Mo_(2)CT_(x)MXene is a novel two-dimensional material,which is generally made by the etching of inorganic acid solutions,such as hydrofluoric acid(HF)or hydrochloric acid(HCl).Those solutions are always corrosive and ...Mo_(2)CT_(x)MXene is a novel two-dimensional material,which is generally made by the etching of inorganic acid solutions,such as hydrofluoric acid(HF)or hydrochloric acid(HCl).Those solutions are always corrosive and hazardous.In this paper,a mild organic acid,acetic acid(CH_(3)COOH),was selected to synthesize Mo_(2)CT_(x)MXene.30 mL acetic acid(HAc)with the concentration of 13 mol/L was mixed with 2 g acetate(CH_(3)COONa or CH_(3)COOK)and 10 mL water to make etching solution(NaAc+HAc or KAc+HAc).In the solution,the concentration of CH_(3)COO^(-)was 10 mol/L,the concentration of Na^(+)/K^(+)is 0.6/0.5 mol/L.The pH value is 2.8.Mo_(2)CT_(x)was obtained by hydrothermal etching at 240℃for 1 d.Compared with the general method of HF etching,the etchant is milder and the etching process is safer.On the surface of Mo_(2)CT_(x)nanosheet made by this method,acetate group(CH_(3)COO^(-))was adsorbed as termination,which is larger than the F/O/OH termination of that made by general HF etching.The lattice parameter c(LP c)of Mo_(2)CT_(x)etched with NaAc+HAc/KAc+HAc is 21.09Å/20.89Å.Moreover,the specific surface areas of the samples etched by NaAc+HAc and KAc+HAc were 18.1 m^(2)/g and 14.1 m^(2)/g,respectively,which were much larger than those etched by conventional methods.As the anode of lithium-ion battery,the specific capacity under current density of 100 mA/g at 100 th cycle was 108 mA·h/g,which is higher than the capacity of samples made by general HF etching.This work reports a novel method to make Mo_(2)CT_(x)MXene by the solution of mild acetic acid.The samples made by this method had very high specific surface area and relatively high lithium-storage performance.展开更多
Iron oxide nanoparticles(IONPs)with intrinsic peroxidase(POD)-mimic activity have gained significant attention as nanozymes.Reducing sizes of IONPs is the mostly applied strategy to boost their enzymatic activity due ...Iron oxide nanoparticles(IONPs)with intrinsic peroxidase(POD)-mimic activity have gained significant attention as nanozymes.Reducing sizes of IONPs is the mostly applied strategy to boost their enzymatic activity due to their high specific surface areas.Herein,we synthesized a series of uniformly sized IONPs ranging from3.17 to 21.2 nm,and found that POD activity of IONPs is not monotone increased by reducing their sizes,with the optimal size of 7.82 nm rather than smaller sized 3.17 nm.The reason for this unnormal phenomenon is that electronic structure also had great influence on POD activity,especially at the ultrasmall size region.Since Fe^(2+)are with higher enzymatic activity than Fe^(3+),3.17 nm IONPs although have the largest specific surface area,are prone to be oxidized,which reduced their iron content and ratio of Fe^(2+)to Fe^(3+),and consequently decreased their POD activity.By intentionally oxidized 7.82 nm IONPs in air,POD activity was obviously reduced,illustrating electronic structure cannot be overlooked.At the larger sized region ranging from 7.82 to 21.2 nm,oxidation degree of IONPs is similar,and surface electronic structure had a negligible effect on POD activity,and therefore,POD activity is predominantly influenced by specific surface area.By using the optimized 7.82 nm IONPs,tumor growth was obviously inhibited,demonstrating their potential in cancer therapeutics.Our results reveal that the designing of nanozymes should comprehensively balance their influence of surface electronic structure and specific surface area.展开更多
A procedure of low temperature solid-phase sintering（LTSS） was carried out to fabricate sintered metal fibrous media（SMFM） with high specific surface area.Stainless steel fibers which were produced by cutting proc...A procedure of low temperature solid-phase sintering（LTSS） was carried out to fabricate sintered metal fibrous media（SMFM） with high specific surface area.Stainless steel fibers which were produced by cutting process were first plated with a coarse copper coating layer by electroless plating process.A low-temperature sintering process was then completed at about 800 °C for 1 h under the protection of hydrogen atmosphere.The results show that a novel SMFM with complex surface morphology and high specific surface area（0.2 m2/g） can be obtained in this way.The effect of sintering temperature on the surface morphology and specific surface area of SMFM was studied by means of scanning electron microscopy and Brunauer-Emmett-Teller.The damage of micro-structure during the sintering process mainly contributed to the loss of specific surface area of SMFM and the optimal sintering temperature was 800 °C.展开更多
Specific Catchment Area （SCA） is defined as the upstream catchment area of a unit contour. As one of the key terrain parameters, it is widely used in the modeling of hydrology, soil erosion and ecological environmen...Specific Catchment Area （SCA） is defined as the upstream catchment area of a unit contour. As one of the key terrain parameters, it is widely used in the modeling of hydrology, soil erosion and ecological environment. However, SCA value changes significantly at different DEM resolutions, which inevitably affect terrain analysis results. SCA can be described as the ratio of Catchment Area （CA） and DEM grid length. In this paper, the scale effect of CA is firstly investigated. With Jiuyuangou Gully, a watershed about 70 km2 in northern Shaanxi Province of China, as the test area, it is found that the impacts of DEM scale on CA are different in spatial distribution. CA value in upslope location becomes bigger with the decrease of the DEM resolution. When the location is close to downstream areas the impact of DEM scale on CA is gradually weakening. The scale effect of CA can be concluded as a mathematic trend of exponential decline. Then, a downscaling model of SCA is put forward by introducing the scale factor and the location factor. The scaling model can realize the conversion of SCA value from a coarse DEM resolution to a finer one at pixel level. Experiment results show that the downscaled SCA was well revised, and consistent with SCA at the target resolution with respect to the statistical indexes, histogram and spatial distribution. With the advantages of no empirical parameters, the scaling model could be considered as a simple and objective model for SCA scaling in a rugged drainage area.展开更多
