真空紫外协同Co^(2+)催化过硫酸氢钾降解罗丹明B

有机染料具有毒性强、色度高、不易降解等特性,为了高效去除有机染料,实验以真空紫外(VUV)为光源,研究了VUV协同Co^(2+)催化过硫酸氢钾(PMS)降解典型有机染料罗丹明B(RhB)的反应机制和转化途径.结果表明:①在RhB初始浓度为80 mg/L,Co^(2+)和PMS投加量分别为15μmol/L、0.5 mmol/L的条件下,VUV/Co^(2+)/PMS体系反应10 min,RhB去除率可达99.1%.VUV/Co^(2+)/PMS体系对RhB降解遵循一级动力学规律,反应速率常数(k)随初始质量浓度的增加而减小.②溶液初始pH对反应速率有较大的影响,随着pH减小,反应速率也同时减小.投加量为30 mmol/L的HCO_(3)^(−)、Cl^(−)均表现出显著的抑制作用,相较于对照组,RhB去除率由99.1%分别降至66.0%、84.2%,而NO_(3)^(−)和SO_(4)^(2−)抑制作用不显著;印染助剂柠檬酸钠也会显著抑制RhB降解.③自由基捕获实验和电子顺磁共振(EPR)测试结果表明,VUV/Co^(2+)/PMS体系中存在的氧化物种包括硫酸根自由基(SO_(4)^(−)·)、羟基自由基(·OH)、单线态氧(1O2).④根据紫外可见吸收光谱和质谱结果,初步推断RhB分子降解主要通过活性氧(ROS)攻击造成共轭结构破坏和N-位脱乙基等作用.另外,对总有机碳(TOC)进行测试,30 min时RhB矿化度可达到43.8%.研究显示,VUV/Co^(2+)/PMS体系能够有效去除RhB.

Co-doped BaFe_(2)As_(2) Josephson junction fabricated with a focused helium ion beam

Josephson junction plays a key role not only in studying the basic physics of unconventional iron-based superconductors but also in realizing practical application of thin-film based devices,therefore the preparation of high-quality iron pnictide Josephson junctions is of great importance.In this work,we have successfully fabricated Josephson junctions from Co-doped BaFe_(2)As_(2)thin films using a direct junction fabrication technique which utilizes high energy focused helium ion beam(FHIB).The electrical transport properties were investigated for junctions fabricated with various He^(+)irradiation doses.The junctions show sharp superconducting transition around 24 K with a narrow transition width of 2.5 K,and a dose correlated foot-structure resistance which corresponds to the effective tuning of junction properties by He^(+)irradiation.Significant J_c suppression by more than two orders of magnitude can be achieved by increasing the He^(+)irradiation dose,which is advantageous for the realization of low noise ion pnictide thin film devices.Clear Shapiro steps are observed under 10 GHz microwave irradiation.The above results demonstrate the successful fabrication of high quality and controllable Co-doped BaFe_(2)As_(2)Josephson junction with high reproducibility using the FHIB technique,laying the foundation for future investigating the mechanism of iron-based superconductors,and also the further implementation in various superconducting electronic devices.

Neutral and metallic vs.charged and semiconducting surface layer in acceptor doped CeO_(2)

