We reported effect of various alkaline oxides on the broadband infrared luminescence from bismuth-doped aluminophosphate glasses. The samples of （99-x）P2O3-17Al2O3-xR2O-IBi2O3 （R=Li, Na and K, x=0 and 10 in mol%） ...We reported effect of various alkaline oxides on the broadband infrared luminescence from bismuth-doped aluminophosphate glasses. The samples of （99-x）P2O3-17Al2O3-xR2O-IBi2O3 （R=Li, Na and K, x=0 and 10 in mol%） were prepared under reducing condition controlled by additional carbon powders. The fluorescent intensity decreased with increasing content of alkaline oxides and basicity of host glasses. The 1/e fluorescence lifetime of the 72P2O3-17Al2O3-10R2O-1Bi2O3 （R=Li, Na and K） glasses decreased from 461 to 316 μs, as alkaline ions changed from Li^＋ to K^＋.展开更多
Triggering structural asymmetry can induce charge redistribution and modify electronic structures,which is of great significance for the design of high-performance hydrogen oxidation reaction(HOR)electrocatalysts.Here...Triggering structural asymmetry can induce charge redistribution and modify electronic structures,which is of great significance for the design of high-performance hydrogen oxidation reaction(HOR)electrocatalysts.Herein,we propose a dual anion-induced strategy to create an innovative RuS_(2)-RuO_(2)heterostructure featuring abundant S-Ru-O interfaces(RuS_(2)-RuO_(2)@C).This RuS_(2)-RuO_(2)@C demonstrates an impressive mass activity of 2.61 mAμg_(RU)^(-1)and an exchange current density of 2.96 mA cm^(-2),surpassing Pt/C and other comparative samples by over 20 times.Durability assessments confirm the superior stability of RuS_(2)-RuO_(2)@C,with only minimal performance loss during operation.Density functional theory(DFT)calculations indicate that the asymmetric S-Ru-O configuration optimizes the interfacial electronic structure and shifts the d-band center closer to the Fermi level,effectively reducing the energy barrier of the rate-determining step(RDS)in the alkaline HOR process.Moreover,in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy(ATR-SEIRAS)characteristics disclose the formation of a substantial hydrogen bond network at the S-Ru-o interface,which aids in the desorption of H_(2)O_(ad)and facilitates the vital Volmer step in the HOR pathway.展开更多
Methane conversions at lower temperature were studied. The aetivity of Y_2O_3 sample at 823K was fairly high with some formation of C_2H_4 and C_2H_6, the catalysts based on alkaline earth oxides and yttria would give...Methane conversions at lower temperature were studied. The aetivity of Y_2O_3 sample at 823K was fairly high with some formation of C_2H_4 and C_2H_6, the catalysts based on alkaline earth oxides and yttria would give better results. The influences of flux ratio, space velocity, and reaction temperature were also discussed.展开更多
Lignin serves as one of the most important molecular fossils for tracing Terrestrial Organic Matters （TOMs） in marine environment. Extraction and derivatization of lignin oxidation products （LOPs） are crucial for ...Lignin serves as one of the most important molecular fossils for tracing Terrestrial Organic Matters （TOMs） in marine environment. Extraction and derivatization of lignin oxidation products （LOPs） are crucial for accurate quantification of lignin in marine sediment. Here we report a modification of the conventional alkaline cupric oxide （CuO） oxidation method, the modification consisting in a solid phase extraction （SPE） and a novel on-column derivatization being employed for better efficiency and reproducibility. In spiking blanks, recoveries with SPE for the LOPs are between 77.84% and 99.57% with relative standard deviations （RSDs） ranging from 0.57% to 8.04% （n=3）, while those with traditional liquid-liquid extraction （LLE） are from 44.52% to 86.16% With RSDs being from 0.53% to 13.14% （n=3）. Moreover, the reproducibility is greatly improved with