Titania-based composite catalysts were prepared through a sol-gel route employing multi-walled carbon nanotubes with different diameters. The materials were characterized using thermogravimetric analysis, nitrogen ads...Titania-based composite catalysts were prepared through a sol-gel route employing multi-walled carbon nanotubes with different diameters. The materials were characterized using thermogravimetric analysis, nitrogen adsorption-desorption isotherm, powder X-ray diffraction, scanning electron microscopy, and diffuse reflectance UV-Vis absorption spectra. The application of the catalysts to photocatalytic degradation of phenol was tested under UV-Vis irradiation. A synergetic effect on phenol removal was observed in case of composite catalysts, which was evaluated in terms of apparent rate constant, total organic carbon removal and photonic efficiency.展开更多
TiO2/V2O5 catalyst doped with rare earth ions was prepared by sol-gel method. Titanium tetrapropoxide and vanadium pentoxide were used as precursor of the composite catalyst and rare earth ions were used as dopant. Th...TiO2/V2O5 catalyst doped with rare earth ions was prepared by sol-gel method. Titanium tetrapropoxide and vanadium pentoxide were used as precursor of the composite catalyst and rare earth ions were used as dopant. The crystal phases, crystalline sizes, microstructure, absorption spectra of doped composite catalyst were studied by XRD, EDS, FT-IR and UV-Vis. Photoactivity of the prepared catalyst under ultraviolet irradiation were evaluated by degradation of methyl orange （MO） in aqueous solution. It is shown that the prepared catalyst is composed of anatase and futile. The rare earth ions are highly dispersed in composite catalyst. All the doped catalysts appear higher photocatalytic activity than TiO2/V2O5 catalyst and catalyst doped with Ce^4＋ present the best activity to MO.展开更多
A series of La-doped TiO2 with different mass fractions were prepared by sol-gel method. Composite catalysts H3PW12O40/La-TiO2 with different loading levels were synthesized using impregnation method. The prepared sam...A series of La-doped TiO2 with different mass fractions were prepared by sol-gel method. Composite catalysts H3PW12O40/La-TiO2 with different loading levels were synthesized using impregnation method. The prepared samples were charac- terized by foutler transform infrared spectroscopy （FT-IR）, X-ray diffraction （XRD）, scanning electron microscopy （SEM）, UV vis diffuse reflectance spectroscopy （DRS） and nitrogen adsorption-desorption analysis. The Keggin structure of H3PWI2040 （HPW） re- mained intact on the surface of the composites, they had relatively uniform spherical grains of diameter less than 20 nm. The visible light activity of prepared composites were improved by loading HPW and doping La. The prepared composites were used as photo- catalysts in degradation of pesticide imidacloprid. Results revealed that 20%H3PWL204o/0.3%La-TiO2 possessed the best photocata- lyric activity. Thus, the degradation conversion of imidacloprid reached 98.17% after 60 rain irradiation when 20%H3PW12O4/0.3% La-TiO2 was used as catalysts. The degradation of imidacloprid corresponded with first-order kinetic reaction, and the half life of the degradation of imidacloprid was 9.35 min in the optimal conditions.展开更多
Syngas to aromatics(STA)over bifunctional catalysts has attracted much attention in recent years,but the mechanism underlying the formation of aromatics remains controversial.The critical reaction intermediates,carbox...Syngas to aromatics(STA)over bifunctional catalysts has attracted much attention in recent years,but the mechanism underlying the formation of aromatics remains controversial.The critical reaction intermediates,carboxylates,were first identified and then confirmed to essentially promote aromatization in the syngas conversion over a ZnCrAlO_(x)&H-ZSM-5 composite catalyst.This study provides evidence that the carboxylates can be formed during the reactions of formate species and olefins.In addition,it is shown that the carboxylates favor the formation of aromatics over H-ZSM-5 even in the presence of H2.A novel mechanism for the formation of aromatics via the generation and transformation of carboxylate intermediates is proposed,and the transformation of carboxylates to aromatics via methyl-2-cyclopenten-1-one(MCPO)intermediates is indeed likely.A better understanding of the formation mechanism of aromatics would help optimize the composite catalyst.展开更多
The utilization of metal oxide‐zeolite catalysts in the syngas‐to‐olefin reaction is a promising strategy for producing C_(2)–C_(4) olefins from non‐petroleum resources.However,the effect of the crystal phase of ...The utilization of metal oxide‐zeolite catalysts in the syngas‐to‐olefin reaction is a promising strategy for producing C_(2)–C_(4) olefins from non‐petroleum resources.However,the effect of the crystal phase of metal oxides on the catalytic activity of these oxides is still ambiguous.Herein,typical metal oxides(ZnO/ZrO_(2))with different crystal phases(monoclinic(m‐ZrO_(2))and tetragonal(t‐ZrO_(2)))were employed for syngas conversion.The(ZnO/m‐ZrO_(2)+SAPO‐34)composite catalyst exhibited 80.5%selectivity for C_(2)–C_(4) olefins at a CO conversion of 27.9%,where the results are superior to those(CO conversion of 16.4%and C_(2)–C_(4) olefin selectivity of 76.1%)obtained over(ZnO/t‐ZrO_(2)+SAPO‐34).The distinct differences are ascribed to the larger number of hydroxyl groups,Lewis acid sites,and oxygen defects in ZnO/m‐ZrO_(2) compared to ZnO/t‐ZrO_(2).These features result in the formation of more formate and methoxy intermediate species on the ZnO/m‐ZrO_(2) oxides during syngas conversion,followed by the formation of more light olefins over SAPO‐34.The present findings provide useful information for the design of highly efficient ZrO_(2)‐based catalysts for syngas conversion.展开更多
Pt-free counter electrode(CE) composed of La2 MoO(LaO-MoO) was successfully synthesized by simple pyrolysis of lanthanum acetate(CHOLa·xHO) and hexaammonium heptamolybdate tetrahydrate((NH4)6 MoO·4 HO). Furt...Pt-free counter electrode(CE) composed of La2 MoO(LaO-MoO) was successfully synthesized by simple pyrolysis of lanthanum acetate(CHOLa·xHO) and hexaammonium heptamolybdate tetrahydrate((NH4)6 MoO·4 HO). Furthermore,three proportions composites catalysts of La2 MoO@MWCNTs based on La2 MoOand multiwall carbon nanotubes(MWCNTs) were prepared and characterized as Ptfree catalyst for CE in dye-sensitized solar cells(DSSCs). The morphology and structure of La2 MoO@MWCNTs composites were determined by scanning electron microscopy, transmission electron microscope and X-ray diffraction. The electrochemical performance of La2 MoO@MWCNTs composite catalysts for CEs was determined by photocurrent-voltage measurements, cyclic voltammetry,electrochemical impedance spectroscopy, and Tafel polarization. The power conversion efficiencies of4.68%, 4.87% and 5.06% are obtained for La2 MoO:MWCNTs with the mass ratios of 5:1, 3:1 and 1:1 towards the reduction of I~-to I~-under the same conditions,respectively,which are superior to those of MWCNTs(3,94%) and La2 MoO(1.71%) electrodes. The experimental results reveal that the presence of MWCNTs results in an augmented active catalytic surface area and enhanced charge transfer from CE to the electrolyte.展开更多