The monomolecular surface layer of acceptor doped CeO_(2) may become neutral and metallic or charged and semiconducting.This is revealed in the theoretical analysis of the oxygen pressure dependence of the surface defects concentration in acceptor doped ceria with two different dopant types and operated under different oxygen pressures.Recently published experimental data for highly reduced Sm0.2Ce0.8O1.9-x(SDC)containing a fixed valence dopant Sm3+are very different from those published for Pr0.1Ce0.9O_(2)-x(PCO) with the variable valence dopant Pr4+/Pr3+being reduced under milder conditions.The theoretical analysis of these experimental results fits very well the experimental results of SDC and PCO.It leads to the following predictions:the highly reduced surface of SDC is metallic and neutral,the metallic surface electron density of state is gs=0.9×10^(38)J-1·m^(-2)(1.4×1015eV^(-1)·cm^(-2)),the electron effective mass is meff,s=3.3me,and the phase diagram of the reduced surface has theα(fcc)structure as in the bulk.In PCO a double layer is predicted to be formed between the surface and the bulk with the surface being negatively charged and semiconducting.The surface of PCO maintains high Pr^(3+) defect concentration as well as relative high oxygen vacancy concentration at oxygen pressures higher than in the bulk.The reasons for the difference between a metallic and semiconducting surface layer of acceptor doped CeO_(2) are reviewed,as well as the key theoretical considerations applied in coping with this problem.For that we make use of the experimental data and theoretical analysis available for acceptor doped ceria.

Memristive feature and mechanism induced by laser-doping in defect-free 2D semiconductor materials

Memristors as non-volatile memory devices have gained numerous attentions owing to their advantages in storage,in-memory computing, synaptic applications, etc. In recent years, two-dimensional(2D) materials with moderate defects have been discovered to exist memristive feature. However, it is very difficult to obtain moderate defect degree in 2D materials, and studied on modulation means and mechanism becomes urgent and essential. In this work, we realized memristive feature with a bipolar switching and a configurable on/off ratio in a two-terminal MoS_(2) device(on/off ratio ~100), for the first time, from absent to present using laser-modulation to few-layer defect-free MoS_(2)(about 10 layers), and its retention time in both high resistance state and low resistance state can reach 2×10^(4) s. The mechanism of the laser-induced memristive feature has been cleared by dynamic Monte Carlo simulations and first-principles calculations. Furthermore, we verified the universality of the laser-modulation by investigating other 2D materials of TMDs. Our work will open a route to modulate and optimize the performance of 2D semiconductor memristive devices.

Selective core-shell doping enabling high performance 4.6 V-LiCoO_(2)

Constructing robust surface and bulk structure is the prerequisite for realizing high performance high voltage LiCoO_(2)(LCO).Herein,we manage to synthesize a surface Mg-doping and bulk Al-doping coreshell structured LCO,which demonstrates excellent cycling performance.Half-cell shows 94.2%capacity retention after 100 cycles at 3.0-4.6 V(vs.Li/Li^(+))cycling,and no capacity decay after 300 cycles for fullcell test(3.0-4.55 V).Based on comprehensive microanalysis and theoretical calculations,the degradation mechanisms and doping effects are systematically revealed.For the undoped LCO,high voltage cycling induces severe interfacial and bulk degradations,where cracks,stripe defects,fatigue H2 phase,and spinel phase are identified in grain bulk.For the doped LCO,Mg-doped surface shell can suppress the interfacial degradations,which not only stabilizes the surface structure by forming a thin rock-salt layer but also significantly improves the electronic conductivity,thus enabling superior rate performance.Bulk Al-doping can suppress the lattice"breathing"effect and the detrimental H3 to H1-3 phase transition,which minimizes the internal strain and defects growth,maintaining the layered structure after prolonged cycling.Combining theoretical calculations,this work deepens our understanding of the doping effects of Mg and Al,which is valuable in guiding the future material design of high voltage LCO.

Durable hierarchical phosphorus‐doped biphase MoS_(2)electrocatalysts with enhanced H^(*)adsorption

