Lithium-sulfur batteries are severely restricted by low electronic conductivity of sulfur and Li_(2)S,shuttle effect,and slow conversion reaction of lithium polysulfides(LiPSs).Herein,we report a facile and highyield ...Lithium-sulfur batteries are severely restricted by low electronic conductivity of sulfur and Li_(2)S,shuttle effect,and slow conversion reaction of lithium polysulfides(LiPSs).Herein,we report a facile and highyield strategy for synthesizing dual-core single-atom catalyst(ZnCoN_(4)O_(2)/CN)with atomically dispersed nitrogen/oxygen-coordinated Zn-Co sites on carbon nanosheets.Based on density functional theory(DFT)calculations and LiPSs conversion catalytic ability,ZnCoN_(4)O_(2)/CN provides dual-atom sites of Zn and Co,which could facilitate Li^(+)transport and Li_(2)S diffusion,and catalyze LiPSs conversion more effectively than homonuclear bimetallic single-atom catalysts or their simple mixture and previously reported singleatom catalysts.Li-S cell with ZnCoN_(4)O_(2)/CN modified separator showed excellent rate performance(789.4 mA h g^(-1)at 5 C)and stable long cycle performance(0.05%capacity decay rate at 6C with 1000cycles,outperforming currently reported single atomic catalysts for LiPSs conversion.This work highlights the important role of metal active centers and provides a strategy for producing multifunctional dual-core single atom catalysts for high-performance Li-S cells.展开更多
The regulation of interface electron-transfer and catalytic kinetics is very important to design the efficient electrocatalyst for alkaline hydrogen oxidation reaction(HOR).Here,we show the Pt-Ni alloy nanoparticles(P...The regulation of interface electron-transfer and catalytic kinetics is very important to design the efficient electrocatalyst for alkaline hydrogen oxidation reaction(HOR).Here,we show the Pt-Ni alloy nanoparticles(PtNi_(2))have an enhanced HOR activity compared with single component Pt catalyst.While,the interface electron-transfer kinetics of PtNi_(2)catalyst exhibits a very wide electron-transfer speed distribution.When combined with carbon dots(CDs),the interface charge transfer of PtNi_(2)-CDs composite is optimized,and then the PtNi_(2)-5 mg CDs exhibits about 2.67 times and 4.04 times higher mass and specific activity in 0.1 M KOH than that of 20%commercial Pt/C.In this system,CDs also contribute to trapping H^(+)and H_(2)O generated during HOR,tuning hydrogen binding energy(HBE),and regulating interface electron transfer.This work provides a deep understanding of the interface catalytic kinetics of Pt-based alloys towards highly efficient HOR catalysts design.展开更多
It has been reported that two Schiff base transition metal complexes bearing the side chain of the morpholine ring were synthesized and characterized, and two complexes with the same base agent but different metal ion...It has been reported that two Schiff base transition metal complexes bearing the side chain of the morpholine ring were synthesized and characterized, and two complexes with the same base agent but different metal ions were used as a simulant hydrolase in the catalytic hydrolysis of p-nitrophenyl picolinate in this paper. The mechanism of PNPP catalytic hydrolysis is proposed and supported by the results of the spectral analysis and the kinetic calculation. A kinetic mathematical model, applied to the calculation of the kinetic and thermodynamics parameters of PNPP catalytic hydrolysis, has been established on the foundation of the mechanism proposed. The result of the study shows that the two complexes have a good catalytic activity in PNPP catalytic hydrolysis, and the rate of the PNPP catalytic hydrolysis was increased with the increase of the pH values in the buffer solution and affected by the polarization effect of metal ion of the complexes.展开更多
Herein, a stable and efficient CoS_(2)-ReS_(2) electrocatalyst is successfully constructed by using the different molar ratios of CoS_(2) on ReS_(2). The size and morphology of the catalysts are significantly changed ...Herein, a stable and efficient CoS_(2)-ReS_(2) electrocatalyst is successfully constructed by using the different molar ratios of CoS_(2) on ReS_(2). The size and morphology of the catalysts are significantly changed after the CoS_(2) is grown on ReS_(2), providing regulation of the catalytic activity of ReS_(2). Particularly, the optimized CoS_(2)-ReS_(2) shows superior electrocatalytic properties with a low voltage of 1.48 V at 20 mA cm^(-2) for overall water splitting in 1.0 M KOH, which is smaller than the noble metal-based catalysts(1.77 V at 20 mA cm^(-2)). The XPS, XAS, and theoretical data confirm that the interfacial regulation of ReS_(2) by CoS_(2) can provide rich edge catalytic sites, which greatly optimizes the catalytic kinetics and drop the energy barrier for oxygen/hydrogen evolution reactions. Our results demonstrated that interfacial engineering is an efficient route for fabricating high-performance water splitting electrocatalysts.展开更多