Developing efficient oxygen evolution reaction(OER) electrocatalysts such as transition metal sulfides(TMSs) is of great importance to advance renewable hydrogen fuel toward further practical applications.Herein,NiCoS...Developing efficient oxygen evolution reaction(OER) electrocatalysts such as transition metal sulfides(TMSs) is of great importance to advance renewable hydrogen fuel toward further practical applications.Herein,NiCoS_(2) nanoparticles well decorated on double-sided N-doped reduced graphene oxide sheets(NiCoS_(2)/rGO) are prepared from an Al-containing ternary NiCoAl-layered double hydroxide precursor(NiCoAl-LDH) grown on GO support as an OER electrocatalyst.The Al-confinementassisted sulfurization,followed by selective acid treatment,endows the resulting NiCoS_(2)/rGO composite with the advantages:well-dispersed NiCoS_(2) nanoparticles,dualsided rGO support,as well as a large specific surface area of 119.4 m^(2)·g^(-1) and meso-/macroporous size distribution.The NiCoS_(2)/rGO electrocatalyst exhibits an overpotential of 273 mV at 10 mA·cm^(-2) and a good stability of 24 h,which outperform those of the counterparts of NiS_(2)/rGO and CoS_(2)/rGO.The results of electrochemical active surface area and electrochemical impedance spectra experimentally provide convincing rationales of the information of active sites and good conductivity,both underpin the enhanced electrocatalytic performances.展开更多
As a substitute for synthetic ammonia under mild condition, electrocatalytic nitrogen reduction reaction(NRR) provides a hopeful approach for the development of ammonia. Nevertheless, the current development of NRR el...As a substitute for synthetic ammonia under mild condition, electrocatalytic nitrogen reduction reaction(NRR) provides a hopeful approach for the development of ammonia. Nevertheless, the current development of NRR electrocatalysts is far from enough and a systematic research is needed to gain a better improvement. This article presents that 2 D C_(3)N_(4)-NV with a large specific surface area and abundant nitrogen vacancies is prepared by a simple and feasible method, and used as a metal-free catalyst for electrocatalytic NRR. Experiment result and density functional theory(DFT) calculation reveal that nitrogen vacancies in 2 D C_(3)N_(4)-NV can act as an efficient active site for catalytic NRR, which is conducive to capturing and activating N_(2), lowering Gibbs free energy(DG) in reaction and inhibiting hydrogen evolution reaction(HER) at the same time. In addition, the larger specific surface area also makes more active site exposed, which is good for the contact between the electrolyte and the active site, thus enhancing its NRR activity. The electrocatalyst shows an excellent catalytic activity for NRR in 0.1 M HCl, including Faradaic efficiency of 10.96%, NH_(3) yields of 17.85 lg h^(-1) mg_(cat)^(-1)., and good stability(over 20 h).展开更多
In this paper, three kinds of MgO with different specific surface area were prepared, and their effects on the catalytic performance of nickel catalysts for the carbon dioxide reforming of methane were investigated. T...In this paper, three kinds of MgO with different specific surface area were prepared, and their effects on the catalytic performance of nickel catalysts for the carbon dioxide reforming of methane were investigated. The results showed that MgO support with the higher specific surface area led to the higher dispersion of the active metal, which resulted in the higher initial activity. On the other hand, the specific surface area of MgO materials might not be the dominant factor for the basicity of support to chemisorb and activate CO2, which was another important factor for the performance of catalysts. Herein, Ni/MgO(CA) catalyst with proper specific surface area and strong ability to activate CO2exhibited stable catalytic property and the carbon species deposited on the Ni/MgO(CA) catalyst after 10 h of reaction at 650 ?C were mainly activated carbon species.展开更多
In this work,a facile"carbonization-activation"strategy is developed to synthesize N,P-codoped hierarchical porous carbon.Phosphoric acid is innovatively introduced during the hydrothermal process to achieve...In this work,a facile"carbonization-activation"strategy is developed to synthesize N,P-codoped hierarchical porous carbon.Phosphoric acid is innovatively introduced during the hydrothermal process to achieve in-situ P doping as well as create abundant pores,and the employment of sodamide is of vital importance to simultaneously serve as activating agent and N-source to succeed a high-level N doping.Thus,the obtained samples exhibit a unique three-dimensional hierarchical structure with an ultra-high specific surface area(3646 m^(2)g^(-1))and ultra-high N-doping level(9.81 at.%).Computational analyses confirm that N,P co-doping and higher N content can enhance active sites and widen potential differences of carbon materials to improve their capacitance.The as-prepared carbon materials demonstrate superior electrochemical performances,such as an ultra-high capacitance of 586 Fg^(-1)at 1 Ag^(-1),a superior rate capability of 409 Fg^(-1)at 20 Ag^(-1),and excellent long-term stability of 97%capacitance retention after10,000 cycles in 6 M KOH.Moreover,an assembled symmetric supercapacitor delivers a high energy density of 28.1 Wh kg^(-1)at the power density of 450 W kg^(-1)in 1 M Na_(2)SO_(4),demonstrating a great potential for applications in supercapacitors.展开更多
Adding fumed silica(Si0_(2))has been considered as an effective method for tailoring the phase morphology and performance of elastomer-toughened plastic binary blends.It has been demonstrated that the selective distri...Adding fumed silica(Si0_(2))has been considered as an effective method for tailoring the phase morphology and performance of elastomer-toughened plastic binary blends.It has been demonstrated that the selective distribution of SiO_(2) plays a decisive role in the mechanical properties of plastic/elastomer/SiO_(2)nanocomposites,especially for the impact toughness.In this work,we aim to illuminate the role of specific surface area in controlling their selective distribution of fumed SiO_(2) and consequent mechanical properties of plastic/elastomer binary blends.Three types of SiO_(2) with different specific surface areas were incorporated into polylactide/ethylene-co-vinyl-acetate(PLA/EVA)model blends by melt blending directly.It was found that the selective distribution of SiO_(2) is largely determined by their specific surface areas,i.e.SiO_(2) nanoparticles with low specific surface area has a stronger tendency to be located at the interface between PLA matrix and EVA dispersed phase as compared to those with high specific surface area.The specific surface area-dependent interfacial selective distribution of SiO_(2) is mainly attributed to the extent of increased viscosity of EVA dispersed phase in which SiO_(2)nanoparticles are initially dispersed and resultant migration rate of SiO_(2) nanoparticles.The interfacial localized SiO_(2) nanoparticles induce an obvious enhancement in the impact toughness with strength and modulus well maintained.More importantly,in the case of the same interfacial distribution,toughening efficiency is increased with the specific surface area of SiO_(2).Therefore,this is an optimum specific surface area of SiO_(2) for the toughening.This work not only provides a novel way to manipulate the selective distribution of SiO_(2) in elastomer-toughened plastic blends toward high-performance,but also gives a deep insight into the role of interfacial localized nanoparticles in the toughening mechanism.展开更多