Phase engineering is an efficient strategy for enhancing the kinetics of electrocatalytic reactions.Herein,phase engineering was employed to prepare high‐performance phosphorous‐doped biphase(1T/2H)MoS_(2)(P‐BMS)nanoflakes for hydrogen evolution reaction(HER).The doping of MoS_(2)with P atoms modifies its electronic structure and optimizes its electrocatalytic reaction kinetics,which significantly enhances its electrical conductivity and structural stability,which are verified by various characterization tools,including X‐ray photoelectron spectroscopy,high‐resolution transmission electron microscopy,X‐ray absorption near‐edge spectroscopy,and extended X‐ray absorption fine structure.Moreover,the hierarchically formed flakes of P‐BMS provide numerous catalytic surface‐active sites,which remarkably enhance its HER activity.The optimized P‐BMS electrocatalysts exhibit low overpotentials(60 and 72 mV at 10 mA cm^(−2))in H_(2)SO_(4)(0.5 M)and KOH(1.0 M),respectively.The mechanism of improving the HER activity of the material was systematically studied using density functional theory calculations and various electrochemical characterization techniques.This study has shown that phase engineering is a promising strategy for enhancing the H*adsorption of metal sulfides.

Unveiling the pressure-driven metal–semiconductor–metal transition in the doped TiS_(2)

Conventional theories expect that materials under pressure exhibit expanded valence and conduction bands,leading to increased electrical conductivity.Here,we report the electrical properties of the doped 1T-TiS_(2) under high pressure by electrical resistance investigations,synchrotron x-ray diffraction,Raman scattering and theoretical calculations.Up to 70 GPa,an unusual metal-semiconductor-metal transition occurs.Our first-principles calculations suggest that the observed anti-Wilson transition from metal to semiconductor at 17 GPa is due to the electron localization induced by the intercalated Ti atoms.This electron localization is attributed to the strengthened coupling between the doped Ti atoms and S atoms,and the Anderson localization arising from the disordered intercalation.At pressures exceeding 30.5 GPa,the doped TiS_(2) undergoes a re-metallization transition initiated by a crystal structure phase transition.We assign the most probable space group as P2_(1)2_(1)2_(1).Our findings suggest that materials probably will eventually undergo the Wilson transition when subjected to sufficient pressure.

Enhanced stability of FA-based perovskite:Rare-earth metal compound EuBr_(2) doping

It is highly desirable to enhance the long-term stability of perovskite solar cells(PSCs)so that this class of photovoltaic cells can be effectively used for the commercialization purposes.In this contribution,attempts have been made to use the two-step sequential method to dope EuBr_(2)into FAMAPbI_(3)perovskite to promote the stability.It is shown that the device durability at 85℃in air with RH of 20%-40%is improved substantially,and simultaneously the champion device efficiency of 23.04%is achieved.The enhancement in stability is attributed to two points:(ⅰ)EuBr_(2)doping effectively inhibits the decomposition andα-δphase transition of perovskite under ambient environment,and(ⅱ)EuBr_(2)aggregates in the oxidized format of Eu(BrO_(3))_(3)at perovskite grain boundaries and surface,hampering humidity erosion and mitigates degradation through coordination with H_(2)O.

Small but mighty:Empowering sodium/potassium-ion battery performance with S-doped SnO_(2) quantum dots embedded in N,S codoped carbon fiber network

SnO_(2) has been extensively investigated as an anode material for sodium-ion batteries(SIBs)and potassium-ion batteries(PIBs)due to its high Na/K storage capacity,high abundance,and low toxicity.However,the sluggish reaction kinetics,low electronic conductivity,and large volume changes during charge and discharge hinder the practical applications of SnO_(2)-based electrodes for SIBs and PIBs.Engineering rational structures with fast charge/ion transfer and robust stability is important to overcoming these challenges.Herein,S-doped SnO_(2)(S-SnO_(2))quantum dots(QDs)(≈3 nm)encapsulated in an N,S codoped carbon fiber networks(S-SnO_(2)-CFN)are rationally fabricated using a sequential freeze-drying,calcination,and S-doping strategy.Experimental analysis and density functional theory calculations reveal that the integration of S-SnO_(2) QDs with N,S codoped carbon fiber network remarkably decreases the adsorption energies of Na/K atoms in the interlayer of SnO_(2)-CFN,and the S doping can increase the conductivity of SnO_(2),thereby enhancing the ion transfer kinetics.The synergistic interaction between S-SnO_(2) QDs and N,S codoped carbon fiber network results in a composite with fast Na+/K+storage and extraordinary long-term cyclability.Specifically,the S-SnO_(2)-CFN delivers high rate capacities of 141.0 mAh g^(−1) at 20 A g^(−1) in SIBs and 102.8 mAh g^(−1) at 10 A g^(−1) in PIBs.Impressively,it delivers ultra-stable sodium storage up to 10,000 cycles at 5 A g^(−1) and potassium storage up to 5000 cycles at 2 A g^(−1).This study provides insights into constructing metal oxide-based carbon fiber network structures for high-performance electrochemical energy storage and conversion devices.

