An efficient acetic acid mediated metal-free oxidative C—H cross coupling of imidazo[1,2-a]pyridines with glyoxal hydrates has been developed under air atmosphere.The present protocol exhibits broad substrate scope,g...An efficient acetic acid mediated metal-free oxidative C—H cross coupling of imidazo[1,2-a]pyridines with glyoxal hydrates has been developed under air atmosphere.The present protocol exhibits broad substrate scope,good functional group tolerance,and enables the construction of a series of 1,2-dicarbonyl imidazo[1,2-a]pyridines in good yields.The reaction mechanism studies suggest that the reactions proceed through the electrophilic substitution and subsequent oxidation pathway.展开更多
Thiol-ene click polymerization has become an effective synthetic tool for constructing diverse sulfurcontaining polymers with advanced functions.However,the polymerization of internal alkene and thiol has been rarely ...Thiol-ene click polymerization has become an effective synthetic tool for constructing diverse sulfurcontaining polymers with advanced functions.However,the polymerization of internal alkene and thiol has been rarely used to prepare functional polymers because of large steric hindrance and relatively weak reactivity.In this work,a base-catalyzed click polymerization of thiols and internal olefins was successfully established in air.Notably,the polymerization went smoothly in halogen-containing solvent even without any catalyst via a radical step-growth polymerization.The polymerization enjoys excellent monomer applicability,which affords 16 well-defined polythioethers in high yields(up to 99%)with high molecular weights(Mwup to 19,600),good thermal stability(Td,5%up to 326℃),broadly regulated glass transition temperatures(-24~95℃),and unconventional fluorescence.Via a simple solvent regulation strategy,the vanillin-derived polythioether could be used as a turn-off fluorescence probe for Fe3+ions in DMF/H2O and a turn-on probe for Ag+ions in THF,with low detection limits of 9.15×10^(-7)mol/L and 4.60×10^(-7)mol/L,respectively.Additionally,the detection of Ag+presented a transformation from a clear solution to an emulsion,expanding the application prospects through observing colorimetric and fluorescent dual signals.Thus,this work not only holds significance in establishing an efficient polymerization,but also provides a strategy to prepare sensitive fluorescent probes for multiple metal ions.展开更多
Metal-free carbon catalysts have garnered significant attention since their inception.Despite substantial advancements,including widely adopted strategies such as heteroatom doping and defect engineering,their catalyt...Metal-free carbon catalysts have garnered significant attention since their inception.Despite substantial advancements,including widely adopted strategies such as heteroatom doping and defect engineering,their catalytic performance remains inferior to that of metal-based catalysts.In this study,we have predicted and demonstrated that the curvature of carbon plays a pivotal role in the adsorption of acetylene and the overall catalytic performance.First-principles calculations suggest that a tip-enhanced local electric field at the defect site on the curved carbon catalyst enhances the reaction kinetics for acetylene hydrochlorination.The experimental results highlight the structural advantages of the curved defect site,revealing that high-curvature defective carbon(HCDC)demonstrates an adsorption capacity for acetylene that is almost two orders of magnitude higher than that of defective carbon.Notably,HCDC achieves an acetylene conversion of up to 90%at 220℃under a gas hourly space velocity of 300 h^(-1),significantly surpassing the performance of the benchmark 0.25%Au/AC catalyst.This proof-of-concept study reveals the fundamental mechanisms driving the superior performance of carbon catalysts with curved nanostructures and presents a straightforward,environmentally friendly method for large-scale production of carbon materials with precisely controlled nanostructures.It highlights the potential for commercializing metal-free carbon catalysts in acetylene hydrochlorination and related heterogenous catalytic reactions.展开更多
The development of high-voltage tandem thin-film supercapacitors(TFSCs)has been limited by the issues such as expensive electrode materials,indispensable commercial separators and metal current collectors,and complex ...The development of high-voltage tandem thin-film supercapacitors(TFSCs)has been limited by the issues such as expensive electrode materials,indispensable commercial separators and metal current collectors,and complex manufacturing processes.Herein,we develop a potentially scalable approach to address all these issues by using CO_(2) laser pyrolysis of polyimide(PI)paper into the three-dimensional(3D)morphology of graphene paper in air.The formation process and mechanism of PI to graphene were clarified by microstructure and chemical characterizations and reaction molecular dynamics.The influences of laser scan density,power,defocus,and scan speed on the sheet resistance,longitudinal resistance,Raman spectra,and electrochemical performance of graphene papers were systematically investigated.Results indicate that high-quality graphene papers with ultralow sheet resistance(4.88Ω·square^(-1))and longitudinal resistance(3.46Ω)and extra-large crystalline size(96.1 nm)were achieved under optimized process parameters.The graphene papers can simultaneously serve as active electrode materials,current collectors,and interconnectors.The active area of electrodes is defined by a PI mask,with the help of which a hydrogel electrolyte functions as a separator.The assembled graphene paper-based TFSCs demonstrate outstanding electrochemical performance and mechanical flexibility,with the areal capacitance of 54.5 mF·cm^(-2),energy density of 10.9µWh·cm^(-2),and cycle stability retention of 86.9%over 15000 cycles.Moreover,all the tandem metal-free TFSCs,ranging from 1 to 160 cells,show excellent performance uniformity.The output voltage increases linearly from 1.2 V to 200 V.Significantly,the 160-tandem TFSCs exhibit a high voltage density within a compact volume of∼3.8 cm^(3).This work provides an avenue for achieving tandem metal-free TFSCs in a simple and efficient manner.展开更多
We report a general method for the synthesis of polymer-decorated metal-organic frameworks(MOFs)for the fabrication of superhy-drophobic materials through photoinduced metal-free atom transfer radical polymerization(A...We report a general method for the synthesis of polymer-decorated metal-organic frameworks(MOFs)for the fabrication of superhy-drophobic materials through photoinduced metal-free atom transfer radical polymerization(ATRP).Firstly,an MOF material,ZIF-8-NH_(2),was syn-thesized through the self-assembly of metal ions and organic ligands at room temperature.ZIF-8-NH_(2)was then reacted with glycidyl methacry-late(GMA)to form ZIF-8@GMA.Finally,ZIF-8@GMA-PHFBA was prepared by grafting fluorinated monomer 2,2,3,4,4,4-hexafluorobutyl acrylate(HFBA),from the ZIF-8@GMA surface via photoinduced ATRP under 365 nm UV light.The structural evolution during the metal-free ATRP modifi-cation of ZIF-8-NH_(2)was characterized by Fourier transform infrared spectroscopy(FTIR),X-ray powder diffraction(XRD),X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM),and thermogravimetry analysis(TGA).The test results verified that ZIF-8-NH_(2)and ZIF-8@GMA-PHFBA were successfully synthesized,and that the surface graft polymerization did not change the structure and morphology of ZIF-8-NH_(2).After anchoring the ZIF-8@GMA-PHFBA hybrid material on the fabric surface,the water contact angle(WCA)of the ZIF-8@GMA-PHFBA hy-brid material-modified fabric surface reached 154.2,which achieved a superhydrophobic state.In addition,the oil-water separation experiment and self-cleaning test demonstrated that the ZIF-8@GMA-PHFBA hybrid material-modified fabric has an excellent oil-water separation effect and self-cleaning performance.This material shows promising potential for applications in self-cleaning and oil-water separation technologies.展开更多
