Liquid-phase Synthesis Method Research Articles

Green massive mechanical synthesis of highly efficient Zn-Doped Cs3Cu2I5 for LED and X-ray imaging applications

As a new generation of environmentally friendly halide materials, Cs3Cu2I5 shows up the promising application in scintillation, LED, and photoelectric detection fields. However, liquid phase methods cannot produce Cs3Cu2I5 on a large scale, and the preparation process is accompanied by serious pollution. Although the ball milling method can solve the problems caused by the liquid phase synthesis method, the Cs3Cu2I5 obtained has many surface defects and low luminescence efficiency. In this work, a strategy of doping-assisted ball-milling synthesis using ZnI2 is proposed. Similar to the chemical preparation of Cs3Cu2I5, the iodine-rich environment during the modified ball milling process can also play a role in repairing surface defects. And it has been demonstrated through experiments and first principles calculations that the distortion of [Cu2I5]3- under ground/excited state can be adjusted through doping Zn into the Cu1 site, the formation barrier of self-trapped excitons is reduced, and the luminous efficiency of Cs3Cu2I5 is significantly improved. Subsequently, using the simple hot-pressing method, the representative Cs3Cu2I5:1.0Zn sample was combined with commercially available polypropylene to fabricate Cs3Cu2I5:1.0Zn@PP film. Finally, the potential applications of the newly-developed film in portable and customizable WLED and scintillation fields were explored.

A simple approach through reduction of Na2SO4 to prepare high-purity Na2S for sulfide electrolytes toward all-solid-state sodium batteries

Development of sulfide solid-state electrolytes (SSEs) with high ionic conductivity plays a leading role in achieving all-solid-state sodium batteries (ASSSBs). As an important raw material for synthesizing sulfide SSEs, the purity of Na2S significantly affects the ionic conductivity and electrochemical properties of sulfide SSEs. In order to obtain high-purity and low-cost Na2S, a hydrogen reduction of industrial grade Na2SO4 followed by ethanol purification has been successfully employed to synthesize and purify Na2S, which possesses a high purity of 98 %. Na3SbS4 has been synthesized by as-synthesized Na2S (A-Na2S) and commercial Na2S (C–Na2S) by liquid-phase synthesis and solid-state reaction methods, respectively. The electrochemical properties indicate that Na3SbS4 samples synthesized by A-Na2S possess higher ionic conductivity and lower Ea, and the assembled ASSSBs exhibit higher specific capacities, superior cycle and rate performance. At 0.5C, the assembled TiS2/Na3SbS4/NaSn ASSSB exhibits a high initial capacity of 211.4 mAh g−1 with capacity retention of 96.2 % after 360 cycles at room temperature. This work provides a simple approach for synthesizing high-purity Na2S at low cost, enabling the large-scale application of sulfide SSEs for ASSSBs.

New Approach to Synthesizing Cathode PtCo/C Catalysts for Low-Temperature Fuel Cells

The presented study is concerned with a new multi-step method to synthesize PtCo/C materials based on composite CoxOy/C that combines the advantages of different liquid-phase synthesis methods. Based on the results of studying the materials at each stage of synthesis with the TG, XRD, TEM, SEI, TXRF, CV and LSV methods, a detailed overview of the sequential changes in catalyst composition and structure at each stage of the synthesis is presented. The PtCo/C catalyst synthesized with the multi-step method is characterized by a uniform distribution of bimetallic nanoparticles of about 3 nm in size over the surface of the support, which result in its high ESA and ORR activity. The activity study for the synthesized PtCo/C catalyst in an MEA showed better current–voltage characteristics and a higher maximum specific power compared with an MEA based on a commercial Pt/C catalyst. Therefore, the results of the presented study demonstrate high prospects for the developed approach to the multi-step synthesis of PtM/C catalysts, which may enhance the characteristics of proton-exchange membrane fuel cells (PEMFCs).

Synthesis and functionalities of FeSn12 superatom prepared by single atom introduction with a dendrimer template.

