A highly dispersed Pt/copper modified-MnO_(2)catalyst for the complete oxidation of volatile organic compounds:The effect of oxygen species on the catalytic mechanism

Manganese oxide(MnO_(2))exhibits excellent activity for volatile organic compound oxidation.However,it is currently unknown whether lattice oxygen or adsorbed oxygen is more conducive to the progress of the catalytic reaction.In this study,novel hollow highly dispersed Pt/Copper modified-MnO_(2)catalysts were fabricated.Cu^(2+)was stabilized into theδ-MnO_(2)cladding substituting original K+,which produced lattice defects and enhance the content of adsorbed oxygen.The 2.03 wt%Pt Cu_(0.050)-MnO_(2)catalyst exhibited the highest catalytic activity and excellent stability for toluene and benzene oxidation,with T_(100)=160℃under high space velocity(36,000 mL g^(-1)h^(-1)).The excellent performance of catalytic oxidation of VOCs is attributed to the abundant adsorbed oxygen content,excellent low-temperature reducibility and the synergistic catalytic effect between the Pt nanoparticles and Cu_(0.050)-MnO_(2).This study provides a comprehensive understanding of the Langmuir-Hinshelwood(L-H)mechanism occurring on the catalysts.

Pt–Pd bimetallic nanoparticles anchored on uniform mesoporous MnO_(2) sphere as an advanced nanocatalyst for highly efficient toluene oxidation

Improving catalytic performance is a yet still challenge in thermal catalytic oxidation.Herein,uniform mesoporous MnO_(2) nanospheresupported bimetallic Pt–Pd nanoparticles were successfully fabricated via a SiO_(2) template strategy for the total catalytic degradation of volatile organic compounds at low temperature.The introduction of mesopores into the MnO_(2) support induces a large specific surface area and pore size,thus providing numerous accessible active sites and enhanced diffusion properties.Moreover,the addition of a secondary noble metal can adjust the O_(ads)/O_(latt) molar ratios,resulting in high catalytic activity.Among them,the catalyst having a Pt/Pd molar ratio of 7:3 exhibits optimized catalytic activity at a weight hourly space velocity of 36,000 mL g^(-1) h^(-1),reaching 100%toluene oxidation at 175℃ with a lower activation energy(57.0 kJ mol^(-1))than the corresponding monometallic Pt or non-Pt-based catalysts(93.8 kJ mol^(-1) and 214.2 kJ mol^(-1)).Our findings demonstrate that the uniform mesoporous MnO_(2) nanosphere-supported bimetallic Pt–Pd nanoparticles catalyst is an effective candidate for application in elimination of toluene.

A mini-review on ZnIn_(2)S_(4)-Based photocatalysts for energy and environmental application

As one of the most attractive and eco-friendly technologies,semiconductor photocatalysis is demonstrated as a potential strategy to solve global energy shortage environmental pollution problems.Regarding semiconductor-based photocatalysts,Zinc indium sulfide(ZnIn_(2)S_(4)) with various morphological structures has become research hotspots owing to its superior visible light absorption,high chemical durability and low cost.Nevertheless,the photocatalytic activity of pristine ZnIn_(2)S_(4) is unsatisfactory due to limited range of visible light absorption and fast recombination rate of light-induced electrons and holes.Different modification strategies,such as metal deposition,element doping,vacancy engineering and semiconductor combination,have been systematically developed for enhancing the photocatalytic performance of ZnIn_(2)S_(4) materials.In order to promote further developments of ZnIn_(2)S_(4) in photocatalytic applications,this mini-review summarizes the progress of recent research works for the construction of highly activity ZnIn_(2)S_(4)-based photocatalysts for the first time.In addition,the typical applications of ZnIn_(2)S_(4)-based photocatalytic materials have been critically reviewed and described such as in hydrogen evolution from photocatalytic water splitting,carbon dioxide photoreduction,and treatment of water pollution.The current challenges and further prospects for the development of ZnIn_(2)S_(4) semiconductor photocatalysts are finally pointed out.

Research Progress on the Occupational Hazards and Protective Measures of Emergency Department Nurses

The emergency department is a department that is crucial for medical institutions.It is mainly responsible for rescuing critically ill patients and dealing with all kinds of public health emergencies.There are significant differences in the working environment and working mode between the nurses in emergency departments and those of other departments.They tend to come into contact with various occupational risk factors,resulting in high incidence of occupational hazards and accidental injuries.Therefore,it is necessary to analyze the common occupational risk factors of nurses in the emergency department and propose protective measures to ensure that these nurses are able to provide nursing services safely and effectively.