High-entropy catalysts featuring exceptional properties are,in no doubt,playing an increasingly significant role in aprotic lithium-oxygen batteries.Despite extensive effort devoted to tracing the origin of their unpa...High-entropy catalysts featuring exceptional properties are,in no doubt,playing an increasingly significant role in aprotic lithium-oxygen batteries.Despite extensive effort devoted to tracing the origin of their unparalleled performance,the relationships between multiple active sites and reaction intermediates are still obscure.Here,enlightened by theoretical screening,we tailor a high-entropy perovskite fluoride(KCoMnNiMgZnF_(3)-HEC)with various active sites to overcome the limitations of conventional catalysts in redox process.The entropy effect modulates the d-band center and d orbital occupancy of active centers,which optimizes the d–p hybridization between catalytic sites and key intermediates,enabling a moderate adsorption of LiO_(2)and thus reinforcing the reaction kinetics.As a result,the Li–O2 battery with KCoMnNiMgZnF_(3)-HEC catalyst delivers a minimal discharge/charge polarization and long-term cycle stability,preceding majority of traditional catalysts reported.These encouraging results provide inspiring insights into the electron manipulation and d orbital structure optimization for advanced electrocatalyst.展开更多
The new catalytic kinetic spectrophotometric method for Au(III) determination was developed and validated. It was based on the catalytic effect of gold on the oxidation of sudan red III by ammonium peroxodisulfate ...The new catalytic kinetic spectrophotometric method for Au(III) determination was developed and validated. It was based on the catalytic effect of gold on the oxidation of sudan red III by ammonium peroxodisulfate ((NH4)2S2O8) with nitrilo triacetic acid as an activator in microemulsion and H2SO4 medium. Under optimum conditions, there was the linearity of the calibration curve in the concentration range from 0 to 20 μg/L Au(Ⅲ) at 520 nm. The relative standard deviation was 3.0% with a correlation coefficient of 0.9986. The detection limit achieved was 9.75 × 10^-5 μg/mL. A new method using a column packed with sulfhydryl dextrose gel (SDG) as a solid-phase extractant has been developed for the preconcentration and separation of Au(Ⅲ) ions. The method has been applied to the determination of trace gold with satisfactory results.展开更多
The oxidative dehydrogenation (ODH) of isobutane over Cr_2O_3/La_2(CO_3)_3 has been investigated in a low-pressure Knudsen cell reactor, under conditions where the kinetics of the primary reaction steps can be accurat...The oxidative dehydrogenation (ODH) of isobutane over Cr_2O_3/La_2(CO_3)_3 has been investigated in a low-pressure Knudsen cell reactor, under conditions where the kinetics of the primary reaction steps can be accurately determined. By heating the catalyst at a constant rate from 150-300℃, temperature fluctuations due to non-equilibrium adsorption are minimized. The evolved gas profiles show that ODH to isobutene and water is a primary reaction pathway, while carbon dioxide, which forms from the catalyst during reaction, is the only other product. This CO2 evolution may enhance the activity of the catalyst. Isobutene formation proceeds with the participation of lattice oxygen from the Cr2O3/La2(CO3)3 catalyst. The intrinsic Arrhenius rate constant for the ODH of isobutane isk(s-1) = 1011.5±2.2exp{-((55±5) -ΔHads kJmol-1)/RT}The small pre-exponential factor is expected for a concerted mechanism and for such a catalyst with a small surface area and limited porosity.展开更多
During oxygen evolution reaction(OER),complex changes have been reported on surfaces of bimetallic Fe-Ni-based catalysts,and regulating the dynamic evolution could improve their electrocatalytic performances.Herein,a ...During oxygen evolution reaction(OER),complex changes have been reported on surfaces of bimetallic Fe-Ni-based catalysts,and regulating the dynamic evolution could improve their electrocatalytic performances.Herein,a pyrrolidone-promoted reconstruction of pentlandite was investigated to uncover the correlation between the reconstructed surface and the OER performance.The theoretical calculations indicated the preferential implantation of pyrrolidone at Fe atoms,useful for regulating the electronic structures of pentlandite.The vale nce state of Ni increased,suggesting the promotion of the in-situ reconstruction of pentlandite via strengthening hydroxyl adsorption to generate highly active NiOOH.The electron-rich pentlandite was also found conducive to charge transfer under applied voltages.The Operando Raman and various quasi-in-situ characterizations confirmed the realization of more delocalized electronic structures of pentlandite by introducing pyrrolidone.This,in turn,promoted the accumulation of hydroxyl groups on the pentlandite surface,thereby boosting the formation of highly active NiOOH at lower OER potentials.Consequently,the adsorption energies of intermediates were optimized,conducive to enhanced OER reaction kinetics.As a proof of concept,the pentlandite decorated by pyrrolidone exhibited an overpotential as low as 265 mV at 10 mA cm^(-2) coupled with stable catalysis for 1000 hours at a high current density of 100 mA cm^(-2).In sum,new insights into unlocking the high catalytic activity of bimetallic Fe-Ni-based catalysts were provided,promising for future synthesis of advanced catalysts.展开更多