Preparation of rice husk ash with high specific surface area and chemical reactivity of the product are reported in this paper. The amorphous rice husk ash with high specific surface area of 311 m2·g-1 was produc...Preparation of rice husk ash with high specific surface area and chemical reactivity of the product are reported in this paper. The amorphous rice husk ash with high specific surface area of 311 m2·g-1 was produced by heating acid treated rice husk at 700℃ for 4 h. The isotherms of rice husk ash are similar in shape to type Ⅱof Brunaner's classification with mesopores being predominant. The rice husk ash has a high chemical reactivity,especially that pretreated with acid. This chemical reactivity depends on ashing temperature and pretreatment conditions. There is an exponential relation between the specific surface area of rice husk ash and the change in the conductivity of saturated Ca(OH)2 solution with rice husk ash, from which the specific surface area can be known according to the conductivity change.展开更多
An activated carbon with ash content less than 10% and specific surface area more than 1 600 m 2 /g was prepared from coal and the effect of K containing compounds in preparation of coal based activated carbon was inv...An activated carbon with ash content less than 10% and specific surface area more than 1 600 m 2 /g was prepared from coal and the effect of K containing compounds in preparation of coal based activated carbon was investigated in detail in this paper. KOH was used in co carbonization with coal, changes in graphitic crystallites in chars derived from carbonization of coal with and without KOH were analyzed by X ray diffraction (XRD) technique, activation rates of chars with different contents of K containing compounds were deduced, and resulting activated carbons were characterized by nitrogen adsorption isotherms at 77 K and iodine numbers. The results showed that the addition of KOH to the coal before carbonization can realize the intensive removal of inorganic matters from chars under mild conditions, especially the efficient removal of dispersive quartz, an extremely difficult separated mineral component in other processes else. Apart from this, KOH demonstrates a favorable effect in control over coal carbonization with the goal to form nongraphitizable isotropic carbon precursor, which is a necessary prerequisite for the formation and development of micro pores. However, the K containing compounds such as K 2 CO 3 and K 2 O remaining in chars after carbonization catalyze the reaction between carbon and steam in activation, which leads to the formation of macro pores. In the end an innovative method, in which KOH is added to coal before carbonization and K containing compounds are removed by acid washing after carbonization, was proposed for the synthesis of quality coal based activated carbon.展开更多
The relationship between the specific surface area（SSA） of rust and the electrochemical behavior of rusted steel under wet-dry acid corrosion conditions was investigated. The results showed that the corrosion curren...The relationship between the specific surface area（SSA） of rust and the electrochemical behavior of rusted steel under wet-dry acid corrosion conditions was investigated. The results showed that the corrosion current density first increased and then decreased with increasing SSA of the rust during the corrosion process. The structure of the rust changed from single-layer to double-layer, and the γ-FeOOH content decreased in the inner layer of the rust with increasing corrosion time; by contrast, the γ-FeOOH content in the outer layer was constant. When the SSA of the rust was lower than the critical SSA corresponding to the relative humidity during the drying period, condensed water in the micropores of the rust could evaporate, which prompted the diffusion of O_2 into the rust and the following formation process of γ-FeOOH, leading to an increase of corrosion current density with increasing corrosion time. However, when the SSA of the rust reached or exceeded the critical SSA, condensate water in the micro-pores of the inner layer of the rust could not evaporate which inhibited the diffusion of O_2 and decreased the γ-FeOOH content in the inner rust, leading to a decrease of corrosion current density with increasing corrosion time.展开更多
An improved biosorbent of thiourea modified chitosan microsphere（TMCM） with high specific surface,favorable mechanical strength and excellent adsorption performance had been synthesized via microfluidic technology. ...An improved biosorbent of thiourea modified chitosan microsphere（TMCM） with high specific surface,favorable mechanical strength and excellent adsorption performance had been synthesized via microfluidic technology. Polyethylene glycol was used as a significant component added in aqueous solution of chitosan to produce such microspheres through droplets forming, chemical crosslinking and pores creating. For the improvement of adsorption capacity, thiourea was considered as an excellent choice in increasing amino functional group by graft modification. The SEM, FTIR and EDS were employed to detect distinct features of TMCM. Copper（Ⅱ） was used to test the adsorption performance of TMCM. The experimental results indicated that TMCM exhibited higher adsorption capacity（q_e= 60.6 mg g_（-1）） and faster adsorption rate than that non-modified chitosan microsphere（NMCM）.The adsorption kinetic was described well by the pseudo-second order kinetic model, which suggested that chemical adsorption along with electrons transferring was dominant in adsorption process.展开更多
