MXene composites with abundant active sites are proposed to effectively achieve elec‐...In this study,TiO_(2) nanosheets(NSs)grown in situ on extremely conductive Ti_(3)C_(2)T_(x) MXene to form TiO_(2)/Ti_(3)C_(2)T_(x) MXene composites with abundant active sites are proposed to effectively achieve elec‐trocatalytic NH_(3) synthesis.Electron transfer can be promoted by Ti_(3)C_(2)T_(x) MXene with high conduc‐tivity.Meanwhile,the TiO_(2) NSs in‐situ formation can not only avoid Ti_(3)C_(2)T_(x) MXene microstacking but also enhance the surface specific area of Ti_(3)C_(2)T_(x) MXene.The TiO_(2)/Ti_(3)C_(2)T_(x) MXene catalyst reach‐es a high Faradaic efϐiciency(FE)of 44.68%at−0.75 V vs.RHE and a large NH3 yield of 44.17µg h^(-1) mg^(-1)cat.at−0.95 V,with strong electrochemical durability.15N isotopic labeling experiments imply that the N in the produced NH3 originated from the N2 of the electrolyte.DFT calculations were conducted to determine the possible NRR reaction pathways for TiO_(2)/Ti_(3)C_(2)T_(x) MXene composites.MXene catalysts combined with other materials have been rationally designed for efficient ammonia production under ambient conditions。展开更多
The non-isothermal decomposition reaction of Nd[(C_5H_ 10NS_2)_3(C_ 12H_8N_2)] were carried out by means of TG-DTG and the thermal decomposition mechanism, and the associated kinetics was investigated. The kinetic par...The non-isothermal decomposition reaction of Nd[(C_5H_ 10NS_2)_3(C_ 12H_8N_2)] were carried out by means of TG-DTG and the thermal decomposition mechanism, and the associated kinetics was investigated. The kinetic parameters are obtained from an analysis of the TG-DTG curves at different heating rate by integral and differential methods. The most probable kinetic model function of the decomposition reaction is Maple Power of n=3/2, f(α)=2/3α -1/2 and the apparent activation energy E is 116.67 kJ·mol -1 and the pre-exponential factor lg[A/s -1] is 7.6891.展开更多
The design and construction of heterojunction photocatalysts,which possess a staggered energy band structure and appropriate interfacial contact,is an effective way to achieve outstanding photocatalytic performance.In...The design and construction of heterojunction photocatalysts,which possess a staggered energy band structure and appropriate interfacial contact,is an effective way to achieve outstanding photocatalytic performance.In this study,2D/2D BiOBr/g‐C_(3)N_(4)heterojunctions were successfully obtained by a convenient in situ self‐assembly route.Under simulated sunlight irradiation,99%of RhB(10 mg·L–1,100 mL)was efficiently degraded by 1.5‐BiOBr/g‐C_(3)N_(4)within 30 min,which is better than the performance of both BiOBr and g‐C_(3)N_(4),and it has superior stability.In addition,the composite also exhibits enhanced photocatalytic activity for H2 production.The enhanced activity can be attributed to the intimate interface contact,the larger surface area,and the highly efficient separation of photoinduced electron–hole pairs.Based on the experimental results,a novel S‐scheme model was proposed to illuminate the transfer process of charge carriers.This study presents a simple way to develop novel step‐scheme photocatalysts for environmental and related applications.展开更多
Developing highly conductive,stable,and active hydrogen evolution reaction(HER)catalysts is a critical step towards establishing the hydrogen economy.However,there are few catalysts,except for noble metals,that can me...Developing highly conductive,stable,and active hydrogen evolution reaction(HER)catalysts is a critical step towards establishing the hydrogen economy.However,there are few catalysts,except for noble metals,that can meet all the requirements.Recently,two-dimensional(2D)transition metal carbon/nitride(MXene)materials have shown excellent performance in catalysis,and have attracted wide attention from researchers.In this study,the effectiveness of non-metal element(B,C,N,P,and S)-doped Ti_(3)C_(2)O_(2)MXene in the electrocatalytic hydrogen evolution reaction was investigated using density functional theory(DFT)calculations.Non-metal atoms as elec-tron donors can provide additional electrons to