A certain weighted Herz-type Hardy space is introduced and its atom-decomposition theory is established. As applications of this theory, a boundedness theorem of sublinear operators and an interpolation theorem of lin...A certain weighted Herz-type Hardy space is introduced and its atom-decomposition theory is established. As applications of this theory, a boundedness theorem of sublinear operators and an interpolation theorem of linear operators on these spaces are given.展开更多
The development of efficient and cost-effective catalysts to catalyze a wide variety of electrochemical reactions is key to realize the large-scale applicati on of ren ewable and clean en ergy tech no logies.Owing to ...The development of efficient and cost-effective catalysts to catalyze a wide variety of electrochemical reactions is key to realize the large-scale applicati on of ren ewable and clean en ergy tech no logies.Owing to the maximum atom-utilization efficie ncy and unique electronic and geometric structures,single atom catalysts(SACs)have exhibited superior performance in various catalytic systems.Recently,assembled from the function alized orga nic lin kers and metal no des,metal-organic frameworks(MOFs)with ultrafi ne porosity have received treme ndous attention as precursors or self-sacrificing templates for preparing porous SACs.Here,the recent advances toward the synthesis strategies for using MOF precursors/templates to con struct SACs are systematically summarized with special emphasis on the types of central metal sites.The electrochemical applications of these recently emerged MOF-derived SACs for various energy-conversion processes,such as oxygen reduction/evolution reaction(ORR/OER),hydrogen evolution reaction(HER),and CO2 reduction reaction(CO2RR),are also discussed and reviewed.Fin ally,the curre nt challe nges and prospects regardi ng the developme nt of MOF-derived SACs are proposed.展开更多
The oxidation of hydrocarbons to produce high value-added compounds(ketones or alcohols)using oxygen in air as the only oxidant is an efficient synthetic strategy from both environmental and economic views.Herein,we s...The oxidation of hydrocarbons to produce high value-added compounds(ketones or alcohols)using oxygen in air as the only oxidant is an efficient synthetic strategy from both environmental and economic views.Herein,we successfully synthesized cobalt single atom site catalysts(Co SACs)with high metal loading of 23.58 wt.%supported on carbon nitride(CN),which showed excellent catalytic properties for oxidation of ethylbenzene in air.Moreover,Co SACs show a much higher turn-over frequency(19.6 h^(−1))than other reported non-noble catalysts under the same condition.Comparatively,the as-obtained nanosized or homogenous Co catalysts are inert to this reaction.Co SACs also exhibit high selectivity(97%)and stability(unchanged after five runs)in this reaction.DFT calculations reveal that Co SACs show a low energy barrier in the first elementary step and a high resistance to water,which result in the robust catalytic performance for this reaction.展开更多
An important issue in Knowledge Discovery in Databases is to allow the discovered knowledge to be as close as possible to natural languages to satisfy user needs with tractability on one hand, and to offer KDD systems...An important issue in Knowledge Discovery in Databases is to allow the discovered knowledge to be as close as possible to natural languages to satisfy user needs with tractability on one hand, and to offer KDD systems robustness on the other hand. At this junction, this paper describes a new concept of linguistic atoms with three digital characteristics: expected value Ex, entropy En, and deviation D. The mathematical description has effectively illtegrated the fuzziness and randomness of linguistic terms in a unified way Based on this model a method of knowledge representation in KDD is developed which bridges the gap between quantitative knowledge and qualitative knowledge. Mapping between quantitatives and qualitatives becomes much easier and interchangeab1e. In order to discover genera1ized knowledge from a database, one may use virtual linguistic terms and cloud transforms for the auto-generation of concept hierarchies to attributes. Predictive data mining with the cloud model is given for implementation. This further illustrates the advantages of this linguistic model in KDD.展开更多