Effects of specific surface area and tiny amount of impurities of reactive alumina on the workability, sinte- ring and high temperature mechanical strength of corun- dum based castables were investigated. The results ...Effects of specific surface area and tiny amount of impurities of reactive alumina on the workability, sinte- ring and high temperature mechanical strength of corun- dum based castables were investigated. The results show that the presence of reactive alumina with high specific surface area leads to accelerating of the hydration of calcium aluminate cement, thus shortening the working time and setting time of the castables, which can be as- cribed that the critical energy barrier for stable nuclei of hydration products of cement can be reduced by the high specific surface area of reactive alumina. The sintering of the corundum based castables can be accelerated by the reactive alumina with high specific surface area and high amount of impurities, however, the reactive alumina with too high specific surface area and impurities can al- so lead to noticeable shrinkage of castables. In addition, high temperature mechanical strength of corundum based castables can be decreased by the higher amount of trace impurities of reactive alumina due to formation of low- melting phase at high temperatures.展开更多
Principle and method of measuring Specific Surface Area (SSA) of ceramisite made from dredged river sediment, sewage sludge and adherent materials are discussed. Brunauer-Emmett-Teller Procedure tests SSA of the ceram...Principle and method of measuring Specific Surface Area (SSA) of ceramisite made from dredged river sediment, sewage sludge and adherent materials are discussed. Brunauer-Emmett-Teller Procedure tests SSA of the ceramisite. Influences of sewage sludge content, adherent content and sintering point on the SSA of ceramisite made of river sediment are also analyzed. Results show that with the right sewage sludge content, adherent content and sintering point, the ceramisite can have the highest SSA value and be widely used.展开更多
More than 500 datasets from the literature have been used to evaluate the relationships of specific surface area (SSA),cation exchange capacity (CEC) and activity versus the liquid limit (LL).The correlations gave R^2...More than 500 datasets from the literature have been used to evaluate the relationships of specific surface area (SSA),cation exchange capacity (CEC) and activity versus the liquid limit (LL).The correlations gave R^2 values ranging between 0.71 and 0.92.Independent data were also used to validate the correlations.Estimated SSA values slightly overestimate the measured SSA up to 100 m^2/g.Regarding the estimated CEC values,they overestimated the measured CEC values up to 20 meq/(100 g).A probabilistic approach was performed for the correlations of SSA,CEC and activity versus LL.The analysis shows that the relations of SSA,CEC and activity with LL are robust.Using the LL values,it is possible to assess other basic engineering properties of clays.展开更多
Carbon deposition on nickel powders in methane involves three stages in different reaction temperature ranges. Temperature programing oxidation test and Raman spectrum results indicated the formation of complex and or...Carbon deposition on nickel powders in methane involves three stages in different reaction temperature ranges. Temperature programing oxidation test and Raman spectrum results indicated the formation of complex and ordered carbon structures at high deposition temperatures. The values of I（D）/I（G） of the deposited carbon reached 1.86, 1.30, and 1.22 in the first, second, and third stages, respectively. The structure of carbon in the second stage was similar to that in the third stage. Carbon deposited in the first stage rarely contained homogeneous pyrolytic deposit layers. A kinetic model was developed to analyze the carbon deposition behavior in the first stage. The rate-determining step of the first stage is supposed to be interfacial reaction. Based on the investigation of carbon deposition kinetics on nickel powders from different resources, carbon deposition rate is suggested to have a linear relation with the square of specific surface area of nickel particles.展开更多
Surface distribution and seasonal variation of alkalinity and specific alkalinity in Kuroshio area of the East ChinaSea and their application to the water mass tracing are discussed in this paper. Results show a disti...Surface distribution and seasonal variation of alkalinity and specific alkalinity in Kuroshio area of the East ChinaSea and their application to the water mass tracing are discussed in this paper. Results show a distinct seasonal variation of the alkalinity, which is concerned with the process of vertical mixing. Different specific alkalinity in various water masses has been found. On the basis of the difference of the specific alkalinity and the distribution of alkalinity, two water fronts in summer season, located at 27°-30°N and 124°-1 27°E, (Ⅰ), and at the northern waters about one latitude from the Taiwan Island, (Ⅱ); one in winter season at about one longitude from coast of mainland of China and 26°-30°N were found. In summer season, about 1-2 longitudes eastward shift of front (Ⅰ) is found by comparison of data in May and August. And the high alkalinity of the northern East China Sea in summer season may be caused by the Huanghe River runoff flowing southward along with the Huanghai Sea Coastal Current.展开更多
The electrochemical reduction of CO2(CO2 RR) can substantially contribute to the production of useful chemicals and reduction of global CO2 emissions. Herein, we presented N and S dual-doped high-surface-area carbon m...The electrochemical reduction of CO2(CO2 RR) can substantially contribute to the production of useful chemicals and reduction of global CO2 emissions. Herein, we presented N and S dual-doped high-surface-area carbon materials(SZ-HCN) as CO2 RR catalysts. N and S were doped by one-step pyrolysis of a N-containing polymer and S powder. ZnCl2 was applied as a volatile porogen to prepare porous SZ-HCN. SZ-HCN with a high specific surface area(1510 m2 g–1) exhibited efficient electrocatalytic activity and selectivity for CO2 RR. Electrochemical measurements demonstrated that SZ-HCN showed excellent catalytic performance for CO2-to-CO reduction with a high CO Faradaic efficiency(~93%) at-0.6 V. Furthermore, SZ-HCN offered a stable current density and high CO selectivity over at least 20 h continuous operation, revealing remarkable electrocatalytic durability. The experimental results and density functional theory calculations indicated that N and S dual-doped carbon materials required lower Gibbs free energy to form the COOH* intermediate than that for single-N-doped carbon for CO2-to-CO reduction, thereby enhancing CO2 RR activity.展开更多
