The photocatalytic hydrogen peroxide(H_(2)O_(2))production by graphitic carbon nitride is a sustainable and environment-benign alternative approach of conventional anthraquinone autoxidation technology,but it is great...The photocatalytic hydrogen peroxide(H_(2)O_(2))production by graphitic carbon nitride is a sustainable and environment-benign alternative approach of conventional anthraquinone autoxidation technology,but it is great challenges to promote two-electron O_(2)reduction and water oxidation.Herein,we present the well-dispersed graphitic carbon nitride quantum dots decorated with cyano groups(Na-CNQD and K-CNQD)by thermal polymerization of melamine in the presence of metal fluoride.The quantum confinement and edge effect have endowed the photocatalysts with rich active sites,wide light absorption range and the inhibited charge recombination.The cyano moieties function as O_(2)reduction centers to accept the photogenerated electrons and facilitate their rapid transfer to O_(2)molecules.This process enables the selective two-electron reduction of O_(2),leading to the production of H_(2)O_(2).Concurrently,the valence band holes on the heptazine moiety oxidize water into H_(2)O_(2).These synergistic effects promote photocatalytic H_(2)O_(2)production from O_(2)and H_(2)O without the need for additional photosensitizers,organic scavengers and co-catalysts.In contrast,pristine carbon nitride nanosheets remain inactive under the same conditions.This study offers new strategies for rational design of carbon-based materials for solar-to-chemical energy conversion.展开更多
The dual incorporation of two important functional groups—trifluoromethyl and cyano moieties into one heterocyclic core in a single-step reaction represents an appealing but largely unaddressed synthetic challenge.He...The dual incorporation of two important functional groups—trifluoromethyl and cyano moieties into one heterocyclic core in a single-step reaction represents an appealing but largely unaddressed synthetic challenge.Here we demonstrate that a silver-catalyzed[3+2]cycloaddition reaction of dicyanoalkenes with trifluorodiazoethane(CF_(3)CHN2)could render a facile construction of a unique category of pyrazoles that are simultaneously adorned by trifluoromethyl and cyano groups.Changing the location pattern of the cyano group in starting dicyanoalkene material allows regiodivergent access to two series of previously elusive trifluoromethyl cyanopyrazoles with an exquisite level of regiocontrol.Thus,this method could be applied in the preparation of cyano-analogues of CF_(3)-containing drugs(Celecoxib)and agrochemicals(Penthiopyrad and Fluazolate).Notably,several cyano-analogues of Celecoxib demonstrate enhanced inhibitory activity towards cyclooxygenase-2(COX-2),thereby laying a good foundation for developing new lead-based antiinflammatory agents.展开更多
Developing highly efficient and recyclable photocatalysts has been regarded as an attractive strategy to solve antibiotic contaminants.Herein,we designed and fabricated Cy-C_(3) N_(4)/TiO_(2) S-scheme heterojunction f...Developing highly efficient and recyclable photocatalysts has been regarded as an attractive strategy to solve antibiotic contaminants.Herein,we designed and fabricated Cy-C_(3) N_(4)/TiO_(2) S-scheme heterojunction film with boosted charge transfer and a highly hydrophilic surface.The as-prepared heterojunction exhibited outstanding removal efficiency on tetracyclines and fluoroquinolone antibiotics(more than 80% within 90 min).The removal rate of 300-Cy-C_(3) N_(4)/TiO_(2) on norfloxacin(NOR)was 2.12,and 1.59 times higher than that of pristine TiO_(2),C_(3) N_(4)/TiO_(2),respectively.The excellent photocatalytic performance of 300-Cy-C_(3) N_(4)/TiO_(2) was attributed to the highly hydrophilic surface and effective transfer and separation of carriers.Moreover,the NOR degradation pathways were proposed based on the results of density functional theory(DFT),and liquid chromatography-mass spectrometry.The toxicity assessment indicated the toxicity of intermediates can be remarkably alleviated.The DFT calculation and selective photo-deposition experiment demonstrated that an internal electric field was formed at the heterojunction interface,and the charge carriers migrated between Cy-C_(3) N_(4) and TiO_(2) following an S-scheme transfer pathway.This research not only provides a promising method for tracking charge distribution on thin-film heterojunction photocatalysts but also helps us to design high-efficiency,and recyclable heterojunctions to solve antibiotic contaminants.展开更多
