MXene-碳黑/硫复合材料在锂硫电池一体式电极的研究

锂硫电池的实际能量密度不高和多硫化物（LiPSs）的穿梭效应等问题严重影响了该电池的实际应用。本文通过将二维的Ti₃C₂T_x Mxene纳米片与碳黑/硫（CB/S）材料进行混合,制备了Ti₃C₂T_x-CB/S正极材料并将其涂覆在商业隔膜（PP）上,最终获得了Ti₃C₂T_x-CB/S-PP一体式电极并用于锂硫电池。利用Ti₃C₂T_x纳米片对CB/S进行修饰,不仅能提高活性物质硫的导电性,还能对扩散的LiPSs进行物理阻挡和化学吸附。而一体式电极的设计有利于提高电池的能量密度。恒流充放电测试结果表明,Ti₃C₂T_x-CB/S-PP电极在0.1 C电流下的初始放电容量为1028.8 mAh·g^-1,高于不含Ti₃C₂T_x的CB/S-PP电极的896.8 mAh·g^-1。Ti₃C₂T_x-CB/S-PP电极还展示出了比基于传统铝箔集流体的Ti₃C₂T_x-CB/S-Al电极更好的循环稳定性,前者在0.5 C下400圈长循环测试中的每圈衰减率为0.072%,而后者则为更高的0.10%。本文利用Ti₃C₂T_x-CB/S构建一体式电极的策略为实现高性能和高能量密度的锂硫电池提供了新的研究方向。     

Microwave assisted hydrothermal synthesis of tin niobates nanosheets with high cycle stability as lithium-ion battery anodes

SnNb₂O₆ and Sn₂Nb₂O₇ nanosheets were synthetized via microwave assisted hydrothermal method, and innovatively employed as anode materials for lithium-ion battery. Compared with Sn₂Nb₂O₇ and the previously reported pure Sn-based anode materials, the SnNb₂O₆ electrode exhibited outstanding cycling performance.     

Dnd点群的几点释疑

Point group in crystallography is one of the important subjects in structural chemistry.Some topics are very difficult to understand.To name a few, why does point group of D_2d belong to tetragonal? Why are D_4d and D_6d not included in 32 kinds of crystallographic point groups? The two questions are easy to answer if we understand the following topic:for the D_nd point group, when n is odd, it contains an I_n symmetry axis; when n is even, it contains an I_2n symmetry axis.In this work, graphic method and matrix method are adopted to clarify why the D_nd point group includes an S_2n axis, and thus give explanations that D_2d belongs to tetragonal as well as D_4d and D_6d are not included in 32 kinds of crystallographic point groups.     

CoAl2O4包覆LiNi1/3Co1/3Mn1/3O2的电化学性能

通过共沉淀法制得类球形锂离子电池正极材料LiNi_1/3Co_1/3Mn_1/3O₂,并用非水相共沉法对其进行CoAl₂O₄包覆得到LNCMO(x). 采用X射线衍射（XRD）、扫描电子显微术（SEM）和透射电子显微术（TEM）测试材料的结构和观察材料形貌. 结果表明,CoAl₂O₄在材料表面形成8 nm均匀包覆层,未改变主体材料的结构. 电化学性能测试表明,1%（by mass）CoAl₂O₄包覆量的LiNi1/3Co1/3Mn1/3O2材料（LNCMO(1)）高充电电压（3.0 ~ 4.6 V,150 mA·g^-1）100周期循环放电容量保持率为93.7%（无包覆LNCMO(0)保持率为74.4%）;55 °C高温100周期循环容量保持率为77%（无包覆LNCMO(0)保持率17%）. XRD和电感耦合等离子体原子发射光谱（ICP-AES）测试表明,CoAl₂O₄包覆的LNCMO(x)材料可有效地减缓材料中Mn离子在电解液的溶解,提高材料结构稳定性和热稳定性.     