A simple and sensitive spectrophotometric method was described for the determination of cerium(IV) based on its catalytic effect on the oxidation of naphthol green B by potassium periodate in the medium of sulfuric ...A simple and sensitive spectrophotometric method was described for the determination of cerium(IV) based on its catalytic effect on the oxidation of naphthol green B by potassium periodate in the medium of sulfuric acid. The influences of acidity, concentration of reactants, reaction time, reaction temperature, and foreign ions were discussed, and the optimum reaction conditions were established. The reaction was monitored spectrophotometrieally by measuring the decrease in absorbance of naphthol green B at 710 nm after a fixed time (8 min). The proposed method allowed the determination of cerium(IV) in the range of 0.08-2.4 μg·mL^-1 with good precision and accuracy, and the detection limit was 0.012 μg·mL^-1. The method was applied successfully for the determination of trace cerium in hair samples without previous separation. Recovery experiments were also performed, and the recovery was between 95.7%-111.0%.展开更多
Platinated W/Zr mixed oxides supported on mesoporous silica with various amounts of Si/Zr, namely PtWO_3/ZrO_2([76_TD$IF]x)-HMS, were prepared and studied for n-heptane isomerization reaction at 200–350 C. The vari...Platinated W/Zr mixed oxides supported on mesoporous silica with various amounts of Si/Zr, namely PtWO_3/ZrO_2([76_TD$IF]x)-HMS, were prepared and studied for n-heptane isomerization reaction at 200–350 C. The various methods such as XRD, XRF, FT-IR, UV–vis DRS, NH_3-TPD, H_2 chemisorption, nitrogen adsorption–desorption, Py-IR, SEM and TGA techniques were used for characterization of these materials. Kinetics of n-heptane isomerization was also investigated under various hydrogen. n-Heptane pressures and the influence of reaction conditions on catalytic performance were studied. The ideal catalytic performance was observed on HMS with 0.6%Pt/12%WO_3/ZrO_2 and Si/Zr = 10.展开更多
The highly electrically conductive graphene papers prepared from graphene oxide have shown promising perspectives in flexible electronics,electromagnetic interference(EMI)shielding,and electrodes.To achieve high elect...The highly electrically conductive graphene papers prepared from graphene oxide have shown promising perspectives in flexible electronics,electromagnetic interference(EMI)shielding,and electrodes.To achieve high electrical conductivity,the graphene oxide precursor usually needs to be graphitized at extremely high temperature(~2,800°C),which severely increases the energy consumption and production costs.Here,we report an efficient catalytic graphitization approach to fabricate highly conductive graphene papers at lower annealing temperature.The graphene papers with boron catalyst annealed at 2,000°C show a high conductivity of~3,400 S·cm^(-1),about 47%higher than pure graphene papers.Boron catalyst facilitates the recovery of structural defects and improves the degree of graphitization by 80%.We further study the catalytic effect of boron on the graphitization behavior of graphene oxide.The results show that the activation energy of the catalytic graphitization process is as low as 80.1 kJ·mol^(–1)in the temperature ranges studied.This effective strategy of catalytic graphitization should also be helpful in the fabrication of other kinds of highly conductive graphene macroscopic materials.展开更多
A new procedure for the determination of cerium was established using the catalytic effect of Ce(IV) on the oxidation of tribromoarsenazo(TB-ASA) by potassium bromate.In 0.080 mol/L sulfuric acid medium,the maximum ab...A new procedure for the determination of cerium was established using the catalytic effect of Ce(IV) on the oxidation of tribromoarsenazo(TB-ASA) by potassium bromate.In 0.080 mol/L sulfuric acid medium,the maximum absorption peak of Ce(IV)-(TB-ASA)-KBrO3 system is at 510 nm.The amount of Ce(IV) and the difference of absorbance(△A) showed a good linear relationship over the range of 5.7×10-8-5.1×10-7 mol/L.The regression equation is △A=2.3×10-11 C(C:mol/L)+0.0196,with a regression coefficient of 0.9914 at t...展开更多
There was a significant catalytic effect of trace Gd(III) ions on the oxidative reaction of potassium persulfate with Saffron T in the acetic acid–sodium acetate buffer solution. Thus, a catalytic kinetic fluorimetry...There was a significant catalytic effect of trace Gd(III) ions on the oxidative reaction of potassium persulfate with Saffron T in the acetic acid–sodium acetate buffer solution. Thus, a catalytic kinetic fluorimetry method for the determination of trace Gd(III) ions was established. The factors such as acidity, concentration of reagents, reaction time, and temperature as well as influence of coexisting ions were discussed. The optimum reaction conditions were established. The apparent rate constant and apparent activation energy of the reaction were determined. The linear range is 0.02–0.10 lgáml-1,and the detection limit is 7.27 9 10-4lgáml-1. This method was used for the determination of gadolinium in the samples of lanthanum acetate with RSD of 0.9 %–3.1 %.展开更多