Superatoms are promising as new building block materials that can be designed by precise controlling of the constituent atoms. Stannaspherene (Sn12 2-) is a rigid cage-like cluster with icosahedral symmetry, for which one-atom encapsulation was theoretically expected and detected in the gas phase. Here, a single-atom introduction method into stannaspherene using a dendrimer template with polyvinylpyrrolidone (PVP) protection is demonstrated. This advanced solution-phase synthesis allows not only the selective doping of one atom into the cluster cage, but also enable further detail characterization of optical and magnetic properties that were not possible in the gas-phase synthesis. In other words, this liquid-phase synthesis method has enabled the adaptation of detailed analytical methods. In this study, FeSn12 was synthesized and characterized, revealing that a single Fe atom introduction in the Sn12 2- cage result in the appearance of near-infrared emission and enhancement in the magnetism.

Preparation of Pt/WO3@ZnO hollow spheres for low-temperature and high-efficiency detection of triethylamine.

In this work, hollow spherical Pt-loaded WO3/ZnO heterostructured composites were prepared by a chemical liquid phase synthesis method. The morphology, crystal structure and components of the composites were characterized by SEM, TEM, XRD, XPS, etc. The sensing performance for various gases was also tested. Compared with the pristine WO3 (S = 44@225 °C, 50 ppm) gas sensor, the gas sensor that is functionalized with 1 wt% Pt and 0.5 mmol ZnO (1Pt/WZ-2) has a high response of 842-50 ppm at a relatively low temperature of 100 °C for TEA, with a quick response/recovery time of 34/120 s, a lower detection limit of 50 ppb, and good selectivity and moisture resistance. This study provides a highly efficient synthesis method of composite materials for TEA gas detection and the sensitivity mechanism is also discussed in detail.

Synthesis and characterization of the sea urchin-like γ-AlOOH/Fe3O4@SiO2 nanosorbent with ultra-high performance of Congo red removal

To manifest the benefits of nanosorbents in microstructure, the strong magnetism of Fe3O4 nanospheres is fully utilized to realize the rapid solid–liquid separation of adsorbent and aqueous solution. A sea urchin-like magnetic composite nanosorbent with a hierarchical structure was successfully manufactured by a simple and efficient liquid-phase hydrothermal synthesis method. Furthermore, its graded structure can sufficiently enhance the porosity and Zeta potential value of the material to increase the adsorption site and adsorption force between the material and CR molecular. The synthesized nanosorbent was then explored by a series of material physical and chemical characterization tools. It can be illustrated that the adsorbent is a strong magnetic composite nanomaterial with uniform particle size distribution and high dispersion, and is based on Fe3O4@SiO2 smooth nanoparticles as the inner core and γ-AlOOH as the shell. The saturation adsorption capacity reached 4534.57 mg g−1 with due expedition (under the adsorbent mass of 50 mg, CR mass concentration of 1500 mg/L, temperature of 25 °C and solution pH value of 3), whereas the γ-AlOOH of 925.34 mg g−1, Fe3O4 of 41.25 mg g−1 and Fe3O4@SiO2 of 93.21 mg g−1. After eight cycles of adsorption tests, the saturation capacity could still maintain 94.46% of the original adsorption capacity. Moreover, the adsorbent could be recovered by a simple applied magnetic field and the whole adsorption process conforms to the Pseudo-second kinetic model and the Langmuir isotherm model. Therefore, the sea urchin-like magnetic composite nanomaterials with a graded structure synthesized in this study could be widely utilized as a potential adsorbent material for CR removal.

PdO-modified ZnSnO3 hollow rounded cubes for high-performance TEA gas sensors at low temperature

Given human health and environmental safety issues, it is particularly imperative to detect triethylamine (TEA) rapidly and effectively at low temperatures. In this work, ZnSnO3 hollow rounded cubes (HZTO) with different PdO contents were prepared by liquid phase synthesis methods. The characterization results show that the side length of the hollow-rounded cubes is 500 – 700 nm, and the thickness is about 50 nm. Synthetic materials were applied to TEA gas sensors, and the sensing characteristics of the sensors were evaluated. The gas sensing results indicate that the modification of PdO can adjust the optimal operating temperature and the response of the gas sensor. The response value of the sensor with the best gas sensing performance can be as high as 532 to 100 ppm TEA at 175 °C, which is 17 times that of the unmodified material, and the working temperature is reduced by 125 °C. In addition, the sensor has good performance in selectivity, response time (1 s), low detection limit (500 ppb), and long-term stability. The improved TEA gas sensing performance is attributed to the structural characteristics of the hollow rounded cube of the material, p-n heterojunction, and the catalytic effect of PdO.

