TiO2@SiO2微球的制备及其光催化性能研究

采用模板法以钛酸丁酯为钛源,SiO2为模板球,制备出了TiO2包覆SiO2微球。利用SEM、TEM、XRD、EDS对样品形貌、结构和成分进行了表征分析,并测试了样品的光催化性能。结果表明TiO2@SiO2微球的光催化性能优于用相同方法制得的TiO2的光催化性能,当使用TiO2@SiO2微球为光催化剂时,在光照180min后甲基橙的降解率达到82%,而相同方法制得的TiO2为56%,较后者提高了26%,具有良好的光催化活性。     

Synthesis of CaO2 Nanocrystals and Their Spherical Aggregates with Uniform Sizes for Use as a Biodegradable Bacteriostatic Agent

As a solid precursor to O₂ and hydrogen peroxide (H₂O₂), calcium peroxide (CaO₂) has found widespread use in applications related to disinfection and contaminant degradation. The lack of uniform nanoparticles, however, greatly limits the potential use of this material in other applications related to medicine. Here, a new route to the facile synthesis of CaO₂ nanocrystals and their spherical aggregates with uniform, controllable sizes is reported. The synthesis involves the reaction between CaCl₂ and H₂O₂ to generate CaO₂ primary nanocrystals of 2–15 nm in size in ethanol, followed by their aggregation into uniform, spherical particles with the aid of poly(vinyl pyrrolidone) (PVP). The average diameter of the spherical aggregates can be easily tuned in the range of 15–100 nm by varying the concentrations of CaCl₂ and/or PVP. For the spherical aggregates with a smaller size, they release H₂O₂ and O₂ more quickly when exposed to water, resulting in superior antimicrobial activity. This study not only demonstrates a new route to the synthesis of uniform CaO₂ nanocrystals and their spherical aggregates but also offers a promising bacteriostatic agent with biodegradability.     

TiO2 nanoparticles catalysed synthesis of 2-arylbenzimidazoles and 2-arylbenzothiazoles using hydrogen peroxide under ambient light

A H₂O₂/TiO₂ P25 nanoparticle system has been examined and applied towards synthesis of a wide range of 2-substituted benzimidazole and benzothiazole derivatives from oxidative coupling of aromatic 1,2-phenylendiamine and 2-aminothiophenol with aromatic aldehydes bearing different types of substituents.     

酶-二维MXene复合材料的制备及其电化学检测H2O2的应用

本研究合成了具有垂直栅栏结构的二维MXene材料, 与辣根过氧化物酶进行固定, 构筑了过氧化氢电化学酶传感器。合成的MXene纳米栅栏具有大的比表面积, 优良的电子传导特性和在水溶液中的良好分散特性; 固定化在酶电极上的辣根过氧化物酶分子表现出了优良的过氧化氢催化效果。结果表明HRP@MXene/chitosan/GCE酶电化学传感器在过氧化氢浓度为5~1650 μmol/L范围内表现出很好的线性关系, 最低检测限为0.74 μmol/L, 且具有很好的操作稳定性, 该生物传感器被成功地应用于固态与液态食品中过氧化氢残留检测。     

Photothermal‐Responsive Microporous Nanosheets Confined Ionic Liquid for Efficient CO2 Separation

2D materials hold promising potential for novel gas separation. However, a lack of in‐plane pores and the randomly stacked interplane channels of these membranes still hinder their separation performance. In this work, ferrocene based‐MOFs (Zr‐Fc MOF) nanosheets, which contain abundant of in‐plane micropores, are synthesized as porous supports to fabricate Zr‐Fc MOF supported ionic liquid membrane (Zr‐Fc‐SILM) for highly efficient CO₂ separation. The micropores of Zr‐Fc MOF nanosheets not only provide extra paths for CO₂ transportation, and thus increase its permeance up to 145.15 GPU, but also endow the Zr‐Fc‐SILM with high selectivity (216.9) of CO₂/N₂ through the nanoconfinement effect, which is almost ten times higher than common porous polymer SILM. Furthermore, based on the photothermal‐responsive properties of Zr‐Fc MOF, the performance is further enhanced (35%) by light irradiation through a photothermal heating process. This provides a brand new way to design light facilitating gas separation membranes.     