量子自旋霍尔绝缘体Bi_(4)Br_(4)体与边缘的可区分的光学性质研究

量子自旋霍尔绝缘体拥有具有带隙的体态和无能隙的一维拓扑边缘态.然而,由于拓扑边缘态局域在纳米尺度,所以很难用光学手段直接观测并区分体态和边缘态,这就限制了对拓扑边缘态独特的光学特性和光电响应等方面的研究和应用.Bi_(4)Br_(4)体材料的台阶存在一维非平庸的边缘态,多个台阶累加的效应使得通过较为宏观的光学和光电分析手段来研究一维边缘态成为可能.该工作利用中远红外显微吸收光谱和泵浦探测光谱,对比研究了Bi_(4)Br_(4)体和边缘的光学响应行为.研究发现Bi_(4)Br_(4)的边缘在小于带隙(约0.22 eV)的波段存在明显的强于体内的红外吸收,且该吸收呈现较强的各向异性.室温下的红外泵浦探测首次观察到边缘处载流子激发态超长的弛豫时间(1.5 ns),该激发态载流子寿命要比体内载流子寿命长两个量级.该工作证实体态和拓扑边缘态具有明显不同的光学和光电响应行为,为未来设计新型红外探测器提供了材料和物理基础.

2D/2D hierarchical Co_(3)O_(4)/ZnIn_(2)S_(4)heterojunction with robust builtin electric field for efficient photocatalytic hydrogen evolution

Because of its importance in enhancing charge separation and transfer,built-in electric field engineering has been acknowledged as an effective technique for improving photocatalytic performance.Herein,a stable p–n heterojunction of 2D/2D(2D:twodimensional)Co_(3)O_(4)/ZnIn_(2)S_(4)with a strong built-in electric field is precisely constructed.The Co_(3)O_(4)/ZnIn_(2)S_(4)heterojunction exhibits a higher visible-light photocatalytic hydrogen(H2)evolution rate than the individual components,which is primarily attributed to the synergy effect of improved light absorption,abundant active sites,short charge transport distance,high separation efficiency of photogenerated carriers.Furthermore,the photoelectrochemical studies and density functional theory(DFT)calculation results demonstrate that the enhanced interfacial charge separation and migration induced by the generated built-in electric field are the critical reasons for the boosted photocatalytic performance.This research might pave the way for the rational design and manufacturing of 2D/2D heterojunction photocatalysts with extremely efficient photocatalytic performance for solar energy conversion.

Zeolitic Imidazolate Framework 8-Derived Au@ZnO for Efficient and Robust Photocatalytic Degradation of Tetracycline

Summary of main observation and conclusion Tetracycline (TC) and other antibiotics accumulated in groundwater and soil pollute ecological environment and threaten human health. Gold nan oparticles doped on photocatalysts are able to enhance the photodegradation efficiency during removing these antibiotics, but preparation of Au nanoparticles of well-dispersion on photocatalysts remains challenging. In this work, zeolite imidazolate (ZIF-8) was employed as the precursor to prepare Au@ZnO photocatalyst via impregnation and in-situ reduction method to efficiently degrade the tetracycline in the aqueous solution. Au nanoparticles are of 10 nm in size and uniformly dispersed on the surfaces of ZnO microstructures. The as-prepared Au@ZnO is able to remove 85.5% of TC of 0.010 mg/mL within 2h, presenting higher photocatalytic activity than pure ZnO catalyst. Most importantly, the catalyst shows its superior stability after five cycles without structure and activity changing. The mechanism of the photocatalytic degradation was discussed in detail.

Weakened interlayer coupling in two-dimensional MoSe2 flakes with screw dislocations

The screw dislocations are intriguing defects that are often observed in natural and artificial materials. The dislocation spirals break the reflection and inversion symmetries of the lattices and modify the interlayer coupling in layer-structured materials, inducing additional complexity in layer stacking and thus novel properties in materials. Here, we report on the interlayer coupling of two-dimensional (2D) MoSe2 flakes with screw dislocations by atomic force microscopy (AFM), Raman spectra and photoluminescence (PL) spectra. By controlling the supersaturation conditions, 2D MoSe2 flakes with screw dislocations are grown on amorphous SiO2 substrates by chemical vapor deposition (CVD). AFM measurements reveal that the interlayer spacing in such 2D MoSe2 flakes with screw dislocation is slightly widened with respect to the normal AA- or AB-stacked ones due to the presence of the screw dislocations. Raman and PL spectra show that the interlayer coupling is weaker and thus the band gap is wider than that in the normal AA- or AB-stacked ones. Our work demonstrates that the interlayer coupling of 2D transition metal dichalcogenides (TMDCs) flakes can be tuned by the induction of screw dislocations, which is very helpful for developing novel catalysts and electronic devices.

Negative effect on molecular planarity to achieve organic ternary memory: triphenylamine as the spacer

Adjusting the spacers between the electron-acceptor and the elector-donor is important to design organic ternary memory material but rarely reported. In this paper, two small molecules, ZIPGA and ZIPCAD with benzene ring or triphenylamine as the spacers,were designed and synthesized to fabricate memory devices. The Al/ZIPGA/indium-tin oxide (ITO) device showed ternary characteristics, whereas Al/ZIPCAD/ITO had no obvious memory characteristics. Density functional theory calculation, X-ray diffraction (XRD) and atomic force microscopy (AFM) were employed to interpret the different memory properties. ZIPGA thin film has the closer intermolecular packing and flatter surface morphology than ZIPCAD film, which was favorable to the electron migration. This work demonstrates the importance of spacers and reveals that triphenylamine may be not a good spacer in design of new memory material.