Relationship between the molybdenum phases and the conversion of n-butane over Mo/HZSM-5

The conversion of n-C₄H₁₀ was undertaken on MoO₃/HZSM-5 catalyst at 773–973 K and the phases of molybdenum species were detected by XRD. The XRD results show that bulk MoO₃ on HZSM-5 can be readily reduced by n-C₄H₁₀ to MoO₂ at 773 K and MoO₂ can be gradually carburized to molybdenum carbide above 813 K. The molybdenum carbide formed from the carburization of MoO₂ with n-C₄H₁₀ below 893 K is -MoC_1−x with fcc-structure, while hcp-molybdenum carbide formed above 933 K. During the evolution of MoO₃ to MoO₂ (>773 K) or the carburization of MoO₂ to molybdenum carbide (>813 K), deep oxidation, cracking and coke deposition are serious, in particular at higher reaction temperatures, these lead to the poor selectivity to aromatics. Aromatization of n-C₄H₁₀ can proceed catalytically on both Mo₂C/HZSM-5 and MoO₂/HZSM-5, the distribution of the products for the two catalysts is similar below 813 K, but the activity for Mo₂C/HZSM-5 is much higher than that for MoO₂/HZSM-5.     

CeO2担载Cu纳米粒子电催化CO2还原产乙烯：CeO2不同暴露晶面对催化性能的影响

Fossil fuels are expected to be the major source of energy for the next few decades. However, combustion of nonrenewable resources leads to the release of large quantities of CO₂, the primary greenhouse gas. Notably, the concentration of CO₂ in the atmosphere is increasing annually at an astounding rate. Electrochemical CO₂ reduction (ECR) to value-added fuels and chemicals using electricity from intermittent renewable energy sources is a carbon-neutral method to alleviate anthropogenic CO₂ emissions. Despite the steady progress in the selective generation of C₁ products (CO and formic acid), the production of multi-carbon species still suffers from low selectivity and efficiency. As an ECR product, ethylene (C₂H₄) has a higher energy density than do C₁ species and is an important industrial feedstock in high demand. However, the conversion of CO₂ to C₂H₄ is plagued by low productivity and large overpotential, in addition to the severe competing hydrogen evolution reaction (HER) during the ECR. To address these issues, the design and development of advanced electrocatalysts are critical. Here, we demonstrate fine-tuning of ECR to C₂H₄ by taking advantage of the prominent interaction of Cu with shape-controlled CeO₂ nanocrystals, that is, cubes, rods, and octahedra predominantly covered with (100), (110), and (111) surfaces, respectively. We found that the selectivity and activity of the ECR depended strongly on the exposed crystal facets of CeO₂. The overall ECR Faradaic efficiency (FE) over Cu/CeO₂(110) (FE ≈ 56.7%) surpassed that of both Cu/CeO₂(100) (FE ≈ 51.5%) and Cu/CeO₂(111) (FE ≈ 48.4%) in 0.1 mol·L^-1 KHCO₃ solutions with an H-type cell. This was in stark contrast to the exclusive occurrence of the HER over pure carbon paper, CeO₂(100), CeO₂(110), and CeO₂(111). In particular, the FE toward C₂H₄ formation and the partial current density increased in the sequence Cu/CeO₂(111) < Cu/CeO₂(100) < Cu/CeO₂(110) within applied bias potentials from -1.00 to -1.15 V (vs. the reversible hydrogen electrode), reaching 39.1% over Cu/CeO₂(110) at a mild overpotential (1.13 V). The corresponding values for Cu/CeO₂(100) and Cu/CeO₂(111) were FE_C2H4 ≈ 31.8% and FE_C2H4 ≈ 29.6%, respectively. The C₂H₄ selectivity was comparable to that of many reported Cu-based electrocatalysts at similar overpotentials. Furthermore, the FE for C₂H₄ remained stable even after 6 h of continuous electrolysis. The superior ECR activity of Cu/CeO₂(110) to yield C₂H₄ was attributed to the metastable (110) surface, which not only promoted the effective adsorption of CO₂ but also remarkably stabilized Cu⁺, thereby boosting the ECR to produce C₂H₄. This work offers an alternative strategy to enhance the ECR efficiency by crystal facet engineering.     