The development of metal-free carbon catalysts has garnered significant attention as a promising approach to address the challenges of sustainable catalysis,particularly in the replacement of toxic and environmentally...The development of metal-free carbon catalysts has garnered significant attention as a promising approach to address the challenges of sustainable catalysis,particularly in the replacement of toxic and environmentally hazardous mercury-based systems for the coal-based PVC industry.Within a decade of development,the catalytic performance of carbon catalysts has been improved greatly and even shows superiorities over metal catalysts in some cases,which have demonstrated great potential as sustainable alternatives to mercury catalysts.This review provides a comprehensive summary of the recent advancements in carbon catalysts for acetylene hydrochlorination.It encompasses a wide range of aspects,including the identification of active sites from heteroatom doping to intrinsic carbon defects,the various synthetic strategies employed,the reaction and deactivation mechanisms of carbon catalysts,and the current insights into the key challenges that are encountered on the journey from laboratory research to scalable commercialization within the field of carbon catalysts.The review offers foundational insights and practical guidelines for designing green carbon catalysts systems,not only for acetylene hydrochlorination but also for other heterogeneous catalytic reactions.展开更多
Designing exceptional-performance and long-lasting oxygen reduction reaction(ORR)catalysts is a critical challenge for the development of rechargeable Zn-air batteries(ZABs).In this study,we introduce a metal-free ORR...Designing exceptional-performance and long-lasting oxygen reduction reaction(ORR)catalysts is a critical challenge for the development of rechargeable Zn-air batteries(ZABs).In this study,we introduce a metal-free ORR catalyst composed of F-N co-doped hollow carbon(FNC),specifically engineered to address the limitations of conventional catalysts.The FNC catalysts were synthesized using a template-assisted pyrolysis method,resulting in a hollow,porous architecture with a high specific surface area and numerous active sites.Concurrently,F doping optimized the electronic configuration of pyridinic nitrogen.The introduction of C-F bonds reduced the reaction energy barrier,and the resulting N-C-F configuration enhanced the stability of the nitrogen center.The catalyst exhibits outstanding ORR activity in alkaline media,exhibiting a half-wave potential(E_(1/2))of 0.87 V,surpassing that of commercial Pt/C(E_(1/2)=0.85 V).When applied to both aqueous and flexible ZAB configurations,the FNC catalyst achieved peak power densities of 172 and 85 mW cm^(-2),respectively,along with exceptional cycling stabilities exceeding 5300 and 302 h,respectively.This study establishes a novel approach for designing metal-free ORR catalysts and next-generation ZABs,particularly for use in flexible and wearable microelectronic devices.展开更多
A transition-metal-and oxidant-free amination/cyclization reaction to access 1,2,4-triazolo[1,5-a]pyridines was realized in water by using amino diphenylphosphinate as amino source.A broad array of readily accessible ...A transition-metal-and oxidant-free amination/cyclization reaction to access 1,2,4-triazolo[1,5-a]pyridines was realized in water by using amino diphenylphosphinate as amino source.A broad array of readily accessible N-(pyridyl)amides could be converted into the products featuring a diverse set of functional groups.The sustainable methodology was successfully applied to the late-stage functionalization of natural products and drugs.展开更多
Tumor heterogeneity and diversity significantly undermine the effectiveness of monotherapy.Collaborative therapy emerges as a promising approach to mitigate tumor recurrence resulting from monotherapy.Combining chemod...Tumor heterogeneity and diversity significantly undermine the effectiveness of monotherapy.Collaborative therapy emerges as a promising approach to mitigate tumor recurrence resulting from monotherapy.Combining chemodynamic therapy(CDT)with photothermal therapy(PTT)offers a compelling solution for eradicating residual tumor cells post-PTT.In this study,we harness the Fenton-like response facilitated by glucose oxidase(GOD)and the mild hyperthermia induced by polyethyleneimine(PEI)functionalized nitrogen-containing graphene oxide to enhance tumor therapy through a metal-free bionic nanozyme.GOD catalyzes a substantial amount of hydrogen peroxide,and,with the carrier's involvement,triggers a Fenton-like reaction,yielding a wealth of hydroxyl radicals.These hydroxyl radicals effectively target tumor cells following photothermal action,bolstering CDT and culminating in a bidirectional amplification treatment that effectively prevents tumor recurrence and metastasis.This research amalgamates the physical and chemical attributes of nanomaterials with the unique characteristics of the tumor microenvironment,presenting a compelling and efficacious alternative for tumor treatment.展开更多
The aim of ＂green chemistry＂ and ＂atom economy＂ is to utilize carbon dioxide and replace harmful reactants such as CO and phosgene for the production of cyclic carbonates. In this paper, metal-free catalysts inclu...The aim of ＂green chemistry＂ and ＂atom economy＂ is to utilize carbon dioxide and replace harmful reactants such as CO and phosgene for the production of cyclic carbonates. In this paper, metal-free catalysts including organic bases, ionic liquids, supported catalysts, organic copolymers and carbon materials for the synthesis of cyclic carbonates by the cycloaddition of carbon dioxide to epoxides are reviewed. Recent advances in the design of the catalysts and the understanding of the reaction mechanism are summarized and discussed. The synergistic effects of organic bases and hydrogen bond donors, organic bases and nucleophilic anions, hydrogen bond donors and nucleophilic anions and active components and supports are highlighted. The challenge is to develop metal-free catalysts suitable for carbon dioxide capture and fixation. The ultimate goal is to synthesize cyclic carbonates in a flow reactor directly using carbon dioxide from industrial flue gas at ambient temperature and atmospheric pressure. By using synergetic effects, a multi-functional approach can meet the design strategy of metal-free catalysts for carbon dioxide adsorption and activation as well as epoxide ring opening.展开更多