The electrochemical CO_(2) reduction reaction(eCO_(2)RR),producing gaseous C_(2+)products such as ethylene(C_(2)H_(4)),represents a sustainable strategy to mitigate the greenhouse effect.Inspired by the promotion effe...The electrochemical CO_(2) reduction reaction(eCO_(2)RR),producing gaseous C_(2+)products such as ethylene(C_(2)H_(4)),represents a sustainable strategy to mitigate the greenhouse effect.Inspired by the promotion effect of the cyano group(-C≡N) for C-C coupling in organic chemistry,several cyano-containing organocatalysts have been found to be capable of directly converting CO_(2) into C_(2)H_(4) with-C≡N as the active center during the eCO_(2)RR.The selectivity of C_(2)H_(4) for the representative catalyst,metal-free dicyandiamide(DCD),reached 27.6 % after partial hydrogenation in KHCO_(3) solution.In addition,its selectivity can be further improved to 57.7 % when coupled with oriented Cu crystals.The experimental and computational results collectively reveal that charge redistribution between Cu{100} and DCD promotes the partial hydrogenation of the cyano group and lays the foundation for the reduced energy barrier for the CO_(2) reduction on-C≡N.This study breaks the limitations of traditional metal/metal oxide-based catalysts by using cyano-containing organocatalysts for direct C_(2+) product generation,expanding the eCO_(2)RR catalyst library.In addition,this research elucidates the role of charge redistribution and cyano group hydrogenation in lowering reaction barriers,providing fundamental guidance for the design of new organocatalysts.展开更多
The existence of defects in perovskite films is a major obstacle that prevents perovskite solar cells (PSCs) from high efficiency and long-term stability. A variety of additives have been introduced into perovskite fi...The existence of defects in perovskite films is a major obstacle that prevents perovskite solar cells (PSCs) from high efficiency and long-term stability. A variety of additives have been introduced into perovskite films for reducing the number of defects. Lewis base-based additive engineering has been considered as an effective way to eliminate defects, especially the defects caused by the uncoordinated Pb^(2+). In this work, for the first time, a bilateral cyano molecule (succinonitrile, SN) which is a commonly used plasticizer in solid electrolyte of solid-state lithium batteries was selected as an additive to modify organic–inorganic hybrid perovskite films in PSCs. SN is featured with two cyano groups (–C≡N) distributing at both terminals of the carbon chain, providing two cross-linking points to interact with perovskites crystals via coordinating with uncoordinated Pb2+ and forming hydrogen bonds with –NH2 groups in perovskite. It was found that the addition of SN into perovskite precursor solution could effectively reduce defects, particularly inhibit the appearance of Pb0 and thus suppress trap-assisted nonradiative charge carrier recombination. As a result, the efficiency of CH_(3)NH_(3)PbI_(3)(Cl) (MAPbI_(3)(Cl))-based PSCs was improved from 18.4% to 20._(3)% with enhanced long-term stability at N2 and humid air atmosphere. This work provides a facile and effective strategy to enhance the PCE and stability of PSCs simultaneously, facilitating the commercialization of PSCs.展开更多
The active site amount of photocatalysts,being the key factors in photocatalytic reactions,directly affects the photocatalytic performance of the photocatalyst.Pristine graphitic carbon nitride(g‐C_(3)N_(4))exhibits ...The active site amount of photocatalysts,being the key factors in photocatalytic reactions,directly affects the photocatalytic performance of the photocatalyst.Pristine graphitic carbon nitride(g‐C_(3)N_(4))exhibits moderate photocatalytic activity due to insufficient active sites.In this study,cyano‐modified porous g‐C_(3)N_(4)nanosheets(MCN‐0.5)were synthesized through molecular self‐assembly and alkali‐assisted strategies.The cyano group acted as the active site of the photocatalytic reaction,because the good electron‐withdrawing property of the cyano group promoted carrier separation.Benefiting from the effect of the active sites,MCN‐0.5 exhibited significantly enhanced photocatalytic activity for CO2 reduction under visible light irradiation.Notably,the photocatalytic activity of MCN‐0.5 was significantly reduced when the cyano groups were removed by hydrochloric acid(HCl)treatment,further verifying the role of cyano groups as active sites.The photoreduction of Pt nanoparticles provided an intuitive indication that the introduction of cyano groups provided more active sites for the photocatalytic reaction.Furthermore,the controlled experiments showed that g‐C_(3)N_(4)grafted with cyano groups using melamine as the precursor exhibited enhanced photocatalytic activity,which proved the versatility of the strategy for enhancing the activity of g‐C_(3)N_(4)via cyano group modification.In situ diffuse reflectance infrared Fourier transform spectroscopy and theoretical calculations were used to investigate the mechanism of enhanced photocatalytic activity for CO2 reduction by cyano‐modified g‐C_(3)N_(4).This work provides a promising route for promoting efficient solar energy conversion by designing active sites in photocatalysts.展开更多
Graphite carbon nitride has many excellent properties as a two-dimensional semiconductor material so that it has a wide application prospect in the field of photocatalysis.However,the traditional problems such as high...Graphite carbon nitride has many excellent properties as a two-dimensional semiconductor material so that it has a wide application prospect in the field of photocatalysis.However,the traditional problems such as high recombination rate of photogenerated carriers limit its application.In this work,we introduce nitrogen deficiency into g-C_(3)N_(4)to solve this problem a simple and safe in-situ reduction method.g-C_(3)N_(4)/CaCO_(3)was obtained by a simple and safe one-step calcination method with industrial-grade micron particles CaCO_(3).Cyano group modification was in-situ reduced during the thermal polymerization process,which would change the internal electronic structure of g-C_(3)N_(4).The successful combination of g-C_(3)N_(4)and CaCO_(3)and the introduction of cyanide have been proved by Fourier transform infrared spectroscopy and X-ray photoelectron spectrometer.The formation of the cyano group,an electron-absorbing group,promotes the effective separation of photogenic electron hole pairs and inhibits the recombination of photogenic carriers.These advantages result in the generation of more·O_(2)-and1O_(2)in the catalytic system,which increases the photocatalytic efficiency of nicotine degradation by ten times.Furthermore,the degradation process of nicotine has been studied in this work to provide a basis for the degradation of nicotine organic pollutants in the air.展开更多