SPE, with less solvent consumption and shorter processing time. The average efficiency of on-column derivatization for LOPs is 100.8%±0.68%, which is significantly higher than those of in-vial or in-syringe derivatization, thus resulting in still less consumption of derivatizing reagents.Lignin in the surface sediments sampled from the south of Yangtze River estuary, China, was determined with the established method. Recoveries of 72.66% to 85.99% with standard deviation less than 0.01mg/10g dry weight are obtained except for p-hydroxybenzaldehyde. The lignin content ∑8 （produced from 10g dry sediment） in the research area is between 0.231 and 0.587mg. S/V and C/V ratios （1.028 ± 0.433 and 0.192±0.066, respectively） indicate that the TOMs in this region are originated from a mixture of woody and nonwoody angiosperm plants; the high values or （Ad/Al）v suggest that the TOMs has been highly degraded.展开更多
Five types of rare earth/alkaline earth oxide-doped CeO2 superfine-powders were synthesized by a low-temperature combustion technique. The relevant solid electrolyte materials were also sintered by pressureless sinter...Five types of rare earth/alkaline earth oxide-doped CeO2 superfine-powders were synthesized by a low-temperature combustion technique. The relevant solid electrolyte materials were also sintered by pressureless sintering at different temperatures. The results of X-ray diffraction and transmission electron microscopy showed that the grain size of the powders was approximately 20-30 nm, and rare earth/alkaline earth oxides were completely dissolved into ceria-based solid solution with fluorite structure. The electrical conductivities of the SmzO3-CeO2 system were measured by the ac impedance technique in air at temperatures ranging from 513-900℃. The results indicated that the ionic conductivities of Srno.2oCe0.8Ol.875 solid electrolyte increase with increasing sintering temperature, and the relationship between the conductivities and measuring temperature obeys the An＇henius equation. Then the SmzO3-CeO2 material was further doped with other rare earth/alkaline earth oxide, and the conductivities improve with the effective index.展开更多
Several compounds of rare earth complex oxides containing manganese and titanium were synthesized in Ar, and their crystal structures were analyzed by powder X-ray diffraction data and Rietveld method. Structures of A...Several compounds of rare earth complex oxides containing manganese and titanium were synthesized in Ar, and their crystal structures were analyzed by powder X-ray diffraction data and Rietveld method. Structures of A0.67Ln0.33 Mn0.33Ti0.6703（A = Ca or Sr and Ln = rare earth） were found to have orthorhombic symmetry with the space group Pnrna, and their interatomic distances and bond angles were obtained. This space group was also derived from electron microscopic study. Electrical conductivity of Cao.67Ln0.33Mn0.33Ti0.6703 for several rare earth elements showed a semiconducting property with the activation energy of 0.4 eV. Some of these compounds of the strontium system show the antiferromagnetic properties below 10 K.展开更多
We conducted two-stage acidification-bioleaching experiments to probe the feasibility of bioleaching for a kind of mixed alkaline copper oxide and sulphide mineral. We used the uniform design method for data analysis ...We conducted two-stage acidification-bioleaching experiments to probe the feasibility of bioleaching for a kind of mixed alkaline copper oxide and sulphide mineral. We used the uniform design method for data analysis and experimental optimization, with initial pH value, pulp density, inoculation of bacteria and ferrous iron concentration selected as the influential factors. Polynomial regression shows that the four factors sequentially influence the copper recovery by 14.430%, 8.555%, 1.982% and 3.895%. Acid equilibrium in the bioleaching system is mainly