Electrochemical CO2 reduction to chemicals or fuels presents one of the most promising strategies for managing the global carbon balance, which yet poses a significant challenge due to lack of efficient and durable el...Electrochemical CO2 reduction to chemicals or fuels presents one of the most promising strategies for managing the global carbon balance, which yet poses a significant challenge due to lack of efficient and durable electrocatalyst as well as the understanding of the CO2 reduction reaction(CO2RR) mechanism.Benefiting from the large surface area, high electrical conductivity, and tunable structure, carbon-based metal-free materials(CMs) have been extensively studied as cost-effective electrocatalysts for CO2RR.The development of CMs with low cost, high activity and durability for CO2RR has been considered as one of the most active and competitive directions in electrochemistry and material science.In this review article,some up-to-date strategies in improving the CO2RR performance on CMs are summarized.Specifically, the approaches to optimize the adsorption of CO2RR intermediates, such as tuning the physical and electronic structure are introduced, which can enhance the electrocatalytic activity of CMs effectively.Finally, some design strategies are proposed to prepare CMs with high activity and selectivity for CO2RR.展开更多
Ordered macroporous materials with rapid mass transport and enhanced active site accessibility are essential for achieving improved catalytic activity.In this study,boron phosphate crystals with a three-dimensionally ...Ordered macroporous materials with rapid mass transport and enhanced active site accessibility are essential for achieving improved catalytic activity.In this study,boron phosphate crystals with a three-dimensionally interconnected ordered macroporous structure and a robust framework were fabricated and used as stable and selective catalysts in the oxidative dehydrogenation(ODH)of propane.Due to the improved mass diffusion and higher number of exposed active sites in the ordered macroporous structure,the catalyst exhibited a remarkable olefin productivity of^16 golefin gcat^-1 h^-1,which is up to 2–100 times higher than that of ODH catalysts reported to date.The selectivity for olefins was 91.5%(propene:82.5%,ethene:9.0%)at 515℃,with a propane conversion of 14.3%.At the same time,the selectivity for the unwanted deep-oxidized CO2 product remained less than 1.0%.The tri-coordinated surface boron species were identified as the active catalytic sites for the ODH of propane.This study provides a route for preparing a new type of metal-free catalyst with stable structure against oxidation and remarkable catalytic activity,which may represent a potential candidate to promote the industrialization of the ODH process.展开更多
Nanocarbon materials have been used as important metal-free catalysts for various reactions including alkane dehydrogenation.However,clarifying the active sites and tuning the nanocarbon structure for direct dehydroge...Nanocarbon materials have been used as important metal-free catalysts for various reactions including alkane dehydrogenation.However,clarifying the active sites and tuning the nanocarbon structure for direct dehydrogenation have always been significantly challenging owing to the lack of fundamental understanding of the structure and surface properties of carbon materials.Herein,mesoporous carbon materials with different pore ordering and surface properties were synthesized through a soft-templating method with different formaldehyde/resorcinol ratios and carbonization temperatures and used for catalytic dehydrogenation of propane to propylene.The highly ordered mesoporous carbons were found to have higher catalytic activities than disordered and ordered mesoporous carbons,mainly because the highly ordered mesopores favor mass transportation and provide more accessible active sites.Furthermore,mesoporous carbons can provide a large amount of surface active sites owing to their high surface areas,which is favorable for propane dehydrogenation reaction.To control the surface oxygenated functional groups,highly ordered mesoporous carbons were carbonized at different temperatures(600,700,and 800℃).The propylene formation rates exhibit an excellent linear relationship with the number of ketonic C=O groups,suggesting that C=O groups are the most possible active sites.展开更多
Two-dimensional(2D)carbon nitride(CN)photocatalysts are attracting extensive attention owing to their excellent photocatalytic properties.In this study,we successfully prepared CN materials with heterogeneous structur...Two-dimensional(2D)carbon nitride(CN)photocatalysts are attracting extensive attention owing to their excellent photocatalytic properties.In this study,we successfully prepared CN materials with heterogeneous structures via hydrothermal treatment,high-temperature roasting,ball milling,sintering,and other processes.Benefitting from interface interactions in hybrid architectures,the CN photocatalysts exhibited high photocatalytic activity.The rate of hydrogen production using these CN photocatalysts reached 17028.82μmol h^(−1)g^(−1),and the apparent quantum efficiency was 11.2%at 420 nm.The ns-level time-resolved photoluminescence(PL)spectra provided information about the time-averaged lifetime of fluorescence charge carriers;the lifetime of the charge carriers causing the fluorescence of CN reached 9.99 ns.Significantly,the CN photocatalysts displayed satisfactory results in overall water splitting without the addition of sacrificial agents.The average hydrogen and oxygen production rates were 270.95μmol h^(−1)g^(−1)and 115.21μmol h^(−1)g^(−1)in 7 h,respectively,which were promising results for the applications of the catalysts in overall water splitting processes.We investigated the high efficiency of the prepared CN photocatalysts via a series of tests(UV-vis diffuse reflectance spectroscopy,photocurrent response measurements,PL emission spectroscopy,time-resolved PL spectroscopy,and Brunauer-Emmett-Teller analysis).Furthermore,the Mott-Schottky plot and current-voltage curve were acquired via electrochemical tests.The fabricated CN photocatalyst had a small p-n junction in its heterogeneous structure,which further enhanced its photocatalytic efficiency.Therefore,this work can promote the development of CN photocatalysts.展开更多
To date,much efforts have been devoted to the high-efficiency noble metal-free electrocatalysts for hydrogen-and oxygen-involving energy conversion reactions,due to their abundance,low cost and nultifunctionally.Surfa...To date,much efforts have been devoted to the high-efficiency noble metal-free electrocatalysts for hydrogen-and oxygen-involving energy conversion reactions,due to their abundance,low cost and nultifunctionally.Surface/interface engineering is found to be effective in achieving novel physicochemical properties and synergistic effects in nanomaterials for electrocatalysis.Among various engineering strategies,heteroatom-doping has been regarded as a most promising method to improve the electrocatalytic performance via the regulation of electronic structure of catalysts,and numerous works were reported on the synthesis method and mechanism investigation of heteroatom-doping electrocatalysts,though the heteroatom-doping can only provide limited active sites.Engineering of other defects such as vacancies and edge sites and construction of heterostructure have shown to open up a potential avenue for the development of noble metal-free electrocatalysts.In addition,surface functionalization can attach various molecules onto the surface of materials to easily modify their physical or chemical properties,being as a promising complement or substitute for offering materials with catalytic properties.This paper gives the insights into the diverse strategies of surface/interface engineering of the highefficiency noble metal-free electrocatalysts for energy-related electrochemical reactions.The significant advances are summarized.The unique advantages and mechanisms for specific applications are highlighted.The current challenges and outlook of this growing field are also discussed.展开更多