We introduce certain Calderón-Zygmund-type operators and discuss their boundedness on spaces such as weighted Lebesgue spaces,weighted weak Lebesgue spaces,weighted Hardy spaces and weighted weak Hardy spaces.The...We introduce certain Calderón-Zygmund-type operators and discuss their boundedness on spaces such as weighted Lebesgue spaces,weighted weak Lebesgue spaces,weighted Hardy spaces and weighted weak Hardy spaces.The sharpness of some results is also investigated.展开更多
Hydrogen production from water splitting using renewable electric energy is an interesting topic towards the carbon neutral future.Single atom catalysts(SACs)have emerged as a new frontier in the field of catalysis su...Hydrogen production from water splitting using renewable electric energy is an interesting topic towards the carbon neutral future.Single atom catalysts(SACs)have emerged as a new frontier in the field of catalysis such as hydrogen evolution reaction(HER),owing to their intriguing properties like high activity and excellent chemical selectivity.The catalytic active moiety is often comprised of a single metal atom and its neighboring environment from the supports.Recent published reviews about electricdriven HER tend to classify these SACs by the species of active center atom,nevertheless the influence of their neighboring coordinated atoms from the supports is somehow neglected.Thus we classify the SACs for HER through the type of supports,highlighting the electronic metal–support interaction and their coordination environment from support.Then,we put forward some structural designing strategies including regulating of the central atoms,coordination environments,and metal-support interactions.Finally,the current challenges and future research perspectives of SACs for HER are briefly proposed.展开更多
Supported and colloidal single‐atom catalysts(SACs),which possess excellent catalytic properties,are particularly important in both fundamental studies and practical applications.The progress made in the preparation ...Supported and colloidal single‐atom catalysts(SACs),which possess excellent catalytic properties,are particularly important in both fundamental studies and practical applications.The progress made in the preparation methods,characterization,catalytic performances and mechanisms of SACs anchored to metal oxides,two‐dimensional materials and the surface of metal nanoclusters(NCs)are reviewed.The different techniques for SAC fabrication,including conventional solution methods based on co‐precipitation,incipient wetness co‐impregnation,and the chemical vapor deposition method,as well as the newer atom layer deposition(ALD)and galvanic replacement methods,are summarized.The main results from experimental and theoretical studies of various catalytic reactions over SACs,including oxidation reactions,hydrogenation,water gas shift,photocatalytic H2evolution and electrochemical reactions,are also discussed.Moreover,the electronic properties of the single atoms and their interactions with the supports are described to assist in understanding the origin of the high catalytic activity and selectivity of SACs.Finally,possible future research directions of SACs and their applications are proposed.展开更多
Let [b,T] be the commutator of the functionb ∈ Lip β (? n ) (0 <β ? 1)and the Calderón-Zygmund singular integral operatorT. The authors study the boundedness properties of [b,T] on the classical Hardy space...Let [b,T] be the commutator of the functionb ∈ Lip β (? n ) (0 <β ? 1)and the Calderón-Zygmund singular integral operatorT. The authors study the boundedness properties of [b,T] on the classical Hardy spaces and the Herz-type Hardy spaces in non-extreme cases. For the boundedness of these commutators in extreme cases, some characterizations are also given. Moreover, the authors prove that these commutators are bounded from Hardy type spaces to the weak Lebesgue or Herz spaces in extreme cases展开更多
Single-atom catalysts (SACs) have recently attracted broad attention in the catalysis field due to their maximized atom efficiency and unique catalytic properties.An atomic-level understanding of the interaction betwe...Single-atom catalysts (SACs) have recently attracted broad attention in the catalysis field due to their maximized atom efficiency and unique catalytic properties.An atomic-level understanding of the interaction between the metal atoms and support is vital for developing stable and high-performance SACs.In this work,Pt1 single atoms with Ioadings up to 4 wt.