Ethane conversion to ethylene and aromatics over Zn/zeolite catalysts is a promising technology for efficient exploitation of light alkanes. However, the reaction faces two major hurdles including the limited ethane c...Ethane conversion to ethylene and aromatics over Zn/zeolite catalysts is a promising technology for efficient exploitation of light alkanes. However, the reaction faces two major hurdles including the limited ethane conversion due to thermodynamics and the drastic catalyst deactivation by kinetical coke accumulation. Here we present a route to improve ethane conversion using a composite catalyst, involving Zn/HZSM-5 for ethane dehydroaromatization and CaMnO3-δperovskite for in situ selective hydrogen oxidation. The in situ H2 consumption shifts ethane dehydrogenation equilibrium to the desired side and can obviously increase the yield of target product. Furthermore, it is found that the in situ generated H2 O through H2 combustion can significantly suppress the coke formation and consequently enhance the stability of the composite catalyst. After 400 min reaction, a product yield of 23% was retained over the composite catalyst, almost a threefold increase with respect to the Zn/HZSM-5 reference(8%). It is anticipated that this novel composite catalyst combined with an efficient reactor technology may improve the viability of ethane aromatization in utilization.展开更多
High activity and productivity of MoVNbTeO_(x) catalyst are challenging tasks in oxidative dehydrogenation of ethane(ODHE)for industrial application.In this work,phase-pure M1 with 30 wt%CeO_(2) composite catalyst was...High activity and productivity of MoVNbTeO_(x) catalyst are challenging tasks in oxidative dehydrogenation of ethane(ODHE)for industrial application.In this work,phase-pure M1 with 30 wt%CeO_(2) composite catalyst was treated by oxygen plasma to further enhance catalyst performance.The results show that the oxygen vacancies generated by the solid-state redox reaction between M1 and CeO_(2) capture active oxygen species in gas and transform V^(4+)to V^(5+)without damage to M1 structure.The space-time yield of ethylene of the plasma-treated catalyst was significantly increased,in which the catalyst shows an enhancement near~100% than that of phase-pure M1 at 400℃ for ODHE process.Plasma treatment for catalysts demonstrates an effective way to convert electrical energy into chemical energy in catalyst materials.Energy conversion is achieved by using the catalyst as a medium.展开更多
Ce_(x)Co_(y)Cuzoxide composite catalysts were prepared by using polyethylene glycol, citrate sol-gel method combined with PMMA template for the oxidation of o-xylene. The catalysts were characterized by the Xray diffr...Ce_(x)Co_(y)Cuzoxide composite catalysts were prepared by using polyethylene glycol, citrate sol-gel method combined with PMMA template for the oxidation of o-xylene. The catalysts were characterized by the Xray diffraction(XRD), H2-temperature programmed reduction(H2-TPR), X-ray photoelectron spectroscopy(XPS) and Fourier transform infrared spectroscopy(FT-IR), etc. The catalytic activity for o-xylene was investigated. The catalytic degradation pathway and mechanism of o-xylene were inferred. The results show that Ce O_(2)is mainly present on the surface of all catalysts. The surface area of Ce_(2)Co1Cu1is up to 77.2 m^(2)/g, and the average pore size is 10.62 nm. It exhibits redox and sufficient Ce^(4+)and Ce^(^(3+)), and reactive oxygen species, and has maximum O-H and C=O in the five catalyst samples. The catalytic activity of Ce2Co1Cu1is the best at low temperature, with the T50and T90values of 235 and 258°C at a space velocity of 32000 h-1, respectively. The o-xylene is oxidized to o-methyl benzaldehyde, and then further oxidized to o-methylbenzoic acid, and finally CO_(2)and H2O are formed.展开更多
Framework materials such as zeolites and mesoporous silicas are commonly used for many applications,especially catalysis and separation.Here zeolite-mesoporous silica composite catalysts(employing zeolite Y,ZSM-5,KIT-...Framework materials such as zeolites and mesoporous silicas are commonly used for many applications,especially catalysis and separation.Here zeolite-mesoporous silica composite catalysts(employing zeolite Y,ZSM-5,KIT-6,SBA-15 and MCM-41 mesoporous silica)were prepared(with different weight percent of zeolite Y and ZSM-5)and assessed for catalytic cracking(using n-heptane,as the model compound at 550°C)with the aim to improve the selectivity/yield of light olefins of ethylene and propylene from n-heptane.Physicochemical properties of the parent zeolites and the prepared composites were characterized comprehensively using several techniques including X-ray diffraction,nitrogen physisorption,scanning electron microscopy,fourier transform infrared spectroscopy,pulsed-field gradient nuclear magnetic resonance and thermogravimetric analysis.Catalytic cracking results showed that the ZY/ZSM-5/KIT-6 composite(20:20:60 wt%)achieved a high n-heptane conversion of 85%with approximately 6%selectivity to ethylene/propylene.In contrast,the ZY/ZSM-5/SBA-15 composite achieved a higher conversion of 95%and an ethylene/propylene ratio of 8%,indicating a more efficient process in terms of both conversion and selectivity.Magnetic resonance relaxation analysis of the ZY/ZSM-5/KIT-6(20:20:60)catalyst confirmed a micro-mesoporous environment that influences n-heptane diffusion and mass transfer.As zeolite Y and ZSM-5 have micropores,n-heptane can move and undergo hydrogen transfer reactions,whereas KIT-6 has mesopores that facilitate n-heptane’s accessibility to the active sites of zeolite Y and ZSM-5.展开更多
Owing to outstanding hydrophilicity and ionic interaction,layered double hydroxides(LDHs)have emerged as a promising carrier for high performance catalysts.However,the synthesis of new specialized catalytic LDHs for d...Owing to outstanding hydrophilicity and ionic interaction,layered double hydroxides(LDHs)have emerged as a promising carrier for high performance catalysts.However,the synthesis of new specialized catalytic LDHs for degradation of antibiotics still faces some challenges.In this study,a CoFe_(2)O_(4)/MgAl-LDH composite catalyst was synthesized using a hydrothermal coprecipitation method.Comprehensive characterization reveals that the surface of MgAl-LDH is covered with nanometer CoFe_(2)O_(4) particles.The specific surface area of CoFe_(2)O_(4)/MgAl-LDH is 82.84 m^(2)·g^(-)1,which is 2.34 times that of CoFe_(2)O_(4).CoFe_(2)O_(4)/MgAl-LDH has a saturation magnetic strength of 22.24 A·m^(2)·kg^(-1) facilitating efficient solid-liquid separation.The composite catalyst was employed to activate peroxymonosulfate(PMS)for the efficient degradation of tetracycline hydrochloride(TCH).It is found that the catalytic performance of CoFe_(2)O_(4)/MgAl-LDH significantly exceeds that of CoFe_(2)O_(4).The maximum TCH removal reaches 98.2%under the optimal conditions([TCH]=25 mg/L,[PMS]=1.5 mmol/L,CoFe_(2)O_(4)/MgAl-LDH=0.20 g/L,pH 7,and T=25℃).Coexisting ions in the solution,such as SO_(4)^(2-),Cl-,H_(2)PO_(4)^(-),and CO_(3)^(2-),have a negligible effect on catalytic performance.Cyclic tests demonstrate that the catalytic performance of CoFe_(2)O_(4)/MgAl-LDH remains 67.2%after five cycles.Mechanism investigations suggest that O_(2)^(•-)and ^(1)O_(2) produced by CoFe_(2)O_(4)/MgAl-LDH play a critical role in the catalytic degradation.展开更多