Oxidative desulfurization(ODS)has been proved to be an efficient strategy for the production of clean fuel oil.Numerous metal-based materials have been employed as excellent ODS catalysts,but being hindered by their h...Oxidative desulfurization(ODS)has been proved to be an efficient strategy for the production of clean fuel oil.Numerous metal-based materials have been employed as excellent ODS catalysts,but being hindered by their high-cost and potential secondary pollution.In this work,we employed graphene analogous hexagonal boron nitride(h-BN)as a metal-free catalyst for ODS with hydrogen peroxide(H2O2)as the oxidant.The h-BN catalyst was characterized and proved to be a few-layered structure with relatively high specific surface areas.The h-BN catalyst showed a 99.4%of sulfur removal in fuel oil under the optimized reaction conditions.Besides,the h-BN can be recycled for 8 times without significant decrease in the catalytic performance.Detailed mechanism analysis found that it is the boron radicals in h-BN activated H2O2 to generate·OH species,which can readily oxidize sulfides to corresponding sulfones for separation.This work would provide another choice in choosing metal-free catalysts for ODS.展开更多
Although scientists have conducted long-term and extensive studies on oxygen reduction reaction(ORR)catalyzed by metal-free carbon materials,they mainly have focused on the preparation and properties of various doped ...Although scientists have conducted long-term and extensive studies on oxygen reduction reaction(ORR)catalyzed by metal-free carbon materials,they mainly have focused on the preparation and properties of various doped carbon materials.There is still a lack of systematic scientific guidance on the relationship between the surface structure regulation and activity of carbon-based catalysts.In this review,some of electrochemical and computational fundamental concepts about ORR are concisely summarized.The effects of edge defect and nonmetallic doping of carbon materials on ORR behavior and mechanism have been reviewed,and activity origin identification and intermediate conversion mechanism have been discussed.The outlooks for future researches on metal-free ORR electrocatalysis are suggested.展开更多
The metal-free synthesis of graphene on singlecrystal silicon substrates, the most common commercial semiconductor, is of paramount significance for many technological applications. In this work, we report the growth ...The metal-free synthesis of graphene on singlecrystal silicon substrates, the most common commercial semiconductor, is of paramount significance for many technological applications. In this work, we report the growth of graphene directly on an upside-down placed,single-crystal silicon substrate using metal-free, ambientpressure chemical vapor deposition. By controlling the growth temperature, in-plane propagation, edge-propagation, and core-propagation, the process of graphene growth on silicon can be identified. This process produces atomically flat monolayer or bilayer graphene domains, concave bilayer graphene domains, and bulging few-layer graphene domains. This work would be a significant step toward the synthesis of large-area and layer-controlled, high-quality graphene on single-crystal silicon substrates.展开更多
The oxygen reduction/evolution reactions(ORR/OER) are a key electrode process in the development of electrochemical energy conversion and storage devices,such as metal-air batteries and reversible fuel cells.The searc...The oxygen reduction/evolution reactions(ORR/OER) are a key electrode process in the development of electrochemical energy conversion and storage devices,such as metal-air batteries and reversible fuel cells.The search for low-cost high-performance nanocarbon-based metal-free and non-precious metal bifunctional electrocatalysts for ORR/OER alternatives to the widely-used noble metal-based catalysts is a research focus.This review aims to outline the opportunities and available options for these nanocarbon-based bifunctional electrocatalysts.Through discussion of some current scientific issues,we summarize the development and breakthroughs of these electrocatalysts.Then we provide our perspectives on these issues and suggestions for some areas in the further work.We hope that this review can improve the interest in nanocarbon-based metal-free and non-precious metal bifunctional electrocatalysts for ORR/OER.展开更多
Covalent organic frameworks(COFs)have emerged as a kind of rising star materials in photocatalysis.However,their photocatalytic activities are restricted by the high photogenerated electron-hole pairs recombination ra...Covalent organic frameworks(COFs)have emerged as a kind of rising star materials in photocatalysis.However,their photocatalytic activities are restricted by the high photogenerated electron-hole pairs recombination rate.Herein,a novel metal-free 2D/2D van der Waals heterojunction,composed of a two-dimensional(2D)COF with ketoenamine linkage(TpPa-1-COF)and 2D defective hexagonal boron nitride(h-BN),is successfully constructed through in situ solvothermal method.Benefitting from the presence of VDW heterojunction,larger contact area and intimate electronic coupling can be formed between the interface of TpPa-1-COF and defective h-BN,which make contributions to promoting charge car-riers separation.The introduced defects can also endow the h-BN with porous structure,thus providing more reactive sites.Moreover,the TpPa-1-COF will undergo a structural transformation after being integrated with defective h-BN,which can enlarge the gap between the conduction band position of the h-BN and TpPa-1-COF,and suppress electron backflow,corroborated by experimental and density functional theory calculations results.Accordingly,the resulting porous h-BN/TpPa-1-COF metal-free VDW heterojunction displays out-standing solar energy catalytic activity for water splitting without co-catalysts,and the H_(2) evolution rate can reach up to 3.15 mmol g^(−1) h^(−1),which is about 67 times greater than that of pristine TpPa-1-COF,also surpassing that of state-of-the-art metal-free-based photocatalysts reported to date.In particular,it is the first work for constructing COFs-based heterojunctions with the help of h-BN,which may provide new avenue for designing highly efficient metal-free-based photocatalysts for H_(2) evolution.展开更多
文摘An efficient acetic acid mediated metal-free oxidative C—H cross coupling of imidazo[1,2-a]pyridines with glyoxal hydrates has been developed under air atmosphere.The present protocol exhibits broad substrate scope,good functional group tolerance,and enables the construction of a series of 1,2-dicarbonyl imidazo[1,2-a]pyridines in good yields.The reaction mechanism studies suggest that the reactions proceed through the electrophilic substitution and subsequent oxidation pathway.