Mg-doped SrTaO_(2)N as a visible-light-driven H_(2)-evolution photocatalyst for accelerated Z-scheme overall water splitting

Perovskite SrTaO_(2)N is one of the most promising narrow-bandgap photocatalysts for Z-scheme overall water splitting.However,the formation of defect states during thermal nitridation severely hinders the separation of charges,resulting in poor photocatalytic activity.In the present study,we successfully synthesize SrTaO_(2)N photocatalyst with low density of defect states,uniform morphology and particle size by flux-assisted one-pot nitridation combined with Mg doping.Some important parameters,such as the size of unit cell,the content of nitrogen,and microstructure,prove the successful doping of Mg.The defect-related carrier recombination has been significantly reduced by Mg doping,which effectively promotes the charge separation.Moreover,Mg doping induces a change of the band edge,which makes proton reduction have a stronger driving force.After modifying with the core/shell-structured Pt/Cr_(2)O_(3)cocatalyst,the H_(2)evolution activity of the optimized SrTaO_(2)N:Mg is 10 times that of the undoped SrTaO_(2)N,with an impressive apparent quantum yield of 1.51%at 420 nm.By coupling with Au-FeCoO_(x)modified BiVO_(4)as an O_(2)-evolution photocatalyst and[Fe(CN)_(6)]_(3)−/[Fe(CN)_(6)]_(4)−as the redox couple,a redox-based Z-scheme overall water splitting system is successfully constructed with an apparent quantum yield of 1.36%at 420 nm.This work provides an alternative way to prepare oxynitride semiconductors with reduced defects to promote the conversion of solar energy.

Nitrogen-doping boosts ^(*)CO utilization and H_(2)O activation on copper for improving CO_(2) reduction to C_(2+) products

To improve the electrocatalytic transformation of carbon dioxide (CO_(2)) to multi-carbon (C_(2+)) products is of great importance.Here we developed a nitrogen-doped Cu catalyst,by which the maximum C_(2+) Faradaic efficiency can reach 72.7%in flow-cell system,with the partial current density reaching 0.62 A cm^(-2).The in situ Raman spectra demonstrate that the *CO adsorption can be strengthened on such a N-doped Cu catalyst,thus promoting the *CO utilization in the subsequent C–C coupling step.Simultaneously,the water activation can be well enhanced by N doping on Cu catalyst.Owing to the synergistic effects,the selectivity and activity for C_(2+) products over the N-deoped Cu catalyst are much improved.

Homovalent doping:An efficient strategy of the enhanced TiNb_(2)O_(7)anode for lithium-ion batteries

The low energy density,unsatisfied cycling performance,potential safety issue and slow charging kinetics of the commercial lithium-ion batteries restrained their further application in the fields of fast charging and long-haul electric vehicles.Monoclinic TiNb_(2)O_(7)(TNO)with the theoretical capacity of 387 mAh g^(-1)has been proposed as a high-capacity anode materials to replace Li4Ti5O12.In this work,homovalent doping strategy was used to enhance the electrochemical performance of TiNb_(2)O_(7)(TNO)by employing Zr to partial substitute Ti through solvothermal method.The doping of Zr^(4+)ions can enlarge the lattice structure without changing the chemical valence of the original elements,refine and homogenize the grains,improve the electrical conductivity,and accelerate the ion diffusion kinetics,and finally enhance the cycle and rate performance.Specifically,Z0.05-TNO shows initial discharge capacity of as high as 312.2 mAh g^(-1)at 1 C and 244.8 mAh g^(-1)at 10 C,and still maintains a high specific capacity of 171.3 mAh g^(-1)after 800 cycles at 10 C.This study provides a new strategy for high-performance fast-charging energy storage electrodes.