Silicon-containing arylacetylene (PSA) resins have broad application prospects because of their excellent heat resistance.However,improving their mechanical properties and interfacial bonding with reinforcement fibers...Silicon-containing arylacetylene (PSA) resins have broad application prospects because of their excellent heat resistance.However,improving their mechanical properties and interfacial bonding with reinforcement fibers while maintaining heat resistance is a challenge in engineering applications.Here,poly(diethynylbenzene-methylsilyl-3-benzonitrile)(DEB-CN) and poly(diethynylbenzene-methylsilyl-3,6-diethynylcarbazole-3-benzonitrile)(DEC-CN) were synthesized via an isopropylmagnesium chloride lithium-chloride complex (i-PrMgCl·LiCl),overcoming the compatibility problem between cyano groups and Grignard reagents.The cyano and alkyne groups in the resin underwent cyclization to form pyridine,catalyzed by the-NH-moiety in DEC-CN,resulting in extremely high thermal stability (5%weight loss temperature:669.3°C,glass transition temperature>650°C).The combination of cyano dipole-dipole pairing and hydrogen bonding greatly enhanced the resin-fiber interface properties,while the generated pyridine promoted stress relief in the crosslinked network,substantially improving the mechanical properties of the cyano-silicon-containing arylacetylene resin composites.The flexural strength of quartz fiber cloth/DEC-CN composites was 298.2 MPa at room temperature and 145.9 MPa at 500°C,corresponding to 84.0%and 127.6%enhancements,respectively,over the cyano-free counterpart.These cyano-silicon-containing arylacetylene resins exhibited a dual reinforcement mechanism involving physical interfacial interactions and chemical crosslinking,achieving a good balance between thermal stability and mechanical properties.展开更多
Revealing the factors that affect the vibrational frequency of Stark probe at interface is a pre-requirement for evaluating the absolute interfacial electric field.Here using surface-enhanced infrared absorption(SEIRA...Revealing the factors that affect the vibrational frequency of Stark probe at interface is a pre-requirement for evaluating the absolute interfacial electric field.Here using surface-enhanced infrared absorption(SEIRA)spectroscopy,attenuated total reflection(ATR)spectroscopy and molecular dynamics(MD),we reveal the assembled C≡N at gold nanofilm exhibits a reduced Stark tuning rate(STR)referring to the vibrational frequency shift in response to electric field comparing with the bulk which was regulated by the electron transfer between S and Au.These findings lead to a deeper understanding of the vibrational Stark effect at the interface and provide guidance for improving the interface electric field theory.展开更多
Organic redox compounds are attractive cathode materials in aqueous zinc-ion batteries owing to their low cost,environmental friendliness,multiple-electron-transfer reactions,and resource sustainability.However,the re...Organic redox compounds are attractive cathode materials in aqueous zinc-ion batteries owing to their low cost,environmental friendliness,multiple-electron-transfer reactions,and resource sustainability.However,the realized energy density is constrained by the limited capacity and low voltage.Herein,copper-tetracyanoquinodimethane(CuTCNQ),an organic charge-transfer complex is evaluated as a zinc-ion battery cathode owing to the good electron acceptation ability in the cyano groups that improves the voltage output.Through electrochemical activation,electrolyte optimization,and adoption of graphene-based separator,CuTCNQ-based aqueous zinc-ion batteries deliver much improved rate performance and cycling stability with anti-self-discharge properties.The structural evolution of CuTCNQ during discharge/charge are investigated by ex situ Fourier transform infra-red(FT-IR)spectra,ex situ X-ray photoelectron spectroscopy(XPS),and in situ ultraviolet visible spectroscopy(UV-vis),revealing reversible redox reactions in both cuprous cations(Cu^(+))and organic anions(TCNQ^(x-1)),thus delivering a high voltage output of 1.0 V and excellent discharge capacity of 158 mAh g^(-1).The remarkable electrochemical performance in Zn//CuTCNQ is ascribed to the strong inductive effect of cyano groups in CuTCNQ that elevated the voltage output and the graphene-modified separator that inhibited CuTCNQ dissolution and shuttle effect in aqueous electrolytes.展开更多
The intermolecular coupling of a nitro group with a cyano group mediated by a Sm(Hg) amalgam prepared from metal samarium powder and catalytic mercury dichloride was studied.