influenced by alkaline gangue content, chemical reactions and bacterial activity. A maximal portion of refractory copper extracted reaches 71.08%. The dynamic analysis of copper recovery indicates that bioleaching goes through a lag leaching phase, prime leaching phase and leaching stationary phase corresponding to the growth phases of bacteria. Compared with the predicted value of 80.87%, the confirmatory experiment observes a 78.21% copper recovery under the optimal conditions of pH of 1.5, pulp density of 5%, bacteria inoculation of 30% and initial ferrous iron concentration of 9 g L-1. Results suggest that bioleaching is technically feasible to improving total copper recovery.展开更多
In this paper, the components of furfural residue are analyzed. Total sugar content occupies 47.36% of absolute drying residue, and glucose occupies 83.23% of total sugar content. By combining the phcnyl nucleus excha...In this paper, the components of furfural residue are analyzed. Total sugar content occupies 47.36% of absolute drying residue, and glucose occupies 83.23% of total sugar content. By combining the phcnyl nucleus exchange reaction with nitrobenzene oxidation, the quantity of structural units of phcnyl nuclei was determined, products from syringyl units occupy 50% of klason lignin. Especially, diphcnyl methane type syringyl units occupy 38.80%, and guaiacyl units 25%, other condensed guaiacyl units about 20%. The furfural residue is not a good material for the manufacture of adhcsivcs, but for active carbon. The yield of furfural residue may achieve about 350 thousand tons per year, but it has not been used in industry in China.展开更多
In gaseous reduction of iron ore fines, alkaline earth oxides have profound effects on the precipitation behavior of fresh metal- lic iron on the particle surface. In this work, in situ observation was performed to re...In gaseous reduction of iron ore fines, alkaline earth oxides have profound effects on the precipitation behavior of fresh metal- lic iron on the particle surface. In this work, in situ observation was performed to reveal the influence of alkaline earth oxides on the precipitation morphology and micro-structure variation of fresh metallic iron from microscopic level by simulation of the gas-solid reaction condition on the surface of ore particles. Experimental results indicate that doping MgO in the particle surface can inhibit the reduction of iron oxide and however doping CaO, SrO and BaO promote; all alkaline earth oxides tested in this study can change the precipitation morphology of fresh metallic iron; minimum doping mole fraction of one oxide to inhibit iron whiskers growth （ NAO ） is related to its cation radius （ r：＋ ） and its extranuclear electronic layers（nAD ）, which can be expressed as NAO = 1.3 × 10^-5r^2AD,√nA^2.展开更多
The objective of this study was to understand toxicity of mixture of nanoparticles （NPs） （ZnO and TiO2） and their ions to Escherichia coll. Results indicated the decrease in percentage growth of E. coli with the i...The objective of this study was to understand toxicity of mixture of nanoparticles （NPs） （ZnO and TiO2） and their ions to Escherichia coll. Results indicated the decrease in percentage growth of E. coli with the increase in concentration of NPs both in single and mixture setups. Even a small concentration of I mg/L was observed to be significantly toxic to E. coli in binary mixture setup （exposure concentration： 1 mg/L ZnO and 1 mg/L TiO2; 21.15% decrease in plate count concentration with respect to control）. Exposure ofE. coli to mixture of NPs at 1000 mg/L （i.e., 1000 mg/L ZnO and 1000 mg/L TiO2） resulted in 99.63% decrease in plate count concentration with respect to control. Toxic effects of ions to E. coli were found to be lesser than their corresponding NPs. The percentage growth reduction was found to be 36% for binary mixture of zinc and titanium ions at the highest concentration （i.e., 803.0 mg/L Zn and 593.3 mg/L Ti where ion concentrations are equal to the Zn ions present in 1000 mg/L ZnO NP solution and Ti＋4 ions present in 1000 mg/L TiO2 NP solution）. Nature of mixture toxicity of the two NPs to E. coli was found to be antagonistic. The alkaline phosphatase （Alp） assay indicated that the maximum damage was observed when E. coli was exposed to 1000 mg/L of mixture of NPs. This study tries to fill the knowledge gap on information of toxicity of mixture of NPs to bacteria which has not been reported earlier.展开更多