Defect Engineering in Earth-Abundant Cu_(2)ZnSnSe_(4) Absorber Using Efficient Alkali Doping for Flexible and Tandem Solar Cell Applications

To demonstrate flexible and tandem device applications,a low-temperature Cu_(2)ZnSnSe_(4)(CZTSe)deposition process,combined with efficient alkali doping,was developed.First,high-quality CZTSe films were grown at 480℃by a single co-evaporation,which is applicable to polyimide(PI)substrate.Because of the alkali-free substrate,Na and K alkali doping were systematically studied and optimized to precisely control the alkali distribution in CZTSe.The bulk defect density was significantly reduced by suppression of deep acceptor states after the(NaF+KF)PDTs.Through the low-temperature deposition with(NaF+KF)PDTs,the CZTSe device on glass yields the best efficiency of 8.1%with an improved Voc deficit of 646 mV.The developed deposition technologies have been applied to PI.For the first time,we report the highest efficiency of 6.92%for flexible CZTSe solar cells on PI.Additionally,CZTSe devices were utilized as bottom cells to fabricate four-terminal CZTSe/perovskite tandem cells because of a low bandgap of CZTSe(~1.0 eV)so that the tandem cell yielded an efficiency of 20%.The obtained results show that CZTSe solar cells prepared by a low-temperature process with in-situ alkali doping can be utilized for flexible thin-film solar cells as well as tandem device applications.

Enhancing potassium-ion storage of Bi_(2)S_(3) through external–internal dual synergism: Ti_(3)C_(2)T_(x) compositing and Cu^(2+) doping

Potassium-ion batteries(PIBs)offer a cost-effective and resource-abundant solution for large-scale energy storage.However,the progress of PIBs is impeded by the lack of high-capacity,long-life,and fast-kinetics anode electrode materials.Here,we propose a dual synergic optimization strategy to enhance the K^(+)storage stability and reaction kinetics of Bi_(2)S_(3) through two-dimensional compositing and cation doping.Externally,Bi_(2)S_(3) nanoparticles are loaded onto the surface of three-dimensional interconnected Ti_(3)C_(2)T_(x) nanosheets to stabilize the electrode structure.Internally,Cu^(2+)doping acts as active sites to accelerate K^(+)storage kinetics.Various theoretical simulations and ex situ techniques are used to elucidate the external–internal dual synergism.During discharge,Ti_(3)C_(2)T_(x) and Cu^(2+)collaboratively facilitate K+intercalation.Subsequently,Cu^(2+)doping primarily promotes the fracture of Bi2S3 bonds,facilitating a conversion reaction.Throughout cycling,the Ti_(3)C_(2)T_(x) composite structure and Cu^(2+)doping sustain functionality.The resulting Cu^(2+)-doped Bi2S3 anchored on Ti_(3)C_(2)T_(x)(C-BT)shows excellent rate capability(600 mAh g^(-1) at 0.1 A g^(–1);105 mAh g^(-1) at 5.0 A g^(-1))and cycling performance(91 mAh g^(-1) at 5.0 A g^(-1) after 1000 cycles)in half cells and a high energy density(179 Wh kg–1)in full cells.