Effect of promoter Ce on silver-molybdenum-phosphate catalysts for selective oxidation of propane to acrolein

A series of Me_nAg_0.3Mo_0.5P_0.3O_y (Me=Cu, Zn, Mn, W, Ce, Pr, Nd) and Ag_0.3Mo_0.5P_0.3O_x catalysts were prepared. The addition of Ce to Ag_0.3Mo_0.5P_0.3O_x catalysts improved the catalytic performance in selective oxidation of propane to acrolein, and Ce_0.1Ag_0.3Mo_0.5P_0.3O_x catalysts showed the highest acrolein selectivity (28.7%) and yield (4.4%). The physicochemical properties of Ag_0.3Mo_0.5P_0.3O_x and Ce_nAg_0.3Mo_0.5P_0.3O_x (n=0.1–0.5) catalysts have been comparatively characterized by BET, XRD, H₂-TPR, XPS, EPR and C₃H₈(C₃H₆)-TPD. Significant differences in physicochemical properties between Ag_0.3Mo_0.5P_0.3O_x and Ce doped Ag_0.3Mo_0.5P_0.3O_x catalysts have been observed, which is due to the formation of the redox cycle (Ce³⁺+Mo⁶⁺Ce⁴⁺+Mo⁵⁺) in the Ce_nAg_0.3Mo_0.5P_0.3O_y catalyst. Such effect modified the reducibility, the concentration of Mo⁵⁺, the activation of propane and the transformation of possible intermediate propene to acroelin, which in return greatly influenced the catalytic performance of Ce doped Ag_0.3Mo_0.5P_0.3O_x catalysts in selective oxidation of propane to acroelin. The proper addition of Ce to Ag_0.3Mo_0.5P_0.3O_x catalyst improved the acrolein selectivity and yield.     

Crystal Structures and Electrochemical Properties of R1.5Ca1.5MgNi14(R=Nd,Gd and Er)Hydrogen Storage Alloys

Ca₃MgNi₁₄, Nd_1.5Ca_1.5MgNi₁₄, Gd_1.5Ca_1.5MgNi₁₄ and Er_1.5Ca_1.5MgNi₁₄ alloys were prepared by high frequency induction melting and sintering. Characterization and analysis were performed by X-ray diffraction/Rietveld full-spectrum fitting, gaseous P-C-T hydrogen storage test and electrochemical properties tests. It can be found that all alloys consist of Gd₂Co₇-type 3R phase and Ce₂Ni₇-type 2H phase. Although the hydrogen storage capacities of Nd_1.5Ca_1.5MgNi₁₄, Gd_1.5Ca_1.5MgNi₁₄ and Er_1.5Ca_1.5MgNi₁₄ decrease to some extent compared to that of Ca₃MgNi₁₄, their equilibrium pressures for absorption and desorption increase markedly. Moreover, R_1.5Ca_1.5MgNi₁₄ alloys have better cycling stabilities and high-rate discharge(HRD) properties as compared to Ca₃MgNi₁₄. The hydrogen diffusion in alloy electrodes is the main factor to influence the HRD performance.     

在TiO2纳米阵列上电沉积RuO2用于CO2电还原

传统上,RuO₂/TiO₂复合电极制备是通过在TiO₂/Ti基体上多次涂覆含Ru前驱体溶液和随后热分解（TD）来实现的. 为克服上述方法中Ru用量大和利用率低之不足, 本工作主要基于循环伏安法（CV）在TiO₂纳米管阵列（TNA）上电沉积RuO₂制备RuO₂^CV/TNA复合电极. SEM、GIXRD和CV结果表明, 电沉积的RuO₂为无定型结构, 所制备电极中的Ru用量约为传统的RuO₂^TD/TNA电极中Ru用量的1/30. 尽管两电极催化CO₂还原产物的法拉第效率接近, 但是RuO₂^CV/TNA电极比RuO₂^TD/TNA电极展示了更高的还原电流, 较正的初始还原电位和更好的稳定性. 与磷酸盐缓冲溶液中电还原CO₂相比,RuO₂^CV/TNA电极在0.1 mol•L^-1 KHCO₃中电还原CO₂除生成更高法拉第效率的甲酸根和甲烷外,还检测到CO的生成.     