Hole transporting materials(HTMs)containing passivating groups for perovskite materials have attracted much attention for efficient and stable perovskite solar cells(PSCs).Among them,C≡N-based molecules have been pro...Hole transporting materials(HTMs)containing passivating groups for perovskite materials have attracted much attention for efficient and stable perovskite solar cells(PSCs).Among them,C≡N-based molecules have been proved as efficient HTMs.Herein,a series of novel C≡N functionalized carbazole-arylamine derivatives with variable C≡N substitution positions(para,meta,and ortho)on benzene-carbazole skeleton(on the adjacent benzene of carbazole)were synthesized(p-HTM,m-HTM and o-HTM).The experimental results exhibit that the substitution positions of the Ctriple bondN unit on HTMs have minor difference on the HOMO energy level and hydrophobicity.m-HTM has a relatively lower glass transition temperature compared with that of p-HTM and o-HTM.The functional theory calculations show that the C≡N located on meta position exposed very well,and the exposure direction is also the same with the methoxy.Upon applying these molecules as HTMs in PSCs,their device performance is found to sensitively depend on the substitution position of the C≡N unit on the molecule skeleton.The devices using m-HTM and o-HTM exhibit better performance than that of p-HTM.Moreover,m-HTM-based devices exhibit better light-soaking performance and long-term stability,which could be resulted from better interaction with the perovskite according to DFT results.Moreover,we further prepared a HTM with two C≡N units on the symmetrical meta position of molecular skeleton(2m-HTM).Interestingly,2m-HTM-based devices exhibit relatively inferior performance compared with that of the m-HTM,which could be resulted from weak negative electrical character of C≡N unit on 2m-HTM.The results give some new insights for designing ideal HTM for efficient and stable PSCs.展开更多
One-pot reaction of aldehydes, ?haloketones and (phenylsulfonyl)acetonitrile promoted by SmI3 proceeded smoothly to give 1-cyano-1-phenylsulfonyl-2-aryl-3-aroyl-propane derivatives in moderate to good yields.
Potassium ions(K^(+))doped graphitic carbon nitride(g-C_(3)N_(4))was prepared by a thermal etching method using potassium hydroxide(KOH)as an ion source.Fourier transform infrared spectroscopy(FTIR)and X-ray photoelec...Potassium ions(K^(+))doped graphitic carbon nitride(g-C_(3)N_(4))was prepared by a thermal etching method using potassium hydroxide(KOH)as an ion source.Fourier transform infrared spectroscopy(FTIR)and X-ray photoelectron spectroscopy(XPS)results showed that the generation of the cyano group was detected while introducing K^(+).Under simulated sunlight irradiation,the sample with a K^(+)doping amount of 10%showed the highest hydrogen peroxide(H_(2)O_(2))generation rate of2,140.2μmol h^(-1)g^(-1).The apparent quantum yield(AQY)at 400 nm and the solar-to-chemical conversion(SCC)are 4.35%and1.23%,respectively.K^(+)acted as a bridge between g-C_(3)N_(4)layers,which enhanced charge transfer efficiency.Meanwhile,the cyano group enhanced the adsorption capacity of protons(H^(+))and promoted the yield of H_(2)O_(2).The catalyst exhibited excellent photocatalytic stability based on four-cycle experiments.In addition,a mechanism study showed that superoxide radicals(·O_(2)^(-))were the most important active species in the reaction system.Photocatalytic production of H_(2)O_(2)was achieved through consecutive single-electron steps.This study deepens the understanding of the oxygen reduction reaction process and opens up a new venue for improving H_(2)O_(2)generation.展开更多
Herein,a nickel-catalyzed arylcyanation of unactivated alkenes via cyano group translocation with aryl boronic acids has been developed.These transformations provided a robust approach to constructing structurally div...Herein,a nickel-catalyzed arylcyanation of unactivated alkenes via cyano group translocation with aryl boronic acids has been developed.These transformations provided a robust approach to constructing structurally diverse 1,n-dinitriles or 4-amino nitriles from easily prepared and commercially available starting materials.The cyano group translocation was achieved,involving the addition into the intramolecular C–N triple bond followed by the retro-Thorpe reaction.Mechanistic studies revealed that high temperature and CsHCO_(3) as the base were crucial for the cyano group translocation.展开更多
基金supported by the National Natural Science Foundation of China(22361024 and 22471055)Natural Science Foundation of Jiangxi Province(20232ACB203001)+1 种基金Natural Science Foundation of Hebei Province(B2024202021,B2022202039)S&T Program of Hebei(236Z4308G)。
文摘The photocatalytic hydrogen peroxide(H_(2)O_(2))production by graphitic carbon nitride is a sustainable and environment-benign alternative approach of conventional anthraquinone autoxidation technology,but it is great challenges to promote two-electron O_(2)reduction and water oxidation.Herein,we present the well-dispersed graphitic carbon nitride quantum dots decorated with cyano groups(Na-CNQD and K-CNQD)by thermal polymerization of melamine in the presence of metal fluoride.The quantum confinement and edge effect have endowed the photocatalysts with rich active sites,wide light absorption range and the inhibited charge recombination.The cyano moieties function as O_(2)reduction centers to accept the photogenerated electrons and facilitate their rapid transfer to O_(2)molecules.This process enables the selective two-electron reduction of O_(2),leading to the production of H_(2)O_(2).Concurrently,the valence band holes on the heptazine moiety oxidize water into H_(2)O_(2).These synergistic effects promote photocatalytic H_(2)O_(2)production from O_(2)and H_(2)O without the need for additional photosensitizers,organic scavengers and co-catalysts.In contrast,pristine carbon nitride nanosheets remain inactive under the same conditions.This study offers new strategies for rational design of carbon-based materials for solar-to-chemical energy conversion.