不同条件下Co^(2+)对锌电积的影响

Co^(2+)是湿法炼锌中重点关注的有害杂质之一。以含Co^(2+)的硫酸锌溶液作为模拟研究对象,整体研究含Co^(2+)的硫酸锌溶液中分别存在松醇油和Mg^(2+)时,Co^(2+)对锌电解的影响行为。结果表明,当电积液中不存在松醇油和Mg^(2+)时,Co^(2+)的存在造成了锌板的穿孔,出现了轻微“烧板”现象,需要将电积液中Co^(2+)浓度控制在0.6 mg/L以下。当电积液中加入0.21 g/L的松醇油时,Co^(2+)的含量对锌电积的不利影响比电积液中不存在松醇油时的影响更大,需要将电积液中Co^(2+)浓度控制在0.4 mg/L以下。当Mg^(2+)浓度分别为5 g/L和10 g/L时,需要将电积液中Co^(2+)浓度控制在0.4 mg/L和0.2 mg/L以下。当Mg^(2+)浓度为15 g/L时,电积液中的Co^(2+)应尽量除尽。

微量Co^(2+)-Si^(4+)取代对多晶石榴石铁氧体材料旋矩磁性能的影响

采用传统陶瓷工艺制备了多晶石榴石铁氧体,研究了微量Co^(2+)-Si^(4+)联合取代对GdCaSnV-YIG、GdCaZrV-YIG、GdCaInV-YIG和GdAl-YIG材料旋矩磁性能的影响。结果表明,Co^(2+)-Si^(4+)联合取代GdAl-YIG可使其矫顽力显著增高,而Co^(2+)-Si^(4+)取代GdCaSnV-YIG、GdCaZrV-YIG和GdCaInV-YIG,可调节其矫顽力和剩磁比。当Co^(2+)-Si^(4+)取代量为0.015时得到GdCaSnV-YIG的矫顽力为0.17 Oe,取代量为0.025时得到GdCaZrV-YIG的矫顽力为0.23 Oe,取代量大于等于0.035时三者的剩磁比均能达到0.79或以上。

Cu^(2+)和Co^(2+)促进芬顿氧化处理垃圾渗滤液的研究

通过在传统芬顿体系中加入Cu^(2+)、Co^(2+),研究Cu^(2+)/Co^(2+)/Fe^(2+)/H_(2)O_(2)、Cu^(2+)/Fe^(2+)/H_(2)O_(2)、Co^(2+)/Fe^(2+)/H_(2)O_(2)和Fe^(2+)/H_(2)O_(2)四种芬顿体系对垃圾渗滤液的处理效果,发现当初始pH分别为2、3、4、5、6时,各体系去除COD_(Cr)的效果排序为Cu^(2+)/Co^(2+)/Fe^(2+)/H_(2)O_(2)>Cu^(2+)/Fe^(2+)/H_(2)O_(2)>Co^(2+)/Fe^(2+)/H_(2)O_(2)>Fe^(2+)/H_(2)O_(2),Cu^(2+)、Co^(2+)对芬顿反应效果的提升具有促进作用;Cu^(2+)/Co^(2+)/Fe^(2+)/H_(2)O_(2)和Cu^(2+)/Fe^(2+)/H_(2)O_(2)体系比传统芬顿体系具有更宽的pH响应范围;Cu^(2+)、Co^(2+)的引入明显加快芬顿反应速率,反应时间可由3h缩短至2h。在Cu^(2+)/Co^(2+)/Fe^(2+)/H_(2)O_(2)体系中,m(H_(2)O_(2)):m(COD_(Cr))比值下降至2.4:1,COD_(Cr)去除率仍高达93%,具有优异的处理效果。