% were fabricated on ceria nanorods using the atomic layer deposition technique.To understand the Pt-O-Ce bond interfacial interactions,the stability of Pt1 single atoms in the hydrogen reducing environment was extensively investigated by using in situ diffuse reflectance infrared Fourier transform spectroscopy CO chemisorption measurements.It was found that ceria defect sites,metal Ioadings and high-temperature calcination are effective ways to tune the stability of Pt1 single atoms in the hydrogen environment.X-ray photoemission spectroscopy further showed that Pt1 single atoms on ceria are dominantly at a +2 valence state at the defect and step edge sites,while those on terrace sites are at a +4 state.The above tailored stability and electronic properties of Pt1 single atoms are found to be strongly correlated with the catalytic activity in the dry and water-mediated CO oxidation reactions.展开更多
In this paper we define some weak martingale Hardy spaces and three kinds of weak atoms. They are the counterparts of martingale Hardy spaces and atoms in the classical martingale Hp-theory. And then three atomic deco...In this paper we define some weak martingale Hardy spaces and three kinds of weak atoms. They are the counterparts of martingale Hardy spaces and atoms in the classical martingale Hp-theory. And then three atomic decomposition theorems for martingales in weak martingale Hardy spaces are proved. With the help of the weak atomic decompositions of martingale, a sufficient condition for a sublinear operator defined on the weak martingale Hardy spaces to be bounded is given. Using the sufficient condition, we obtain a series of martingale inequalities with respect to the weak Lp-norm, the inequalities of weak (p ,p)-type and some continuous imbedding relationships between various weak martingale Hardy spaces. These inequalities are the weak versions of the basic inequalities in the classical martingale Hp-theory.展开更多
20 Quantum chemical parameters of chlorophenol compounds were fully optimized by using B3LYP method on both 6-31G^＊ and 6-311G^＊ basis sets. These structural parameters are taken as theoretical descriptors, and the ...20 Quantum chemical parameters of chlorophenol compounds were fully optimized by using B3LYP method on both 6-31G^＊ and 6-311G^＊ basis sets. These structural parameters are taken as theoretical descriptors, and the experimental data of 20 compounds＇ aquatic photogen toxicity（-lgEC50） are used to perform stepwise regression in order to obtain two predicted -lgEC50 correlation models whose correlation coefficients R^2 are respectively 0.9186 and 0.9567. In addition, parameters of chlorine atom＇s substitutive positions and their correlations （NPCs） are taken as descriptors to obtain another predicted -lgEC50 model with the correlation coefficient R2 of 0.9444. Correlation degree of each independent variable in the three models is verified by using variance inflation factors （VIF） and t value. In the cross-validation method, cross-validation coefficients q^2 of 3 models are respectively 0.8748, 0.9119 and 0.8993, which indicates that the relativity and prediction ability of this model are superior to those of the model obtained by topological and BLYP methods.展开更多
The processes of photocatalytic CO_(2) reduction(pCO_(2)R)and electrochemical CO_(2) reduction(ECO_(2)R)have attracted considerable interest owing to their high potential to address many environmental and energy-relat...The processes of photocatalytic CO_(2) reduction(pCO_(2)R)and electrochemical CO_(2) reduction(ECO_(2)R)have attracted considerable interest owing to their high potential to address many environmental and energy-related issues.In this aspect,a single Cu atom decorated on a carbon nitride(CN)surface(Cu-CN)has gained increasing popularity because of its unique advantages,such as excellent atom utilization and ultrahigh catalytic activity.CN-particularly graphitic CN(g-C_(3)N_(4))-is a photo-and electrocatalyst and used as an important support material for single Cu atom-based catalysts.These key functions of Cu-CN-based catalysts can improve the catalytic performance and stability in the pCO_(2)R and ECO_(2)R during the application process.In this review,we focus on Cu as a single metal atom decorated on CN for efficient photoelectrochemical CO_(2) reduction(pECO_(2)R),where ECO_(2)R increases the electrocatalytic active area and promotes electron transfer,while pCO_(2)R enhances the surface redox reaction by efficiently using photogenerated charges and offering integral activity as well as an active interface between Cu and CN.Interactions of single Cu atom-based photo-,electro-,and photoelectrochemical catalysts with g-C_(3)N_(4) are discussed.Moreover,for a deeper understanding of the history of the development of pCO_(2)R and ECO_(2)R,the basics of CO_(2) reduction,including pCO_(2)R and ECO_(2)R over g-C_(3)N_(4),as well as the structural composition,characterization,unique design,and mechanism of a single atom site are reviewed in detail.Finally,some future prospects and key challenges are discussed.展开更多