2D Transition‐Metal‐Dichalcogenide‐Nanosheet‐Based Composites for Photocatalytic and Electrocatalytic Hydrogen Evolution Reactions

Hydrogen (H₂) is one of the most important clean and renewable energy sources for future energy sustainability. Nowadays, photocatalytic and electrocatalytic hydrogen evolution reactions (HERs) from water splitting are considered as two of the most efficient methods to convert sustainable energy to the clean energy carrier, H₂. Catalysts based on transition metal dichalcogenides (TMDs) are recognized as greatly promising substitutes for noble‐metal‐based catalysts for HER. The photocatalytic and electrocatalytic activities of TMD nanosheets for the HER can be further improved after hybridization with many kinds of nanomaterials, such as metals, oxides, sulfides, and carbon materials, through different methods including the in situ reduction method, the hot‐injection method, the heating‐up method, the hydro(solvo)thermal method, chemical vapor deposition (CVD), and thermal annealing. Here, recent progress in photocatalytic and electrocatalytic HERs using 2D TMD‐based composites as catalysts is discussed.     

浸渍-沉积法制备一维Au/TiO_2的光催化性能研究

以钛酸纳米管为载体、HAuCl4为金前驱体,通过浸渍-沉积法制备一维金修饰TiO2光催化剂(Au/TiO2)。通过X射线衍射和紫外-可见漫反射吸收光谱研究材料的结构和性质。以甲基橙溶液作为模拟废液,研究Au/TiO2材料在紫外光条件下的光催化活性。研究表明,由于金可以接受电子,从而促进光生电子和光生空穴的分离,使TiO2的光催化活性提高;Au/TiO2的光催化活性还与金的含量密切相关,金的最佳负载量为1%(质量分数)。     

甲烷/氢气在超微孔金属有机骨架中的吸附与分离性能研究

使用巨正则蒙特卡罗方法(GCMC)对CH₄和H₂在3种具有不同结构的超微孔金属有机骨架(UM-MOFs)中的吸附与分离性能进行了研究。获得了这3种材料对CH₄和H₂分子的单组分吸附。通过分析它们对CH₄/H₂二元混合物的吸附数据,获得了相应的吸附选择性分布曲线,探索了UM-MOFs对CH₄/H₂分子的吸附与分离机理。     

Porous Microrod Arrays Constructed by Carbon‐Confined NiCo@NiCoO2 Core@Shell Nanoparticles as Efficient Electrocatalysts for Oxygen Evolution

The study of cost‐efficient and high‐performance electrocatalysts for oxygen evolution reaction (OER) has attracted much attention. Here, porous microrod arrays constructed by carbon‐confined NiCo@NiCoO₂ core@shell nanoparticles (NiCo@NiCoO₂/C PMRAs) are fabricated by the reductive carbonization of bimetallic (Ni, Co) metal–organic framework microrod arrays (denoted as NiCo‐MOF MRAs) and subsequent controlled oxidative calcination. They successfully combine the desired merits including large specific surface areas, high conductivity, and multiple electrocatalytic active sites for OER. In addition, the oxygen vacancies in NiCo@NiCoO₂/C PMRAs significantly improve the conductivity of NiCoO₂ and accelerate the kinetics of OER. The above advantages obviously enhance the electrocatalytic performance of NiCo@NiCoO₂/C PMRAs. The experimental results demonstrate that the NiCo@NiCoO₂/C PMRAs as electrocatalysts exhibit high catalytic activity, low overpotential, and high stability for OER in alkaline media. The strategy reported will open up a new route for the fabrication of porous bimetallic composite electrocatalysts derived from MOFs with controllable morphology for electrochemical energy conversion devices.     

Bi2WO6/NH2-MIL-88B(Fe) heterostructure: An efficient sunlight driven photocatalyst for the degradation of antibiotic tetracycline in aqueous medium

The development of highly efficient sunlight assisted photocatalysts has been acknowledged as a promising strategy for the enhanced degradation of antibiotics. In this work, effectual fabrication of a novel Bi₂WO₆/NH₂-MIL-88B(Fe) heterostructure was carried through solvothermal route. The structural, morphological and compositional analysis was done by employing number of analytical techniques, namely XRD, FTIR, HRTEM, FESEM, XPS, PL and BET surface area. The prepared Bi₂WO₆/NH₂-MIL-88B(Fe) heterostructure was utilized as an efficient photocatalyst towards decomposition of a typical antibiotic tetracycline (TC) in aqueous medium. It was found that Bi₂WO₆/NH₂-MIL-88B(Fe) heterostructure exhibited improved degradation efficiency of about 89.4% within 130 min of solar illumination than pristine NH₂-MIL-88B(Fe) under optimized parameters i.e. initial drug solution of 10 mg/L concentration at pH 4 with 0.35 g/L dose of catalyst. Moreover, adsorption studies, kinetics and isotherms of adsorption on TC were also investigated. Results revealed that adsorption kinetics followed pseudo 2nd order model and isotherm data fitted well with Freundlich model (R² = 0.99803) as compared to Temkin and Langmuir. The ameliorating photocatalytic capability could be primarily accredited to the heterojunction created among Bi₂WO₆ and NH₂-MIL-88B(Fe) which facilitated the charge transfer and thus determines high catalytic efficiency. The enhanced photocatalyic effect was further verified by electrochemical impedance and photocurrent studies. The prepared composite also exhibited longer carrier lifetime (140.72 ns) compared to pure MOF (132.05 ns) and Bi₂WO₆ (136.39 ns). Further, based on the radical trapping investigations, role of superoxide radicals was dominant and detailed mechanism was proposed for the photocatalytic degradation process. The major intermediates formed during the course of reaction were also examined using LCMS analysis. The photodegradation was also carried over simulated hospital wastewater by the prepared heterostructure and 60.5% TOC was obtained under solar light in 390 min. Moreover, the synthesized heterostructure showed good recyclability up to three cycles depicting good stability.     