Electrocatalysis for nitrate(NO_(3^(–)))removal from wastewater faces the challenge of merging efficient reduction and high selectivity to nitrogen(N2)with economic viability in a durable catalyst.In this study,bimet...Electrocatalysis for nitrate(NO_(3^(–)))removal from wastewater faces the challenge of merging efficient reduction and high selectivity to nitrogen(N2)with economic viability in a durable catalyst.In this study,bimetallic PdCu/TiO_(x)composite catalysts were synthesized with varying Pd and Cu ratios through electrochemical deposition on defective TiOxnanotube arrays.Denitrification experiments demonstrated that the Pd_(1)Cu_(1)/TiO_(x)catalyst exhibited the highest(NO_(3^(–)))removal rate(81.2%)and N_(2)selectivity(67.2%)among all tested catalysts.Leveraging the exceptional light-responsive property of TiO_(x),the introduction of light energy as an assisting factor in electrocatalysis further augmented the(NO_(3^(–)))treatment rate,resulting in a higher(NO_(3^(–)))removal rate of 95.1%and N_(2)selectivity of approximately 90%.Compared to individual electrocatalysis and photocatalysis systems,the overpotential for the catalytic interface active*H formation in the photo-assisted electrocatalysis system was remarkably reduced,thus accelerating electron migration and promoting(NO_(3^(–)))reduction kinetics.Economic analysis revealed an energy consumption of 2.74 k Wh/mol and a corresponding energy consumption per order(EEO)of 0.79 k Wh/m^(3)for the Pd_(1)Cu_(1)/TiOxcatalyst to reduce 25.2 mg/L of(NO_(3^(–)))-N in water to N_(2),showcasing remarkable competitiveness and economic advantages over other water treatment technologies.This study developed the PdCu/TiOxelectrocatalysts with high(NO_(3^(–)))removal rates and N_(2)selectivity,particularly when combined with light energy,the efficiency and selectivity were significantly enhanced,offering a competitive and economically viable solution for wastewater treatment.展开更多
The perfluorosulfonic acid （PFSA）/SiO2 composite catalysts were prepared by sol-gel method. Differences concerning pore structure analysis of PFSA/SiO2 catalysts were discussed on the basis of nitrogen adsorption. T...The perfluorosulfonic acid （PFSA）/SiO2 composite catalysts were prepared by sol-gel method. Differences concerning pore structure analysis of PFSA/SiO2 catalysts were discussed on the basis of nitrogen adsorption. Their surface area and pore size distributions were evaluated by Brunauer-Emmett-Teller （BET） and Barrett-Joyner-Halenda （BJH） methods, respectively. The nitrogen adsorption-desorption isotherms associated with adsorption hysteresis of PFSA/SiO2 catalysts were analyzed in detail. The adsorption isotherms of PFSA/SiOe catalysts belonged to Type IV isotherms accompanied by hysteresis loops of Type H1 for PFSA/SiO2 catalysts with content of 5%, 13% and 20% PFSA （PFSA-5, PFSA-13 and PFSA-20）, and the hysteresis loop of Type H2 for PFSA/SiO2 catalyst with 40% PFSA content （PFSA-40）. It indicated that PFSA-5, PFSA-13 and PFSA-20 catalysts had narrow pore size distributions and the well-defined cylindrical pores, while PFSA-40 catalyst had wide pore size distribution and inkbottle-like pores. The pore structure of PFSA-40 catalyst from the analysis of the hysteresis loop was not in agreement with that from BJH method. As an emendation for evaluation of pore size distributions of PFSA/SiOz catalysts, the comparison plots method was introduced, which was helpful to evaluate the pore structure of PFSA/SiO2 catalysts more factually.展开更多
Searching for effective hydrogen evolution reaction(HER)electrocatalysts is crucial for water splitting.Transition metal nitrides(TMNs)are very attractive potential candidates since of high electrical conductivity,rob...Searching for effective hydrogen evolution reaction(HER)electrocatalysts is crucial for water splitting.Transition metal nitrides(TMNs)are very attractive potential candidates since of high electrical conductivity,robust stability,element rich and high activity.Antiperovskite metal nitrides provide chemical flexibility since two different types of transition metal elements are contained,allowing partial substitution both for A-and M-sites.Herein,we report a novel antiperovskite metal nitride Ag_(x)Ni_(1-x)NNi_(3)(0≤x≤0.80)thin film used as highly effective HER electrocatalysts.Pure phase antiperovskite nitride can be successfully obtained for Ag_(x)Ni_(1-x)NNi_(3)with x less than 0.80.The Ag_(0.76)Ni_(0.24)NNi_(3) towards HER shows an overpotential of 122 mV at 10 mA cm^(-2)in alkaline media.Furthermore,considering the role of Ag for adsorbing hydroxyl groups,chemical engineering has been carried out for designing metal/antiperovskite nitride Ag/Ag_(x)Ni_(1-x)NNi_(3)composite electrocatalysts.The 0.18 Ag/Ag_(0.80)Ni_(0.20)NNi_(3)electrocatalyst shows a mere 13 and 81 mV of overpotential to reach 1 and 10 mA cm^(-2),respectively,showing high durability in alkaline media.These results will provide a novel type of HER catalysts based on antiperovskite metal nitrides and a strategic design for metal/antiperovskite metal nitride composite electrocatalysts for HER in alkaline media.展开更多
Transition metal Ni anchored in carbon material represents outstanding 2e^(-) oxygen reduction reaction(ORR)catalytic selectivity,but enhancing the adsorption strength of intermediate*OOH to promote its selectivity re...Transition metal Ni anchored in carbon material represents outstanding 2e^(-) oxygen reduction reaction(ORR)catalytic selectivity,but enhancing the adsorption strength of intermediate*OOH to promote its selectivity remains a major challenge.Herein,the NiX/Ni@NCHS composite catalyst with heteroatom doping(O,S)is modulated by controlling partial pyrolysis strategies on honeycomb-like porous carbon to manipulate the electronic structure of the metal Ni.With the synergistic effect of honeycomb structure and O atom,NiO/Ni@NCHS-700 exhibits an exceptional H_(2)O_(2)selectivity of above 89.1%across a wide potential range from 0.1 to 0.6 V in an alkaline electrolyte,and an unexpected H_(2)O_(2)production rate up to 1.47 mol gcat^(-1) h^(-1)@0.2 V,which outperforms most of the state-of-the-art catalyst.Meanwhile,NiS/Ni@NCHS exhibits excellent electrocatalytic performance,with 2e^(-) ORR selectivity of 91.3%,H_(2)O_(2)yield of 1.85@0.3 V.Density functional theory simulations and experiments results reveal that the heteroatom doping(O,S)method has been employed to regulate the adsorption strength of Ni atoms with*OOH,and combined with the self-sacrificing template-assisted pyrolysis approach to improve the microstructure of catalysts and optimize the active site.The heteroatom doping method in this work provides significant guidance for promoting 2e^(-) ORR electrocatalysis to produce H_(2)O_(2).展开更多