Single-atom Pt catalysts are designed to promote efficient atom utilization,whereas effective decrease of Pt loading and improvement of photocatalytic activity in monoatomic Pt-deposited systems is still ongoing.Atomi...Single-atom Pt catalysts are designed to promote efficient atom utilization,whereas effective decrease of Pt loading and improvement of photocatalytic activity in monoatomic Pt-deposited systems is still ongoing.Atomically dispersed metal species in crystalline carbon nitride are still challenging owing to their high crystallization and structural stability.In this study,we developed a novel single-atomic Pt-Cu catalyst for reducing noble metal loading by combining Pt with earth-abundant Cu atoms and enhancing photocatalytic CO_(2)reduction.N-vacancy-rich crystalline carbon nitride was used as a fine-tuning ligand for isolated Pt-Cu atom dispersion based on its accessible functional N vacancies as the seeded centers.The synthesized dimetal Pt-Cu atoms on crystalline carbon nitride(Pt Cu-cr CN)exhibited high selectivity and activity for CO_(2)conversion without the addition of any cocatalyst or sacrificial agent.In particular,we demonstrated that the diatomic Pt-Cu exhibited high mass activity with only 0.32 wt% Pt loading and showed excellent photocatalytic selectivity toward CH_(4)generation.The mechanism of CO_(2)photoreduction for Pt Cu-cr CN was proposed based on the observations and analysis of aberration-corrected high-angle annular dark-field scanning transmission electron microscopy images,in situ irradiated X-ray photoelectron spectroscopy,and in situ diffuse reflectance infrared Fourier transform spectroscopy.The findings of this work provide insights for abrogating specific bifunctional atomic metal sites in noble metal-based photocatalysts by reducing noble metal loading and maximizing their effective mass activity.展开更多
Based on Hall et al. electrotopological state indices（EK） of atom types, two quantitative structure-activity relationship（QSAR） models were developed to estimate and predict the action strength（W） of D（OM）（di...Based on Hall et al. electrotopological state indices（EK） of atom types, two quantitative structure-activity relationship（QSAR） models were developed to estimate and predict the action strength（W） of D（OM）（dimethoxy-methyl-amphetamine） for 18 phenyl-isopropyl-amine dopes（PPAD） through linear method（multiple linear regression, MLR） and non-linear method（Back propagation artificial neural network, BP-ANN）. On the basis of EK, the optimal three-parameter（E14, E9, E7） QSAR model of W for 18 PPAD was constructed. The traditional correlation coefficient（R^2） and cross-validation correlation coefficient（Rcv^2） are 0.878 and 0.815, respectively. The result demonstrates that the model is highly reliable（from the point of view of statistics） and has good predictive ability by using R^2, Rcv^2, VIF, FIT, AIC and F tests. Form the three parameters of the model, it is known that the dominant influence factors of inhibited activity are the molecular structure fragments： =CH–（secondary carbon）, =C〈（tertiary carbon atom） in aromatic ring and –O–（phenol ether bond）. The results showed that the structure parameters E14, E9 and E7 have good rationality and efficiency for the W of phenyl-isopropyl-amine dope（PPAD） analogues. A BP-ANN with 3-3-1 architecture was generated by using three electrotopological state index descriptors（E14, E9, E7） appearing in the MLR model, the above descriptors were inputs and its output was action strength（W）. The nonlinear BP-ANN model has better predictive ability compared to the linear MLR model with R^2 and Rcv^2 of leave-one-out（LOO） to be 0.995 and 0.994, respectively. The regression method gave support to the neural network with physical explanation, which offers a more accurate model for QSAR. Those models can be used in the rational design of higher stimulating extent PPAD, which provide meaningful reference information to improve the detection methods of PPAD.展开更多
基金Project supported by the National Natural Science Foundation of China.