Development of the efficient preparation method for thermoresponsive elastin-like peptides using liquid-phase synthesis combined with fragment condensation strategy.

Elastin-like peptides (ELPs) are synthetic peptides that mimic the characteristic hydrophobic amino acid repeat sequences of elastin and exhibit temperature-dependent reversible self-assembly properties. ELPs are expected to be used as temperature-responsive biomolecular materials across diverse industrial and research fields, and there is a requirement for a straightforward method to mass-produce them. Previously, we demonstrated that phenylalanine-containing ELP analogs, namely, (FPGVG)n , can undergo coacervation with short chains (n = 5). The Fmoc solid-phase peptide synthesis method is one strategy used to synthesize these short ELPs. However, owing to its low reaction efficiency, an efficient method for preparing ELPs is required. In this study, efficient preparation of ELPs was investigated using a liquid-phase synthesis method with a hydrophobic benzyl alcohol support (HBA-tag). Because HBA-tags are highly hydrophobic, they can be easily precipitated by the addition of poor solvents and recovered by filtration. This property allows the method to combine the advantages of the simplicity of solid-phase methods and the high reaction efficiency of liquid-phase methods. By utilizing liquid-phase fragment condensation with HBA-tags, short ELPs were successfully obtained in high yield and purity. Finally, the temperature-dependent response of the ELPs generated through fragment condensation was assessed using turbidity measurements, which revealed a reversible phase transition. Consequently, the ELPs exhibited a reversible phase transition, indicating successful synthesis of ELPs via fragment preparation with tags. These findings provide evidence of the potential for mass production of ELPs using this approach.

Review on Preparation of Polystyrene Microspheres

The traditional preparation methods of polystyrene microspheres are emulsion polymerization and suspension polymerization. The diameter of the microspheres prepared by the former is generally less than 0.5 m, and the diameter of the microspheres prepared by the latter is about several hundred microns and is difficult to control. With the continuous development of science and technology, scientists have found multiple methods to prepare micron-sized monodisperse polymer microspheres in recent years. Such as soap-free or low-soap emulsion method, dispersion polymerization method, liquid-phase synthesis method. The four preparation methods of dispersion polymerization, emulsion polymerization, liquid-phase synthesis, suspension polymerization and their respective advantages and disadvantages are discussed in detail, and the prospect of synthetic application is prospected.

PVDF/PLA electrospun fiber membrane impregnated with metal nanoparticles for emulsion separation, surface antimicrobial, and antifouling activities.

Although many superwetting materials have been designed for the treatment of oil-containing wastewater, separation strategies for oil-in-water systems containing bacteria have rarely been reported. Herein, poly(vinylidene difluoride)- and poly(lactic acid)-blended fibrous membranes loaded with silver and copper oxide nanoparticles were successfully prepared by a two-step method of electrostatic spinning and liquid-phase synthesis. The product membrane showed excellent super-oleophilic properties in air and hydrophobicity under oil. It could separate water-in-oil emulsion systems containing surfactants with an efficiency above 90%. More importantly, the nanoparticle-loaded fibers were characterized by material degradability and slowly released ions. The fibers exhibited excellent antibacterial activities against both gram-positive and -negative bacteria. This work provides a feasible strategy for water-in-oil emulsion separation and bacterial treatment of wastewater.

Obtaining of Metal-Matrix Alloys Based on Ni-Al for ESD Coatings Formation

The experimental results of obtaining complex-alloyed intermetallic alloys by the method of liquid-phase self-propagating high-temperature synthesis (SHS) and their subsequent use for the formation of wear-resistant coatings by the method of electrospark deposition (ESD) are submitted. Metal oxides Cr2O3, NiO, CoO and mineral concentrate containing a larger part of ZrO2 in its composition were used as a melt charge for the SHS experiments. Alloys based on Ni-Al system dopped with Cr, Zr, Co, and C were obtained. It was established that extra addition of C led to the refinement of the alloys microstructure (3-5 times). ESD coatings were formed on steel 45 using the obtained alloys as anode material. The coatings formed by using the alloys doped by Co, Zr, Cr and extra addition of C (0.4 wt%) proved to be maximum wear resistant.