the O functional group on the catalyst surface,thereby reducing charge transfer from H to O and the interaction between H and O.The Gibbs free energy(ΔG H)of non-metal element-doped Ti_(3)C_(2)O_(2)is closer to 0 than that of pristine Ti_(3)C_(2)O_(2),demonstrating better hydrogen evolution performance.Furthermore,in the hydrogen evolution path,the desorption process is more inclined to the Hey-rovsky mechanism,and doping greatly reduces the energy barrier of the reaction,thereby improving the catalytic efficiency.The present results prove that doping with non-metallic elements is an effective means of improving the catalytic activity of Ti_(3)C_(2)O_(2)for hydrogen evolution.展开更多
Cu-based electrocatalysts have provoked much attention for their high activity and selectivity in carbon dioxide(CO_(2))conversion into multi-carbon hydrocarbons.However,during the electrochemical reaction,Cu catalyst...Cu-based electrocatalysts have provoked much attention for their high activity and selectivity in carbon dioxide(CO_(2))conversion into multi-carbon hydrocarbons.However,during the electrochemical reaction,Cu catalysts inevitably undergo surface reconstruction whose impact on CO_(2)conversion performance remains contentious.Here we report that polycrystalline Cu nanoparticles(denoted as Cu-s)with rich high-index facets,derived from Cu_(2−x)S through desulphurization and surface reconstruction,offer an excellent platform for investigating the role of surface reconstruction in electrocatalytic CO_(2)conversion.During the formation of Cu-s catalyst,the two stages of desulphurization and surface reconstruction can be clearly resolved by in situ X-ray absorption spectroscopy and OH−adsorption characterizations,which are well correlated with the changes in electrocatalytic performance.It turns out that the high CO_(2)conversion performance,achieved by the Cu-s catalyst(Faradic efficiency of 68.6%and partial current density of 40.8 mA/cm^(2)in H-cell toward C_(2)H_(4)production),is attributed to the increased percentage of high-index facets in Cu-s during the surface reconstruction.Furthermore,the operando electrochemical Raman spectroscopy further reveals that the conversion of the CO_(2)into the C_(2)H_(4)on Cu-s is intermediated by the production of*COCHO.Our findings manifest that the surface reconstruction is an effective method for tuning the reaction intermediate of the CO_(2)conversion toward high-value multicarbon(C2+)chemicals,and highlight the significance of in situ characterizations in enhancing the understanding of the surface structure and its role in electrocatalysis.展开更多
The photo-Fenton reaction is a key source of the highly reactive hydroxyl radical(HOU) that is produced by the reaction of simultaneous photo-induced generation of Fe^(2+)-dissolved organic matter(DOM) with H_2...The photo-Fenton reaction is a key source of the highly reactive hydroxyl radical(HOU) that is produced by the reaction of simultaneous photo-induced generation of Fe^(2+)-dissolved organic matter(DOM) with H_2O_2 in sunlit surface waters as well as in the treatment of organic pollutants in the advanced oxidation processes(AOPs).Concentrations of both H_2O_2 and Fe^(2+)-DOM were dependent on time and total solar intensity flux,and their levels were highest in the diurnal samples collected at noon compared with the samples collected during the period before sunrise and after sunset.H_2O_2 and Fe^(2+)-DOM concentrations during monthly readings were also found higher in comparison with the diurnal samples,shortly before sunrise or after sunset.A π-electron bonding system is formed between Fe and the functional groups in DOM(Fe-DOM),through electron donation from the functional groups of DOM to an empty d-orbital of Fe.The π-electron is loosely bound and is highly susceptible to a rapid excitation upon light exposure that will provide better understanding of the formation of aqueous electrons,superoxide radical anions,H_2O_2 and finally,photo-Fenton reactions,too.Our results imply that simultaneous generation of H_2O_2 and Fe^(2+)-DOM upon sunlight exposure during the daytime is most likely to be the key photo-Fenton reaction pathway,taking place in surface waters.展开更多