文摘A certain weighted Herz-type Hardy space is introduced and its atom-decomposition theory is established. As applications of this theory, a boundedness theorem of sublinear operators and an interpolation theorem of linear operators on these spaces are given.
基金This work was supported by the National Key R&D Program of China(No.2016YFA0202801)the National Natural Science Foundation of China(Nos.21671117,21871159,21890383,and 21676018)and the China Postdoctoral Science Foundation(No.2017M610864).
文摘The development of efficient and cost-effective catalysts to catalyze a wide variety of electrochemical reactions is key to realize the large-scale applicati on of ren ewable and clean en ergy tech no logies.Owing to the maximum atom-utilization efficie ncy and unique electronic and geometric structures,single atom catalysts(SACs)have exhibited superior performance in various catalytic systems.Recently,assembled from the function alized orga nic lin kers and metal no des,metal-organic frameworks(MOFs)with ultrafi ne porosity have received treme ndous attention as precursors or self-sacrificing templates for preparing porous SACs.Here,the recent advances toward the synthesis strategies for using MOF precursors/templates to con struct SACs are systematically summarized with special emphasis on the types of central metal sites.The electrochemical applications of these recently emerged MOF-derived SACs for various energy-conversion processes,such as oxygen reduction/evolution reaction(ORR/OER),hydrogen evolution reaction(HER),and CO2 reduction reaction(CO2RR),are also discussed and reviewed.Fin ally,the curre nt challe nges and prospects regardi ng the developme nt of MOF-derived SACs are proposed.
基金This work was supported by the National Key R&D Program of China(Nos.2018YFA0702003 and 2016YFA0202801)the National Natural Science Foundation of China(Nos.21890383,21671117,21871159,and 21901135)+2 种基金Science and Technology Key Project of Guangdong Province of China(No.2020B010188002)Beijing Municipal Science&Technology Commission(No.Z191100007219003)China Postdoctoral Science Foundation(No.2018M640114).
文摘The oxidation of hydrocarbons to produce high value-added compounds(ketones or alcohols)using oxygen in air as the only oxidant is an efficient synthetic strategy from both environmental and economic views.Herein,we successfully synthesized cobalt single atom site catalysts(Co SACs)with high metal loading of 23.58 wt.%supported on carbon nitride(CN),which showed excellent catalytic properties for oxidation of ethylbenzene in air.Moreover,Co SACs show a much higher turn-over frequency(19.6 h^(−1))than other reported non-noble catalysts under the same condition.Comparatively,the as-obtained nanosized or homogenous Co catalysts are inert to this reaction.Co SACs also exhibit high selectivity(97%)and stability(unchanged after five runs)in this reaction.DFT calculations reveal that Co SACs show a low energy barrier in the first elementary step and a high resistance to water,which result in the robust catalytic performance for this reaction.
文摘An important issue in Knowledge Discovery in Databases is to allow the discovered knowledge to be as close as possible to natural languages to satisfy user needs with tractability on one hand, and to offer KDD systems robustness on the other hand. At this junction, this paper describes a new concept of linguistic atoms with three digital characteristics: expected value Ex, entropy En, and deviation D. The mathematical description has effectively illtegrated the fuzziness and randomness of linguistic terms in a unified way Based on this model a method of knowledge representation in KDD is developed which bridges the gap between quantitative knowledge and qualitative knowledge. Mapping between quantitatives and qualitatives becomes much easier and interchangeab1e. In order to discover genera1ized knowledge from a database, one may use virtual linguistic terms and cloud transforms for the auto-generation of concept hierarchies to attributes. Predictive data mining with the cloud model is given for implementation. This further illustrates the advantages of this linguistic model in KDD.