基金This work is supported by the National Natural Science Foundation of China(grant nos.92156025,21901181,and 21961142015)the National Key Research and Development Program of China(grant nos.2019YFA0905100 and 2021YFF0701700)Tianjin Municipal Science and Technology Commission(grant no.19JCQNJC04700).
文摘The dual incorporation of two important functional groups—trifluoromethyl and cyano moieties into one heterocyclic core in a single-step reaction represents an appealing but largely unaddressed synthetic challenge.Here we demonstrate that a silver-catalyzed[3+2]cycloaddition reaction of dicyanoalkenes with trifluorodiazoethane(CF_(3)CHN2)could render a facile construction of a unique category of pyrazoles that are simultaneously adorned by trifluoromethyl and cyano groups.Changing the location pattern of the cyano group in starting dicyanoalkene material allows regiodivergent access to two series of previously elusive trifluoromethyl cyanopyrazoles with an exquisite level of regiocontrol.Thus,this method could be applied in the preparation of cyano-analogues of CF_(3)-containing drugs(Celecoxib)and agrochemicals(Penthiopyrad and Fluazolate).Notably,several cyano-analogues of Celecoxib demonstrate enhanced inhibitory activity towards cyclooxygenase-2(COX-2),thereby laying a good foundation for developing new lead-based antiinflammatory agents.
基金funded by the National Natural Science Foundation of China(Nos.51772003 and 51701001)the Excellent Research and Innovation Team Project of Anhui Province(No.2023AH010077)the Key Research and Development Projects in Anhui Province(No.202004b11020021).
文摘Developing highly efficient and recyclable photocatalysts has been regarded as an attractive strategy to solve antibiotic contaminants.Herein,we designed and fabricated Cy-C_(3) N_(4)/TiO_(2) S-scheme heterojunction film with boosted charge transfer and a highly hydrophilic surface.The as-prepared heterojunction exhibited outstanding removal efficiency on tetracyclines and fluoroquinolone antibiotics(more than 80% within 90 min).The removal rate of 300-Cy-C_(3) N_(4)/TiO_(2) on norfloxacin(NOR)was 2.12,and 1.59 times higher than that of pristine TiO_(2),C_(3) N_(4)/TiO_(2),respectively.The excellent photocatalytic performance of 300-Cy-C_(3) N_(4)/TiO_(2) was attributed to the highly hydrophilic surface and effective transfer and separation of carriers.Moreover,the NOR degradation pathways were proposed based on the results of density functional theory(DFT),and liquid chromatography-mass spectrometry.The toxicity assessment indicated the toxicity of intermediates can be remarkably alleviated.The DFT calculation and selective photo-deposition experiment demonstrated that an internal electric field was formed at the heterojunction interface,and the charge carriers migrated between Cy-C_(3) N_(4) and TiO_(2) following an S-scheme transfer pathway.This research not only provides a promising method for tracking charge distribution on thin-film heterojunction photocatalysts but also helps us to design high-efficiency,and recyclable heterojunctions to solve antibiotic contaminants.