Novel composite material with a wide pore distribution was synthesized by an in situ technique using spent FCC catalyst as raw material. The characterization results indicated that the composite material contained 56....Novel composite material with a wide pore distribution was synthesized by an in situ technique using spent FCC catalyst as raw material. The characterization results indicated that the composite material contained 56.7% of zeolite Y and exhibited a much larger specific surface area and pore volume as well as strong hydrothermal stability. Fluid catalytic cracking(FCC) catalyst was prepared based on the composite material. The results indicated that the as-prepared catalyst possessed a unique pore structure that was advantageous to the diffusion-controlled reactions. In addition, the attrition resistance, activity and hydrothermal stability of the studied catalyst were superior to those of the reference catalyst. The catalyst also exhibited excellent nickel and vanadium passivation performance, strong bottoms upgrading selectivity, and better gasoline and coke selectivity. In comparison to the reference catalyst, the yields of the gasoline and light oil increased by 1.61 and 1.31 percentage points, respectively, and the coke yield decreased by 0.22 percentage points, and the olefin content in the produced gasoline reduced by 2.51 percentage points, with the research octane number increased by 0.7 unit.展开更多
The composite ZSM—5 zeolite/vermiculite catalyst,in which tiny ZSM—5 zeolite parti- cles embedded in the vermiculite substrate,has been synthesized by hydrothermal method with vermiculite as silicon source.The catal...The composite ZSM—5 zeolite/vermiculite catalyst,in which tiny ZSM—5 zeolite parti- cles embedded in the vermiculite substrate,has been synthesized by hydrothermal method with vermiculite as silicon source.The catalytic behavior of resulting catalyst for xylene isomerization,propylene aromatization and toluene disproportionation is better than that of HZSM—5 zeolite.展开更多
Formation of a p–n heterojunction rather than p-type or n-type semiconductors can enhance the separation of photogenerated electrons and holes and increase the quantum efficiency of photocatalytic reactions owing to ...Formation of a p–n heterojunction rather than p-type or n-type semiconductors can enhance the separation of photogenerated electrons and holes and increase the quantum efficiency of photocatalytic reactions owing to the difference of the electric potential in the inner electric field near the junction,pointing from n toward p. n-Ag3PO4/p-Ag2CO3 p–n heterojunction composites are prepared through a facile coprecipitation process. The obtained Ag3PO4/Ag2CO3 p–n heterojunctions exhibit excellent photocatalytic performance in the removal of rhodamine B（RhB） compared with Ag3PO4 and Ag2CO3. The 40%-Ag3PO4/Ag2CO3 composite photocatalyst（40 mol% Ag3PO4 and 60 mol% Ag2CO3） exhibits the best photocatalytic activity under visible light,demonstrating the ability to completely degrade RhB within 15 min. Transient photovoltage characterization and an active species trapping experiment further indicate that the formation of a p–n heterojunction structure can greatly enhance the separation efficiency of photogenerated carriers and produce more free h＋active species,which is the predominant contributor for RhB removal.展开更多
Over the past decade,electrocatalytic reduction of CO_(2)has gained substantial attention.However,hardly any of the previous reviews have focused on the systematic discussion of polymer-molecular catalyst composites a...Over the past decade,electrocatalytic reduction of CO_(2)has gained substantial attention.However,hardly any of the previous reviews have focused on the systematic discussion of polymer-molecular catalyst composites as an emerging system for the electrochemical transformation of CO_(2)to value-added products.In this review,we first give a brief overview of the general features of solid-state and molecular catalysts,and then advance the discussion to polymer-catalyst composite systems,with particular emphasis on polymer-encapsulated molecular catalysts,where the coordination environment surrounding molecular catalysts can be modified via polymer encapsulation to promote the overall performance of CO_(2)electrocatalysis.The elucidation of the possible reaction mechanisms of this emerging electrocat-alytic system along with proposed optimization strategies is also summarized and discussed based on recently published reports,followed by the challenges and prospects of their industrial applications at the end of this review.From this review,we hope the audience can gain a comprehensive understanding of the electrocatalytic mechanism of the coordinating polymers and valuable insights into engineering the microenvironment surrounding the metal complexes for potential future research directions.展开更多
The hollow α-MnO2 nanoneedle-based microspheres coated with Pd nanoparticles were reported as a novel catalyst for rechargeable lithium-air batteries. The hollow microspheres are composed ofα-MnO2 nanoneedles. Pd na...The hollow α-MnO2 nanoneedle-based microspheres coated with Pd nanoparticles were reported as a novel catalyst for rechargeable lithium-air batteries. The hollow microspheres are composed ofα-MnO2 nanoneedles. Pd nanoparticles are deposited on the hollow microspheres through an aqueous-solution reduction of PdCl2 with NaBH4 at room temperature. The results of TEM, XRD, and EDS show that the Pd nanoparticles are coated on the surface ofα-MnO2 nanoneedles uniformly and the mass fraction of Pd in the Pd-coated α-MnO2 catalyst is about 8.88%. Compared with the counterpart of the hollow α-MnO2 catalyst, the hollow Pd-coated α-MnO2 catalyst improves the energy conversion efficiency and the charge-discharge cycling performance of the air electrode. The initial specific discharge capacity of an air electrode composed of Super P carbon and the as-prepared Pd-coatedα-MnO2 catalyst is 1220 mA＆#183;h/g （based on the total electrode mass） at a current density of 0.1 mA/cm2, and the capacity retention rate is about 47.3% after 13 charge-discharge cycles. The results of charge-discharge cycling tests demonstrate that this novel Pd-coatedα-MnO2 catalyst with a hierarchical core-shell structure is a promising catalyst for the lithium-air battery.展开更多
基金ACKNOWLEDGMENT This work was supported Science Foundation of China by the National Natural （No.20703042）.