Rechargeable lithium-oxygen batteries(LOBs)have received incremental attention owing to their high energy density and applicability to mobile devices and electric vehicles.However,the lack of robust,low-cost,and envir...Rechargeable lithium-oxygen batteries(LOBs)have received incremental attention owing to their high energy density and applicability to mobile devices and electric vehicles.However,the lack of robust,low-cost,and environmentally benign bifunctional catalysts is a major impediment to the commercial application.The introduction of vacancies is one of the effective strategies to enhance the performance of cathode catalysts for lithium-oxygen batteries,but the preparation is complicated.In this work,needle-like microsphere cathode catalysts of nickel-cobalt oxide containing cationic vacancies are constructed by controlling the annealing temperature.It is demonstrated that the presence of cationic vacancies can modulate the electronic structure of the catalyst,reduce the energy barrier for the oxygen electrode re-action,meanwhile enhance the bifunctional catalytic activity.Impressively,the nickel-cobalt oxide-based LOB with cationic vacancies exhibits large specific capacity(12,205 mAh g^(-1)at 200 mA g^(-1))and good durability.This work provides worthwhile insight into the formation and catalytic enhancement mech-anism of transition metal oxide catalysts with cationic vacancies,and to some extent,the creation of efficient and low-cost oxygen electrocatalysts for LOBs.展开更多
Two cobalt(Ⅱ) complexes of the Schiff base with morpholino or aza-crown ether pendants, CoL^1 and CoL^2, as mimic hydrolytic metalloenzyme, were used in catalytic hydrolysis of carboxylic ester (PNPP). The analys...Two cobalt(Ⅱ) complexes of the Schiff base with morpholino or aza-crown ether pendants, CoL^1 and CoL^2, as mimic hydrolytic metalloenzyme, were used in catalytic hydrolysis of carboxylic ester (PNPP). The analysis of specific absorption spectra of the hydrolytic reaction systems indicates that key intermediates, made up of PNPP and Co(Ⅱ) complexes, have been formed in reaction processes of the PNPP catalytic hydrolysis. The mechanism of PNPP catalytic hydrolysis has been proposed based on the analytic result of specific absorption spectrum. A kinetic mathematical model, applied to the calculation of the kinetic parameter of PNPP catalytic hydrolysis, has been established based on the mechanism proposed. The acid effect of buffer solution, structural effect of the complexes, and effect of temperature on the rate of PNPP hydrolysis catalyzed by the complexes have been also discussed.展开更多
Electrocatalysis provides various technologies for energy storage and conversion,which is an important part of realizing sustainable clean energy for the future.COFs,as emerging porous crystalline polymers,possess hig...Electrocatalysis provides various technologies for energy storage and conversion,which is an important part of realizing sustainable clean energy for the future.COFs,as emerging porous crystalline polymers,possess high specific surface areas,tunable pore structures,high crystallinity and tailorable functionalization.These features endow COFs with abundant active sites and fast electron transport channels,making them potentially efficient electrocatalysts.In recent years,COF-based electrocatalysts have been widely developed for hydrogen evolution reaction(HER),hydrogen oxidation reaction(HOR),oxygen evolution reaction(OER),oxygen reduction reaction(ORR),nitrogen reduction reaction(NRR)and carbon dioxide reduction reaction(CO_(2)RR).In this review,design strategies of COF-based electrocatalysts are briefly summarized,including applying COF as supports,introducing active metals in COF,constructing two-dimensional conductive COF,formation of COF-based hybrid and pyrolysis of COF to obtain carbon materials.Then,the recent research progress in COF-derived catalysts for specific electrocatalytic reactions is introduced systematically.Finally,the outlook and challenges of future applications of COFs in electrocatalysis are highlighted.展开更多
Three novel Schiff base cobalt(Ⅱ) complexes containing benzoaza-15-crown-5, CoL^1, CoL^2 and CoL^3 were synthesized and characterized, and these complexes were used in catalytic hydrolysis of carboxylic ester (PNP...Three novel Schiff base cobalt(Ⅱ) complexes containing benzoaza-15-crown-5, CoL^1, CoL^2 and CoL^3 were synthesized and characterized, and these complexes were used in catalytic hydrolysis of carboxylic ester (PNPP, p-nitrophenyl picolinate) as mimic hydrolytic metalloenzyme. The analysis of specific absorption spectra of the hydrolytic reaction systems indicated that the catalytic hydrolysis involved the key intermediates formed by PNPP with cobalt(Ⅱ) complexes. The CoL^3 bearing the electron withdrawing group shows better catalytic activity due to its stabilization effect on active species MLS^-. The catalytic mechanism of PNPP hydrolysis was also proposed. The kinetic parameter of PNPP catalytic hydrolysis has been calculated and the activation energy for the catalytic hydrolysis is 43.69, 39.76 and 35.44 kJ·mol^-1, respectively.展开更多