Acetylene purification from methane is challenging in the field of porous organic polymers(POPs).Herein,we have provided one-pot Ullmann coupling reaction to synthesize a series of POPs with rich N-sites,named FJU-POP...Acetylene purification from methane is challenging in the field of porous organic polymers(POPs).Herein,we have provided one-pot Ullmann coupling reaction to synthesize a series of POPs with rich N-sites,named FJU-POP-n,wherein the low-cost and non-toxic Cu(acac)2 and environmental-friendly glycerol are employed as catalyst and solvent,respectively.展开更多
The mechanism of the reaction of Ni^+ (~2D) with ethane in the gas-phase wasstudied by using density functional theory. Both the B3LYP and BLYP functionals with standardall-electron basis sets are used to give the det...The mechanism of the reaction of Ni^+ (~2D) with ethane in the gas-phase wasstudied by using density functional theory. Both the B3LYP and BLYP functionals with standardall-electron basis sets are used to give the detailed information of the potential energy surface(PES) of [Ni, C_2, H_6]^+. The mechanisms forming the products CH_4 and H_2 in the reaction of Ni^+with ethane are proposed. The reductive eliminations of CH_4 and H_2 are typicaladdition-elimination reactions. Each of the two reactions consists of two elementary steps; C―C orC―H bond activations to form inserted species followed by isomerizations to form product-likeintermediate. The rate determining steps for the elimination reactions of forming CH_4 and H_2 arethe isomerizations of the inserted species rather than C―C or C―H bond activations. Theelimination reaction of forming H_2 was found to be thermodynamically favored compared to that ofCH_4.展开更多
Incorporating metal nanodots(NDs)into heterostructures for high charge separation and transfer capacities is one of the most effective strategies for improving their photocatalytic activities.However,controlling the s...Incorporating metal nanodots(NDs)into heterostructures for high charge separation and transfer capacities is one of the most effective strategies for improving their photocatalytic activities.However,controlling the space distribution of metal NDs for optimizing charge transport pathways remains a significant challenge,particularly in two-dimensional(2D)face-to-face heterostructures.Herein,we develop a simple targeted self-reduction strategy for selectively loading Ru NDs onto the Ti_(3−x)C_(2)T_(y)(TC)surface of 2D TC/g-C_(3)N_(4)(CN)heterojunction based on the reductive Ti vacancy defects creatively increased during the preparation of TC/CN by reducing calcination.Notably,the optimized Ru/TC/CN photocatalyst exhibits an outstanding H_(2)evolution rate of 3.21 mmol·g^(−1)·h^(−1)and a high apparent quantum efficiency of 30.9%at 380 nm,which is contributed by the unidirectional transfer of the photogenerated electrons from CN to Ru active sites(CN→TC→Ru)and the suppressed backflow of electrons from Ru sites to CN,as revealed by comprehensive characterizations and density functional theory(DFT)calculations.This work provides a novel strategy for synthesizing the highly efficient photocatalysts with a controllable charge transfer paths,which will boost the development of photocatalysis.展开更多
Developing efficient energy storage for sodium-ion batteries(SIBs)by creating high-performance heterojunctions and understanding their interfacial interaction at the atomic/molecular level holds promise but is also ch...Developing efficient energy storage for sodium-ion batteries(SIBs)by creating high-performance heterojunctions and understanding their interfacial interaction at the atomic/molecular level holds promise but is also challenging.Besides,sluggish reaction kinetics at low temperatures restrict the operation of SIBs in cold climates.Herein,cross-linking nanoarchitectonics of WS_(2)/Ti_(3)C_(2)T_(x) heterojunction,featuring built-in electric field(BIEF),have been developed,employing as a model to reveal the positive effect of heterojunction design and BIEF for modifying the reaction kinetics and electrochemical activity.Particularly,the theoretical