Ultrathin Zincophilic Interphase Regulated Electric Double Layer Enabling Highly Stable Aqueous Zinc‑Ion Batteries

The practical application of aqueous zinc-ion batteries for large-grid scale systems is still hindered by uncontrolled zinc dendrite and side reactions.Regulating the elec-trical double layer via the electrode/electrolyte interface layer is an effective strategy to improve the stability of Zn anodes.Herein,we report an ultrathin zincophilic ZnS layer as a model regu-lator.At a given cycling current,the cell with Zn@ZnS electrode displays a lower potential drop over the Helmholtz layer(stern layer)and a suppressed diffuse layer,indicating the regulated charge distribution and decreased electric double layer repulsion force.Boosted zinc adsorption sites are also expected as proved by the enhanced electric double-layer capacitance.Consequently,the symmetric cell with the ZnS protection layer can stably cycle for around 3,000 h at 1 mA cm^(-2) with a lower overpotential of 25 mV.When coupled with an I2/AC cathode,the cell demonstrates a high rate performance of 160 mAh g^(-1) at 0.1 A g^(-1) and long cycling stability of over 10,000 cycles at 10 A g^(-1).The Zn||MnO_(2) also sustains both high capacity and long cycling stability of 130 mAh g^(-1) after 1,200 cycles at 0.5 A g^(-1).

Effects of Layer Change and Chemical Composition on Thermal Stability and Catalytic Activity of Pillared Montmorillonite

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Hierarchical Ni-Al hydrotalcite supported Pt catalyst for efficient catalytic oxidation of formaldehyde at room temperature

Catalytic oxidation at room temperature is recognized as the most promising method for formaldehyde(HCHO)removal.Pt‐based catalysts are the optimal catalyst for HCHO decomposition at room temperature.Herein,flower‐like hierarchical Pt/NiAl‐LDHs catalysts with different[Ni2+]/[Al3+]molar ratios were synthesized via hydrothermal method followed by NaBH4 reduction of Pt precursor at room temperature.The flower‐like hierarchical Pt/NiAl‐LDHs were composed of interlaced nanoplates and metallic Pt nanoparticles(NPs)approximately 3–4 nm in diameter were loaded on the surface of the Pt/NiAl‐LDHs with high dispersion.The as‐prepared Pt/NiAl21 nanocomposite was highly efficient in catalyzing oxidation of HCHO into CO2 at room temperature.The high activity of the hierarchical Pt/NiAl21 nanocomposite was maintained after seven recycle tests,suggesting the high stability of the catalyst.Based on in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)studies,a reaction mechanism was put forward about HCHO decomposition at room temperature.This work provides new insights into designing and fabricating high‐performance catalysts for efficient indoor air purification.

Catalytic hydrogenolysis of organosolv lignin: Cleaving C–O bonds over CuMgAlO_(x)-layered porous metal oxide catalysts for oriented monophenols production

To understand the catalytic conversion of lignin into high-value products,lignin depolymerization was performed using a layered polymetallic oxide(CuMgAlO_(x))catalyst.The effects of the conversion temperature,hydrogen pressure,and reaction time were studied,and the ability of CuMgAlO_(x)to break the C–O bond was evaluated.The CuMgAlO_(x)(Mg/Al=3:1)catalyst contained acidic sites and had a relatively homogeneous elemental distribution with a high pore size and specific surface area.Theβ-O-4 was almost completely converted by disassociating the C–O bond,resulting in yields of 14.74%ethylbenzene,47.58%α-methylphenyl ethanol,and 36.43%phenol.The highest yield of lignin-derived monophenols was 85.16%under reaction conditions of 280℃ and 3 Mpa for 4 h.As the reaction progressed,depolymerization and condensation reactions occurred simultaneously.Higher temperatures(>280℃)and pressures(>3 Mpa)tended to produce solid char.This study establishes guidelines for the high-value application of industrial lignin in the catalytic conversion of polymetallic oxides.