基金supported by the National Natural Science Foundation of P.R.China(22001082)the Applied Science and Technology Planning Project of Guangdong Province,Guangzhou,China(2017B090917002)+5 种基金the Guangdong Basic and Applied Basic Research Fund Project(2019B1515120027)the Research and Development(R&D)Projects in Key Areas of Guangdong Province(2020B0101028005)the Guangdong Natural Science Foundation Project(No.2019A1515010841)the Guangdong Province International Science and Technology Cooperation Project(No.2019A050510038)the Guangzhou Science and Technology Association Young Talents Promotion Project(X20210201043)the Guangzhou Basic and Applied Basic Research Project(202102020624)。
文摘Lithium-sulfur batteries are severely restricted by low electronic conductivity of sulfur and Li_(2)S,shuttle effect,and slow conversion reaction of lithium polysulfides(LiPSs).Herein,we report a facile and highyield strategy for synthesizing dual-core single-atom catalyst(ZnCoN_(4)O_(2)/CN)with atomically dispersed nitrogen/oxygen-coordinated Zn-Co sites on carbon nanosheets.Based on density functional theory(DFT)calculations and LiPSs conversion catalytic ability,ZnCoN_(4)O_(2)/CN provides dual-atom sites of Zn and Co,which could facilitate Li^(+)transport and Li_(2)S diffusion,and catalyze LiPSs conversion more effectively than homonuclear bimetallic single-atom catalysts or their simple mixture and previously reported singleatom catalysts.Li-S cell with ZnCoN_(4)O_(2)/CN modified separator showed excellent rate performance(789.4 mA h g^(-1)at 5 C)and stable long cycle performance(0.05%capacity decay rate at 6C with 1000cycles,outperforming currently reported single atomic catalysts for LiPSs conversion.This work highlights the important role of metal active centers and provides a strategy for producing multifunctional dual-core single atom catalysts for high-performance Li-S cells.
基金supported by the National Key R&D Program of China(2020YFA0406104,2020YFA0406101)the National MCF Energy R&D Program of China(2018YFE0306105)+5 种基金the Innovative Research Group Project of the National Natural Science Foundation of China(51821002)the National Natural Science Foundation of China(51725204,21771132,51972216,52041202)the Natural Science Foundation of Jiangsu Province(BK20190041)the Key-Area Research and Development Program of Guang Dong Province(2019B010933001)the Collaborative Innovation Center of Suzhou Nano Science&Technologythe 111 Project。
文摘The regulation of interface electron-transfer and catalytic kinetics is very important to design the efficient electrocatalyst for alkaline hydrogen oxidation reaction(HOR).Here,we show the Pt-Ni alloy nanoparticles(PtNi_(2))have an enhanced HOR activity compared with single component Pt catalyst.While,the interface electron-transfer kinetics of PtNi_(2)catalyst exhibits a very wide electron-transfer speed distribution.When combined with carbon dots(CDs),the interface charge transfer of PtNi_(2)-CDs composite is optimized,and then the PtNi_(2)-5 mg CDs exhibits about 2.67 times and 4.04 times higher mass and specific activity in 0.1 M KOH than that of 20%commercial Pt/C.In this system,CDs also contribute to trapping H^(+)and H_(2)O generated during HOR,tuning hydrogen binding energy(HBE),and regulating interface electron transfer.This work provides a deep understanding of the interface catalytic kinetics of Pt-based alloys towards highly efficient HOR catalysts design.
基金Project supported by the National Natural Science Foundation (No. 50572121) and the Science Fund (No. 2005A145) of the Sichuan Province Educational Department of China.
文摘It has been reported that two Schiff base transition metal complexes bearing the side chain of the morpholine ring were synthesized and characterized, and two complexes with the same base agent but different metal ions were used as a simulant hydrolase in the catalytic hydrolysis of p-nitrophenyl picolinate in this paper. The mechanism of PNPP catalytic hydrolysis is proposed and supported by the results of the spectral analysis and the kinetic calculation. A kinetic mathematical model, applied to the calculation of the kinetic and thermodynamics parameters of PNPP catalytic hydrolysis, has been established on the foundation of the mechanism proposed. The result of the study shows that the two complexes have a good catalytic activity in PNPP catalytic hydrolysis, and the rate of the PNPP catalytic hydrolysis was increased with the increase of the pH values in the buffer solution and affected by the polarization effect of metal ion of the complexes.