Sodium-potassium co-doped layered manganese dioxide cathode material for high performance aqueous zinc-ion batteries

Manganese dioxide with high operating voltage and satisfactory energy density have been identified as the promising cathode materials for aqueous zinc-ion batteries (AZIBs). However, the structural instability of manganese-based materials during the (dis)charging process limits their further development. Herein, sodium-potassium co-doped layered K0.37Na0.18MnO2·xH2O (KNMOH) are synthesized by a liquid-phase synthesis method at room temperature. The co-doping of Na+ and K+ stabilizes the layered structure, widens the layer spacing and has the effect of electrostatic shielding to facilitate the (de)intercalation of Zn2+. Benefiting from the stable structure and nanoscale size, the flower-like KNMOH cathode maintained a high specific capacity of 239.1 mAh·g−1 after 700 cycles at 500 mA·g−1. Simultaneously, this work firstly reveals that the presence of K8(SO4)(SO3OH)6 suppressed the generation of Zn4SO4(OH)6·0.5H2O, resulting in more free Zn2+ and high reversibility. This co-doped design of bimetallic ions insertion enhances the electrochemical performance and provides a new idea for the improvement of the manganese-based cathode materials for AZIBs.

Simple Synthesis of Monodisperse Ultrasmall Au Icosahedral Nanoparticles

Ultrasmall metal nanoparticles (NPs) with a mean diameter below 2 nm are being intensively studied due to their unique structural and chemical properties. At such small sizes, metal particles can appear as various polyhedra with different atomic structures depending on whether electronic effects, surface energy, or the nucleation mechanism govern their crystallization. Therefore, the synthesis of monodisperse nanoparticles of a very small size and well-defined structure requires a good understanding of the different steps of the crystallization process, which can be achieved by conducting and coupling in situ studies at different length and time scales. In this article, we describe the synthesis of ultrasmall gold NPs by reduction of HAuCl4 in solution of oleylamine (OY) in hexane using trialkylsilanes as reducing agents. Thanks to time-resolved in situ small-angle X-ray scattering and X-ray absorption spectroscopy kinetic studies, a competition between nucleation of Au NPs from a solution containing Au(III) clusters and crystallization of a lamellar phase of composition OY-Au(I)-Cl was revealed. In situ X-ray diffraction and pair distribution function (PDF) analysis showed that the first chemical pathway leads to icosahedral NPs while the reduction of OY-Au(I)-Cl leads to fcc NPs. Increasing the reaction rate, achieved by adjusting the silane concentration, changing the nature of the silane (triethylsilane instead of triisopropylsilane), and/or increasing the temperature of reaction, avoided the formation of the Au(I) lamellar phase as the intermediate, leading to monodisperse Au NPs with an icosahedral structure. This fairly simple liquid-phase synthesis method yields highly concentrated suspensions of icosahedral gold NPs, paving the way for their future use in practical applications such as catalysis.

Synthesis, Composition, Structure, and Electrochemical Behavior of Platinum–Ruthenium Catalysts

The bimetallic PtRu nanoparticles deposited on the carbon support with the metals’ atomic ratio of 1:1 have been obtained by different liquid-phase synthesis methods. The metals’ mass fraction in the obtained PtRu/C catalysts is about 27%. The average size of the bimetallic nanoparticles ranges from 1.9 to 3.9 nm. The activity of the obtained PtRu/C catalysts in the methanol electrooxidation reaction as well as their tolerance to intermediate products of its oxidation have been studied. The sample synthesized by the polyol method has proved to be the most active material. The values of its electrochemical surface area and activity in the methanol electrooxidation reaction are 1.5–1.7 times higher than those of the commercial PtRu/C analogue. Nevertheless, the use of the polyol method leads to losses of the metals during the synthesis. Therefore, this method needs further optimization.