基金Dachun Yang was partially supported by the NNSF and the SEDF of China
文摘We introduce certain Calderón-Zygmund-type operators and discuss their boundedness on spaces such as weighted Lebesgue spaces,weighted weak Lebesgue spaces,weighted Hardy spaces and weighted weak Hardy spaces.The sharpness of some results is also investigated.
基金the National Key Research and Development Program of China(No.2018YFA0702003)the National Natural Science Foundation of China(Nos.21890383 and 21871159)+1 种基金the Science and Technology Key Project of Guangdong Province of China(No.2020B010188002)China Postdoctoral Science Foundation(2021M691834).
文摘Hydrogen production from water splitting using renewable electric energy is an interesting topic towards the carbon neutral future.Single atom catalysts(SACs)have emerged as a new frontier in the field of catalysis such as hydrogen evolution reaction(HER),owing to their intriguing properties like high activity and excellent chemical selectivity.The catalytic active moiety is often comprised of a single metal atom and its neighboring environment from the supports.Recent published reviews about electricdriven HER tend to classify these SACs by the species of active center atom,nevertheless the influence of their neighboring coordinated atoms from the supports is somehow neglected.Thus we classify the SACs for HER through the type of supports,highlighting the electronic metal–support interaction and their coordination environment from support.Then,we put forward some structural designing strategies including regulating of the central atoms,coordination environments,and metal-support interactions.Finally,the current challenges and future research perspectives of SACs for HER are briefly proposed.
基金supported by the National Natural Science Foundation of China(51472184 and 51472185)the Science and Technology Support Program of Hubei Province(2013BHE003)the Program for Innovative Teams of Outstanding Young and Middle-Aged Researchers in the Higher Education Institutions of Hubei Province(T201602)~~
文摘Supported and colloidal single‐atom catalysts(SACs),which possess excellent catalytic properties,are particularly important in both fundamental studies and practical applications.The progress made in the preparation methods,characterization,catalytic performances and mechanisms of SACs anchored to metal oxides,two‐dimensional materials and the surface of metal nanoclusters(NCs)are reviewed.The different techniques for SAC fabrication,including conventional solution methods based on co‐precipitation,incipient wetness co‐impregnation,and the chemical vapor deposition method,as well as the newer atom layer deposition(ALD)and galvanic replacement methods,are summarized.The main results from experimental and theoretical studies of various catalytic reactions over SACs,including oxidation reactions,hydrogenation,water gas shift,photocatalytic H2evolution and electrochemical reactions,are also discussed.Moreover,the electronic properties of the single atoms and their interactions with the supports are described to assist in understanding the origin of the high catalytic activity and selectivity of SACs.Finally,possible future research directions of SACs and their applications are proposed.
基金This work was supported by the National 973 Project of China (Grant No.G19990751) the National Natural Science Foundation of China (Grant No. 19131080) the State Education Department Foundation of China (Grant No. 20010027002).
文摘Let [b,T] be the commutator of the functionb ∈ Lip β (? n ) (0 <β ? 1)and the Calderón-Zygmund singular integral operatorT. The authors study the boundedness properties of [b,T] on the classical Hardy spaces and the Herz-type Hardy spaces in non-extreme cases. For the boundedness of these commutators in extreme cases, some characterizations are also given. Moreover, the authors prove that these commutators are bounded from Hardy type spaces to the weak Lebesgue or Herz spaces in extreme cases
基金the National Natural Science Foundation of China (Nos.21673215 and 21473169)the Fundamental Research Funds for the Central Universities (No.WK2060030029)the Max-Planck Partner Group,Hefei Science Center,CAS,Users with Potential. The authors also gratefully thank the BL10B beamlines at National Synchrotron Radiation Laboratory (NSRL),China.