基金financial support provided by the National Natural Science Foundation of China (52472304)。
文摘The electrochemical CO_(2) reduction reaction(eCO_(2)RR),producing gaseous C_(2+)products such as ethylene(C_(2)H_(4)),represents a sustainable strategy to mitigate the greenhouse effect.Inspired by the promotion effect of the cyano group(-C≡N) for C-C coupling in organic chemistry,several cyano-containing organocatalysts have been found to be capable of directly converting CO_(2) into C_(2)H_(4) with-C≡N as the active center during the eCO_(2)RR.The selectivity of C_(2)H_(4) for the representative catalyst,metal-free dicyandiamide(DCD),reached 27.6 % after partial hydrogenation in KHCO_(3) solution.In addition,its selectivity can be further improved to 57.7 % when coupled with oriented Cu crystals.The experimental and computational results collectively reveal that charge redistribution between Cu{100} and DCD promotes the partial hydrogenation of the cyano group and lays the foundation for the reduced energy barrier for the CO_(2) reduction on-C≡N.This study breaks the limitations of traditional metal/metal oxide-based catalysts by using cyano-containing organocatalysts for direct C_(2+) product generation,expanding the eCO_(2)RR catalyst library.In addition,this research elucidates the role of charge redistribution and cyano group hydrogenation in lowering reaction barriers,providing fundamental guidance for the design of new organocatalysts.
基金This work was supported by the Australian Research Council Discovery Projects(DPI 50104365 and DPI 60104835)the National Natural Science Foundation of China(No.21908106 and 21878158)+2 种基金the Jiangsu Natural Science Foundation(No.BK20190682)the Program forjiangsu Specially-Appointed Professors,the Funding from State Key Laboratory of Materials-Oriented Chemical Engineering(No.ZK201808)a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘The existence of defects in perovskite films is a major obstacle that prevents perovskite solar cells (PSCs) from high efficiency and long-term stability. A variety of additives have been introduced into perovskite films for reducing the number of defects. Lewis base-based additive engineering has been considered as an effective way to eliminate defects, especially the defects caused by the uncoordinated Pb^(2+). In this work, for the first time, a bilateral cyano molecule (succinonitrile, SN) which is a commonly used plasticizer in solid electrolyte of solid-state lithium batteries was selected as an additive to modify organic–inorganic hybrid perovskite films in PSCs. SN is featured with two cyano groups (–C≡N) distributing at both terminals of the carbon chain, providing two cross-linking points to interact with perovskites crystals via coordinating with uncoordinated Pb2+ and forming hydrogen bonds with –NH2 groups in perovskite. It was found that the addition of SN into perovskite precursor solution could effectively reduce defects, particularly inhibit the appearance of Pb0 and thus suppress trap-assisted nonradiative charge carrier recombination. As a result, the efficiency of CH_(3)NH_(3)PbI_(3)(Cl) (MAPbI_(3)(Cl))-based PSCs was improved from 18.4% to 20._(3)% with enhanced long-term stability at N2 and humid air atmosphere. This work provides a facile and effective strategy to enhance the PCE and stability of PSCs simultaneously, facilitating the commercialization of PSCs.
文摘The active site amount of photocatalysts,being the key factors in photocatalytic reactions,directly affects the photocatalytic performance of the photocatalyst.Pristine graphitic carbon nitride(g‐C_(3)N_(4))exhibits moderate photocatalytic activity due to insufficient active sites.In this study,cyano‐modified porous g‐C_(3)N_(4)nanosheets(MCN‐0.5)were synthesized through molecular self‐assembly and alkali‐assisted strategies.The cyano group acted as the active site of the photocatalytic reaction,because the good electron‐withdrawing property of the cyano group promoted carrier separation.Benefiting from the effect of the active sites,MCN‐0.5 exhibited significantly enhanced photocatalytic activity for CO2 reduction under visible light irradiation.Notably,the photocatalytic activity of MCN‐0.5 was significantly reduced when the cyano groups were removed by hydrochloric acid(HCl)treatment,further verifying the role of cyano groups as active sites.The photoreduction of Pt nanoparticles provided an intuitive indication that the introduction of cyano groups provided more active sites for the photocatalytic reaction.Furthermore,the controlled experiments showed that g‐C_(3)N_(4)grafted with cyano groups using melamine as the precursor exhibited enhanced photocatalytic activity,which proved the versatility of the strategy for enhancing the activity of g‐C_(3)N_(4)via cyano group modification.In situ diffuse reflectance infrared Fourier transform spectroscopy and theoretical calculations were used to investigate the mechanism of enhanced photocatalytic activity for CO2 reduction by cyano‐modified g‐C_(3)N_(4).This work provides a promising route for promoting efficient solar energy conversion by designing active sites in photocatalysts.
基金supported by the National Natural Science Foundation of China (No.51703201)。
文摘Graphite carbon nitride has many excellent properties as a two-dimensional semiconductor material so that it has a wide application prospect in the field of photocatalysis.However,the traditional problems such as high recombination rate of photogenerated carriers limit its application.In this work,we introduce nitrogen deficiency into g-C_(3)N_(4)to solve this problem a simple and safe in-situ reduction method.g-C_(3)N_(4)/CaCO_(3)was obtained by a simple and safe one-step calcination method with industrial-grade micron particles CaCO_(3).Cyano group modification was in-situ reduced during the thermal polymerization process,which would change the internal electronic structure of g-C_(3)N_(4).The successful combination of g-C_(3)N_(4)and CaCO_(3)and the introduction of cyanide have been proved by Fourier transform infrared spectroscopy and X-ray photoelectron spectrometer.The formation of the cyano group,an electron-absorbing group,promotes the effective separation of photogenic electron hole pairs and inhibits the recombination of photogenic carriers.These advantages result in the generation of more·O_(2)-and1O_(2)in the catalytic system,which increases the photocatalytic efficiency of nicotine degradation by ten times.Furthermore,the degradation process of nicotine has been studied in this work to provide a basis for the degradation of nicotine organic pollutants in the air.