文摘Titania-based composite catalysts were prepared through a sol-gel route employing multi-walled carbon nanotubes with different diameters. The materials were characterized using thermogravimetric analysis, nitrogen adsorption-desorption isotherm, powder X-ray diffraction, scanning electron microscopy, and diffuse reflectance UV-Vis absorption spectra. The application of the catalysts to photocatalytic degradation of phenol was tested under UV-Vis irradiation. A synergetic effect on phenol removal was observed in case of composite catalysts, which was evaluated in terms of apparent rate constant, total organic carbon removal and photonic efficiency.
基金Project supported by the National Natural Science Foundation of China (50571003)
文摘TiO2/V2O5 catalyst doped with rare earth ions was prepared by sol-gel method. Titanium tetrapropoxide and vanadium pentoxide were used as precursor of the composite catalyst and rare earth ions were used as dopant. The crystal phases, crystalline sizes, microstructure, absorption spectra of doped composite catalyst were studied by XRD, EDS, FT-IR and UV-Vis. Photoactivity of the prepared catalyst under ultraviolet irradiation were evaluated by degradation of methyl orange （MO） in aqueous solution. It is shown that the prepared catalyst is composed of anatase and futile. The rare earth ions are highly dispersed in composite catalyst. All the doped catalysts appear higher photocatalytic activity than TiO2/V2O5 catalyst and catalyst doped with Ce^4＋ present the best activity to MO.
基金supported by Institution of Chemical Materials,China Academy of Engineering Physics
文摘A series of La-doped TiO2 with different mass fractions were prepared by sol-gel method. Composite catalysts H3PW12O40/La-TiO2 with different loading levels were synthesized using impregnation method. The prepared samples were charac- terized by foutler transform infrared spectroscopy （FT-IR）, X-ray diffraction （XRD）, scanning electron microscopy （SEM）, UV vis diffuse reflectance spectroscopy （DRS） and nitrogen adsorption-desorption analysis. The Keggin structure of H3PWI2040 （HPW） re- mained intact on the surface of the composites, they had relatively uniform spherical grains of diameter less than 20 nm. The visible light activity of prepared composites were improved by loading HPW and doping La. The prepared composites were used as photo- catalysts in degradation of pesticide imidacloprid. Results revealed that 20%H3PWL204o/0.3%La-TiO2 possessed the best photocata- lyric activity. Thus, the degradation conversion of imidacloprid reached 98.17% after 60 rain irradiation when 20%H3PW12O4/0.3% La-TiO2 was used as catalysts. The degradation of imidacloprid corresponded with first-order kinetic reaction, and the half life of the degradation of imidacloprid was 9.35 min in the optimal conditions.
文摘Syngas to aromatics(STA)over bifunctional catalysts has attracted much attention in recent years,but the mechanism underlying the formation of aromatics remains controversial.The critical reaction intermediates,carboxylates,were first identified and then confirmed to essentially promote aromatization in the syngas conversion over a ZnCrAlO_(x)&H-ZSM-5 composite catalyst.This study provides evidence that the carboxylates can be formed during the reactions of formate species and olefins.In addition,it is shown that the carboxylates favor the formation of aromatics over H-ZSM-5 even in the presence of H2.A novel mechanism for the formation of aromatics via the generation and transformation of carboxylate intermediates is proposed,and the transformation of carboxylates to aromatics via methyl-2-cyclopenten-1-one(MCPO)intermediates is indeed likely.A better understanding of the formation mechanism of aromatics would help optimize the composite catalyst.
文摘The utilization of metal oxide‐zeolite catalysts in the syngas‐to‐olefin reaction is a promising strategy for producing C_(2)–C_(4) olefins from non‐petroleum resources.However,the effect of the crystal phase of metal oxides on the catalytic activity of these oxides is still ambiguous.Herein,typical metal oxides(ZnO/ZrO_(2))with different crystal phases(monoclinic(m‐ZrO_(2))and tetragonal(t‐ZrO_(2)))were employed for syngas conversion.The(ZnO/m‐ZrO_(2)+SAPO‐34)composite catalyst exhibited 80.5%selectivity for C_(2)–C_(4) olefins at a CO conversion of 27.9%,where the results are superior to those(CO conversion of 16.4%and C_(2)–C_(4) olefin selectivity of 76.1%)obtained over(ZnO/t‐ZrO_(2)+SAPO‐34).The distinct differences are ascribed to the larger number of hydroxyl groups,Lewis acid sites,and oxygen defects in ZnO/m‐ZrO_(2) compared to ZnO/t‐ZrO_(2).These features result in the formation of more formate and methoxy intermediate species on the ZnO/m‐ZrO_(2) oxides during syngas conversion,followed by the formation of more light olefins over SAPO‐34.The present findings provide useful information for the design of highly efficient ZrO_(2)‐based catalysts for syngas conversion.
基金Project supported by the National Natural Science Foundation of China(21473048 and 21303039)the Natural Science Foundation of Hebei Province(B2015205163,B2016205161)the 2015 Hebei Province Undergraduate Training Programs for Innovation and Entrepreneurship
文摘Pt-free counter electrode(CE) composed of La2 MoO(LaO-MoO) was successfully synthesized by simple pyrolysis of lanthanum acetate(CHOLa·xHO) and hexaammonium heptamolybdate tetrahydrate((NH4)6 MoO·4 HO). Furthermore,three proportions composites catalysts of La2 MoO@MWCNTs based on La2 MoOand multiwall carbon nanotubes(MWCNTs) were prepared and characterized as Ptfree catalyst for CE in dye-sensitized solar cells(DSSCs). The morphology and structure of La2 MoO@MWCNTs composites were determined by scanning electron microscopy, transmission electron microscope and X-ray diffraction. The electrochemical performance of La2 MoO@MWCNTs composite catalysts for CEs was determined by photocurrent-voltage measurements, cyclic voltammetry,electrochemical impedance spectroscopy, and Tafel polarization. The power conversion efficiencies of4.68%, 4.87% and 5.06% are obtained for La2 MoO:MWCNTs with the mass ratios of 5:1, 3:1 and 1:1 towards the reduction of I~-to I~-under the same conditions,respectively,which are superior to those of MWCNTs(3,94%) and La2 MoO(1.71%) electrodes. The experimental results reveal that the presence of MWCNTs results in an augmented active catalytic surface area and enhanced charge transfer from CE to the electrolyte.