analysis manifests the discrepancy in work functions leads to the electronic flow from the electron-rich Ti_(3)C_(2)T_(x) to layered WS_(2),spontaneously forming the BIEF and“ion reservoir”at the heterogeneous interface.Besides,the generation of cross-linking pathways further promotes the transportation of electrons/ions,which guarantees rapid diffusion kinetics and excellent structure coupling.Consequently,superior sodium storage performance is obtained for the WS_(2)/Ti_(3)C_(2)T_(x) heterojunction,with only 0.2%decay per cycle at 5.0 A g^(-1)(25℃)up to 1000 cycles and a high capacity of 293.5 mA h g^(-1)(0.1A g^(-1)after 100 cycles)even at-20℃.Importantly,the spontaneously formed BIEF,accompanied by“ion reservoir”,in heterojunction provides deep understandings of the correlation between structure fabricated and performance obtained.展开更多
基金financially National Natural Science Foundation of China (22288102, 22172134, U1932201, U2032202)Science and Technology Planning Project of Fujian Province (2022H0002)support from the EPSRC (EP/W03784X/1)。
文摘The efficacy of the oxygen reduction reaction(ORR) in fuel cells can be significantly enhanced by optimizing cobalt-based catalysts,which provide a more stable alternative to iron-based catalysts.However,their performance is often impeded by weak adsorption of oxygen species,leading to a 2e^(-)pathway that negatively affects fuel cell discharge efficiency.Here,we engineered a high-density cobalt active center catalyst,coordinated with nitrogen and sulfur atoms on a porous carbon substrate.Both experimental and theoretical analyses highlighted the role of sulfur atoms as electron donors,disrupting the charge symmetry of the original Co active center and promoting enhanced interaction with Co 3d orbitals.This modification improves the adsorption of oxygen and reaction intermediates during ORR,significantly reducing the production of hydrogen peroxide(H_(2)O_(2)).Remarkably,the optimized catalyst demonstrated superior fuel cell performance,with peak power densities of 1.32 W cm^(-2) in oxygen and 0.61 W cm^(-2) in air environments,respectively.A significant decrease in H_(2)O_(2) by-product accumulation was observed during the reaction process,reducing catalyst and membrane damage and consequently improving fuel cell durability.This study emphasizes the critical role of coordination symmetry in Co/N/C catalysts and proposes an effective strategy to enhance fuel cell performance.
基金supported by the National Natural Science Foundation of China(Nos.61804082,21671108 and 51473078)Synergetic Innovation Center for Organic Electronics and Information Displays and Projects of International Cooperation and Exchanges NSFC(Nos.51811530018)+4 种基金National Natural Science Foundation of China(No.61935017)the China Postdoctoral Science Foundation Funded Project(No.2018M642286)National Program for Support of Top-Notch Young Professionals,Scientific and Technological Innovation Teams of Colleges and Universities in Jiangsu Province(No.TJ215006)Priority Academic Program Development of Jiangsu Higher Education Institutions(No.YX03003)Jiangsu Planned Projects for Postdoctoral Research Funds(No.2019K047A)。
文摘One-dimensional ultrathin nanowires(NWs)offer a great deal of promising properties for electrochemical energy storage and conversion due to their nanoscale confinement effect and high surface-to-volume ratios.It is highly desirable to precisely design and synthesize ultrathin Ti_(3)C_(2)NWs in the aspect of size,crystalline structure and composition.Here,we report a simple alkalization strategy to design the ultrathin Ti_(3)C_(2)NWs for hydrogen evolution reaction(HER)by modulating the surface-active sites.The design principle can well improve the amount of the defect sites and ion accessibility to increase the interactions between Ti_(3)C_(2)NWs and H^(*).The optimized Ti_(3)C_(2)NWs achieve an overpotential of 476 mV at the current density of 10 mA/cm^(2)and a Tafel slope of 129 mV/dec for HER catalysis,which are superior to that of Ti_(3)C_(2)nanosheets and m-Ti_(3)C_(2).It paves an avenue for the rational transformation of MXene bulks to one-dimensional NWs catalysts for HER.