基金financially supported by the National Natural Science Foundation of China(Nos.22479102,22001078)the Guangdong Talent Program(No.2023TQ07L822)+1 种基金the Guangdong Basic and Applied Basic Research Foundation(No.2024A1515011716)the startup funding of Songshan Lake Materials Laboratory(No.Y1D1031H311)。
文摘Thiol-ene click polymerization has become an effective synthetic tool for constructing diverse sulfurcontaining polymers with advanced functions.However,the polymerization of internal alkene and thiol has been rarely used to prepare functional polymers because of large steric hindrance and relatively weak reactivity.In this work,a base-catalyzed click polymerization of thiols and internal olefins was successfully established in air.Notably,the polymerization went smoothly in halogen-containing solvent even without any catalyst via a radical step-growth polymerization.The polymerization enjoys excellent monomer applicability,which affords 16 well-defined polythioethers in high yields(up to 99%)with high molecular weights(Mwup to 19,600),good thermal stability(Td,5%up to 326℃),broadly regulated glass transition temperatures(-24~95℃),and unconventional fluorescence.Via a simple solvent regulation strategy,the vanillin-derived polythioether could be used as a turn-off fluorescence probe for Fe3+ions in DMF/H2O and a turn-on probe for Ag+ions in THF,with low detection limits of 9.15×10^(-7)mol/L and 4.60×10^(-7)mol/L,respectively.Additionally,the detection of Ag+presented a transformation from a clear solution to an emulsion,expanding the application prospects through observing colorimetric and fluorescent dual signals.Thus,this work not only holds significance in establishing an efficient polymerization,but also provides a strategy to prepare sensitive fluorescent probes for multiple metal ions.
文摘Metal-free carbon catalysts have garnered significant attention since their inception.Despite substantial advancements,including widely adopted strategies such as heteroatom doping and defect engineering,their catalytic performance remains inferior to that of metal-based catalysts.In this study,we have predicted and demonstrated that the curvature of carbon plays a pivotal role in the adsorption of acetylene and the overall catalytic performance.First-principles calculations suggest that a tip-enhanced local electric field at the defect site on the curved carbon catalyst enhances the reaction kinetics for acetylene hydrochlorination.The experimental results highlight the structural advantages of the curved defect site,revealing that high-curvature defective carbon(HCDC)demonstrates an adsorption capacity for acetylene that is almost two orders of magnitude higher than that of defective carbon.Notably,HCDC achieves an acetylene conversion of up to 90%at 220℃under a gas hourly space velocity of 300 h^(-1),significantly surpassing the performance of the benchmark 0.25%Au/AC catalyst.This proof-of-concept study reveals the fundamental mechanisms driving the superior performance of carbon catalysts with curved nanostructures and presents a straightforward,environmentally friendly method for large-scale production of carbon materials with precisely controlled nanostructures.It highlights the potential for commercializing metal-free carbon catalysts in acetylene hydrochlorination and related heterogenous catalytic reactions.
基金funded by the National Natural Science Foundation of China(Grant Nos.52205457 and 52422511)the National Key R&D Program of China(Grant No.2022YFB4701000)+3 种基金the Guangdong Basic and Applied Basic Research Foundation,China(Grant Nos.2024A1515010043,2025A1515010890 and 2022B1515120011)the Young Talent Support Project of Guangzhou Association for Science and Technology(Grant No.QT2024-010)the Guangzhou Basic and Applied Basic Research Foundation(Grant No.SL2024A04J01501)the State Key Laboratory of Precision Electronic Manufacturing Technology and Equipment(Grant No.JMDZ202303).
文摘The development of high-voltage tandem thin-film supercapacitors(TFSCs)has been limited by the issues such as expensive electrode materials,indispensable commercial separators and metal current collectors,and complex manufacturing processes.Herein,we develop a potentially scalable approach to address all these issues by using CO_(2) laser pyrolysis of polyimide(PI)paper into the three-dimensional(3D)morphology of graphene paper in air.The formation process and mechanism of PI to graphene were clarified by microstructure and chemical characterizations and reaction molecular dynamics.The influences of laser scan density,power,defocus,and scan speed on the sheet resistance,longitudinal resistance,Raman spectra,and electrochemical performance of graphene papers were systematically investigated.Results indicate that high-quality graphene papers with ultralow sheet resistance(4.88Ω·square^(-1))and longitudinal resistance(3.46Ω)and extra-large crystalline size(96.1 nm)were achieved under optimized process parameters.The graphene papers can simultaneously serve as active electrode materials,current collectors,and interconnectors.The active area of electrodes is defined by a PI mask,with the help of which a hydrogel electrolyte functions as a separator.The assembled graphene paper-based TFSCs demonstrate outstanding electrochemical performance and mechanical flexibility,with the areal capacitance of 54.5 mF·cm^(-2),energy density of 10.9µWh·cm^(-2),and cycle stability retention of 86.9%over 15000 cycles.Moreover,all the tandem metal-free TFSCs,ranging from 1 to 160 cells,show excellent performance uniformity.The output voltage increases linearly from 1.2 V to 200 V.Significantly,the 160-tandem TFSCs exhibit a high voltage density within a compact volume of∼3.8 cm^(3).This work provides an avenue for achieving tandem metal-free TFSCs in a simple and efficient manner.
基金supported by the Natural Science Foundation of Shandong Province(Nos.ZR2021ME126,ZR2022ME139,ZR2021ME149)the Key Research and Development Program of Shandong Province-Project for Enhancing the Innovation Capacity of Teschnology-based Small and Medium-sized Enterprises(No.2024TSGC0957)the Research Foundation of Liaocheng University(Nos.318012012 , 318011905).
文摘We report a general method for the synthesis of polymer-decorated metal-organic frameworks(MOFs)for the fabrication of superhy-drophobic materials through photoinduced metal-free atom transfer radical polymerization(ATRP).Firstly,an MOF material,ZIF-8-NH_(2),was syn-thesized through the self-assembly of metal ions and organic ligands at room temperature.ZIF-8-NH_(2)was then reacted with glycidyl methacry-late(GMA)to form ZIF-8@GMA.Finally,ZIF-8@GMA-PHFBA was prepared by grafting fluorinated monomer 2,2,3,4,4,4-hexafluorobutyl acrylate(HFBA),from the ZIF-8@GMA surface via photoinduced ATRP under 365 nm UV light.The structural evolution during the metal-free ATRP modifi-cation of ZIF-8-NH_(2)was characterized by Fourier transform infrared spectroscopy(FTIR),X-ray powder diffraction(XRD),X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM),and thermogravimetry analysis(TGA).The test results verified that ZIF-8-NH_(2)and ZIF-8@GMA-PHFBA were successfully synthesized,and that the surface graft polymerization did not change the structure and morphology of ZIF-8-NH_(2).After anchoring the ZIF-8@GMA-PHFBA hybrid material on the fabric surface,the water contact angle(WCA)of the ZIF-8@GMA-PHFBA hy-brid material-modified fabric surface reached 154.2,which achieved a superhydrophobic state.In addition,the oil-water separation experiment and self-cleaning test demonstrated that the ZIF-8@GMA-PHFBA hybrid material-modified fabric has an excellent oil-water separation effect and self-cleaning performance.This material shows promising potential for applications in self-cleaning and oil-water separation technologies.