基金Financial support from the National Natural Science Foundation of China (grant 21606249, 21536005)the Director Innovation Fund of Key Laboratory of Biofuels, Chinese Academy of Sciences (grant Y57201190V)QIBEBT and Dalian National Laboratory For Clean Energy (DNL), CAS (Grant QIBEBT I201924)。
文摘Ethane conversion to ethylene and aromatics over Zn/zeolite catalysts is a promising technology for efficient exploitation of light alkanes. However, the reaction faces two major hurdles including the limited ethane conversion due to thermodynamics and the drastic catalyst deactivation by kinetical coke accumulation. Here we present a route to improve ethane conversion using a composite catalyst, involving Zn/HZSM-5 for ethane dehydroaromatization and CaMnO3-δperovskite for in situ selective hydrogen oxidation. The in situ H2 consumption shifts ethane dehydrogenation equilibrium to the desired side and can obviously increase the yield of target product. Furthermore, it is found that the in situ generated H2 O through H2 combustion can significantly suppress the coke formation and consequently enhance the stability of the composite catalyst. After 400 min reaction, a product yield of 23% was retained over the composite catalyst, almost a threefold increase with respect to the Zn/HZSM-5 reference(8%). It is anticipated that this novel composite catalyst combined with an efficient reactor technology may improve the viability of ethane aromatization in utilization.
基金supported by the National Natural Science Foundation of China (No.21776156).
文摘High activity and productivity of MoVNbTeO_(x) catalyst are challenging tasks in oxidative dehydrogenation of ethane(ODHE)for industrial application.In this work,phase-pure M1 with 30 wt%CeO_(2) composite catalyst was treated by oxygen plasma to further enhance catalyst performance.The results show that the oxygen vacancies generated by the solid-state redox reaction between M1 and CeO_(2) capture active oxygen species in gas and transform V^(4+)to V^(5+)without damage to M1 structure.The space-time yield of ethylene of the plasma-treated catalyst was significantly increased,in which the catalyst shows an enhancement near~100% than that of phase-pure M1 at 400℃ for ODHE process.Plasma treatment for catalysts demonstrates an effective way to convert electrical energy into chemical energy in catalyst materials.Energy conversion is achieved by using the catalyst as a medium.
基金Project supported by the Zhejiang Provincial Natural Science Foundation of China (LY20E080003)。
文摘Ce_(x)Co_(y)Cuzoxide composite catalysts were prepared by using polyethylene glycol, citrate sol-gel method combined with PMMA template for the oxidation of o-xylene. The catalysts were characterized by the Xray diffraction(XRD), H2-temperature programmed reduction(H2-TPR), X-ray photoelectron spectroscopy(XPS) and Fourier transform infrared spectroscopy(FT-IR), etc. The catalytic activity for o-xylene was investigated. The catalytic degradation pathway and mechanism of o-xylene were inferred. The results show that Ce O_(2)is mainly present on the surface of all catalysts. The surface area of Ce_(2)Co1Cu1is up to 77.2 m^(2)/g, and the average pore size is 10.62 nm. It exhibits redox and sufficient Ce^(4+)and Ce^(^(3+)), and reactive oxygen species, and has maximum O-H and C=O in the five catalyst samples. The catalytic activity of Ce2Co1Cu1is the best at low temperature, with the T50and T90values of 235 and 258°C at a space velocity of 32000 h-1, respectively. The o-xylene is oxidized to o-methyl benzaldehyde, and then further oxidized to o-methylbenzoic acid, and finally CO_(2)and H2O are formed.
基金China Scholarship Council for his PhD secondment at The University of Manchester(CSC file No.201906120207).
文摘Framework materials such as zeolites and mesoporous silicas are commonly used for many applications,especially catalysis and separation.Here zeolite-mesoporous silica composite catalysts(employing zeolite Y,ZSM-5,KIT-6,SBA-15 and MCM-41 mesoporous silica)were prepared(with different weight percent of zeolite Y and ZSM-5)and assessed for catalytic cracking(using n-heptane,as the model compound at 550°C)with the aim to improve the selectivity/yield of light olefins of ethylene and propylene from n-heptane.Physicochemical properties of the parent zeolites and the prepared composites were characterized comprehensively using several techniques including X-ray diffraction,nitrogen physisorption,scanning electron microscopy,fourier transform infrared spectroscopy,pulsed-field gradient nuclear magnetic resonance and thermogravimetric analysis.Catalytic cracking results showed that the ZY/ZSM-5/KIT-6 composite(20:20:60 wt%)achieved a high n-heptane conversion of 85%with approximately 6%selectivity to ethylene/propylene.In contrast,the ZY/ZSM-5/SBA-15 composite achieved a higher conversion of 95%and an ethylene/propylene ratio of 8%,indicating a more efficient process in terms of both conversion and selectivity.Magnetic resonance relaxation analysis of the ZY/ZSM-5/KIT-6(20:20:60)catalyst confirmed a micro-mesoporous environment that influences n-heptane diffusion and mass transfer.As zeolite Y and ZSM-5 have micropores,n-heptane can move and undergo hydrogen transfer reactions,whereas KIT-6 has mesopores that facilitate n-heptane’s accessibility to the active sites of zeolite Y and ZSM-5.
基金University Synergy Innovation Program of Anhui Province(GXXT-2022-083)Science and Technology Plan Project of Wuhu City,China(2023kx12)Anhui Provincial Department of Education New Era Education Project(2023xscx070)。
文摘Owing to outstanding hydrophilicity and ionic interaction,layered double hydroxides(LDHs)have emerged as a promising carrier for high performance catalysts.However,the synthesis of new specialized catalytic LDHs for degradation of antibiotics still faces some challenges.In this study,a CoFe_(2)O_(4)/MgAl-LDH composite catalyst was synthesized using a hydrothermal coprecipitation method.Comprehensive characterization reveals that the surface of MgAl-LDH is covered with nanometer CoFe_(2)O_(4) particles.The specific surface area of CoFe_(2)O_(4)/MgAl-LDH is 82.84 m^(2)·g^(-)1,which is 2.34 times that of CoFe_(2)O_(4).CoFe_(2)O_(4)/MgAl-LDH has a saturation magnetic strength of 22.24 A·m^(2)·kg^(-1) facilitating efficient solid-liquid separation.The composite catalyst was employed to activate peroxymonosulfate(PMS)for the efficient degradation of tetracycline hydrochloride(TCH).It is found that the catalytic performance of CoFe_(2)O_(4)/MgAl-LDH significantly exceeds that of CoFe_(2)O_(4).The maximum TCH removal reaches 98.2%under the optimal conditions([TCH]=25 mg/L,[PMS]=1.5 mmol/L,CoFe_(2)O_(4)/MgAl-LDH=0.20 g/L,pH 7,and T=25℃).Coexisting ions in the solution,such as SO_(4)^(2-),Cl-,H_(2)PO_(4)^(-),and CO_(3)^(2-),have a negligible effect on catalytic performance.Cyclic tests demonstrate that the catalytic performance of CoFe_(2)O_(4)/MgAl-LDH remains 67.2%after five cycles.Mechanism investigations suggest that O_(2)^(•-)and ^(1)O_(2) produced by CoFe_(2)O_(4)/MgAl-LDH play a critical role in the catalytic degradation.