文摘In this study,TiO_(2) nanosheets(NSs)grown in situ on extremely conductive Ti_(3)C_(2)T_(x) MXene to form TiO_(2)/Ti_(3)C_(2)T_(x) MXene composites with abundant active sites are proposed to effectively achieve elec‐trocatalytic NH_(3) synthesis.Electron transfer can be promoted by Ti_(3)C_(2)T_(x) MXene with high conduc‐tivity.Meanwhile,the TiO_(2) NSs in‐situ formation can not only avoid Ti_(3)C_(2)T_(x) MXene microstacking but also enhance the surface specific area of Ti_(3)C_(2)T_(x) MXene.The TiO_(2)/Ti_(3)C_(2)T_(x) MXene catalyst reach‐es a high Faradaic efϐiciency(FE)of 44.68%at−0.75 V vs.RHE and a large NH3 yield of 44.17µg h^(-1) mg^(-1)cat.at−0.95 V,with strong electrochemical durability.15N isotopic labeling experiments imply that the N in the produced NH3 originated from the N2 of the electrolyte.DFT calculations were conducted to determine the possible NRR reaction pathways for TiO_(2)/Ti_(3)C_(2)T_(x) MXene composites.MXene catalysts combined with other materials have been rationally designed for efficient ammonia production under ambient conditions。
文摘The non-isothermal decomposition reaction of Nd[(C_5H_ 10NS_2)_3(C_ 12H_8N_2)] were carried out by means of TG-DTG and the thermal decomposition mechanism, and the associated kinetics was investigated. The kinetic parameters are obtained from an analysis of the TG-DTG curves at different heating rate by integral and differential methods. The most probable kinetic model function of the decomposition reaction is Maple Power of n=3/2, f(α)=2/3α -1/2 and the apparent activation energy E is 116.67 kJ·mol -1 and the pre-exponential factor lg[A/s -1] is 7.6891.
文摘The design and construction of heterojunction photocatalysts,which possess a staggered energy band structure and appropriate interfacial contact,is an effective way to achieve outstanding photocatalytic performance.In this study,2D/2D BiOBr/g‐C_(3)N_(4)heterojunctions were successfully obtained by a convenient in situ self‐assembly route.Under simulated sunlight irradiation,99%of RhB(10 mg·L–1,100 mL)was efficiently degraded by 1.5‐BiOBr/g‐C_(3)N_(4)within 30 min,which is better than the performance of both BiOBr and g‐C_(3)N_(4),and it has superior stability.In addition,the composite also exhibits enhanced photocatalytic activity for H2 production.The enhanced activity can be attributed to the intimate interface contact,the larger surface area,and the highly efficient separation of photoinduced electron–hole pairs.Based on the experimental results,a novel S‐scheme model was proposed to illuminate the transfer process of charge carriers.This study presents a simple way to develop novel step‐scheme photocatalysts for environmental and related applications.
基金support from the Nature Science Founda-tion of Shandong Province(Grant No:ZR2019BEM019)and the Future Plans of Young Scholars at Shandong University.
文摘Developing highly conductive,stable,and active hydrogen evolution reaction(HER)catalysts is a critical step towards establishing the hydrogen economy.However,there are few catalysts,except for noble metals,that can meet all the requirements.Recently,two-dimensional(2D)transition metal carbon/nitride(MXene)materials have shown excellent performance in catalysis,and have attracted wide attention from researchers.In this study,the effectiveness of non-metal element(B,C,N,P,and S)-doped Ti_(3)C_(2)O_(2)MXene in the electrocatalytic hydrogen evolution reaction was investigated using density functional theory(DFT)calculations.Non-metal atoms as elec-tron donors can provide additional electrons to the O functional group on the catalyst surface,thereby reducing charge transfer from H to O and the interaction between H and O.The Gibbs free energy(ΔG H)of non-metal element-doped Ti_(3)C_(2)O_(2)is closer to 0 than that of pristine Ti_(3)C_(2)O_(2),demonstrating better hydrogen evolution performance.Furthermore,in the hydrogen evolution path,the desorption process is more inclined to the Hey-rovsky mechanism,and doping greatly reduces the energy barrier of the reaction,thereby improving the catalytic efficiency.The present results prove that doping with non-metallic elements is an effective means of improving the catalytic activity of Ti_(3)C_(2)O_(2)for hydrogen evolution.