文摘The development of metal-free carbon catalysts has garnered significant attention as a promising approach to address the challenges of sustainable catalysis,particularly in the replacement of toxic and environmentally hazardous mercury-based systems for the coal-based PVC industry.Within a decade of development,the catalytic performance of carbon catalysts has been improved greatly and even shows superiorities over metal catalysts in some cases,which have demonstrated great potential as sustainable alternatives to mercury catalysts.This review provides a comprehensive summary of the recent advancements in carbon catalysts for acetylene hydrochlorination.It encompasses a wide range of aspects,including the identification of active sites from heteroatom doping to intrinsic carbon defects,the various synthetic strategies employed,the reaction and deactivation mechanisms of carbon catalysts,and the current insights into the key challenges that are encountered on the journey from laboratory research to scalable commercialization within the field of carbon catalysts.The review offers foundational insights and practical guidelines for designing green carbon catalysts systems,not only for acetylene hydrochlorination but also for other heterogeneous catalytic reactions.
文摘Designing exceptional-performance and long-lasting oxygen reduction reaction(ORR)catalysts is a critical challenge for the development of rechargeable Zn-air batteries(ZABs).In this study,we introduce a metal-free ORR catalyst composed of F-N co-doped hollow carbon(FNC),specifically engineered to address the limitations of conventional catalysts.The FNC catalysts were synthesized using a template-assisted pyrolysis method,resulting in a hollow,porous architecture with a high specific surface area and numerous active sites.Concurrently,F doping optimized the electronic configuration of pyridinic nitrogen.The introduction of C-F bonds reduced the reaction energy barrier,and the resulting N-C-F configuration enhanced the stability of the nitrogen center.The catalyst exhibits outstanding ORR activity in alkaline media,exhibiting a half-wave potential(E_(1/2))of 0.87 V,surpassing that of commercial Pt/C(E_(1/2)=0.85 V).When applied to both aqueous and flexible ZAB configurations,the FNC catalyst achieved peak power densities of 172 and 85 mW cm^(-2),respectively,along with exceptional cycling stabilities exceeding 5300 and 302 h,respectively.This study establishes a novel approach for designing metal-free ORR catalysts and next-generation ZABs,particularly for use in flexible and wearable microelectronic devices.
基金financial support from the National Natural Science Foundation of China(No.82003585)the Program for Science&Technology Innovation Talents in Universities of Henan Province(No.24HASTIT069)+5 种基金the Technical Innovation Team of Henan Normal University(No.2022TD03)the Special Project for Fundamental Research in University of Henan Province(No.23ZX009)the Henan Science and Technology Program(No.232102310364)the Key Project of Henan Educational Committee(No.22A150041)Excellent Youth Foundation of Henan Scientific Committee(No.222300420012)the Young Core Instructor Training Program of Xinyang Agriculture and Forestry University(2023)。
文摘A transition-metal-and oxidant-free amination/cyclization reaction to access 1,2,4-triazolo[1,5-a]pyridines was realized in water by using amino diphenylphosphinate as amino source.A broad array of readily accessible N-(pyridyl)amides could be converted into the products featuring a diverse set of functional groups.The sustainable methodology was successfully applied to the late-stage functionalization of natural products and drugs.
基金financial support from the National Natural Science Foundation of China(Nos.82202354,U20A20338,82201247)The Summit Advancement Disciplines of Zhejiang Province(Wenzhou Medical University-Pharmaceutics)the Key R&D Program of Zhejiang Province(No.2021C04019)。
文摘Tumor heterogeneity and diversity significantly undermine the effectiveness of monotherapy.Collaborative therapy emerges as a promising approach to mitigate tumor recurrence resulting from monotherapy.Combining chemodynamic therapy(CDT)with photothermal therapy(PTT)offers a compelling solution for eradicating residual tumor cells post-PTT.In this study,we harness the Fenton-like response facilitated by glucose oxidase(GOD)and the mild hyperthermia induced by polyethyleneimine(PEI)functionalized nitrogen-containing graphene oxide to enhance tumor therapy through a metal-free bionic nanozyme.GOD catalyzes a substantial amount of hydrogen peroxide,and,with the carrier's involvement,triggers a Fenton-like reaction,yielding a wealth of hydroxyl radicals.These hydroxyl radicals effectively target tumor cells following photothermal action,bolstering CDT and culminating in a bidirectional amplification treatment that effectively prevents tumor recurrence and metastasis.This research amalgamates the physical and chemical attributes of nanomaterials with the unique characteristics of the tumor microenvironment,presenting a compelling and efficacious alternative for tumor treatment.
基金supported by the National Science and Technology Support Project of China(2013BAC11B03)the National Natural Science Foundation of China(21401054,21476065,21273067)the Graduate Student Scientific Research Innovation Fund Project of Hunan Province(CX2015B082)~~
文摘The aim of ＂green chemistry＂ and ＂atom economy＂ is to utilize carbon dioxide and replace harmful reactants such as CO and phosgene for the production of cyclic carbonates. In this paper, metal-free catalysts including organic bases, ionic liquids, supported catalysts, organic copolymers and carbon materials for the synthesis of cyclic carbonates by the cycloaddition of carbon dioxide to epoxides are reviewed. Recent advances in the design of the catalysts and the understanding of the reaction mechanism are summarized and discussed. The synergistic effects of organic bases and hydrogen bond donors, organic bases and nucleophilic anions, hydrogen bond donors and nucleophilic anions and active components and supports are highlighted. The challenge is to develop metal-free catalysts suitable for carbon dioxide capture and fixation. The ultimate goal is to synthesize cyclic carbonates in a flow reactor directly using carbon dioxide from industrial flue gas at ambient temperature and atmospheric pressure. By using synergetic effects, a multi-functional approach can meet the design strategy of metal-free catalysts for carbon dioxide adsorption and activation as well as epoxide ring opening.