In the scale-up of water electrolysis,commercial systems require catalysts that are effective,stable,and earth-abundant.Although platinum group metal(PGM)catalysts exhibit remarkable activity,the high cost and scarcit...In the scale-up of water electrolysis,commercial systems require catalysts that are effective,stable,and earth-abundant.Although platinum group metal(PGM)catalysts exhibit remarkable activity,the high cost and scarcity significantly increase the overall capital expenses for alkaline water oxidation[1].As a more sustainable alternative,non-PGM catalysts—particularly first-row(3d)transitionmetal(oxy)hydroxides—show great promise for water oxidation.However,from a theoretical standpoint(e.g.,Pourbaix diagrams)[2],these active phases are often difficult to detect compared to PGM under oxygen evolution reaction(OER)conditions,underscoring the need to stabilize them during operation.Moreover,the rapid degradation of these metal(oxy)hydroxides is potential-dependent and typically occurs at high overpotentials required to achieve practical current densities,often associated with the dissolution of catalytic metal sites or phase segregation under harsh OER conditions[3].Together,these factors present a critical challenge in the development of metal(oxy)hydroxide catalysts—namely,stabilizing both the active phases and active sites,particularly during long-term operations at high current densities[4].展开更多
Alkaline electrolyzers for water splitting under the industrial current densities are always burdened with huge energy consumption due to the high overpotential and poor stability of the anode nanocatalysts for oxygen...Alkaline electrolyzers for water splitting under the industrial current densities are always burdened with huge energy consumption due to the high overpotential and poor stability of the anode nanocatalysts for oxygen evolution reaction(OER).Inspired by the interfacial charge transfer for enhancing the performance,a series of in-situ grown interfacial Mn-NiFe lactate dehydrogenase(LDH)was designed on the Fe_(0.64)Ni_(0.36)/NM(nickel mesh)alloy layer.The optimized Mn_(0.15)-NiFe LDH/Fe_(0.64)Ni_(0.36)/NM exhibited an ultralow overpotential of 295 mV to drive 500 mA·cm^(-2)and an incredible stability under large current density.The interfacial space and heteroatom doping synergistically triggered the electronic structure optimization to promote electron transfer and ensure the durability of the high-current reaction.Notably,the designed Mn_(0.15)-NiFe LDH/Fe_(0.64)Ni_(0.36)/NM as an anode in an integral alkaline electrolyzer exhibited a cell voltage of 1.78 V at 500 mA·cm^(-2) with a stability of 366 h.Density functional theory(DFT)calculations further demonstrated the synergistic effect of alloy layer introduction and Mn doping could accelerate electron transfer and stabilize the charged active center to activate the NiFe LDH and reduce the OER energy barrier.Our work offers new insights into developing efficient self-supported catalysts for high-current alkaline water oxidation.展开更多