Potassium-ion hybrid capacitors(PIHCs)are widely regarded as highly promising energy storage devices,due to their exceptional energy density,impressive power density,and abundant potassium resources.Unfortunately,rest...Potassium-ion hybrid capacitors(PIHCs)are widely regarded as highly promising energy storage devices,due to their exceptional energy density,impressive power density,and abundant potassium resources.Unfortunately,restricted by the inherent capacitive storage mechanism,the carbon cathodes possess a much lower specific capacity than battery-type anodes.Therefore,designing high-performance carbon cathodes is extremely urgent for the development of PIHCs.Herein,N,O codoped porous carbon(NOPC)was fabricated through the NaCl hard template method and combined KOH/melamine chemical activation technique,displaying the characteristics of abundant N/O content(4.7 at%/16.9 at%),ultrahigh specific surface area(3092 m^(2)g^(-1))and hierarchical pore network.The designed NOPC cathode delivers a high specific capacity(164.4 mAh.g^(-1)at 0.05 A.g^(-1))and superior cyclability(95.1%retention ratio at 2 A·g^(-1)over 2500 cycles).Notably,the adjustable ratio of micropores to mesopores facilitates the achievement of the optimal bal-ance between capacity and rate capability.Moreover,the pseudocapacitance can be further augmented through the incorporation of N/O functional groups.As expected,the graphite//NOPC based PIHC possesses a high energy density of 113 Wh·kg-at 747 W·kg^(-1)and excellent capacity retention of 84.4% fter 400 cycles at 1.0 A·g^(-1).This work introduces a novel strategy for designing carbon cathodes that enhances the electrochemical performance of PIHCs.展开更多
基金Projects(52372284,52275187,62004143)supported by the National Natural Science Foundation of ChinaProject(2022BAA084)supported by the Key R&D Program of Hubei Province,ChinaProject(232300421135)supported by the Natural Science Foundation of Henan Province,China。
文摘Mo_(2)CT_(x)MXene is a novel two-dimensional material,which is generally made by the etching of inorganic acid solutions,such as hydrofluoric acid(HF)or hydrochloric acid(HCl).Those solutions are always corrosive and hazardous.In this paper,a mild organic acid,acetic acid(CH_(3)COOH),was selected to synthesize Mo_(2)CT_(x)MXene.30 mL acetic acid(HAc)with the concentration of 13 mol/L was mixed with 2 g acetate(CH_(3)COONa or CH_(3)COOK)and 10 mL water to make etching solution(NaAc+HAc or KAc+HAc).In the solution,the concentration of CH_(3)COO^(-)was 10 mol/L,the concentration of Na^(+)/K^(+)is 0.6/0.5 mol/L.The pH value is 2.8.Mo_(2)CT_(x)was obtained by hydrothermal etching at 240℃for 1 d.Compared with the general method of HF etching,the etchant is milder and the etching process is safer.On the surface of Mo_(2)CT_(x)nanosheet made by this method,acetate group(CH_(3)COO^(-))was adsorbed as termination,which is larger than the F/O/OH termination of that made by general HF etching.The lattice parameter c(LP c)of Mo_(2)CT_(x)etched with NaAc+HAc/KAc+HAc is 21.09Å/20.89Å.Moreover,the specific surface areas of the samples etched by NaAc+HAc and KAc+HAc were 18.1 m^(2)/g and 14.1 m^(2)/g,respectively,which were much larger than those etched by conventional methods.As the anode of lithium-ion battery,the specific capacity under current density of 100 mA/g at 100 th cycle was 108 mA·h/g,which is higher than the capacity of samples made by general HF etching.This work reports a novel method to make Mo_(2)CT_(x)MXene by the solution of mild acetic acid.The samples made by this method had very high specific surface area and relatively high lithium-storage performance.
基金financially supported by the Natural Science Foundation of Zhejiang Province(No.LR22E010001)the National Natural Science Foundation of China(No.52073258)+1 种基金the Fundamental Research Funds for the Provincial Universities of Zhejiang(No.RF-B2022006)the R&D Program of Zhejiang University of Technology(No.KYY-HX-20190730)
文摘Iron oxide nanoparticles(IONPs)with intrinsic peroxidase(POD)-mimic activity have gained significant attention as nanozymes.Reducing sizes of IONPs is the mostly applied strategy to boost their enzymatic activity due to their high specific surface areas.Herein,we synthesized a series of uniformly sized IONPs ranging from3.17 to 21.2 nm,and found that POD activity of IONPs is not monotone increased by reducing their sizes,with the optimal size of 7.82 nm rather than smaller sized 3.17 nm.The reason for this unnormal phenomenon is that electronic structure also had great influence on POD activity,especially at the ultrasmall size region.Since Fe^(2+)are with higher enzymatic activity than Fe^(3+),3.17 nm IONPs although have the largest specific surface area,are prone to be oxidized,which reduced their iron content and ratio of Fe^(2+)to Fe^(3+),and consequently decreased their POD activity.By intentionally oxidized 7.82 nm IONPs in air,POD activity was obviously reduced,illustrating electronic structure cannot be overlooked.At the larger sized region ranging from 7.82 to 21.2 nm,oxidation degree of IONPs is similar,and surface electronic structure had a negligible effect on POD activity,and therefore,POD activity is predominantly influenced by specific surface area.By using the optimized 7.82 nm IONPs,tumor growth was obviously inhibited,demonstrating their potential in cancer therapeutics.Our results reveal that the designing of nanozymes should comprehensively balance their influence of surface electronic structure and specific surface area.
基金Project (50930005) supported by the National Natural Science Foundation of ChinaProject (U0834002) supported by the Key Programof NSFC-Guangdong Joint Funds of China+1 种基金Project (LYM09024) supported by Training Program for Excellent Young Teachers withInnovation of Guangdong University, ChinaProject (2009ZM0121) supported by the Fundamental Research Funds for the CentralUniversities of South China University of Technology,China
文摘A procedure of low temperature solid-phase sintering（LTSS） was carried out to fabricate sintered metal fibrous media（SMFM） with high specific surface area.Stainless steel fibers which were produced by cutting process were first plated with a coarse copper coating layer by electroless plating process.A low-temperature sintering process was then completed at about 800 °C for 1 h under the protection of hydrogen atmosphere.The results show that a novel SMFM with complex surface morphology and high specific surface area（0.2 m2/g） can be obtained in this way.The effect of sintering temperature on the surface morphology and specific surface area of SMFM was studied by means of scanning electron microscopy and Brunauer-Emmett-Teller.The damage of micro-structure during the sintering process mainly contributed to the loss of specific surface area of SMFM and the optimal sintering temperature was 800 °C.