Effects of a novel bimetallic catalytic biofilter-based pretreatment technique on the form of ultrafiltration membrane fouling

Pretreatments of influents using bimetallic catalytic biofilter(BC-biofilter)can help reduce transmembrane pressures.For ultrafiltration membranes coupled with a conventional biofilter pretreatment,the cake layer resistance accounts for 25.0%of the total resistance.However,for those coupled with BC-biofilter pretreatment,the cake layer resistance accounts only for 12.5%of the total resistance.Confocal laser scanning microscopy is employed to determine the porosity of cake layer.It is found that ultrafiltration membranes with BC-biofilter pretreatment show a cake layer porosity of up to 0.56 or greater,whereas those with a conventional biofilter pretreatment exhibit a cake layer porosity of only 0.36.This is because micro-flocculation occurs in the effluents of BC-biofilter.The flocs generated through flocculation deposit on membrane surfaces to create highly porous cake layer.Moreover,catalytic reduction can increase the zeta potentials of the biofilter effluents.This makes the deposition of colloidal particles and flocs on membrane surfaces difficult under electrostatic repulsion.Simultaneously,micro-flocculation after BC-biofilter pretreatment can remove colloidal particles with particle sizes of200–350 nm in water.This can effectively prevent the blockage of ultrafiltration membrane pores.Furthermore,compared to conventional biofilter,BC-biofilter pretreatment can more effectively reduce the number of colloidal particles and the van der Waals forces of ultrafiltration membranes.They can also change the action directions of electric double layers and thereby mitigate ultrafiltration membrane fouling.

Synthesis of bamboo-like carbon nanotubes by ethanol catalytic combustion technique

Bamboo-like carbon nanotubes were synthesized by ethanol catalytic combustion (ECC) technique with combustion method. Copper plate was employed as substrate, ethanol as carbon source, and iron chloride as catalyst precursor. The as-grown black powder was characterized by means of scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. The results show that the thinner bamboo-like carbon nanotubes have a relatively good structure that the compartment layers are more regular, while the thicker carbon nanotubes have a relatively irregular bamboo-like structure; the proposed method is simple to synthesize bamboo-like carbon nanotubes and has some advantages, such as flexible synthesis conditions, simple setup, and environment-friendly.

Identification and comparison of the local physicochemical structures of transition metal-based layered double hydroxides for high performance electrochemical oxygen evolution reactions

Layered double hydroxides(LDHs) have attracted considerable attention as a cost effective alternative to the precious iridium-and ruthenium-based electrocatalysts for an oxygen evolution reaction(OER),a bottleneck of water electrolysis for sustainable hydrogen production.Despite their excellent OER performance,the structural and electronic properties of LDHs,particularly during the OER process,remain to be poorly understood.In this study,a series of LDH catalysts is investigated through in situ X-ray absorption fine structure analyses and density functional theory(DFT) calculations.Our experimental results reveal that the LDH catalyst with equal amounts of Ni and Fe(NF-LDH) exhibits the highest OER activity and catalytic life span when compared with its counterparts having equal amounts of Ni and Co(NC-LDH)and Ni only(Ni-LDH).The NF-LDH shows a markedly enhanced OER kinetics compared to the NC-LDH and the Ni-LDH,as proven by the lower overpotentials of 180,240,and 310 mV,respectively,and the Tafel slopes of 35.1,43.4,and 62.7 mV dec^(-1),respectively.The DFT calculations demonstrate that the lowest overpotential of the NF-LDH is associated with the active sites located at the edge planes of NF-LDH in contrast to those located at the basal planes of Ni-LDH and NC-LDH.The current study pinpoints the active sites on various LDHs and presents strategies for optimizing the OER performance of the LDH catalysts.

孔隙率分布对质子交换膜燃料电池性能的影响

建立平行、蛇形及叶脉流场的三维质子交换膜燃料电池(PEMFC)模型,分析不同模型中催化层(CL)的氧气分布特征.针对不同流场模型提出对应的气体扩散层(GDL)孔隙率梯度分布方案,分析不同流场模型中氧气摩尔分数分布、膜电流密度分布、极化曲线与功率密度曲线.结果表明,所提GDL孔隙率梯度分布方案能够强化氧气由GDL向CL的传输效果,改善CL上局部氧气供应不足现象,提升PEMFC输出性能.与常规孔隙率分布的平行、蛇形及叶脉流场模型相比,采用孔隙率梯度分布的流场模型的峰值功率密度分别提高了8.59%,18.26%和15.46%.