Macroporous composite capacitive bioanode applied in microbial fuel cells

Interfacial electron transfer between electroactive biofilm and the electrode was crucial step for microbial fuel cells(MFCs).A three-dimensional multilayer porous sponge coating with nitrogen-doped carbon nanotube/polyaniline/manganese dioxide(S/N-CNT/PANI/MnO2)electrode has been developed for MFC anode.Here,the S/N-CNT/PANI/MnO2 anode can function as a biocapacitor,able to store electrons generated from the degradation of organic substrate under the open circuit state and release the accumulated electrons upon requirement.Thus,the mismatching of the production and demand of the electricity can be overcome.Comparing with the sponge/nitrogen-doped carbon nanotube(S/N-CNT)bioanode,S/N-CNT/PANI/MnO2 capacitive bioanode displays a strong interaction with the microbial biofilm,advancing the electron transfer from exoelectrogens to the bioanode.The maximum power density of MFC with S/N-CNT/PANI/MnO2 capacitive bioanode is 1019.5 mW/m^2,which is 2.2 and5.8 times as much as that of S/N-CNT/MnO2 bioanode and S/N-CNT bioanode(470.7 mW/m^2 and176.6 mW/m^2),respectively.During the chronoamperometric experiment with 60 min of charging and 20 min of discharging,the S/N-CNT/PANI/MnO2 capacitive bioanode was able to store 10743.9 C/m^2,whereas the S/N-CNT anode was only able to store 3323.4 C/m^2.With a capacitive bioanode,it is possible to use the MFC simultaneously for production and storage of electricity.     

单层石墨相氮化碳负载Pt4团簇吸附O2的第一性理论研究

采用第一性原理密度泛函理论结合周期性平板模型模拟研究了Pt₄团簇吸附单层石墨相氮化碳(g-C₃N₄)的几何结构和电子性质,以及氧气在其表面上的吸附行为。同时,对比分析了氧气在纯净的石墨相氮化碳和Pt₄团簇上的吸附行为。计算结果表明, Pt₄团簇吸附在3-s-三嗪环石墨相氮化碳表面,并与四个边缘氮原子成键,形成两个六元环时为最稳定构型。Pt₄团簇倾向于吸附在三嗪环石墨相氮化碳的空位并与邻近三个氮原子成键。由于Pt与N原子较强的杂化作用,以及金属与底物之间较多电子转移增强了Pt₄团簇吸附g-C₃N₄的稳定性。另外,对比分析了氧气在纯净的g-C₃N₄和金属吸附的g-C₃N₄上吸附行为,发现金属原子的加入促进了电子转移,同时拉长了O―O键长。Pt₄吸附3-s-三嗪环g-C₃N₄比Pt₄吸附三嗪环g-C₃N₄表现出微弱的优势,表现出明显的基底扭曲以及较大的吸附能。这些结果表明,化学吸附通过调节电子结构和表面性质增强催化性能的较好方法。     

沉淀基离子选择电极对干扰离子的动力学响应研究

用活度阶梯法研究了AgI,AgBr,CuS,PbS和CdS电极对干扰离子的动力学响应.溶液中含一定浓度主要离子时上述电极对某些干扰离子响应非单一突跃型瞬时信号;溶液中不含主要离子时,除了AgBr电极响应Cl^-外,其它都响应单一瞬时信号.离子交换产物的溶解度越小,离子的水合焓差越小,瞬时信号峰高度越大.离子水合焓差对瞬时信号峰高度的影响说明,试液高速喷向电极表面时由于扩散层厚度很薄,电极对干扰离子响应瞬时信号的峰电位不决定于离子扩散速度,而决定于离子交换速度.除CuS电极外,根据其它电极非单一突跃型瞬时信号所测定的平衡电位选择性系数K_xy^e与相应化合物溶度积比值是一致的.     