基金supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT)(NRF-2022R1A2C2093415) and (NRF-2018R1A2B6006721)Institute for Basic Science of Korea (IBS-R011-D1)the Korea Medical Device Development Fund grant funded by the Korean government (the Ministry of Science and ICT, the Ministry of Trade, Industry and Energy, the Ministry of Health & Welfare, the Ministry of Food and Drug Safety) (Project Number: KMDF_PR_20200901_0004)。
文摘Herein, a stable and efficient CoS_(2)-ReS_(2) electrocatalyst is successfully constructed by using the different molar ratios of CoS_(2) on ReS_(2). The size and morphology of the catalysts are significantly changed after the CoS_(2) is grown on ReS_(2), providing regulation of the catalytic activity of ReS_(2). Particularly, the optimized CoS_(2)-ReS_(2) shows superior electrocatalytic properties with a low voltage of 1.48 V at 20 mA cm^(-2) for overall water splitting in 1.0 M KOH, which is smaller than the noble metal-based catalysts(1.77 V at 20 mA cm^(-2)). The XPS, XAS, and theoretical data confirm that the interfacial regulation of ReS_(2) by CoS_(2) can provide rich edge catalytic sites, which greatly optimizes the catalytic kinetics and drop the energy barrier for oxygen/hydrogen evolution reactions. Our results demonstrated that interfacial engineering is an efficient route for fabricating high-performance water splitting electrocatalysts.
基金P.G.acknowledges the financial support from the Youth Foundation of Shandong Natural Science Foundation(No.ZR2023OB230)National Natural Science Foundation(No.22309035)Double First-class Discipline Construction Fund Project of Harbin Institute of Technology at Weihai(No.2023SYLHY11).
文摘High-entropy catalysts featuring exceptional properties are,in no doubt,playing an increasingly significant role in aprotic lithium-oxygen batteries.Despite extensive effort devoted to tracing the origin of their unparalleled performance,the relationships between multiple active sites and reaction intermediates are still obscure.Here,enlightened by theoretical screening,we tailor a high-entropy perovskite fluoride(KCoMnNiMgZnF_(3)-HEC)with various active sites to overcome the limitations of conventional catalysts in redox process.The entropy effect modulates the d-band center and d orbital occupancy of active centers,which optimizes the d–p hybridization between catalytic sites and key intermediates,enabling a moderate adsorption of LiO_(2)and thus reinforcing the reaction kinetics.As a result,the Li–O2 battery with KCoMnNiMgZnF_(3)-HEC catalyst delivers a minimal discharge/charge polarization and long-term cycle stability,preceding majority of traditional catalysts reported.These encouraging results provide inspiring insights into the electron manipulation and d orbital structure optimization for advanced electrocatalyst.
文摘The new catalytic kinetic spectrophotometric method for Au(III) determination was developed and validated. It was based on the catalytic effect of gold on the oxidation of sudan red III by ammonium peroxodisulfate ((NH4)2S2O8) with nitrilo triacetic acid as an activator in microemulsion and H2SO4 medium. Under optimum conditions, there was the linearity of the calibration curve in the concentration range from 0 to 20 μg/L Au(Ⅲ) at 520 nm. The relative standard deviation was 3.0% with a correlation coefficient of 0.9986. The detection limit achieved was 9.75 × 10^-5 μg/mL. A new method using a column packed with sulfhydryl dextrose gel (SDG) as a solid-phase extractant has been developed for the preconcentration and separation of Au(Ⅲ) ions. The method has been applied to the determination of trace gold with satisfactory results.
文摘The oxidative dehydrogenation (ODH) of isobutane over Cr_2O_3/La_2(CO_3)_3 has been investigated in a low-pressure Knudsen cell reactor, under conditions where the kinetics of the primary reaction steps can be accurately determined. By heating the catalyst at a constant rate from 150-300℃, temperature fluctuations due to non-equilibrium adsorption are minimized. The evolved gas profiles show that ODH to isobutene and water is a primary reaction pathway, while carbon dioxide, which forms from the catalyst during reaction, is the only other product. This CO2 evolution may enhance the activity of the catalyst. Isobutene formation proceeds with the participation of lattice oxygen from the Cr2O3/La2(CO3)3 catalyst. The intrinsic Arrhenius rate constant for the ODH of isobutane isk(s-1) = 1011.5±2.2exp{-((55±5) -ΔHads kJmol-1)/RT}The small pre-exponential factor is expected for a concerted mechanism and for such a catalyst with a small surface area and limited porosity.
基金financially supported by the Scientific and Technological Development Program of Jilin Province (20220201138GX)。
文摘During oxygen evolution reaction(OER),complex changes have been reported on surfaces of bimetallic Fe-Ni-based catalysts,and regulating the dynamic evolution could improve their electrocatalytic performances.Herein,a pyrrolidone-promoted reconstruction of pentlandite was investigated to uncover the correlation between the reconstructed surface and the OER performance.The theoretical calculations indicated the preferential implantation of pyrrolidone at Fe atoms,useful for regulating the electronic structures of pentlandite.The vale nce state of Ni increased,suggesting the promotion of the in-situ reconstruction of pentlandite via strengthening hydroxyl adsorption to generate highly active NiOOH.The electron-rich pentlandite was also found conducive to charge transfer under applied voltages.The Operando Raman and various quasi-in-situ characterizations confirmed the realization of more delocalized electronic structures of pentlandite by introducing pyrrolidone.This,in turn,promoted the accumulation of hydroxyl groups on the pentlandite surface,thereby boosting the formation of highly active NiOOH at lower OER potentials.Consequently,the adsorption energies of intermediates were optimized,conducive to enhanced OER reaction kinetics.As a proof of concept,the pentlandite decorated by pyrrolidone exhibited an overpotential as low as 265 mV at 10 mA cm^(-2) coupled with stable catalysis for 1000 hours at a high current density of 100 mA cm^(-2).In sum,new insights into unlocking the high catalytic activity of bimetallic Fe-Ni-based catalysts were provided,promising for future synthesis of advanced catalysts.