基金the National Natural Science Foundation of China(No.52300084)China Postdoctoral Science Foundation(No.2023M741151)the Fundamental Research Funds for the Central Universities(No.2024MS063)。
文摘Electrocatalysis for nitrate(NO_(3^(–)))removal from wastewater faces the challenge of merging efficient reduction and high selectivity to nitrogen(N2)with economic viability in a durable catalyst.In this study,bimetallic PdCu/TiO_(x)composite catalysts were synthesized with varying Pd and Cu ratios through electrochemical deposition on defective TiOxnanotube arrays.Denitrification experiments demonstrated that the Pd_(1)Cu_(1)/TiO_(x)catalyst exhibited the highest(NO_(3^(–)))removal rate(81.2%)and N_(2)selectivity(67.2%)among all tested catalysts.Leveraging the exceptional light-responsive property of TiO_(x),the introduction of light energy as an assisting factor in electrocatalysis further augmented the(NO_(3^(–)))treatment rate,resulting in a higher(NO_(3^(–)))removal rate of 95.1%and N_(2)selectivity of approximately 90%.Compared to individual electrocatalysis and photocatalysis systems,the overpotential for the catalytic interface active*H formation in the photo-assisted electrocatalysis system was remarkably reduced,thus accelerating electron migration and promoting(NO_(3^(–)))reduction kinetics.Economic analysis revealed an energy consumption of 2.74 k Wh/mol and a corresponding energy consumption per order(EEO)of 0.79 k Wh/m^(3)for the Pd_(1)Cu_(1)/TiOxcatalyst to reduce 25.2 mg/L of(NO_(3^(–)))-N in water to N_(2),showcasing remarkable competitiveness and economic advantages over other water treatment technologies.This study developed the PdCu/TiOxelectrocatalysts with high(NO_(3^(–)))removal rates and N_(2)selectivity,particularly when combined with light energy,the efficiency and selectivity were significantly enhanced,offering a competitive and economically viable solution for wastewater treatment.
基金supported by the National Basic Research Program of China (2003CB615705)Chemistry & Chemical Technology Research Center Plan of Shanghai Huayi Group Company (A200-8608 and A200-80726)
文摘The perfluorosulfonic acid （PFSA）/SiO2 composite catalysts were prepared by sol-gel method. Differences concerning pore structure analysis of PFSA/SiO2 catalysts were discussed on the basis of nitrogen adsorption. Their surface area and pore size distributions were evaluated by Brunauer-Emmett-Teller （BET） and Barrett-Joyner-Halenda （BJH） methods, respectively. The nitrogen adsorption-desorption isotherms associated with adsorption hysteresis of PFSA/SiO2 catalysts were analyzed in detail. The adsorption isotherms of PFSA/SiOe catalysts belonged to Type IV isotherms accompanied by hysteresis loops of Type H1 for PFSA/SiO2 catalysts with content of 5%, 13% and 20% PFSA （PFSA-5, PFSA-13 and PFSA-20）, and the hysteresis loop of Type H2 for PFSA/SiO2 catalyst with 40% PFSA content （PFSA-40）. It indicated that PFSA-5, PFSA-13 and PFSA-20 catalysts had narrow pore size distributions and the well-defined cylindrical pores, while PFSA-40 catalyst had wide pore size distribution and inkbottle-like pores. The pore structure of PFSA-40 catalyst from the analysis of the hysteresis loop was not in agreement with that from BJH method. As an emendation for evaluation of pore size distributions of PFSA/SiOz catalysts, the comparison plots method was introduced, which was helpful to evaluate the pore structure of PFSA/SiO2 catalysts more factually.
基金financially supported by the National Key R&D Program of China(Nos.2016YFA0401801 and 2014CB931704)the Natural Science Foundation of Anhui Province(No.1608085QE107)+1 种基金the Key Research Program of Frontier Sciences,CAS(No.QYZDB-SSW-SLH015)supported by the Youth Innovation Promotion Association of CAS(No.2014283)。
文摘Searching for effective hydrogen evolution reaction(HER)electrocatalysts is crucial for water splitting.Transition metal nitrides(TMNs)are very attractive potential candidates since of high electrical conductivity,robust stability,element rich and high activity.Antiperovskite metal nitrides provide chemical flexibility since two different types of transition metal elements are contained,allowing partial substitution both for A-and M-sites.Herein,we report a novel antiperovskite metal nitride Ag_(x)Ni_(1-x)NNi_(3)(0≤x≤0.80)thin film used as highly effective HER electrocatalysts.Pure phase antiperovskite nitride can be successfully obtained for Ag_(x)Ni_(1-x)NNi_(3)with x less than 0.80.The Ag_(0.76)Ni_(0.24)NNi_(3) towards HER shows an overpotential of 122 mV at 10 mA cm^(-2)in alkaline media.Furthermore,considering the role of Ag for adsorbing hydroxyl groups,chemical engineering has been carried out for designing metal/antiperovskite nitride Ag/Ag_(x)Ni_(1-x)NNi_(3)composite electrocatalysts.The 0.18 Ag/Ag_(0.80)Ni_(0.20)NNi_(3)electrocatalyst shows a mere 13 and 81 mV of overpotential to reach 1 and 10 mA cm^(-2),respectively,showing high durability in alkaline media.These results will provide a novel type of HER catalysts based on antiperovskite metal nitrides and a strategic design for metal/antiperovskite metal nitride composite electrocatalysts for HER in alkaline media.