Underpotential deposition(UPD) of Cu on an Au electrode followed by redox replacement reaction(RRR) of CuUPD with a Pt source(H2PtCl6 or K2PtCl4) yielded Au-supported Pt adlayers(for short,Pt(CuUPD-Pt4+)n/Au for H2PtC...Underpotential deposition(UPD) of Cu on an Au electrode followed by redox replacement reaction(RRR) of CuUPD with a Pt source(H2PtCl6 or K2PtCl4) yielded Au-supported Pt adlayers(for short,Pt(CuUPD-Pt4+)n/Au for H2PtCl6,or Pt(CuUPD-Pt2+)n/Au for K2PtCl4,where n denotes the number of UPD-redox replacement cycles).The electrochemical quartz crystal microbalance(EQCM) technique was used for the first time to quantitatively study the fabricated electrodes and estimate their mass-normalized specific electrocatalytic activity(SECA) for methanol oxidation in alkaline solution.In comparison with Pt(CuUPD-Pt2+)n/Au,Pt(CuUPD-Pt4+)n/Au exhibited a higher electrocatalytic activity,and the maximum SECA was obtained to be as high as 35.7 mA ?g?1 at Pt(CuUPD-Pt4+)3/Au.The layer-by-layer architecture of Pt atoms on Au is briefly discussed based on the EQCM-revealed redox replacement efficiency,and the calculated distribution percentages of bare Au sites agree with the experimental results deduced from the charge under the AuOx-reduction peaks.The EQCM is highly recommended as an efficient technique to quantitatively examine various electrode-supported catalyst adlayers,and the highly efficient catalyst adlayers of noble metals are promising in electrocatalysis relevant to biological,energy and environmental sciences and technologies.展开更多
基金Funded by the National Natural Science Foundation of China (No.50672087 and No.60778039)National Basic Research Program of China (No.2006CB806000b)National High Technology Program of China (No.2006AA03Z304)
文摘We reported effect of various alkaline oxides on the broadband infrared luminescence from bismuth-doped aluminophosphate glasses. The samples of （99-x）P2O3-17Al2O3-xR2O-IBi2O3 （R=Li, Na and K, x=0 and 10 in mol%） were prepared under reducing condition controlled by additional carbon powders. The fluorescent intensity decreased with increasing content of alkaline oxides and basicity of host glasses. The 1/e fluorescence lifetime of the 72P2O3-17Al2O3-10R2O-1Bi2O3 （R=Li, Na and K） glasses decreased from 461 to 316 μs, as alkaline ions changed from Li^＋ to K^＋.
基金supported by the National Natural Science Foundation of China(no.52363028,21965005)the Natural Science Foundation of Guangxi Province(2021GXNSFAA076001,2018GXNSFAA294077)the Guangxi Technology Base and Talent Subject(GUIKE AD23023004,GUIKE AD20297039).
文摘Triggering structural asymmetry can induce charge redistribution and modify electronic structures,which is of great significance for the design of high-performance hydrogen oxidation reaction(HOR)electrocatalysts.Herein,we propose a dual anion-induced strategy to create an innovative RuS_(2)-RuO_(2)heterostructure featuring abundant S-Ru-O interfaces(RuS_(2)-RuO_(2)@C).This RuS_(2)-RuO_(2)@C demonstrates an impressive mass activity of 2.61 mAμg_(RU)^(-1)and an exchange current density of 2.96 mA cm^(-2),surpassing Pt/C and other comparative samples by over 20 times.Durability assessments confirm the superior stability of RuS_(2)-RuO_(2)@C,with only minimal performance loss during operation.Density functional theory(DFT)calculations indicate that the asymmetric S-Ru-O configuration optimizes the interfacial electronic structure and shifts the d-band center closer to the Fermi level,effectively reducing the energy barrier of the rate-determining step(RDS)in the alkaline HOR process.Moreover,in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy(ATR-SEIRAS)characteristics disclose the formation of a substantial hydrogen bond network at the S-Ru-o interface,which aids in the desorption of H_(2)O_(ad)and facilitates the vital Volmer step in the HOR pathway.
文摘Methane conversions at lower temperature were studied. The aetivity of Y_2O_3 sample at 823K was fairly high with some formation of C_2H_4 and C_2H_6, the catalysts based on alkaline earth oxides and yttria would give better results. The influences of flux ratio, space velocity, and reaction temperature were also discussed.