基金supported by the Natural Sci-ence Foundation of Shandong Province, China (No. Y2008B26)
文摘A simple and sensitive spectrophotometric method was described for the determination of cerium(IV) based on its catalytic effect on the oxidation of naphthol green B by potassium periodate in the medium of sulfuric acid. The influences of acidity, concentration of reactants, reaction time, reaction temperature, and foreign ions were discussed, and the optimum reaction conditions were established. The reaction was monitored spectrophotometrieally by measuring the decrease in absorbance of naphthol green B at 710 nm after a fixed time (8 min). The proposed method allowed the determination of cerium(IV) in the range of 0.08-2.4 μg·mL^-1 with good precision and accuracy, and the detection limit was 0.012 μg·mL^-1. The method was applied successfully for the determination of trace cerium in hair samples without previous separation. Recovery experiments were also performed, and the recovery was between 95.7%-111.0%.
文摘Platinated W/Zr mixed oxides supported on mesoporous silica with various amounts of Si/Zr, namely PtWO_3/ZrO_2([76_TD$IF]x)-HMS, were prepared and studied for n-heptane isomerization reaction at 200–350 C. The various methods such as XRD, XRF, FT-IR, UV–vis DRS, NH_3-TPD, H_2 chemisorption, nitrogen adsorption–desorption, Py-IR, SEM and TGA techniques were used for characterization of these materials. Kinetics of n-heptane isomerization was also investigated under various hydrogen. n-Heptane pressures and the influence of reaction conditions on catalytic performance were studied. The ideal catalytic performance was observed on HMS with 0.6%Pt/12%WO_3/ZrO_2 and Si/Zr = 10.
基金supported by the National Natural Science Foundation of China(Nos.51803177,52090030,and 52106071)the Fundamental Research Funds for the Central Universities,Shanxi-Zheda Institute of New Materials and Chemical Engineering(No.2012SZ-FR004)Key Laboratory of Novel Adsorption and Separation Materials and Application Technology of Zhejiang Province(No.512301-I21502)。
文摘The highly electrically conductive graphene papers prepared from graphene oxide have shown promising perspectives in flexible electronics,electromagnetic interference(EMI)shielding,and electrodes.To achieve high electrical conductivity,the graphene oxide precursor usually needs to be graphitized at extremely high temperature(~2,800°C),which severely increases the energy consumption and production costs.Here,we report an efficient catalytic graphitization approach to fabricate highly conductive graphene papers at lower annealing temperature.The graphene papers with boron catalyst annealed at 2,000°C show a high conductivity of~3,400 S·cm^(-1),about 47%higher than pure graphene papers.Boron catalyst facilitates the recovery of structural defects and improves the degree of graphitization by 80%.We further study the catalytic effect of boron on the graphitization behavior of graphene oxide.The results show that the activation energy of the catalytic graphitization process is as low as 80.1 kJ·mol^(–1)in the temperature ranges studied.This effective strategy of catalytic graphitization should also be helpful in the fabrication of other kinds of highly conductive graphene macroscopic materials.
文摘A new procedure for the determination of cerium was established using the catalytic effect of Ce(IV) on the oxidation of tribromoarsenazo(TB-ASA) by potassium bromate.In 0.080 mol/L sulfuric acid medium,the maximum absorption peak of Ce(IV)-(TB-ASA)-KBrO3 system is at 510 nm.The amount of Ce(IV) and the difference of absorbance(△A) showed a good linear relationship over the range of 5.7×10-8-5.1×10-7 mol/L.The regression equation is △A=2.3×10-11 C(C:mol/L)+0.0196,with a regression coefficient of 0.9914 at t...
基金financially supported by the Natural Science Foundation of Shandong Province (No. Y2008B26)
文摘There was a significant catalytic effect of trace Gd(III) ions on the oxidative reaction of potassium persulfate with Saffron T in the acetic acid–sodium acetate buffer solution. Thus, a catalytic kinetic fluorimetry method for the determination of trace Gd(III) ions was established. The factors such as acidity, concentration of reagents, reaction time, and temperature as well as influence of coexisting ions were discussed. The optimum reaction conditions were established. The apparent rate constant and apparent activation energy of the reaction were determined. The linear range is 0.02–0.10 lgáml-1,and the detection limit is 7.27 9 10-4lgáml-1. This method was used for the determination of gadolinium in the samples of lanthanum acetate with RSD of 0.9 %–3.1 %.