文摘Transition metal Ni anchored in carbon material represents outstanding 2e^(-) oxygen reduction reaction(ORR)catalytic selectivity,but enhancing the adsorption strength of intermediate*OOH to promote its selectivity remains a major challenge.Herein,the NiX/Ni@NCHS composite catalyst with heteroatom doping(O,S)is modulated by controlling partial pyrolysis strategies on honeycomb-like porous carbon to manipulate the electronic structure of the metal Ni.With the synergistic effect of honeycomb structure and O atom,NiO/Ni@NCHS-700 exhibits an exceptional H_(2)O_(2)selectivity of above 89.1%across a wide potential range from 0.1 to 0.6 V in an alkaline electrolyte,and an unexpected H_(2)O_(2)production rate up to 1.47 mol gcat^(-1) h^(-1)@0.2 V,which outperforms most of the state-of-the-art catalyst.Meanwhile,NiS/Ni@NCHS exhibits excellent electrocatalytic performance,with 2e^(-) ORR selectivity of 91.3%,H_(2)O_(2)yield of 1.85@0.3 V.Density functional theory simulations and experiments results reveal that the heteroatom doping(O,S)method has been employed to regulate the adsorption strength of Ni atoms with*OOH,and combined with the self-sacrificing template-assisted pyrolysis approach to improve the microstructure of catalysts and optimize the active site.The heteroatom doping method in this work provides significant guidance for promoting 2e^(-) ORR electrocatalysis to produce H_(2)O_(2).
基金provided by the National Natural Science Foundation of China(No.21371055)the Hunan provincial Natural Science Foundation of China(No.11JJ2008)the Hunan provincial Colleges and Universities Innovation Platform Open Fund Project(No.15K049)
文摘Novel composite material with a wide pore distribution was synthesized by an in situ technique using spent FCC catalyst as raw material. The characterization results indicated that the composite material contained 56.7% of zeolite Y and exhibited a much larger specific surface area and pore volume as well as strong hydrothermal stability. Fluid catalytic cracking(FCC) catalyst was prepared based on the composite material. The results indicated that the as-prepared catalyst possessed a unique pore structure that was advantageous to the diffusion-controlled reactions. In addition, the attrition resistance, activity and hydrothermal stability of the studied catalyst were superior to those of the reference catalyst. The catalyst also exhibited excellent nickel and vanadium passivation performance, strong bottoms upgrading selectivity, and better gasoline and coke selectivity. In comparison to the reference catalyst, the yields of the gasoline and light oil increased by 1.61 and 1.31 percentage points, respectively, and the coke yield decreased by 0.22 percentage points, and the olefin content in the produced gasoline reduced by 2.51 percentage points, with the research octane number increased by 0.7 unit.
文摘The composite ZSM—5 zeolite/vermiculite catalyst,in which tiny ZSM—5 zeolite parti- cles embedded in the vermiculite substrate,has been synthesized by hydrothermal method with vermiculite as silicon source.The catalytic behavior of resulting catalyst for xylene isomerization,propylene aromatization and toluene disproportionation is better than that of HZSM—5 zeolite.
基金supported by the National Natural Science Foundation of China(2100705351302241)+1 种基金the Education Department of Henan Province(2012GGJS-174)Xuchang University Science Research Foundation(2015011)~~
文摘Formation of a p–n heterojunction rather than p-type or n-type semiconductors can enhance the separation of photogenerated electrons and holes and increase the quantum efficiency of photocatalytic reactions owing to the difference of the electric potential in the inner electric field near the junction,pointing from n toward p. n-Ag3PO4/p-Ag2CO3 p–n heterojunction composites are prepared through a facile coprecipitation process. The obtained Ag3PO4/Ag2CO3 p–n heterojunctions exhibit excellent photocatalytic performance in the removal of rhodamine B（RhB） compared with Ag3PO4 and Ag2CO3. The 40%-Ag3PO4/Ag2CO3 composite photocatalyst（40 mol% Ag3PO4 and 60 mol% Ag2CO3） exhibits the best photocatalytic activity under visible light,demonstrating the ability to completely degrade RhB within 15 min. Transient photovoltage characterization and an active species trapping experiment further indicate that the formation of a p–n heterojunction structure can greatly enhance the separation efficiency of photogenerated carriers and produce more free h＋active species,which is the predominant contributor for RhB removal.
基金supported by the National Energy R&D Center of Petroleum Refining Technology(RIPP,SINOPEC)the National Key R&D Program of China(Nos.2021YFE0191200 and 2022YFA1504200).
文摘Over the past decade,electrocatalytic reduction of CO_(2)has gained substantial attention.However,hardly any of the previous reviews have focused on the systematic discussion of polymer-molecular catalyst composites as an emerging system for the electrochemical transformation of CO_(2)to value-added products.In this review,we first give a brief overview of the general features of solid-state and molecular catalysts,and then advance the discussion to polymer-catalyst composite systems,with particular emphasis on polymer-encapsulated molecular catalysts,where the coordination environment surrounding molecular catalysts can be modified via polymer encapsulation to promote the overall performance of CO_(2)electrocatalysis.The elucidation of the possible reaction mechanisms of this emerging electrocat-alytic system along with proposed optimization strategies is also summarized and discussed based on recently published reports,followed by the challenges and prospects of their industrial applications at the end of this review.From this review,we hope the audience can gain a comprehensive understanding of the electrocatalytic mechanism of the coordinating polymers and valuable insights into engineering the microenvironment surrounding the metal complexes for potential future research directions.
基金Project(20973124)supported by the National Natural Science Foundation of ChinaProject(KLAEMC-OP201101)supported by the Open Project of Key Laboratory of Advanced Energy Materials Chemistry of Ministry of Education(Nankai University),China
文摘The hollow α-MnO2 nanoneedle-based microspheres coated with Pd nanoparticles were reported as a novel catalyst for rechargeable lithium-air batteries. The hollow microspheres are composed ofα-MnO2 nanoneedles. Pd nanoparticles are deposited on the hollow microspheres through an aqueous-solution reduction of PdCl2 with NaBH4 at room temperature. The results of TEM, XRD, and EDS show that the Pd nanoparticles are coated on the surface ofα-MnO2 nanoneedles uniformly and the mass fraction of Pd in the Pd-coated α-MnO2 catalyst is about 8.88%. Compared with the counterpart of the hollow α-MnO2 catalyst, the hollow Pd-coated α-MnO2 catalyst improves the energy conversion efficiency and the charge-discharge cycling performance of the air electrode. The initial specific discharge capacity of an air electrode composed of Super P carbon and the as-prepared Pd-coatedα-MnO2 catalyst is 1220 mA＆#183;h/g （based on the total electrode mass） at a current density of 0.1 mA/cm2, and the capacity retention rate is about 47.3% after 13 charge-discharge cycles. The results of charge-discharge cycling tests demonstrate that this novel Pd-coatedα-MnO2 catalyst with a hierarchical core-shell structure is a promising catalyst for the lithium-air battery.