Enhanced Electrochemical Performance of Na0.67Fe0.5Mn0.5O2Cathode with SnO2 Modification

P2-type layered oxide Na_0.67Fe_0.5Mn_0.5O₂ is recognized as a very promising cathode material for sodium-ion batteries due to the merits of high capacity, high voltage, low cost, and easy preparation. However, its unsatisfactory cycle and rate performances remain huge obstacles for practical applications. Here, we report a strategy of SnO₂ modification on P2-type Na_0.67Fe_0.5Mn_0.5O₂ to improve the cycle and rate performance. Scanning electron microscope(SEM) and transmission electron microscope(TEM) images indicate that an insular thin layer SnO₂ is coated on the surface of Na_0.67Fe_0.5Mn_0.5O₂ after medication. The coating layer of SnO₂ can protect Na_0.67Fe_0.5Mn_0.5O₂ from corrosion by electrolyte and the cycle performance is well enhanced. After 100 cycles at 1 C rate(1 C=200 mA/g), the capacity of SnO₂ modified Na_0.67Fe_0.5Mn_0.5O₂ retains 83 mA·h/g(64% to the initial capacity), while the capacity for the pristine Na_0.67Fe_0.5Mn_0.5O₂ is only 38 mA·h/g(33.5% to the initial capacity). X-Ray photoelectron spectroscopy reveals that the ratio of Mn⁴⁺ increases after SnO₂ modification, leading to less oxygen vacancy and expanded lattice. As a result, the capacity of Na_0.67Fe_0.5Mn_0.5O₂ increases from 178 mA·h/g to 197 mA·h/g after SnO₂ modification. Furthermore, the rate performance of Na_0.67Fe_0.5Mn_0.5O₂ is enhanced with SnO₂ coating, due to high electronic conductivity of SnO₂ and expanded lattice after SnO₂ coating. The capacity of SnO₂ modified Na_0.67Fe_0.5Mn_0.5O₂ at 5 C increases from 21 mA·h/g(pristine Na_0.67Fe_0.5Mn_0.5O₂) to 35 mA·h/g.     

醋酸铅作为铅源合成CH3NH3PbBr3-xClx纳米晶体颗粒

Lead acetate, which is highly soluble in dimethylformamide, was used to synthesize mixed halide perovskite CH₃NH₃PbBr_3-xCl_x (MA = CH₃NH₃, 0 ≤ x ≤ 3) nanocrystals (NCs). This method provides an approach to address the low solubility of lead halides, especially lead chloride. Different Br/Cl ratios in MAPbBr_3-xCl_x lead to various optical properties. The photoluminescence emission peak can be tuned from 399 to 527 nm. Their full-widths at half-maxima (FWHM) are about 20 nm. MAPbBr_3-xCl_x NCs have an average diameter of ~(11 ± 3) nm and have uniform dispersion in toluene. The MAPbBr₃ NCs have a long average recombination lifetime (τ_ave = 97.4 ns) and a photoluminescence quantum yield (PLQY) of up to 73%.     

Pd/Co3O4纳米颗粒负载于Al2O3纳米片高效催化甲烷燃烧

We report an efficient catalyst composed of ternary components prepared by inlaying Pd/Co₃O₄ nanoparticles in alkaline Al₂O₃ nanosheets for catalytic oxidation of methane. Pd/Co₃O₄ inlaid in alkaline Al₂O₃ exhibited a higher ability to break the C-H bond of methane than Pd/Co₃O₄ supported on SiO₂, ZrO₂, CeO₂, and acidic or neutral Al₂O₃. Our results show more oxygen vacancies and higher amounts of surface adsorbed oxygen on the surface of Pd/Co₃O₄/alkaline Al₂O₃ than on other catalysts, which is responsible for methane activation and conversion. Further, the Pd/Co₃O₄/alkaline Al₂O₃ catalyst can almost restore to its initial value in the absence of water when 5% (volume fraction) vapor water was cut off, although a decrease in activity occurred when water vapor was introduced to the reaction system. Even under a condition similar to the exhaust of a lean-burn natural gas engine, the catalytic performance of the Pd/Co₃O₄/alkaline Al₂O₃ catalyst is excellent, that is, methane could be completely converted when the sample temperature in the reaction atmosphere was ramped to 400℃.     