基金supported by the National Basic Research Program of China (973 Program, Grant No. 2010CB428901)the National Natural Science Foundation of China (NSFC, Grant No. 41020164005,41276067)the team of 973 Program Grant No. 2010CB428701 for the help during sampling
文摘Lignin serves as one of the most important molecular fossils for tracing Terrestrial Organic Matters （TOMs） in marine environment. Extraction and derivatization of lignin oxidation products （LOPs） are crucial for accurate quantification of lignin in marine sediment. Here we report a modification of the conventional alkaline cupric oxide （CuO） oxidation method, the modification consisting in a solid phase extraction （SPE） and a novel on-column derivatization being employed for better efficiency and reproducibility. In spiking blanks, recoveries with SPE for the LOPs are between 77.84% and 99.57% with relative standard deviations （RSDs） ranging from 0.57% to 8.04% （n=3）, while those with traditional liquid-liquid extraction （LLE） are from 44.52% to 86.16% With RSDs being from 0.53% to 13.14% （n=3）. Moreover, the reproducibility is greatly improved with SPE, with less solvent consumption and shorter processing time. The average efficiency of on-column derivatization for LOPs is 100.8%±0.68%, which is significantly higher than those of in-vial or in-syringe derivatization, thus resulting in still less consumption of derivatizing reagents.Lignin in the surface sediments sampled from the south of Yangtze River estuary, China, was determined with the established method. Recoveries of 72.66% to 85.99% with standard deviation less than 0.01mg/10g dry weight are obtained except for p-hydroxybenzaldehyde. The lignin content ∑8 （produced from 10g dry sediment） in the research area is between 0.231 and 0.587mg. S/V and C/V ratios （1.028 ± 0.433 and 0.192±0.066, respectively） indicate that the TOMs in this region are originated from a mixture of woody and nonwoody angiosperm plants; the high values or （Ad/Al）v suggest that the TOMs has been highly degraded.
文摘Five types of rare earth/alkaline earth oxide-doped CeO2 superfine-powders were synthesized by a low-temperature combustion technique. The relevant solid electrolyte materials were also sintered by pressureless sintering at different temperatures. The results of X-ray diffraction and transmission electron microscopy showed that the grain size of the powders was approximately 20-30 nm, and rare earth/alkaline earth oxides were completely dissolved into ceria-based solid solution with fluorite structure. The electrical conductivities of the SmzO3-CeO2 system were measured by the ac impedance technique in air at temperatures ranging from 513-900℃. The results indicated that the ionic conductivities of Srno.2oCe0.8Ol.875 solid electrolyte increase with increasing sintering temperature, and the relationship between the conductivities and measuring temperature obeys the An＇henius equation. Then the SmzO3-CeO2 material was further doped with other rare earth/alkaline earth oxide, and the conductivities improve with the effective index.
基金Foundation ite ms:Project supported bythe Grant-in-Aidfor Scientific Research (C) (18560662) bythe Japan Societyfor the Promotion of Science
文摘Several compounds of rare earth complex oxides containing manganese and titanium were synthesized in Ar, and their crystal structures were analyzed by powder X-ray diffraction data and Rietveld method. Structures of A0.67Ln0.33 Mn0.33Ti0.6703（A = Ca or Sr and Ln = rare earth） were found to have orthorhombic symmetry with the space group Pnrna, and their interatomic distances and bond angles were obtained. This space group was also derived from electron microscopic study. Electrical conductivity of Cao.67Ln0.33Mn0.33Ti0.6703 for several rare earth elements showed a semiconducting property with the activation energy of 0.4 eV. Some of these compounds of the strontium system show the antiferromagnetic properties below 10 K.
基金Funded by the National Natural Science Foundation of China (No. 50934002)New Century Excellent Talents (No. NECT-07-0070)Yunnan Provincial Programs for Science and Technology Innovation (No. 2007AD001)
文摘We conducted two-stage acidification-bioleaching experiments to probe the feasibility of bioleaching for a kind of mixed alkaline copper oxide and sulphide mineral. We used the uniform design method for data analysis and experimental optimization, with initial pH value, pulp density, inoculation of bacteria and ferrous iron concentration selected as the influential factors. Polynomial regression shows that the four factors sequentially influence the copper recovery by 14.430%, 8.555%, 1.982% and 3.895%. Acid equilibrium in the bioleaching system is mainly influenced by alkaline gangue content, chemical reactions and bacterial activity. A maximal portion of refractory copper extracted reaches 71.08%. The dynamic analysis of copper recovery indicates that bioleaching goes through a lag leaching phase, prime leaching phase and leaching stationary phase corresponding to the growth phases of bacteria. Compared with the predicted value of 80.87%, the confirmatory experiment observes a 78.21% copper recovery under the optimal conditions of pH of 1.5, pulp density of 5%, bacteria inoculation of 30% and initial ferrous iron concentration of 9 g L-1. Results suggest that bioleaching is technically feasible to improving total copper recovery.