Effect of electrolyte cation-mediated mechanism on electrocatalytic carbon dioxide reduction

The steep reduction in costs and systematic optimization of renewable electricity has ignited an intensifying interest in harnessing electroreduction of carbon dioxide(CO_(2)RR)for the generation of chemicals and fuels.The focus of research over the past few decades has been on the optimization of the electrode and the electrolyte environment.Notably,cation species in the latter have recently been found to dramatically alter the selectivity of CO_(2)RR and even their catalytic activity by multiple orders of magnitude.As a result,the selection of cations is a critical factor in designing catalytic interfaces with high selectivity and efficiency for targeted products.Informed decision-making regarding cation selection relies on a comprehensive understanding of prevailing electrolyte effect models that have been used to elucidate observed experimental trends.In this perspective,we review the hypotheses that explain how electrolyte cations influence CO_(2)RR by mechanisms such as through tuning of the interfacial electric field,buffering of the local pH,stabilization of the key intermediates and regulation of the interfacial water.Our endeavor is to elucidate the molecular mechanisms underpinning cation effects,thus fostering the evolution of more holistic and universally applicable predictive models.In this regard,we highlight the current challenges in this area of research,while also identifying potential avenues for future investigations.

层状结构BiOBr的形成机理及其光催化降解抗生素性能

通过水热合成法片层结构溴氧化铋(BiOBr)颗粒,探究其形成机理,并在氙灯光照下以喹诺酮类抗生素诺氟沙星(NOR)为降解底物,考察BiOBr形貌结构变化对光催化性能的影响。X射线衍射(XRD)和扫描电子显微镜(SEM)分析确认BiOBr制备成功。结果表明,水热合成条件下制备的BiOBr为片层结构,随反应溶液pH值的增加,颗粒尺寸逐渐变小,且分散性越来越差,吸收带边发生蓝移,禁带宽度变大。分析水溶剂环境下片层BiOBr的形貌变化生长机理,当pH=1时,BiOBr形貌为均匀的片状结构,宽度为(3~5)μm,禁带宽度为2.93 eV,表现出最佳的光催化活性,光催化反应60 min后,NOR的降解率达到87.2%,最高降解速率常数为3.31×10^(-2)min^(-1)。

High Density 3D Carbon Tube Nanoarray Electrode Boosting the Capacitance of Filter Capacitor

Electric double-layer capacitors(EDLCs)with fast frequency response are regarded as small-scale alternatives to the commercial bulky aluminum electrolytic capacitors.Creating carbon-based nanoarray electrodes with precise alignment and smooth ion channels is crucial for enhancing EDLCs’performance.However,controlling the density of macropore-dominated nanoarray electrodes poses challenges in boosting the capacitance of line-filtering EDLCs.Herein,a simple technique to finely adjust the vertical-pore diameter and inter-spacing in three-dimensional nanoporous anodic aluminum oxide(3D-AAO)template is achieved,and 3D compactly arranged carbon tube(3D-CACT)nanoarrays are created as electrodes for symmetrical EDLCs using nanoporous 3D-AAO template-assisted chemical vapor deposition of carbon.The 3D-CACT electrodes demonstrate a high surface area of 253.0 m^(2) g^(−1),a D/G band intensity ratio of 0.94,and a C/O atomic ratio of 8.As a result,the high-density 3D-CT nanoarray-based sandwich-type EDLCs demonstrate a record high specific areal capacitance of 3.23 mF cm^(-2) at 120 Hz and exceptional fast frequency response due to the vertically aligned and highly ordered nanoarray of closely packed CT units.The 3D-CT nanoarray electrode-based EDLCs could serve as line filters in integrated circuits,aiding power system miniaturization.

A double-layer covered architecture with spinel phase induced by LiPP for Co-free Li-rich cathode with high-rate performance and long lifespan

Co-free Li-rich Mn-based layered oxides are promising candidates for next-generation lithium-ion batteries(LIBs)due to their high specific capacity,high voltage,low cost.However,their commercialization is hindered by limited cycle life and poor rate performance.Herein,an in-situ simple and low-cost strategy with a nanoscale double-layer architecture of lithium polyphosphate(LiPP)and spinel phase covered on top of the bulk layered phase,is developed for Li_(1.2)Mn_(0.6)Ni_(0.2)O_(2)(LMNO)using Li^(+)-conductor LiPP(denoted as LMNO@S-LiPP).With such a double-layer covered architecture,the half-cell of LMNO@S-LiPP delivers an extremely high capacity of 202.5 mAh·g^(−1)at 1 A·g^(−1)and retains 85.3%of the initial capacity after 300 cycles,so far,the best highrate electrochemical performance of all the previously reported LMNOs.The energy density of the full-cell assembled with commercial graphite reaches 620.9 Wh·kg^(−1)(based on total weight of active materials in cathode and anode).Mechanism studies indicate that the superior electrochemical performance of LMNO@S-LiPP is originated from such a nanoscale double-layer covered architecture,which accelerates Li-ion diffusion,restrains oxygen release,inhibits interfacial side reactions,suppresses structural degradation during cycling.Moreover,this strategy is applicable for other high-energy-density cathodes,such as LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2),Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2),LiCoO_(2).Hence,this work presents a simple,cost-effective,scalable strategy for the development of high-performance cathode materials.