2D Electrocatalysts for Converting Earth-Abundant Simple Molecules into Value-Added Commodity Chemicals: Recent Progress and Perspectives

The electrocatalytic conversion of earth-abundant simple molecules into value-added commodity chemicals can transform current chemical production regimes with enormous socioeconomic and environmental benefits. For these applications, 2D electrocatalysts have emerged as a new class of high-performance electrocatalyst with massive forward-looking potential. Recent advances in 2D electrocatalysts are reviewed for emerging applications that utilize naturally existing H₂O, N₂, O₂, Cl⁻ (seawater) and CH₄ (natural gas) as reactants for nitrogen reduction (N₂ → NH₃), two-electron oxygen reduction (O₂ → H₂O₂), chlorine evolution (Cl⁻ → Cl₂), and methane partial oxidation (CH₄ → CH₃OH) reactions to generate NH₃, H₂O₂, Cl₂, and CH₃OH. The unique 2D features and effective approaches that take advantage of such features to create high-performance 2D electrocatalysts are articulated with emphasis. To benefit the readers and expedite future progress, the challenges facing the future development of 2D electrocatalysts for each of the above reactions and the related perspectives are provided.     

Gold nanoparticles/graphene oxide composite for electrochemical sensing of hydroxylamine and hydrogen peroxide

It has been discovered that the complex formed by cetyltrimethyl ammonium bromide (CTAB) and graphene oxide (GO) is highly stable in aqueous solution and adhesive to the glassy carbon electrode (GCE) surface in our previous research. In this work, the film of CTAB/GO complex was directly formed on GCE and gold nanoparticles were facilely incorporated into the matrix of CTAB/GO complex at the same time. Scanning electron microscopic (SEM) investigation shows that gold nanoparticles were distributed uniformly on the sheets of graphene. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and amperometry were used to investigate the electrochemical behaviors of AuNP/CTAB/GO. The obtained AuNP/CTAB/GO presents excellent catalytic capabilities towards the oxidation of hydroxylamine (HA) and the reduction of H₂O₂. The oxidation current of HA and the reduction current of H₂O₂ are linear with their concentrations in the range of 10～1000 μM and 1.0～5000 μM, respectively. The detection limits for HA and H₂O₂ are 3.5 μM and 0.67 μM, respectively. The mechanism of the oxidation of HA on AuNP/CTAB/GO modified GCE was also studied.     

Effect of Ni+2-substituted Fe2TiO5 on the H2-reduction and CO2 Catalytic Decomposition Reactions at 500℃

CO2 is a major component of the greenhouse gases, which causes the global warming. To reduce CO2 gas,high activity nanosized Ni 2 substituted Fe2TiO5 samples were synthesized by conventional ceramic method.The effect of the composition of the synthesized ferrite on the H2-reduction and CO2-catalytic decomposition was investigated. Fe2TiO5 (iron titanate) phase that has a nanocrystallite size of ～80 nm is formed as a result of heating Fe2O3 and TiO2 while the addition of NiO leads to the formation of new phases (～80 nm)NiTiO3 and NiFe2O4, but the mixed solid of NiO and Fe2O3 results in the formation of NiFe2O4 only.Samples with Ni 2=0 shows the lowest reduction extent (20%); as the extent of Ni 2 increases, the extent of reduction increases. The increase in the reduction percent is attributed to the presence of NiTiO3 and NiFe2O4 phases, which are more reducible phases than Fe2TiO5. The CO2 decomposition reactions were monitored by thermogravimetric analysis (TGA) experiments. The oxidation of the H2-reduced Ni 2 substituted Fe2TiO5 at 500℃ was investigated. As Ni 2 increases, the rate of reoxidation increases. Samples with the highest reduction extents gave the highest reoxidation extent, which is attributed to the highly porous nature and deficiency in oxygen due to the presence of metallic Fe, Ni and/or FeNi alloy. X-ray diffraction (XRD) and transmission electron microscopy (TEM) of oxidized samples show also the presence of carbon in the sample containing Ni 2＞0, which appears in the form of nanotubes (25 nm).     