活性炭电极的改性及对Co^(2+),Mn^(2+)和Ni^(2+)的电吸附性能

以商用活性炭(AC)为原料,分别采用磷酸和氢氧化钠改性的方法制备了两种不同的改性活性炭电极材料.采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、Brunauer-Emmett-Teller(BET)测试、傅里叶变换红外光谱(FTIR)和X射线光电子能谱(XPS)等手段以及电化学分析方法,对改性前后活性炭材料的表面性质和电化学性能进行了探究.结果表明,H_(3)PO_(4)改性使活性炭的孔隙分布更加密集,NaOH改性使活性炭表面的孔隙结构更加清晰均匀;H_(3)PO_(4)和NaOH改性均使活性炭的比表面积增加.循环伏安测试结果表明,改性前后活性炭电极在低扫描速率下均具备良好的双电层特性,并且两种改性处理均能提高活性炭电极的比电容;当扫描速率为5 mV/s时,未改性、H_(3)PO_(4)以及NaOH改性活性炭电极的比电容分别为36.51,77.25和85.19 F/g.电吸附实验结果证明,两种改性活性炭电极对Co^(2+),Mn^(2+)和Ni^(2+)均有较好的去除效果,电吸附过程均更加符合Langmuir模型,在初始浓度、电压和pH相同的条件下,NaOH改性电极对Co^(2+),Mn^(2+)和Ni^(2+)具有更高的去除率和吸附容量,去除率可分别达到96.84%,94.37%和96.90%,吸附容量分别为140.8,111.4和108.5 mg/g.

5%Ag掺杂对MNO_(2)纳米棒和海胆微球形貌及其甲苯氧化性能的影响

采用水热法制备了MNO_(2)纳米棒和海胆微球,并原位掺杂5%Ag制备了Mn-Ag复合氧化物,利用SEM、XRD、BET、Raman等表征技术对其结构进行表征,并考察不同催化剂对甲苯的去除性能。结果表明:(NH_(4))_(2)S_(2)O_(8)的掺入量会对MNO_(2)的形貌产生影响,当其掺入量为2.28 g时,形成MNO_(2)纳米棒,当其掺入量为6.84 g时,形成MNO_(2)海胆微球;MNO_(2)纳米棒掺杂5%的Ag后,形貌未发生变化,但当MNO_(2)海胆微球掺杂5%Ag时,表面的纳米线较MNO_(2)海胆微球有所增长,且出现了缠绕现象,形成了空心鸟巢状结构;5%Ag掺杂后,对MNO_(2)纳米棒和MNO_(2)海胆微球的晶型未产生影响,均为α-MNO_(2),但5%Ag-MNO_(2)纳米棒出现了Mn2O_(3)的衍射峰;MNO_(2)海胆微球较MNO_(2)纳米棒的比表面积、孔径和孔容均增大,且Ag的掺杂进一步提高了MNO_(2)海胆微球的比表面积、孔径和孔容;MNO_(2)海胆微球比MNO_(2)纳米棒具有更好的甲苯去除性能,且5%Ag掺杂后,MNO_(2)海胆微球对甲苯的去除性能达到最好。

Fe、Ir掺杂MoS_(2)表面对N_(2)气敏吸附与解离反应性能提升的第一性原理研究

基于第一性原理方法,采用周期性平板模型,研究了N_(2)分子在掺杂体系TM-MoS_(2)(TM=Fe、Ir)表面的吸附和解离行为.研究表明:N_(2)分子在TM-MoS_(2)(TM=Fe、Ir)表面吸附能依次为0.62和0.47 eV,而完整MoS_(2)表面的吸附能只有0.08 eV,说明掺杂之后对N_(2)表现出略好的吸附性能.差分电荷密度分析表明,N_(2)吸附后,掺杂Fe、Ir原子与两个N原子之间电荷有所增加,N-N键之间的区域电荷密度减少,N-N键的强度减弱.态密度计算结果发现,N_(2)在吸附过程中,主要是N原子的2p_(y)、2p_(z)轨道与Ir的5d_(xy)和5d_(z^(2))以及Fe的3d_(xy)和3d_(z^(2))发生杂化作用.通过分析解离活化能,N_(2)在掺杂体系TM-MoS_(2)(TM=Fe、Ir)表面解离需要活化能均较高,且远大于在相应掺杂表面的吸附能,说明N_(2)在掺杂体系TM-MoS_(2)(TM=Fe、Ir)表面解离应该表现为分子吸附或脱附.