基金financially supported by the Key Laboratory of Specially Functional Polymeric Materials and Related Technology of Ministry of Education, East China University of Science & Technology, and the Fundamental Research Funds for the Central Universities (Nos. 50321041918013 and 50321041917001)。
文摘Silicon-containing arylacetylene (PSA) resins have broad application prospects because of their excellent heat resistance.However,improving their mechanical properties and interfacial bonding with reinforcement fibers while maintaining heat resistance is a challenge in engineering applications.Here,poly(diethynylbenzene-methylsilyl-3-benzonitrile)(DEB-CN) and poly(diethynylbenzene-methylsilyl-3,6-diethynylcarbazole-3-benzonitrile)(DEC-CN) were synthesized via an isopropylmagnesium chloride lithium-chloride complex (i-PrMgCl·LiCl),overcoming the compatibility problem between cyano groups and Grignard reagents.The cyano and alkyne groups in the resin underwent cyclization to form pyridine,catalyzed by the-NH-moiety in DEC-CN,resulting in extremely high thermal stability (5%weight loss temperature:669.3°C,glass transition temperature>650°C).The combination of cyano dipole-dipole pairing and hydrogen bonding greatly enhanced the resin-fiber interface properties,while the generated pyridine promoted stress relief in the crosslinked network,substantially improving the mechanical properties of the cyano-silicon-containing arylacetylene resin composites.The flexural strength of quartz fiber cloth/DEC-CN composites was 298.2 MPa at room temperature and 145.9 MPa at 500°C,corresponding to 84.0%and 127.6%enhancements,respectively,over the cyano-free counterpart.These cyano-silicon-containing arylacetylene resins exhibited a dual reinforcement mechanism involving physical interfacial interactions and chemical crosslinking,achieving a good balance between thermal stability and mechanical properties.
基金The National Key R&D Program of China(No.2022YFE0113000)the National Science Fund for Distinguished Young Scholars(No.22025406)+1 种基金the National Natural Science Foundation of China(Nos.22074138,12174457)the Youth Innovation Promotion Association of CAS(No.2020233)for financial support。
文摘Revealing the factors that affect the vibrational frequency of Stark probe at interface is a pre-requirement for evaluating the absolute interfacial electric field.Here using surface-enhanced infrared absorption(SEIRA)spectroscopy,attenuated total reflection(ATR)spectroscopy and molecular dynamics(MD),we reveal the assembled C≡N at gold nanofilm exhibits a reduced Stark tuning rate(STR)referring to the vibrational frequency shift in response to electric field comparing with the bulk which was regulated by the electron transfer between S and Au.These findings lead to a deeper understanding of the vibrational Stark effect at the interface and provide guidance for improving the interface electric field theory.
基金financially supported by the National Natural Science Foundation of China(Nos.52102117,51173170,and 21773216)the joint project from the Henan-Provincial and the China-National Natural Science Foundations(No.U2004208)Key Science and Technology Program of Henan Province(No.202102310212)
文摘Organic redox compounds are attractive cathode materials in aqueous zinc-ion batteries owing to their low cost,environmental friendliness,multiple-electron-transfer reactions,and resource sustainability.However,the realized energy density is constrained by the limited capacity and low voltage.Herein,copper-tetracyanoquinodimethane(CuTCNQ),an organic charge-transfer complex is evaluated as a zinc-ion battery cathode owing to the good electron acceptation ability in the cyano groups that improves the voltage output.Through electrochemical activation,electrolyte optimization,and adoption of graphene-based separator,CuTCNQ-based aqueous zinc-ion batteries deliver much improved rate performance and cycling stability with anti-self-discharge properties.The structural evolution of CuTCNQ during discharge/charge are investigated by ex situ Fourier transform infra-red(FT-IR)spectra,ex situ X-ray photoelectron spectroscopy(XPS),and in situ ultraviolet visible spectroscopy(UV-vis),revealing reversible redox reactions in both cuprous cations(Cu^(+))and organic anions(TCNQ^(x-1)),thus delivering a high voltage output of 1.0 V and excellent discharge capacity of 158 mAh g^(-1).The remarkable electrochemical performance in Zn//CuTCNQ is ascribed to the strong inductive effect of cyano groups in CuTCNQ that elevated the voltage output and the graphene-modified separator that inhibited CuTCNQ dissolution and shuttle effect in aqueous electrolytes.