基金Key Project of National Natural Science Foundation of China No.40930531 National Youth Science Foun-dation of China No.40901185 Specialized Research Fund for the Doctoral Program of Higher Education No.20093207120008
文摘Specific Catchment Area （SCA） is defined as the upstream catchment area of a unit contour. As one of the key terrain parameters, it is widely used in the modeling of hydrology, soil erosion and ecological environment. However, SCA value changes significantly at different DEM resolutions, which inevitably affect terrain analysis results. SCA can be described as the ratio of Catchment Area （CA） and DEM grid length. In this paper, the scale effect of CA is firstly investigated. With Jiuyuangou Gully, a watershed about 70 km2 in northern Shaanxi Province of China, as the test area, it is found that the impacts of DEM scale on CA are different in spatial distribution. CA value in upslope location becomes bigger with the decrease of the DEM resolution. When the location is close to downstream areas the impact of DEM scale on CA is gradually weakening. The scale effect of CA can be concluded as a mathematic trend of exponential decline. Then, a downscaling model of SCA is put forward by introducing the scale factor and the location factor. The scaling model can realize the conversion of SCA value from a coarse DEM resolution to a finer one at pixel level. Experiment results show that the downscaled SCA was well revised, and consistent with SCA at the target resolution with respect to the statistical indexes, histogram and spatial distribution. With the advantages of no empirical parameters, the scaling model could be considered as a simple and objective model for SCA scaling in a rugged drainage area.
基金financially supported by the National Natural Science Foundation of China(No.U1607128)。
文摘Developing efficient oxygen evolution reaction(OER) electrocatalysts such as transition metal sulfides(TMSs) is of great importance to advance renewable hydrogen fuel toward further practical applications.Herein,NiCoS_(2) nanoparticles well decorated on double-sided N-doped reduced graphene oxide sheets(NiCoS_(2)/rGO) are prepared from an Al-containing ternary NiCoAl-layered double hydroxide precursor(NiCoAl-LDH) grown on GO support as an OER electrocatalyst.The Al-confinementassisted sulfurization,followed by selective acid treatment,endows the resulting NiCoS_(2)/rGO composite with the advantages:well-dispersed NiCoS_(2) nanoparticles,dualsided rGO support,as well as a large specific surface area of 119.4 m^(2)·g^(-1) and meso-/macroporous size distribution.The NiCoS_(2)/rGO electrocatalyst exhibits an overpotential of 273 mV at 10 mA·cm^(-2) and a good stability of 24 h,which outperform those of the counterparts of NiS_(2)/rGO and CoS_(2)/rGO.The results of electrochemical active surface area and electrochemical impedance spectra experimentally provide convincing rationales of the information of active sites and good conductivity,both underpin the enhanced electrocatalytic performances.
基金funded by the National Natural Science Foundation of China (21802058 and 21872066)the Fundamental Research Funds for the Central Universities (China, lzujbky-2020-42)the Natural Science Foundation of Gansu Province (20JR5RA225)。
文摘As a substitute for synthetic ammonia under mild condition, electrocatalytic nitrogen reduction reaction(NRR) provides a hopeful approach for the development of ammonia. Nevertheless, the current development of NRR electrocatalysts is far from enough and a systematic research is needed to gain a better improvement. This article presents that 2 D C_(3)N_(4)-NV with a large specific surface area and abundant nitrogen vacancies is prepared by a simple and feasible method, and used as a metal-free catalyst for electrocatalytic NRR. Experiment result and density functional theory(DFT) calculation reveal that nitrogen vacancies in 2 D C_(3)N_(4)-NV can act as an efficient active site for catalytic NRR, which is conducive to capturing and activating N_(2), lowering Gibbs free energy(DG) in reaction and inhibiting hydrogen evolution reaction(HER) at the same time. In addition, the larger specific surface area also makes more active site exposed, which is good for the contact between the electrolyte and the active site, thus enhancing its NRR activity. The electrocatalyst shows an excellent catalytic activity for NRR in 0.1 M HCl, including Faradaic efficiency of 10.96%, NH_(3) yields of 17.85 lg h^(-1) mg_(cat)^(-1)., and good stability(over 20 h).
基金supported by the South-Central University for Nationalities(CZZ12002)
文摘In this paper, three kinds of MgO with different specific surface area were prepared, and their effects on the catalytic performance of nickel catalysts for the carbon dioxide reforming of methane were investigated. The results showed that MgO support with the higher specific surface area led to the higher dispersion of the active metal, which resulted in the higher initial activity. On the other hand, the specific surface area of MgO materials might not be the dominant factor for the basicity of support to chemisorb and activate CO2, which was another important factor for the performance of catalysts. Herein, Ni/MgO(CA) catalyst with proper specific surface area and strong ability to activate CO2exhibited stable catalytic property and the carbon species deposited on the Ni/MgO(CA) catalyst after 10 h of reaction at 650 ?C were mainly activated carbon species.
基金financially supported by the National Natural Science Foundation of China(Nos.21776147,21606140,61604086,and 21905153)the Qingdao Municipal Science and Technology Bureau,China(19-6-1-91-nsh)+2 种基金the International Science&Technology Cooperation Program of China(No.2014DFA60150)the Department of Science and Technology of Shandong Province(Nos.ZR2018BB066 and 2016GGX104010)the Chemcloudcomputing of National Supercomputing Center in Shenzhen(Shenzhen CloudComputing Center)。
文摘In this work,a facile"carbonization-activation"strategy is developed to synthesize N,P-codoped hierarchical porous carbon.Phosphoric acid is innovatively introduced during the hydrothermal process to achieve in-situ P doping as well as create abundant pores,and the employment of sodamide is of vital importance to simultaneously serve as activating agent and N-source to succeed a high-level N doping.Thus,the obtained samples exhibit a unique three-dimensional hierarchical structure with an ultra-high specific surface area(3646 m^(2)g^(-1))and ultra-high N-doping level(9.81 at.%).Computational analyses confirm that N,P co-doping and higher N content can enhance active sites and widen potential differences of carbon materials to improve their capacitance.The as-prepared carbon materials demonstrate superior electrochemical performances,such as an ultra-high capacitance of 586 Fg^(-1)at 1 Ag^(-1),a superior rate capability of 409 Fg^(-1)at 20 Ag^(-1),and excellent long-term stability of 97%capacitance retention after10,000 cycles in 6 M KOH.Moreover,an assembled symmetric supercapacitor delivers a high energy density of 28.1 Wh kg^(-1)at the power density of 450 W kg^(-1)in 1 M Na_(2)SO_(4),demonstrating a great potential for applications in supercapacitors.
基金the National Natural Science Foundation of China(No.51803130)China Postdoctoral Science Foundation(No.2018M640915)+1 种基金Sichuan Science and Technology Program(No.2019JDRC010)Fundamental Research Funds for Central Universities.