文摘In this paper, the components of furfural residue are analyzed. Total sugar content occupies 47.36% of absolute drying residue, and glucose occupies 83.23% of total sugar content. By combining the phcnyl nucleus exchange reaction with nitrobenzene oxidation, the quantity of structural units of phcnyl nuclei was determined, products from syringyl units occupy 50% of klason lignin. Especially, diphcnyl methane type syringyl units occupy 38.80%, and guaiacyl units 25%, other condensed guaiacyl units about 20%. The furfural residue is not a good material for the manufacture of adhcsivcs, but for active carbon. The yield of furfural residue may achieve about 350 thousand tons per year, but it has not been used in industry in China.
基金supported by the National Natural Science Foundation of China and Baosteel (Grant No.50834007)the National Basic Research Program of China (973 Program) (Grant No.2012CB720401)
文摘In gaseous reduction of iron ore fines, alkaline earth oxides have profound effects on the precipitation behavior of fresh metal- lic iron on the particle surface. In this work, in situ observation was performed to reveal the influence of alkaline earth oxides on the precipitation morphology and micro-structure variation of fresh metallic iron from microscopic level by simulation of the gas-solid reaction condition on the surface of ore particles. Experimental results indicate that doping MgO in the particle surface can inhibit the reduction of iron oxide and however doping CaO, SrO and BaO promote; all alkaline earth oxides tested in this study can change the precipitation morphology of fresh metallic iron; minimum doping mole fraction of one oxide to inhibit iron whiskers growth （ NAO ） is related to its cation radius （ r：＋ ） and its extranuclear electronic layers（nAD ）, which can be expressed as NAO = 1.3 × 10^-5r^2AD,√nA^2.
基金the Department of Science and Technology(India)(through Grant No.SR/FTP/ETA-84/2011)Indian Institute of Technology Delhi(India)for providing financial support for conducting this study
文摘The objective of this study was to understand toxicity of mixture of nanoparticles （NPs） （ZnO and TiO2） and their ions to Escherichia coll. Results indicated the decrease in percentage growth of E. coli with the increase in concentration of NPs both in single and mixture setups. Even a small concentration of I mg/L was observed to be significantly toxic to E. coli in binary mixture setup （exposure concentration： 1 mg/L ZnO and 1 mg/L TiO2; 21.15% decrease in plate count concentration with respect to control）. Exposure ofE. coli to mixture of NPs at 1000 mg/L （i.e., 1000 mg/L ZnO and 1000 mg/L TiO2） resulted in 99.63% decrease in plate count concentration with respect to control. Toxic effects of ions to E. coli were found to be lesser than their corresponding NPs. The percentage growth reduction was found to be 36% for binary mixture of zinc and titanium ions at the highest concentration （i.e., 803.0 mg/L Zn and 593.3 mg/L Ti where ion concentrations are equal to the Zn ions present in 1000 mg/L ZnO NP solution and Ti＋4 ions present in 1000 mg/L TiO2 NP solution）. Nature of mixture toxicity of the two NPs to E. coli was found to be antagonistic. The alkaline phosphatase （Alp） assay indicated that the maximum damage was observed when E. coli was exposed to 1000 mg/L of mixture of NPs. This study tries to fill the knowledge gap on information of toxicity of mixture of NPs to bacteria which has not been reported earlier.