LDHs衍生阵列催化剂在吸收增强式甘油水蒸气重整制氢的应用前景展望

对吸收增强式甘油水蒸气重整(SESRG)制氢反应网络及热力学特性、Ni-Ca基催化-吸收双功能催化剂研究进展及面临的挑战进行归纳总结,系统分析Ni基催化位点、Ca基吸附位点失活机理及改性手段。结合层状双金属氢氧化物(LDHs)材料和阵列催化剂独特的结构优势和物化特性,提出设计研发LDHs衍生阵列催化剂是提高Ni-Ca双功能催化剂反应活性和稳定性的有效手段,并对其在甘油高效稳定制氢领域发展前景进行展望。

钴铜层状双金属氢氧化物合成及其催化还原对硝基苯酚性能的研究

开发高效催化材料降解硝基有机污染物,对于推动绿色化学和化工的发展具有重要的意义。为此,研究了水浴法合成的钴铜层状双金属氢氧化物(CuCo-LDHs)将对硝基苯酚(4-NP)催化还原为对氨基苯酚(4-AP)的反应过程;通过X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、扫描电子显微镜(SEM)、电感耦合等离子体光谱仪(ICP),对材料的晶体结构、表面形貌等进行了表征;同时系统性研究了催化剂用量,4-NP的初始浓度、反应温度及硼氢化钠(NaBH4)浓度对CuCo-LDHs催化还原性能的影响。研究结果表明:CuCo-LDHs在催化还原4-NP的反应中表现出较高的催化活性,且反应条件温和,产物无污染。在室温及反应时间为3 min条件下,10 mg CuCo-LDHs可将100 mL 0.10 mmol/L的4-NP有效还原,转化率可达到95%。最后对CuCo-LDHs催化还原4-NP生成4-AP的反应机理进行了分析讨论。

新型浸渍法制备的超薄燃料电池膜电极组件及其性能表征

质子交换膜燃料电池膜电极组件的性能受限于氢气与氧气在催化层中的不均匀分布。为了促进氢气与氧气在催化层中的扩散,本文使用结合了电势置换反应的新型浸渍法在质子交换膜上沉积一层具有电催化活性的Pt基合金纳米颗粒,形成了超薄的不含碳载体的催化层。在与碳纸复合后即可获得正常工作的新型膜电极。经测试,超薄催化层能提高膜电极的贵金属利用率,降低其制备成本,有利于推动质子交换膜燃料电池与相关产业的发展。

电极孔径及温度对闭式氢氧燃料电池性能的影响机理研究

针对燃料电池内部复杂的水传输机制和水管理策略的影响因素,研究多孔电极的孔径对水传输和水分布情况的影响。建立燃料电池等温模型,通过改变多孔电极的孔径,模拟燃料电池催化层在不同孔径下的水浓度和水分布规律。同时,考虑温度可能带来的影响,在研究过程中选取了燃料电池常见的运行温度,在每个温度值下都进行了模拟。结果表明,在设定的温度下,孔径对水浓度和水分布情况的影响规律是相似的。孔径较大时,电极内的水浓度较低。随着孔径减小,电极内的水浓度不断增大。同时,孔径越小,水浓度增大的速度越快。气体浓度的分布与变化情况正好与水浓度相反。水浓度越高的区域气体浓度越低。随着孔径减小,气体浓度不断上升。从模拟结果来看,当气体扩散层具有微米级孔隙结构时,电极内多余的水分可以较好地排出,同时在较高的温度下水管理更容易较好地实现。阴极流道出口和中部比较容易发生水淹,所以应该对这些区域加设除水装置或设计自除水结构。