文摘Single-atom catalysts (SACs) have recently attracted broad attention in the catalysis field due to their maximized atom efficiency and unique catalytic properties.An atomic-level understanding of the interaction between the metal atoms and support is vital for developing stable and high-performance SACs.In this work,Pt1 single atoms with Ioadings up to 4 wt.% were fabricated on ceria nanorods using the atomic layer deposition technique.To understand the Pt-O-Ce bond interfacial interactions,the stability of Pt1 single atoms in the hydrogen reducing environment was extensively investigated by using in situ diffuse reflectance infrared Fourier transform spectroscopy CO chemisorption measurements.It was found that ceria defect sites,metal Ioadings and high-temperature calcination are effective ways to tune the stability of Pt1 single atoms in the hydrogen environment.X-ray photoemission spectroscopy further showed that Pt1 single atoms on ceria are dominantly at a +2 valence state at the defect and step edge sites,while those on terrace sites are at a +4 state.The above tailored stability and electronic properties of Pt1 single atoms are found to be strongly correlated with the catalytic activity in the dry and water-mediated CO oxidation reactions.
基金This work was supported by National Natural Science Foundation of China (Grant No. 10371093).
文摘In this paper we define some weak martingale Hardy spaces and three kinds of weak atoms. They are the counterparts of martingale Hardy spaces and atoms in the classical martingale Hp-theory. And then three atomic decomposition theorems for martingales in weak martingale Hardy spaces are proved. With the help of the weak atomic decompositions of martingale, a sufficient condition for a sublinear operator defined on the weak martingale Hardy spaces to be bounded is given. Using the sufficient condition, we obtain a series of martingale inequalities with respect to the weak Lp-norm, the inequalities of weak (p ,p)-type and some continuous imbedding relationships between various weak martingale Hardy spaces. These inequalities are the weak versions of the basic inequalities in the classical martingale Hp-theory.
基金973 National Basic Research Program of China (2003CB415002)
文摘20 Quantum chemical parameters of chlorophenol compounds were fully optimized by using B3LYP method on both 6-31G^＊ and 6-311G^＊ basis sets. These structural parameters are taken as theoretical descriptors, and the experimental data of 20 compounds＇ aquatic photogen toxicity（-lgEC50） are used to perform stepwise regression in order to obtain two predicted -lgEC50 correlation models whose correlation coefficients R^2 are respectively 0.9186 and 0.9567. In addition, parameters of chlorine atom＇s substitutive positions and their correlations （NPCs） are taken as descriptors to obtain another predicted -lgEC50 model with the correlation coefficient R2 of 0.9444. Correlation degree of each independent variable in the three models is verified by using variance inflation factors （VIF） and t value. In the cross-validation method, cross-validation coefficients q^2 of 3 models are respectively 0.8748, 0.9119 and 0.8993, which indicates that the relativity and prediction ability of this model are superior to those of the model obtained by topological and BLYP methods.
基金This work was supported by the“Scientific and Technical Innovation Action Plan”Basic Research Field of Shanghai Science and Technology Committee(No.19JC1410500)the National Natural Science Foundation of China(No.91645110)the Fundamental Research Funds for the Central Universities and Graduate Student Innovation Fund of Donghua University(No.CUSF-DH-D-2021036).
文摘The processes of photocatalytic CO_(2) reduction(pCO_(2)R)and electrochemical CO_(2) reduction(ECO_(2)R)have attracted considerable interest owing to their high potential to address many environmental and energy-related issues.In this aspect,a single Cu atom decorated on a carbon nitride(CN)surface(Cu-CN)has gained increasing popularity because of its unique advantages,such as excellent atom utilization and ultrahigh catalytic activity.CN-particularly graphitic CN(g-C_(3)N_(4))-is a photo-and electrocatalyst and used as an important support material for single Cu atom-based catalysts.These key functions of Cu-CN-based catalysts can improve the catalytic performance and stability in the pCO_(2)R and ECO_(2)R during the application process.In this review,we focus on Cu as a single metal atom decorated on CN for efficient photoelectrochemical CO_(2) reduction(pECO_(2)R),where ECO_(2)R increases the electrocatalytic active area and promotes electron transfer,while pCO_(2)R enhances the surface redox reaction by efficiently using photogenerated charges and offering integral activity as well as an active interface between Cu and CN.Interactions of single Cu atom-based photo-,electro-,and photoelectrochemical catalysts with g-C_(3)N_(4) are discussed.Moreover,for a deeper understanding of the history of the development of pCO_(2)R and ECO_(2)R,the basics of CO_(2) reduction,including pCO_(2)R and ECO_(2)R over g-C_(3)N_(4),as well as the structural composition,characterization,unique design,and mechanism of a single atom site are reviewed in detail.Finally,some future prospects and key challenges are discussed.