基金National Natural Science Foundation of China (Project No. 20072033) and Natural Science Foundation of Zhejiang province for financial support.
文摘The intermolecular coupling of a nitro group with a cyano group mediated by a Sm(Hg) amalgam prepared from metal samarium powder and catalytic mercury dichloride was studied.
基金Zi'an Zhou and Xianfu Zhang contributed equally to this work.This work was supported by the National Key R&D Program ofChina(2018YFB1500101)the 111 Project(No.B16016)+1 种基金the National Natural Science Foundation of China(No.61904053,51702096,U1705256 and 51961165106)the FundamentalResearch Funds for the Central Universities(No.2019MSO_(2)6.2019MS027,and 2020MS080)。
文摘Hole transporting materials(HTMs)containing passivating groups for perovskite materials have attracted much attention for efficient and stable perovskite solar cells(PSCs).Among them,C≡N-based molecules have been proved as efficient HTMs.Herein,a series of novel C≡N functionalized carbazole-arylamine derivatives with variable C≡N substitution positions(para,meta,and ortho)on benzene-carbazole skeleton(on the adjacent benzene of carbazole)were synthesized(p-HTM,m-HTM and o-HTM).The experimental results exhibit that the substitution positions of the Ctriple bondN unit on HTMs have minor difference on the HOMO energy level and hydrophobicity.m-HTM has a relatively lower glass transition temperature compared with that of p-HTM and o-HTM.The functional theory calculations show that the C≡N located on meta position exposed very well,and the exposure direction is also the same with the methoxy.Upon applying these molecules as HTMs in PSCs,their device performance is found to sensitively depend on the substitution position of the C≡N unit on the molecule skeleton.The devices using m-HTM and o-HTM exhibit better performance than that of p-HTM.Moreover,m-HTM-based devices exhibit better light-soaking performance and long-term stability,which could be resulted from better interaction with the perovskite according to DFT results.Moreover,we further prepared a HTM with two C≡N units on the symmetrical meta position of molecular skeleton(2m-HTM).Interestingly,2m-HTM-based devices exhibit relatively inferior performance compared with that of the m-HTM,which could be resulted from weak negative electrical character of C≡N unit on 2m-HTM.The results give some new insights for designing ideal HTM for efficient and stable PSCs.
基金the National Natural Science Foundation of China(Project No.20072033)the NSF of Zhejiang Province,China for financial support
文摘One-pot reaction of aldehydes, ?haloketones and (phenylsulfonyl)acetonitrile promoted by SmI3 proceeded smoothly to give 1-cyano-1-phenylsulfonyl-2-aryl-3-aroyl-propane derivatives in moderate to good yields.
基金supported by the National Natural Science Foundation of China(51702027)。
文摘Potassium ions(K^(+))doped graphitic carbon nitride(g-C_(3)N_(4))was prepared by a thermal etching method using potassium hydroxide(KOH)as an ion source.Fourier transform infrared spectroscopy(FTIR)and X-ray photoelectron spectroscopy(XPS)results showed that the generation of the cyano group was detected while introducing K^(+).Under simulated sunlight irradiation,the sample with a K^(+)doping amount of 10%showed the highest hydrogen peroxide(H_(2)O_(2))generation rate of2,140.2μmol h^(-1)g^(-1).The apparent quantum yield(AQY)at 400 nm and the solar-to-chemical conversion(SCC)are 4.35%and1.23%,respectively.K^(+)acted as a bridge between g-C_(3)N_(4)layers,which enhanced charge transfer efficiency.Meanwhile,the cyano group enhanced the adsorption capacity of protons(H^(+))and promoted the yield of H_(2)O_(2).The catalyst exhibited excellent photocatalytic stability based on four-cycle experiments.In addition,a mechanism study showed that superoxide radicals(·O_(2)^(-))were the most important active species in the reaction system.Photocatalytic production of H_(2)O_(2)was achieved through consecutive single-electron steps.This study deepens the understanding of the oxygen reduction reaction process and opens up a new venue for improving H_(2)O_(2)generation.
基金supported by the National Natural Science Foundation of China(21971074,22001076)the Natural Science Foundation of Guangdong Province(2022A1515010660,2021A1515220024)the Natural Science Foundation of Guangzhou(202102020982)。
文摘Herein,a nickel-catalyzed arylcyanation of unactivated alkenes via cyano group translocation with aryl boronic acids has been developed.These transformations provided a robust approach to constructing structurally diverse 1,n-dinitriles or 4-amino nitriles from easily prepared and commercially available starting materials.The cyano group translocation was achieved,involving the addition into the intramolecular C–N triple bond followed by the retro-Thorpe reaction.Mechanistic studies revealed that high temperature and CsHCO_(3) as the base were crucial for the cyano group translocation.