基金supported in part by the National Key R&D Program of China(Nos.2017YFA0207301 and 2017YFA0403402)the National Natural Science Foundation of China(Nos.21725102,91961106,U1832156,and 22075267)+4 种基金Science and Technological Fund of Anhui Province for Outstanding Youth(No.2008085J05)Youth Innovation Promotion Association of CAS(No.2019444)Young Elite Scientist Sponsorship Program by CAST,China Postdoctoral Science Foundation(Nos.2019M652190 and 2020T130627)Users with Excellence Program of Hefei Science Center CAS(No.2020HSC-UE003)DNL Cooperation Fund,CAS(No.DNL201922).
文摘Cu-based electrocatalysts have provoked much attention for their high activity and selectivity in carbon dioxide(CO_(2))conversion into multi-carbon hydrocarbons.However,during the electrochemical reaction,Cu catalysts inevitably undergo surface reconstruction whose impact on CO_(2)conversion performance remains contentious.Here we report that polycrystalline Cu nanoparticles(denoted as Cu-s)with rich high-index facets,derived from Cu_(2−x)S through desulphurization and surface reconstruction,offer an excellent platform for investigating the role of surface reconstruction in electrocatalytic CO_(2)conversion.During the formation of Cu-s catalyst,the two stages of desulphurization and surface reconstruction can be clearly resolved by in situ X-ray absorption spectroscopy and OH−adsorption characterizations,which are well correlated with the changes in electrocatalytic performance.It turns out that the high CO_(2)conversion performance,achieved by the Cu-s catalyst(Faradic efficiency of 68.6%and partial current density of 40.8 mA/cm^(2)in H-cell toward C_(2)H_(4)production),is attributed to the increased percentage of high-index facets in Cu-s during the surface reconstruction.Furthermore,the operando electrochemical Raman spectroscopy further reveals that the conversion of the CO_(2)into the C_(2)H_(4)on Cu-s is intermediated by the production of*COCHO.Our findings manifest that the surface reconstruction is an effective method for tuning the reaction intermediate of the CO_(2)conversion toward high-value multicarbon(C2+)chemicals,and highlight the significance of in situ characterizations in enhancing the understanding of the surface structure and its role in electrocatalysis.
基金the Japan Society for the Promotion of Science for the financial support through a Grant-in-Aid for Scientific Research (B) (No.18310010)partly supported by the Key Construction Program of the National "985" Project,Tianjin University,China
文摘The photo-Fenton reaction is a key source of the highly reactive hydroxyl radical(HOU) that is produced by the reaction of simultaneous photo-induced generation of Fe^(2+)-dissolved organic matter(DOM) with H_2O_2 in sunlit surface waters as well as in the treatment of organic pollutants in the advanced oxidation processes(AOPs).Concentrations of both H_2O_2 and Fe^(2+)-DOM were dependent on time and total solar intensity flux,and their levels were highest in the diurnal samples collected at noon compared with the samples collected during the period before sunrise and after sunset.H_2O_2 and Fe^(2+)-DOM concentrations during monthly readings were also found higher in comparison with the diurnal samples,shortly before sunrise or after sunset.A π-electron bonding system is formed between Fe and the functional groups in DOM(Fe-DOM),through electron donation from the functional groups of DOM to an empty d-orbital of Fe.The π-electron is loosely bound and is highly susceptible to a rapid excitation upon light exposure that will provide better understanding of the formation of aqueous electrons,superoxide radical anions,H_2O_2 and finally,photo-Fenton reactions,too.Our results imply that simultaneous generation of H_2O_2 and Fe^(2+)-DOM upon sunlight exposure during the daytime is most likely to be the key photo-Fenton reaction pathway,taking place in surface waters.
基金This work was financially supported by the National Natural Science Foundation of China(grant nos.21975044,21971038 and 219722810)Fujian Provincial Department of Science and Technology(2018J07001,2019L3004,2019H6012 and 2021H0062).
文摘Acetylene purification from methane is challenging in the field of porous organic polymers(POPs).Herein,we have provided one-pot Ullmann coupling reaction to synthesize a series of POPs with rich N-sites,named FJU-POP-n,wherein the low-cost and non-toxic Cu(acac)2 and environmental-friendly glycerol are employed as catalyst and solvent,respectively.