基金supported by the National Key R&D Program of China (2016YFB0600902)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB17000000)+2 种基金Dalian National Laboratory for Clean Energy (DNL180401)the Youth Innovation Promotion Association CASthe Singapore Ministry of Education Academic Research Fund (AcRF) Tier 1: RG9/17, RG115/17, RG115/18 and Tier 2: MOE2016-T2-2-004
文摘Electrochemical CO2 reduction to chemicals or fuels presents one of the most promising strategies for managing the global carbon balance, which yet poses a significant challenge due to lack of efficient and durable electrocatalyst as well as the understanding of the CO2 reduction reaction(CO2RR) mechanism.Benefiting from the large surface area, high electrical conductivity, and tunable structure, carbon-based metal-free materials(CMs) have been extensively studied as cost-effective electrocatalysts for CO2RR.The development of CMs with low cost, high activity and durability for CO2RR has been considered as one of the most active and competitive directions in electrochemistry and material science.In this review article,some up-to-date strategies in improving the CO2RR performance on CMs are summarized.Specifically, the approaches to optimize the adsorption of CO2RR intermediates, such as tuning the physical and electronic structure are introduced, which can enhance the electrocatalytic activity of CMs effectively.Finally, some design strategies are proposed to prepare CMs with high activity and selectivity for CO2RR.
文摘Ordered macroporous materials with rapid mass transport and enhanced active site accessibility are essential for achieving improved catalytic activity.In this study,boron phosphate crystals with a three-dimensionally interconnected ordered macroporous structure and a robust framework were fabricated and used as stable and selective catalysts in the oxidative dehydrogenation(ODH)of propane.Due to the improved mass diffusion and higher number of exposed active sites in the ordered macroporous structure,the catalyst exhibited a remarkable olefin productivity of^16 golefin gcat^-1 h^-1,which is up to 2–100 times higher than that of ODH catalysts reported to date.The selectivity for olefins was 91.5%(propene:82.5%,ethene:9.0%)at 515℃,with a propane conversion of 14.3%.At the same time,the selectivity for the unwanted deep-oxidized CO2 product remained less than 1.0%.The tri-coordinated surface boron species were identified as the active catalytic sites for the ODH of propane.This study provides a route for preparing a new type of metal-free catalyst with stable structure against oxidation and remarkable catalytic activity,which may represent a potential candidate to promote the industrialization of the ODH process.
基金supported by the National Natural Science Foundation of China(21421001,21573115)the Fundamental Research Funds for the Central Universities(63185015)the Foundation of State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering(2017-K13)~~
文摘Nanocarbon materials have been used as important metal-free catalysts for various reactions including alkane dehydrogenation.However,clarifying the active sites and tuning the nanocarbon structure for direct dehydrogenation have always been significantly challenging owing to the lack of fundamental understanding of the structure and surface properties of carbon materials.Herein,mesoporous carbon materials with different pore ordering and surface properties were synthesized through a soft-templating method with different formaldehyde/resorcinol ratios and carbonization temperatures and used for catalytic dehydrogenation of propane to propylene.The highly ordered mesoporous carbons were found to have higher catalytic activities than disordered and ordered mesoporous carbons,mainly because the highly ordered mesopores favor mass transportation and provide more accessible active sites.Furthermore,mesoporous carbons can provide a large amount of surface active sites owing to their high surface areas,which is favorable for propane dehydrogenation reaction.To control the surface oxygenated functional groups,highly ordered mesoporous carbons were carbonized at different temperatures(600,700,and 800℃).The propylene formation rates exhibit an excellent linear relationship with the number of ketonic C=O groups,suggesting that C=O groups are the most possible active sites.
文摘Two-dimensional(2D)carbon nitride(CN)photocatalysts are attracting extensive attention owing to their excellent photocatalytic properties.In this study,we successfully prepared CN materials with heterogeneous structures via hydrothermal treatment,high-temperature roasting,ball milling,sintering,and other processes.Benefitting from interface interactions in hybrid architectures,the CN photocatalysts exhibited high photocatalytic activity.The rate of hydrogen production using these CN photocatalysts reached 17028.82μmol h^(−1)g^(−1),and the apparent quantum efficiency was 11.2%at 420 nm.The ns-level time-resolved photoluminescence(PL)spectra provided information about the time-averaged lifetime of fluorescence charge carriers;the lifetime of the charge carriers causing the fluorescence of CN reached 9.99 ns.Significantly,the CN photocatalysts displayed satisfactory results in overall water splitting without the addition of sacrificial agents.The average hydrogen and oxygen production rates were 270.95μmol h^(−1)g^(−1)and 115.21μmol h^(−1)g^(−1)in 7 h,respectively,which were promising results for the applications of the catalysts in overall water splitting processes.We investigated the high efficiency of the prepared CN photocatalysts via a series of tests(UV-vis diffuse reflectance spectroscopy,photocurrent response measurements,PL emission spectroscopy,time-resolved PL spectroscopy,and Brunauer-Emmett-Teller analysis).Furthermore,the Mott-Schottky plot and current-voltage curve were acquired via electrochemical tests.The fabricated CN photocatalyst had a small p-n junction in its heterogeneous structure,which further enhanced its photocatalytic efficiency.Therefore,this work can promote the development of CN photocatalysts.
基金supported by the Natural Science Foundation of Shandong Province(ZR2019PB013)the Natural Science Foundation of Tianjin(19JCZDJC37700)the National Natural Science Foundation of China(21421001 and 21875118)。
文摘To date,much efforts have been devoted to the high-efficiency noble metal-free electrocatalysts for hydrogen-and oxygen-involving energy conversion reactions,due to their abundance,low cost and nultifunctionally.Surface/interface engineering is found to be effective in achieving novel physicochemical properties and synergistic effects in nanomaterials for electrocatalysis.Among various engineering strategies,heteroatom-doping has been regarded as a most promising method to improve the electrocatalytic performance via the regulation of electronic structure of catalysts,and numerous works were reported on the synthesis method and mechanism investigation of heteroatom-doping electrocatalysts,though the heteroatom-doping can only provide limited active sites.Engineering of other defects such as vacancies and edge sites and construction of heterostructure have shown to open up a potential avenue for the development of noble metal-free electrocatalysts.In addition,surface functionalization can attach various molecules onto the surface of materials to easily modify their physical or chemical properties,being as a promising complement or substitute for offering materials with catalytic properties.This paper gives the insights into the diverse strategies of surface/interface engineering of the highefficiency noble metal-free electrocatalysts for energy-related electrochemical reactions.The significant advances are summarized.The unique advantages and mechanisms for specific applications are highlighted.The current challenges and outlook of this growing field are also discussed.