基金This work was financially supported by research projects from Department of Science and Technology of Shandong Province(Nos.2021CXGC010307,2020CXGC010310,ZR2019MEM052,and 2019TSLH0101)The authors acknowledged the assistance of Shandong University Testing and Manufacturing Center for Ad-vanced Materials.H.G.acknowledges the Science and Technol-ogy Project of Hebei Education Department(No.BJK2022068)Hebei Province Introduced Overseas Students Funding Project(No.C20220306).
文摘Rechargeable lithium-oxygen batteries(LOBs)have received incremental attention owing to their high energy density and applicability to mobile devices and electric vehicles.However,the lack of robust,low-cost,and environmentally benign bifunctional catalysts is a major impediment to the commercial application.The introduction of vacancies is one of the effective strategies to enhance the performance of cathode catalysts for lithium-oxygen batteries,but the preparation is complicated.In this work,needle-like microsphere cathode catalysts of nickel-cobalt oxide containing cationic vacancies are constructed by controlling the annealing temperature.It is demonstrated that the presence of cationic vacancies can modulate the electronic structure of the catalyst,reduce the energy barrier for the oxygen electrode re-action,meanwhile enhance the bifunctional catalytic activity.Impressively,the nickel-cobalt oxide-based LOB with cationic vacancies exhibits large specific capacity(12,205 mAh g^(-1)at 200 mA g^(-1))and good durability.This work provides worthwhile insight into the formation and catalytic enhancement mech-anism of transition metal oxide catalysts with cationic vacancies,and to some extent,the creation of efficient and low-cost oxygen electrocatalysts for LOBs.
基金Project supported by the Educational Department of Sichuan Government (No.2005D007) and the National Natural Science Foundation of China (Nos.20173038, 20107004).
文摘Two cobalt(Ⅱ) complexes of the Schiff base with morpholino or aza-crown ether pendants, CoL^1 and CoL^2, as mimic hydrolytic metalloenzyme, were used in catalytic hydrolysis of carboxylic ester (PNPP). The analysis of specific absorption spectra of the hydrolytic reaction systems indicates that key intermediates, made up of PNPP and Co(Ⅱ) complexes, have been formed in reaction processes of the PNPP catalytic hydrolysis. The mechanism of PNPP catalytic hydrolysis has been proposed based on the analytic result of specific absorption spectrum. A kinetic mathematical model, applied to the calculation of the kinetic parameter of PNPP catalytic hydrolysis, has been established based on the mechanism proposed. The acid effect of buffer solution, structural effect of the complexes, and effect of temperature on the rate of PNPP hydrolysis catalyzed by the complexes have been also discussed.
基金supported by the National Natural Science Foundation of China(52101268)Tianjin Natural Science Foundation(19JCQNJC05000)。
文摘Electrocatalysis provides various technologies for energy storage and conversion,which is an important part of realizing sustainable clean energy for the future.COFs,as emerging porous crystalline polymers,possess high specific surface areas,tunable pore structures,high crystallinity and tailorable functionalization.These features endow COFs with abundant active sites and fast electron transport channels,making them potentially efficient electrocatalysts.In recent years,COF-based electrocatalysts have been widely developed for hydrogen evolution reaction(HER),hydrogen oxidation reaction(HOR),oxygen evolution reaction(OER),oxygen reduction reaction(ORR),nitrogen reduction reaction(NRR)and carbon dioxide reduction reaction(CO_(2)RR).In this review,design strategies of COF-based electrocatalysts are briefly summarized,including applying COF as supports,introducing active metals in COF,constructing two-dimensional conductive COF,formation of COF-based hybrid and pyrolysis of COF to obtain carbon materials.Then,the recent research progress in COF-derived catalysts for specific electrocatalytic reactions is introduced systematically.Finally,the outlook and challenges of future applications of COFs in electrocatalysis are highlighted.
基金Project supported by the Educational Department of Sichuan Government (No. 2005D007) and the National Natural Science Foundation of China (Nos. 20173038, 20107004).
文摘Three novel Schiff base cobalt(Ⅱ) complexes containing benzoaza-15-crown-5, CoL^1, CoL^2 and CoL^3 were synthesized and characterized, and these complexes were used in catalytic hydrolysis of carboxylic ester (PNPP, p-nitrophenyl picolinate) as mimic hydrolytic metalloenzyme. The analysis of specific absorption spectra of the hydrolytic reaction systems indicated that the catalytic hydrolysis involved the key intermediates formed by PNPP with cobalt(Ⅱ) complexes. The CoL^3 bearing the electron withdrawing group shows better catalytic activity due to its stabilization effect on active species MLS^-. The catalytic mechanism of PNPP hydrolysis was also proposed. The kinetic parameter of PNPP catalytic hydrolysis has been calculated and the activation energy for the catalytic hydrolysis is 43.69, 39.76 and 35.44 kJ·mol^-1, respectively.