Design of XS2 (X = W or Mo)-Decorated VS2 Hybrid Nano-Architectures with Abundant Active Edge Sites for High-Rate Asymmetric Supercapacitors and Hydrogen Evolution Reactions

Two-dimensional layered transition metal dichalcogenides have emerged as promising materials for supercapacitors and hydrogen evolution reaction (HER) applications. Herein, the molybdenum sulfide (MoS₂)@vanadium sulfide (VS₂) and tungsten sulfide (WS₂)@VS₂ hybrid nano-architectures prepared via a facile one-step hydrothermal approach is reported. Hierarchical hybrids lead to rich exposed active edge sites, tuned porous nanopetals-decorated morphologies, and high intrinsic activity owing to the strong interfacial interaction between the two materials. Fabricated supercapacitors using MoS₂@VS₂ and WS₂@VS₂ electrodes exhibit high specific capacitances of 513 and 615 F g⁻¹, respectively, at an applied current of 2.5 A g⁻¹ by the three-electrode configuration. The asymmetric device fabricated using WS₂@VS₂ electrode exhibits a high specific capacitance of 222 F g⁻¹ at an applied current of 2.5 A g⁻¹ with the specific energy of 52 Wh kg⁻¹ at a specific power of 1 kW kg⁻¹. For HER, the WS₂@VS₂ catalyst shows noble characteristics with an overpotential of 56 mV to yield 10 mA cm⁻², a Tafel slope of 39 mV dec⁻¹, and an exchange current density of 1.73 mA cm⁻². In addition, density functional theory calculations are used to evaluate the durable heterostructure formation and adsorption of hydrogen atom on the various accessible sites of MoS₂@VS₂ and WS₂@VS₂ heterostructures.     

Pt Nanoparticle Assisted Homogeneous Surface Engineering of Polymer-Based Bulk-Heterojunction Photocathodes for Efficient Charge Extraction and Catalytic Hydrogen Evolution

To fabricate a high-efficiency bulk-heterojunction (BHJ)-based photocathode, introducing suitable interfacial modification layer(s) is a crucial strategy. Surface engineering is especially important for achieving high-performance photocathodes because the photoelectrochemical (PEC) reactions at the photocathode/electrolyte interface are the rate-limiting process. Despite its importance, the influence of interfacial layer morphology regulation on PEC activity has attracted insufficient attention. In this work, RuO₂, with excellent conductivity, capacity and catalytic properties, is utilized as an interfacial layer to modify the BHJ layer. However, the homogeneous coverage of hydrophilic RuO₂ on the hydrophobic BHJ surface is challenging. To address this issue, a Pt nanoparticle-assisted homogeneous RuO₂ layer deposition method is developed and successfully applied to several BHJ-based photocathodes, achieving superior PEC performance compared to those prepared by conventional interface engineering strategies. Among them, the fluorine-doped tin oxide (FTO)/J71:N2200(Pt)/RuO₂ photocathode generates the best photocurrent density of −9.0 mA cm⁻² at 0 V with an onset potential of up to 1.0 V under AM1.5 irradiation.     

活性炭的双氧水表面改性及其吸附二氧化硫性能研究

目的 制备武器装备贮存微环境用单组分的二氧化硫吸附材料。方法 采用双氧水对椰壳活性炭进行表面改性,研究改性活性炭孔隙结构、表面化学性质的变化及其对二氧化硫吸附性能的影响。结果 活性炭存在微孔和中孔,改性后活性炭比表面积略有增加,平均孔径减小。双氧水与活性炭反应起到刻蚀作用,在活性炭表面产生了纳米尺度的网孔结构,降低了活性炭表面碳微晶有序程度,同时双氧水与活性炭反应时起到了氧化作用,提升了活性炭表面氧元素和含氧官能团含量。体积分数为20%的双氧水改性活性炭的吸附容量最高,达到154.15 mg/g,约为改性前的5倍。结论 双氧水对活性炭经表面改性后,产生了纳米尺度的孔隙,并提升了活性炭表面含氧官能团,在两者协同作用下显著提升活性炭对SO₂吸附性能,具有良好的装备应用前景。