理想与还原Fe2O3[001]表面上汞吸附协同催化CO分解作用

煤化学链燃烧必然释放汞,汞与载氧体表面相互作用,影响表界面的氧化还原反应。本文采用密度泛函理论计算,研究汞（Hg⁰）在理想表面（Fe₂O₃[001]）和一系列被还原表面（Fe₂O_2.75、Fe₂O_2.5、Fe₂O_2.25、Fe₂O_1.625、Fe₂O_0.875、Fe₂O_0.375和Fe）的吸附,以及Hg⁰对Fe₂O_1.625、Fe₂O_0.875、Fe₂O_0.375和Fe等表面催化CO分解反应的协同作用机理。Hg⁰物理吸附在理想Fe₂O₃[001]表面。随着Fe₂O₃[001]表面不断被还原,Hg⁰发生化学吸附。Hg⁰吸附降低了CO与Fe₂O₃、Fe₂O_2.75、Fe₂O_2.5和Fe₂O_2.25等表面之间的相互作用,抑制O传递氧化CO为CO₂的反应;载氧体进一步还原过程中,Hg⁰吸附促进了CO与Fe₂O_1.625、Fe₂O_0.875、Fe₂O_0.375及Fe等表面之间的相互作用,进而促进了表面对CO的催化分解反应,加速了载氧体表面的积碳,降低了化学链燃烧效率。因此,合理控制载氧体的还原程度既可以减弱Hg⁰的吸附,也可以抑制积碳的形成,这对化学链燃烧的操作优化至关重要。     

PtNiSnO_2/C的制备、表征及其电催化氧化乙醇活性

采用改进的B?nnemann法成功制备了Pt/C、Pt-Ni_(1/3)/C、Pt-SnO_2/C、Pt-Ni_x-SnO_2/C(x=1/4,1/3,2/3,1)阳极电催化剂。利用X射线衍射(XRD)、高分辨透射电子显微镜(HR-TEM)以及X射线光电子能谱(XPS)对催化剂晶型结构、表面形貌和表面电子结构进行了表征。运用线性扫描伏安(LSV)和电流密度-时间(j-t)曲线进行电化学测试,研究了乙醇电催化氧化(EOR)活性。并用原位红外光谱(in situ FT-IR)研究了EOR过程中产物的分布。结果表明,Pt-Ni_(1/3)-SnO_2/C是由Pt-Ni合金和SnO_2两相组成。XPS结果表明,在Pt-SnO_2中添加微量的Ni,Pt表面电子结构发生了改变。电化学结果表明,三元催化剂的EOR活性均优于二元和纯Pt,其中Pt-Ni_(1/3)-SnO_2/C的EOR活性最佳。Ni和SnO_2的加入并没有显著提高乙醇C―C键的断裂能力,但是二者的协同作用在低电位(0.1 V)下加强了乙醛的进一步氧化,生成了乙酸。     