文摘In the scale-up of water electrolysis,commercial systems require catalysts that are effective,stable,and earth-abundant.Although platinum group metal(PGM)catalysts exhibit remarkable activity,the high cost and scarcity significantly increase the overall capital expenses for alkaline water oxidation[1].As a more sustainable alternative,non-PGM catalysts—particularly first-row(3d)transitionmetal(oxy)hydroxides—show great promise for water oxidation.However,from a theoretical standpoint(e.g.,Pourbaix diagrams)[2],these active phases are often difficult to detect compared to PGM under oxygen evolution reaction(OER)conditions,underscoring the need to stabilize them during operation.Moreover,the rapid degradation of these metal(oxy)hydroxides is potential-dependent and typically occurs at high overpotentials required to achieve practical current densities,often associated with the dissolution of catalytic metal sites or phase segregation under harsh OER conditions[3].Together,these factors present a critical challenge in the development of metal(oxy)hydroxide catalysts—namely,stabilizing both the active phases and active sites,particularly during long-term operations at high current densities[4].
文摘Alkaline electrolyzers for water splitting under the industrial current densities are always burdened with huge energy consumption due to the high overpotential and poor stability of the anode nanocatalysts for oxygen evolution reaction(OER).Inspired by the interfacial charge transfer for enhancing the performance,a series of in-situ grown interfacial Mn-NiFe lactate dehydrogenase(LDH)was designed on the Fe_(0.64)Ni_(0.36)/NM(nickel mesh)alloy layer.The optimized Mn_(0.15)-NiFe LDH/Fe_(0.64)Ni_(0.36)/NM exhibited an ultralow overpotential of 295 mV to drive 500 mA·cm^(-2)and an incredible stability under large current density.The interfacial space and heteroatom doping synergistically triggered the electronic structure optimization to promote electron transfer and ensure the durability of the high-current reaction.Notably,the designed Mn_(0.15)-NiFe LDH/Fe_(0.64)Ni_(0.36)/NM as an anode in an integral alkaline electrolyzer exhibited a cell voltage of 1.78 V at 500 mA·cm^(-2) with a stability of 366 h.Density functional theory(DFT)calculations further demonstrated the synergistic effect of alloy layer introduction and Mn doping could accelerate electron transfer and stabilize the charged active center to activate the NiFe LDH and reduce the OER energy barrier.Our work offers new insights into developing efficient self-supported catalysts for high-current alkaline water oxidation.
基金supported by the National Natural Science Foundation of China (20675029 & 90713018)the State Special Scientific Project on Water Treatment (2009ZX07212-001-06)
文摘Underpotential deposition(UPD) of Cu on an Au electrode followed by redox replacement reaction(RRR) of CuUPD with a Pt source(H2PtCl6 or K2PtCl4) yielded Au-supported Pt adlayers(for short,Pt(CuUPD-Pt4+)n/Au for H2PtCl6,or Pt(CuUPD-Pt2+)n/Au for K2PtCl4,where n denotes the number of UPD-redox replacement cycles).The electrochemical quartz crystal microbalance(EQCM) technique was used for the first time to quantitatively study the fabricated electrodes and estimate their mass-normalized specific electrocatalytic activity(SECA) for methanol oxidation in alkaline solution.In comparison with Pt(CuUPD-Pt2+)n/Au,Pt(CuUPD-Pt4+)n/Au exhibited a higher electrocatalytic activity,and the maximum SECA was obtained to be as high as 35.7 mA ?g?1 at Pt(CuUPD-Pt4+)3/Au.The layer-by-layer architecture of Pt atoms on Au is briefly discussed based on the EQCM-revealed redox replacement efficiency,and the calculated distribution percentages of bare Au sites agree with the experimental results deduced from the charge under the AuOx-reduction peaks.The EQCM is highly recommended as an efficient technique to quantitatively examine various electrode-supported catalyst adlayers,and the highly efficient catalyst adlayers of noble metals are promising in electrocatalysis relevant to biological,energy and environmental sciences and technologies.