Overwhelming low ammonia escape and low temperature denitration efficiency via MnOx-decorated two-dimensional MgAl layered double oxides

Low temperature catalysts are attracting increasing attention in the selective catalytic reduction(SCR)of NO with NH3.Mn Ox-decorated Mg Al layered double oxide(Mn/Mg Al-LDO)was synthesized via a facile fast pour assisted co-precipitation(FP-CP)process.Compared to the Mn/Mg Al-LDO obtained via slow drop assisted coprecipitation(SD-CP)method,the Mn/Mg Al-LDO(FP-CP)has excellent activity.The Mn/Mg Al-LDO(FP-CP)catalyst was shown to possess a high NO conversion rate of 76%-100%from 25 to 150℃,which is much better than the control Mn/Mg Al-LDO(SD-CP)(29.4%-75.8%).In addition,the Mn/Mg Al-LDO(FP-CP)offered an enhanced NO conversion rate of 97%and a N2selectivity of 97.3%at 100℃;the NO conversion rate was 100%and the N2selectivity was 90%at 150℃with a GHSV of 60,000 h^-1.The Mn/Mg Al-LDO(FP-CP)catalyst exhibited a smaller fragment nano-sheet structure(sheet thickness of 7.23 nm).An apparent lattice disorder was observed in the HRTEM image confirming the presence of many defects.The H2-TPR curves show that the Mn/Mg Al-LDO(FP-CP)catalyst has abundant reducing substances.Furthermore,the enhanced surface acidity makes the NH3concentration of the Mn/Mg Al-LDO(FP-CP)catalyst lower than 100 ml·m^-3after the reaction from 25 to 400℃.This can effectively reduce the ammonia escape rate in the SCR reaction.Thus,the Mn/Mg Al-LDO(FP-CP)catalyst has potential applications in stationary industrial installations for environmentally friendly ultra-low temperature SCR.

双极膜的制备及应用研究进展

介绍了双极膜的基本结构原理及其发展历程,总结了近年来用于双极膜制备和改性的各类膜材料,及可提高双极膜水解离性能的中间催化层,并详细梳理了双极膜电渗析技术在不同领域的应用,为双极膜的制备、改性研究提供参考,为深化、拓展双极膜电渗析技术的应用领域提供借鉴.

氢分离非钯合金膜表面处理研究进展

镀有Pd层的氢分离纯化用5B族金属膜具有较高的氢选择性和渗透率,但Pd与基底在高温下易发生热扩散,致使氢的解离效率变差,影响合金膜在氢分离时的连续性和稳定性。目前,在合金膜与Pd之间添加中间层或在合金膜表面直接使用非Pd催化材料是防止氢分离合金膜因金属间扩散而失效的主要方法。介绍了金属催化氢解离与合金膜渗氢机理,并从中间层材料、非Pd催化材料及影响这2种材料效果的内外因素等方面综述了近年来在氢分离合金膜表面处理方面的研究进展。中间层材料的类型以金属化合物为主,还包括氧化物及稀土金属Y,针对这些材料防金属间扩散的效果采用高温下渗氢稳定时间和渗透率进行评价分析;非Pd催化材料主要分为金属碳化物和钒氧化物2类,重点分析了材料的解离效率和通用性,其解离效率与晶体结构和实验温度有关。在通用性方面,氧化物能够与不同基底合金结合,并获得较高的氢渗透率,表现出更好的适应性。影响中间层和非Pd催化材料发挥效用的因素主要包括材料内在因素和工艺外部因素,分析了涂层结构和厚度的材料因素,举例说明了制备工艺和制备参数选择等外部因素对材料发挥效用的影响。最后指出了现有涂层研究中,加入中间层材料或直接使用非Pd催化材料时的不足及相应的改进措施,并对氢分离5B族合金膜表面处理的未来发展进行了展望。

水滑石及其衍生物处理水中污染物的研究进展

水滑石(LDH)由于具有记忆效应、内部结构可调性、层间阴离子可交换性等优良性质,而在水处理领域具有广阔应用前景。综述了水滑石及其衍生物处理水中污染物的最新研究进展。介绍了LDH处理重金属废水和有机废水,利用催化氧化性能或通过与不同材料复合处理废水。此外,还简述了LDH的规模化生产现状及存在问题,对LDH材料在水处理领域的未来发展方向进行了展望。