SnO_2/TiO_2纳米管复合光催化剂的性能及失活再生

基于微波水热法和微乳液法合成SnO2/TiO2纳米管复合光催化剂.通过X射线衍射(XRD)、配有能量色散X射线光谱仪(EDX)的透射电镜(TEM)和电化学手段对光催化剂进行表征.以甲苯为模型污染物,考察光催化剂在紫外光(UV)和真空远紫外光(VUV)下的性能及失活再生.结果表明,SnO2/TiO2纳米管复合光催化剂形成三元异质结(锐钛矿相TiO2(A-TiO2)/金红石相TiO2(R-TiO2)、A-TiO2/SnO2和R-TiO2/SnO2异质结),促使光生电子-空穴对的有效分离,提高光催化活性.SnO2/TiO2表现出最佳的光催化性能,UV和VUV条件下的甲苯降解率均达100%,CO2生成速率(k2)均为P25的3倍左右.但由于UV光照矿化能力不足,中间产物易在催化剂表面累积.随着UV光照时间的增加,SnO2/TiO2逐渐失活,20 h后k2由138.5 mg·m-3·h-1下降到76.1 mg·m-3·h-1.利用VUV再生失活的SnO2/TiO2,过程中产生的·OH、O2-·、O(1D)、O(3P)、O3等活性物质可氧化吸附于催化剂活性位的难降解中间产物,使催化剂得以再生,12 h后k2恢复到143.6 mg·m-3·h-1.UV和VUV的协同效应使UV降解耦合VUV再生成为一种可持续的光催化降解污染物模式.     

热退火气氛对溶液法制备的Sb2S3薄膜组成、结构及光伏性能的影响

采用化学浴(CBD)法在TiO₂薄膜表面制备结晶性Sb₂S₃膜层, 获得了TiO₂/Sb₂S₃平板异质结, 并结合聚[2,6-{4,4-双-(2-乙基己基)-4H-环戊并[2,1-b;3,4-b']-二噻吩}-交替-4,7-(2,1,3-苯并噻二唑)](PCPDTBT)空穴传输层和MoO₃电极界面修饰层, 制备了FTO/TiO₂/Sb₂S₃/PCPDTBT/MoO₃/Au平板结构太阳能电池, 研究了CBD方法中热退火气氛对Sb₂S₃薄膜的组成、 结构及光伏性能的影响. 结果表明, 在N₂气氛下退火时, 所得的Sb₂S₃膜层不致密且含有Sb₂O₃杂相, 电池效率仅为0.90%; 而在N₂-S气氛下退火时, 硫会与杂相Sb₂O₃发生反应生成Sb₂S₃, 进而得到纯净、 致密、 平整的结晶Sb₂S₃膜层. 在平板结构太阳能电池中, 光生空穴对电池光电流的产生有明显的贡献; 随着Sb₂O₃杂相的消除, Sb₂S₃薄膜中载流子的复合减少且传输速率增大, 使太阳能电池器件中电子与空穴的收集效率和短路电流显著提高, 电池效率提高了1.34倍, 达到2.04%.     

Cell surface acid-base properties of Escherichia coli and Bacillus brevis and variation as a function of growth phase, nitrogen source and C:N ratio

Potentiometric titration has been conducted to systematically examine the acid–base properties of the cell surfaces of Escherichia coli K-12 and Bacillus brevis as a function of growth phase, nitrogen source (ammonium or nitrate), and carbon to nitrogen (C:N) ratio of the growth substrate. The two bacterial species revealed four distinct proton binding sites, with pK_a values in the range of 3.08–4.05 (pK₁), 4.62–5.57 (pK₂), 6.47–7.30 (pK₃), and 9.68–10.89 (pK₄) corresponding to phosphoric/carboxylic, carboxylic, phosphoric, and hydroxyl/amine groups, respectively. Two general observations in the data are that for B. brevis the first site concentration (N₁), corresponding to phosphoric/carboxylic groups (pK₁), varied as a function of nitrogen source, while for E. coli the fourth site concentration (N₄), corresponding to hydroxyl/amine groups (pK₄), varied as a function of C:N ratio. Correspondingly, it was found that N₁ was the highest of the four site concentrations for B. brevis and N₄ was the highest for E. coli. The concentrations of the remaining sites showed little variation. Finally, comparison between the titration data and a number of cell surface compositional studies in the literature indicates one distinct difference between the two bacteria is that pK₄ of the Gram-negative E. coli can be attributed to hydroxyl groups while that of the Gram-positive B. brevis can be attributed to amine groups.