文摘Single-atom Pt catalysts are designed to promote efficient atom utilization,whereas effective decrease of Pt loading and improvement of photocatalytic activity in monoatomic Pt-deposited systems is still ongoing.Atomically dispersed metal species in crystalline carbon nitride are still challenging owing to their high crystallization and structural stability.In this study,we developed a novel single-atomic Pt-Cu catalyst for reducing noble metal loading by combining Pt with earth-abundant Cu atoms and enhancing photocatalytic CO_(2)reduction.N-vacancy-rich crystalline carbon nitride was used as a fine-tuning ligand for isolated Pt-Cu atom dispersion based on its accessible functional N vacancies as the seeded centers.The synthesized dimetal Pt-Cu atoms on crystalline carbon nitride(Pt Cu-cr CN)exhibited high selectivity and activity for CO_(2)conversion without the addition of any cocatalyst or sacrificial agent.In particular,we demonstrated that the diatomic Pt-Cu exhibited high mass activity with only 0.32 wt% Pt loading and showed excellent photocatalytic selectivity toward CH_(4)generation.The mechanism of CO_(2)photoreduction for Pt Cu-cr CN was proposed based on the observations and analysis of aberration-corrected high-angle annular dark-field scanning transmission electron microscopy images,in situ irradiated X-ray photoelectron spectroscopy,and in situ diffuse reflectance infrared Fourier transform spectroscopy.The findings of this work provide insights for abrogating specific bifunctional atomic metal sites in noble metal-based photocatalysts by reducing noble metal loading and maximizing their effective mass activity.
基金supported by the National Natural Science Foundation of China(21075138)special fund of State Key Laboratory of Structural Chemistry(20160003)
文摘Based on Hall et al. electrotopological state indices（EK） of atom types, two quantitative structure-activity relationship（QSAR） models were developed to estimate and predict the action strength（W） of D（OM）（dimethoxy-methyl-amphetamine） for 18 phenyl-isopropyl-amine dopes（PPAD） through linear method（multiple linear regression, MLR） and non-linear method（Back propagation artificial neural network, BP-ANN）. On the basis of EK, the optimal three-parameter（E14, E9, E7） QSAR model of W for 18 PPAD was constructed. The traditional correlation coefficient（R^2） and cross-validation correlation coefficient（Rcv^2） are 0.878 and 0.815, respectively. The result demonstrates that the model is highly reliable（from the point of view of statistics） and has good predictive ability by using R^2, Rcv^2, VIF, FIT, AIC and F tests. Form the three parameters of the model, it is known that the dominant influence factors of inhibited activity are the molecular structure fragments： =CH–（secondary carbon）, =C〈（tertiary carbon atom） in aromatic ring and –O–（phenol ether bond）. The results showed that the structure parameters E14, E9 and E7 have good rationality and efficiency for the W of phenyl-isopropyl-amine dope（PPAD） analogues. A BP-ANN with 3-3-1 architecture was generated by using three electrotopological state index descriptors（E14, E9, E7） appearing in the MLR model, the above descriptors were inputs and its output was action strength（W）. The nonlinear BP-ANN model has better predictive ability compared to the linear MLR model with R^2 and Rcv^2 of leave-one-out（LOO） to be 0.995 and 0.994, respectively. The regression method gave support to the neural network with physical explanation, which offers a more accurate model for QSAR. Those models can be used in the rational design of higher stimulating extent PPAD, which provide meaningful reference information to improve the detection methods of PPAD.