基金All authors appreciate the financial support from the National Key R&D Program of China(2017YFB0306504)the National Natural Science Foundation of China(No.21722604,21878133 and 21908082)+2 种基金China Postdoctoral Science Foundation(No.2019M651743)Natural Science Foundation of Jiangsu Province(BK20190852,BK20190854)Natural Science Foundation for Jiangsu Colleges and Universities(19KJB530005).
文摘Oxidative desulfurization(ODS)has been proved to be an efficient strategy for the production of clean fuel oil.Numerous metal-based materials have been employed as excellent ODS catalysts,but being hindered by their high-cost and potential secondary pollution.In this work,we employed graphene analogous hexagonal boron nitride(h-BN)as a metal-free catalyst for ODS with hydrogen peroxide(H2O2)as the oxidant.The h-BN catalyst was characterized and proved to be a few-layered structure with relatively high specific surface areas.The h-BN catalyst showed a 99.4%of sulfur removal in fuel oil under the optimized reaction conditions.Besides,the h-BN can be recycled for 8 times without significant decrease in the catalytic performance.Detailed mechanism analysis found that it is the boron radicals in h-BN activated H2O2 to generate·OH species,which can readily oxidize sulfides to corresponding sulfones for separation.This work would provide another choice in choosing metal-free catalysts for ODS.
基金support from the National Natural Science Foundation of China(nos.21872041,21373091)the Science and Technology Project of Guangzhou city(no.201704030040)。
文摘Although scientists have conducted long-term and extensive studies on oxygen reduction reaction(ORR)catalyzed by metal-free carbon materials,they mainly have focused on the preparation and properties of various doped carbon materials.There is still a lack of systematic scientific guidance on the relationship between the surface structure regulation and activity of carbon-based catalysts.In this review,some of electrochemical and computational fundamental concepts about ORR are concisely summarized.The effects of edge defect and nonmetallic doping of carbon materials on ORR behavior and mechanism have been reviewed,and activity origin identification and intermediate conversion mechanism have been discussed.The outlooks for future researches on metal-free ORR electrocatalysis are suggested.
基金financially supported by the National Natural Science Foundation of China (NSFC) (Grant Nos. 11405253, 11225527, 11575283, 11205235, U1632129, U1332205)Shanghai Science Foundation (14YF1407500)the Youth Innovation Promotion Association CAS (2016237)
文摘The metal-free synthesis of graphene on singlecrystal silicon substrates, the most common commercial semiconductor, is of paramount significance for many technological applications. In this work, we report the growth of graphene directly on an upside-down placed,single-crystal silicon substrate using metal-free, ambientpressure chemical vapor deposition. By controlling the growth temperature, in-plane propagation, edge-propagation, and core-propagation, the process of graphene growth on silicon can be identified. This process produces atomically flat monolayer or bilayer graphene domains, concave bilayer graphene domains, and bulging few-layer graphene domains. This work would be a significant step toward the synthesis of large-area and layer-controlled, high-quality graphene on single-crystal silicon substrates.
基金the financial support provided by the National Natural Science Foundation of China(Grant Nos.51932005 and 21773269)the Joint Research Fund LiaoningShenyang National Laboratory for Materials Science(Grant No.20180510047)Liao Ning Revitalization Talents Program(XLYC1807175)。
文摘The oxygen reduction/evolution reactions(ORR/OER) are a key electrode process in the development of electrochemical energy conversion and storage devices,such as metal-air batteries and reversible fuel cells.The search for low-cost high-performance nanocarbon-based metal-free and non-precious metal bifunctional electrocatalysts for ORR/OER alternatives to the widely-used noble metal-based catalysts is a research focus.This review aims to outline the opportunities and available options for these nanocarbon-based bifunctional electrocatalysts.Through discussion of some current scientific issues,we summarize the development and breakthroughs of these electrocatalysts.Then we provide our perspectives on these issues and suggestions for some areas in the further work.We hope that this review can improve the interest in nanocarbon-based metal-free and non-precious metal bifunctional electrocatalysts for ORR/OER.
基金supported by the National Natural Science Foundation of China(Nos.22101105,52071171,52202248)the Research Fund for the Doctoral Program of Liaoning Province(2021-BS-086)+6 种基金Liaoning BaiQianWan Talents Program(LNBQW2018B0048)Shenyang Science and Technology Project(21-108-9-04)Australian Research Council(ARC)through Future Fellowship(FT210100298,FT210100806)Discovery Project(DP220100603)Linkage Project(LP210100467,LP210200504,LP210200345,LP220100088)Industrial Transformation Training Centre(IC180100005)schemesthe Australian Government through the Cooperative Research Centres Projects(CRCPXIII000077).
文摘Covalent organic frameworks(COFs)have emerged as a kind of rising star materials in photocatalysis.However,their photocatalytic activities are restricted by the high photogenerated electron-hole pairs recombination rate.Herein,a novel metal-free 2D/2D van der Waals heterojunction,composed of a two-dimensional(2D)COF with ketoenamine linkage(TpPa-1-COF)and 2D defective hexagonal boron nitride(h-BN),is successfully constructed through in situ solvothermal method.Benefitting from the presence of VDW heterojunction,larger contact area and intimate electronic coupling can be formed between the interface of TpPa-1-COF and defective h-BN,which make contributions to promoting charge car-riers separation.The introduced defects can also endow the h-BN with porous structure,thus providing more reactive sites.Moreover,the TpPa-1-COF will undergo a structural transformation after being integrated with defective h-BN,which can enlarge the gap between the conduction band position of the h-BN and TpPa-1-COF,and suppress electron backflow,corroborated by experimental and density functional theory calculations results.Accordingly,the resulting porous h-BN/TpPa-1-COF metal-free VDW heterojunction displays out-standing solar energy catalytic activity for water splitting without co-catalysts,and the H_(2) evolution rate can reach up to 3.15 mmol g^(−1) h^(−1),which is about 67 times greater than that of pristine TpPa-1-COF,also surpassing that of state-of-the-art metal-free-based photocatalysts reported to date.In particular,it is the first work for constructing COFs-based heterojunctions with the help of h-BN,which may provide new avenue for designing highly efficient metal-free-based photocatalysts for H_(2) evolution.