文摘Adding fumed silica(Si0_(2))has been considered as an effective method for tailoring the phase morphology and performance of elastomer-toughened plastic binary blends.It has been demonstrated that the selective distribution of SiO_(2) plays a decisive role in the mechanical properties of plastic/elastomer/SiO_(2)nanocomposites,especially for the impact toughness.In this work,we aim to illuminate the role of specific surface area in controlling their selective distribution of fumed SiO_(2) and consequent mechanical properties of plastic/elastomer binary blends.Three types of SiO_(2) with different specific surface areas were incorporated into polylactide/ethylene-co-vinyl-acetate(PLA/EVA)model blends by melt blending directly.It was found that the selective distribution of SiO_(2) is largely determined by their specific surface areas,i.e.SiO_(2) nanoparticles with low specific surface area has a stronger tendency to be located at the interface between PLA matrix and EVA dispersed phase as compared to those with high specific surface area.The specific surface area-dependent interfacial selective distribution of SiO_(2) is mainly attributed to the extent of increased viscosity of EVA dispersed phase in which SiO_(2)nanoparticles are initially dispersed and resultant migration rate of SiO_(2) nanoparticles.The interfacial localized SiO_(2) nanoparticles induce an obvious enhancement in the impact toughness with strength and modulus well maintained.More importantly,in the case of the same interfacial distribution,toughening efficiency is increased with the specific surface area of SiO_(2).Therefore,this is an optimum specific surface area of SiO_(2) for the toughening.This work not only provides a novel way to manipulate the selective distribution of SiO_(2) in elastomer-toughened plastic blends toward high-performance,but also gives a deep insight into the role of interfacial localized nanoparticles in the toughening mechanism.
文摘Preparation of rice husk ash with high specific surface area and chemical reactivity of the product are reported in this paper. The amorphous rice husk ash with high specific surface area of 311 m2·g-1 was produced by heating acid treated rice husk at 700℃ for 4 h. The isotherms of rice husk ash are similar in shape to type Ⅱof Brunaner's classification with mesopores being predominant. The rice husk ash has a high chemical reactivity,especially that pretreated with acid. This chemical reactivity depends on ashing temperature and pretreatment conditions. There is an exponential relation between the specific surface area of rice husk ash and the change in the conductivity of saturated Ca(OH)2 solution with rice husk ash, from which the specific surface area can be known according to the conductivity change.
文摘An activated carbon with ash content less than 10% and specific surface area more than 1 600 m 2 /g was prepared from coal and the effect of K containing compounds in preparation of coal based activated carbon was investigated in detail in this paper. KOH was used in co carbonization with coal, changes in graphitic crystallites in chars derived from carbonization of coal with and without KOH were analyzed by X ray diffraction (XRD) technique, activation rates of chars with different contents of K containing compounds were deduced, and resulting activated carbons were characterized by nitrogen adsorption isotherms at 77 K and iodine numbers. The results showed that the addition of KOH to the coal before carbonization can realize the intensive removal of inorganic matters from chars under mild conditions, especially the efficient removal of dispersive quartz, an extremely difficult separated mineral component in other processes else. Apart from this, KOH demonstrates a favorable effect in control over coal carbonization with the goal to form nongraphitizable isotropic carbon precursor, which is a necessary prerequisite for the formation and development of micro pores. However, the K containing compounds such as K 2 CO 3 and K 2 O remaining in chars after carbonization catalyze the reaction between carbon and steam in activation, which leads to the formation of macro pores. In the end an innovative method, in which KOH is added to coal before carbonization and K containing compounds are removed by acid washing after carbonization, was proposed for the synthesis of quality coal based activated carbon.
基金the National Natural Science Foundation of China(Project No.51571027)for funding support
文摘The relationship between the specific surface area（SSA） of rust and the electrochemical behavior of rusted steel under wet-dry acid corrosion conditions was investigated. The results showed that the corrosion current density first increased and then decreased with increasing SSA of the rust during the corrosion process. The structure of the rust changed from single-layer to double-layer, and the γ-FeOOH content decreased in the inner layer of the rust with increasing corrosion time; by contrast, the γ-FeOOH content in the outer layer was constant. When the SSA of the rust was lower than the critical SSA corresponding to the relative humidity during the drying period, condensed water in the micropores of the rust could evaporate, which prompted the diffusion of O_2 into the rust and the following formation process of γ-FeOOH, leading to an increase of corrosion current density with increasing corrosion time. However, when the SSA of the rust reached or exceeded the critical SSA, condensate water in the micro-pores of the inner layer of the rust could not evaporate which inhibited the diffusion of O_2 and decreased the γ-FeOOH content in the inner rust, leading to a decrease of corrosion current density with increasing corrosion time.
基金support by National Basic Research Program of China(No.2014CB748500)National Natural Science Foundation of China(Nos.51578239,51322805)
文摘An improved biosorbent of thiourea modified chitosan microsphere（TMCM） with high specific surface,favorable mechanical strength and excellent adsorption performance had been synthesized via microfluidic technology. Polyethylene glycol was used as a significant component added in aqueous solution of chitosan to produce such microspheres through droplets forming, chemical crosslinking and pores creating. For the improvement of adsorption capacity, thiourea was considered as an excellent choice in increasing amino functional group by graft modification. The SEM, FTIR and EDS were employed to detect distinct features of TMCM. Copper（Ⅱ） was used to test the adsorption performance of TMCM. The experimental results indicated that TMCM exhibited higher adsorption capacity（q_e= 60.6 mg g_（-1）） and faster adsorption rate than that non-modified chitosan microsphere（NMCM）.The adsorption kinetic was described well by the pseudo-second order kinetic model, which suggested that chemical adsorption along with electrons transferring was dominant in adsorption process.
文摘Effects of specific surface area and tiny amount of impurities of reactive alumina on the workability, sinte- ring and high temperature mechanical strength of corun- dum based castables were investigated. The results show that the presence of reactive alumina with high specific surface area leads to accelerating of the hydration of calcium aluminate cement, thus shortening the working time and setting time of the castables, which can be as- cribed that the critical energy barrier for stable nuclei of hydration products of cement can be reduced by the high specific surface area of reactive alumina. The sintering of the corundum based castables can be accelerated by the reactive alumina with high specific surface area and high amount of impurities, however, the reactive alumina with too high specific surface area and impurities can al- so lead to noticeable shrinkage of castables. In addition, high temperature mechanical strength of corundum based castables can be decreased by the higher amount of trace impurities of reactive alumina due to formation of low- melting phase at high temperatures.