文摘The mechanism of the reaction of Ni^+ (~2D) with ethane in the gas-phase wasstudied by using density functional theory. Both the B3LYP and BLYP functionals with standardall-electron basis sets are used to give the detailed information of the potential energy surface(PES) of [Ni, C_2, H_6]^+. The mechanisms forming the products CH_4 and H_2 in the reaction of Ni^+with ethane are proposed. The reductive eliminations of CH_4 and H_2 are typicaladdition-elimination reactions. Each of the two reactions consists of two elementary steps; C―C orC―H bond activations to form inserted species followed by isomerizations to form product-likeintermediate. The rate determining steps for the elimination reactions of forming CH_4 and H_2 arethe isomerizations of the inserted species rather than C―C or C―H bond activations. Theelimination reaction of forming H_2 was found to be thermodynamically favored compared to that ofCH_4.
基金the National Natural Science Foundation of China(No.22002142)China Postdoctoral Science Foundation(No.2020T130605)+2 种基金Natural Science Foundation of Henan Province(No.202300410436)Support Plan for College Science and Technology Innovation Team of Henan Province(No.16IRTSTHN001)the Science&Technology Innovation Talent Plan of Henan Province(No.174200510018).
文摘Incorporating metal nanodots(NDs)into heterostructures for high charge separation and transfer capacities is one of the most effective strategies for improving their photocatalytic activities.However,controlling the space distribution of metal NDs for optimizing charge transport pathways remains a significant challenge,particularly in two-dimensional(2D)face-to-face heterostructures.Herein,we develop a simple targeted self-reduction strategy for selectively loading Ru NDs onto the Ti_(3−x)C_(2)T_(y)(TC)surface of 2D TC/g-C_(3)N_(4)(CN)heterojunction based on the reductive Ti vacancy defects creatively increased during the preparation of TC/CN by reducing calcination.Notably,the optimized Ru/TC/CN photocatalyst exhibits an outstanding H_(2)evolution rate of 3.21 mmol·g^(−1)·h^(−1)and a high apparent quantum efficiency of 30.9%at 380 nm,which is contributed by the unidirectional transfer of the photogenerated electrons from CN to Ru active sites(CN→TC→Ru)and the suppressed backflow of electrons from Ru sites to CN,as revealed by comprehensive characterizations and density functional theory(DFT)calculations.This work provides a novel strategy for synthesizing the highly efficient photocatalysts with a controllable charge transfer paths,which will boost the development of photocatalysis.
基金supported by the faculty startup funds from the Yangzhou Universitythe Natural Science Foundation of Jiangsu Province(BK20210821)+1 种基金the National Natural Science Foundation of China(22102141)the Lvyangjinfeng Talent Program of Yangzhou。
文摘Developing efficient energy storage for sodium-ion batteries(SIBs)by creating high-performance heterojunctions and understanding their interfacial interaction at the atomic/molecular level holds promise but is also challenging.Besides,sluggish reaction kinetics at low temperatures restrict the operation of SIBs in cold climates.Herein,cross-linking nanoarchitectonics of WS_(2)/Ti_(3)C_(2)T_(x) heterojunction,featuring built-in electric field(BIEF),have been developed,employing as a model to reveal the positive effect of heterojunction design and BIEF for modifying the reaction kinetics and electrochemical activity.Particularly,the theoretical analysis manifests the discrepancy in work functions leads to the electronic flow from the electron-rich Ti_(3)C_(2)T_(x) to layered WS_(2),spontaneously forming the BIEF and“ion reservoir”at the heterogeneous interface.Besides,the generation of cross-linking pathways further promotes the transportation of electrons/ions,which guarantees rapid diffusion kinetics and excellent structure coupling.Consequently,superior sodium storage performance is obtained for the WS_(2)/Ti_(3)C_(2)T_(x) heterojunction,with only 0.2%decay per cycle at 5.0 A g^(-1)(25℃)up to 1000 cycles and a high capacity of 293.5 mA h g^(-1)(0.1A g^(-1)after 100 cycles)even at-20℃.Importantly,the spontaneously formed BIEF,accompanied by“ion reservoir”,in heterojunction provides deep understandings of the correlation between structure fabricated and performance obtained.