文摘Principle and method of measuring Specific Surface Area (SSA) of ceramisite made from dredged river sediment, sewage sludge and adherent materials are discussed. Brunauer-Emmett-Teller Procedure tests SSA of the ceramisite. Influences of sewage sludge content, adherent content and sintering point on the SSA of ceramisite made of river sediment are also analyzed. Results show that with the right sewage sludge content, adherent content and sintering point, the ceramisite can have the highest SSA value and be widely used.
文摘More than 500 datasets from the literature have been used to evaluate the relationships of specific surface area (SSA),cation exchange capacity (CEC) and activity versus the liquid limit (LL).The correlations gave R^2 values ranging between 0.71 and 0.92.Independent data were also used to validate the correlations.Estimated SSA values slightly overestimate the measured SSA up to 100 m^2/g.Regarding the estimated CEC values,they overestimated the measured CEC values up to 20 meq/(100 g).A probabilistic approach was performed for the correlations of SSA,CEC and activity versus LL.The analysis shows that the relations of SSA,CEC and activity with LL are robust.Using the LL values,it is possible to assess other basic engineering properties of clays.
基金financially supported by the National Program on Key Basic Research Project of China (973 Program, No. 2012CB215405)the National Natural Science Foundation of China (No. 51174022)
文摘Carbon deposition on nickel powders in methane involves three stages in different reaction temperature ranges. Temperature programing oxidation test and Raman spectrum results indicated the formation of complex and ordered carbon structures at high deposition temperatures. The values of I（D）/I（G） of the deposited carbon reached 1.86, 1.30, and 1.22 in the first, second, and third stages, respectively. The structure of carbon in the second stage was similar to that in the third stage. Carbon deposited in the first stage rarely contained homogeneous pyrolytic deposit layers. A kinetic model was developed to analyze the carbon deposition behavior in the first stage. The rate-determining step of the first stage is supposed to be interfacial reaction. Based on the investigation of carbon deposition kinetics on nickel powders from different resources, carbon deposition rate is suggested to have a linear relation with the square of specific surface area of nickel particles.
文摘Surface distribution and seasonal variation of alkalinity and specific alkalinity in Kuroshio area of the East ChinaSea and their application to the water mass tracing are discussed in this paper. Results show a distinct seasonal variation of the alkalinity, which is concerned with the process of vertical mixing. Different specific alkalinity in various water masses has been found. On the basis of the difference of the specific alkalinity and the distribution of alkalinity, two water fronts in summer season, located at 27°-30°N and 124°-1 27°E, (Ⅰ), and at the northern waters about one latitude from the Taiwan Island, (Ⅱ); one in winter season at about one longitude from coast of mainland of China and 26°-30°N were found. In summer season, about 1-2 longitudes eastward shift of front (Ⅰ) is found by comparison of data in May and August. And the high alkalinity of the northern East China Sea in summer season may be caused by the Huanghe River runoff flowing southward along with the Huanghai Sea Coastal Current.
文摘The electrochemical reduction of CO2(CO2 RR) can substantially contribute to the production of useful chemicals and reduction of global CO2 emissions. Herein, we presented N and S dual-doped high-surface-area carbon materials(SZ-HCN) as CO2 RR catalysts. N and S were doped by one-step pyrolysis of a N-containing polymer and S powder. ZnCl2 was applied as a volatile porogen to prepare porous SZ-HCN. SZ-HCN with a high specific surface area(1510 m2 g–1) exhibited efficient electrocatalytic activity and selectivity for CO2 RR. Electrochemical measurements demonstrated that SZ-HCN showed excellent catalytic performance for CO2-to-CO reduction with a high CO Faradaic efficiency(~93%) at-0.6 V. Furthermore, SZ-HCN offered a stable current density and high CO selectivity over at least 20 h continuous operation, revealing remarkable electrocatalytic durability. The experimental results and density functional theory calculations indicated that N and S dual-doped carbon materials required lower Gibbs free energy to form the COOH* intermediate than that for single-N-doped carbon for CO2-to-CO reduction, thereby enhancing CO2 RR activity.
基金financially supported by the National Natural Science Foundation of China(Nos.22179123 and52002138)Taishan Scholar Program of Shandong Province+1 种基金China(No.tsqn202211048)the Fundamental Research Funds for the Central Universities(Nos.202262010 and 862201013190)。
文摘Potassium-ion hybrid capacitors(PIHCs)are widely regarded as highly promising energy storage devices,due to their exceptional energy density,impressive power density,and abundant potassium resources.Unfortunately,restricted by the inherent capacitive storage mechanism,the carbon cathodes possess a much lower specific capacity than battery-type anodes.Therefore,designing high-performance carbon cathodes is extremely urgent for the development of PIHCs.Herein,N,O codoped porous carbon(NOPC)was fabricated through the NaCl hard template method and combined KOH/melamine chemical activation technique,displaying the characteristics of abundant N/O content(4.7 at%/16.9 at%),ultrahigh specific surface area(3092 m^(2)g^(-1))and hierarchical pore network.The designed NOPC cathode delivers a high specific capacity(164.4 mAh.g^(-1)at 0.05 A.g^(-1))and superior cyclability(95.1%retention ratio at 2 A·g^(-1)over 2500 cycles).Notably,the adjustable ratio of micropores to mesopores facilitates the achievement of the optimal bal-ance between capacity and rate capability.Moreover,the pseudocapacitance can be further augmented through the incorporation of N/O functional groups.As expected,the graphite//NOPC based PIHC possesses a high energy density of 113 Wh·kg-at 747 W·kg^(-1)and excellent capacity retention of 84.4% fter 400 cycles at 1.0 A·g^(-1).This work introduces a novel strategy for designing carbon cathodes that enhances the electrochemical performance of PIHCs.