One-step solid-state synthesis of NixPy @C nanocomposites for high-performance hybrid supercapacitor

Transition metal phosphides and their composites are very attractive ascribing to their prominent performance in electrochemical energy storage devices, which are generally prepared by cumbersome and time-consuming liquid-phase synthesis methods. In this work, a convenient and efficient one-step solid-phase synthesis method (SPS) is successfully developed for the preparation of NixPy @C nanocomposites under the ambient atmosphere. By controlling the synthesizing temperature, carbon-coated Ni2P, Ni5P4, and NiP2 nanocomposites can be facilely synthesized. The solid-phase synthesized NixPy @C nanocomposites exhibit high charge storage capability and good cycle stability. A high specific capacity of over 197.2 mAh g−1 (709.9 C g−1) is achieved at a current density of 1 A g−1 for the optimal nanocomposite NiP2 @C, and more than 84.3% of initial specific capacitance is kept after 1000 cycles. The assembled hybrid supercapacitor device based on the nanocomposite NiP2 @C and an interconnected hierarchical porous carbon (NiP2 @C//IHPC) delivers specific energy of up to 50.38 Wh kg−1 at the specific power of 0.89 kW kg−1, which value still reaches 29.1 Wh kg−1 at a high specific power of 9.44 kW kg−1. More than 83.8% of initial specific capacity is retained after 20,000 cycles. Compared with the other nickel-based phosphides and their composites prepared by other methods, the prepared NixPy @C nanocomposites by the developed one-step SPS method demonstrate very competitive performance with the distinguished merits of convenient, efficient, target-oriented, cost-efficiency, and eco-friendly. The successfully developed solid-phase synthesis method is proved to be a reliable strategy for facile preparation of TMPs with high performance.

Solution-Phase Syntheses and Photochemical Properties of Silver Bismuth Sulfide Nanoparticles

Introduction When semiconductor nanoparticles are reduced to a size of several nanometers or less, the physico-chemical properties start to change by the quantum confinement. The energy gap of particles is enlarged and their absorption spectrum is blue-shifted with a decrease in the particle size. These nanoparticles have been intensively investigated for developing efficient light energy conversion systems, such as photocatalysts [1] and photovoltaics [2]. Especially, high-efficiency quantum dot solar cells fabricated with PbS and PbSe nanoparticles, which showed the responsivity in near-IR region, have attracted much attention [3]. However, the contents of highly toxic element, Pb and Se, limit their use in a wide range of applications [4].Recently, a multinary AgBiS2 semiconductor can absorb visible and near-IR lights and seems to be a promising material for efficient light energy conversion [5], but there are few reports to prepare size-quantized nanoparticles and control their particle size. In this study, we report the preparation of AgBiS2 nanoparticles using a liquid-phase chemical synthesis method. Their size was varied depending on the preparation conditions. Furthermore, we investigated their photoelectrochemical properties as functions of particle size and composition. Experimental Precursors of bismuth acetate (Bi(OAc)3), silver acetate (Ag(OAc)), and sulfur powder, were dispersed in a mixture solvent of 1-dodecanethiol (DDT) and oleylamine (OLAm), followed by the heat treatment at 373, 393, 423 or 473 K for 30 min. Thus-obtained AgBiS2 nanoparticles were isolated by the addition of methanol as a non-solvent. Results and Discussion The particle size and composition of AgBiS2 nanoparticles were controlled by changing the heating temperature. With an increase of the heating temperature from 373 K to 473 K, the particle size was enlarged from 3.2 nm to 8.1 nm, accompanied by the increase of the Ag fraction in nanoparticles to the stoichiometric value. The onset wavelength in the absorption spectra of AgBiS2 nanoparticles was shifted from 1000 nm to 1200 nm with an increase in the particle size, resulting in the decrease of bandgap from 1.45 eV to 1.05 eV. Since the estimated bandgap values were larger than that of the bulk AgBiS2 (0.80 eV) [6], it was found that the obtained AgBiS2 nanoparticles showed a quantum size effect. The XRD analysis revealed that the obtained nanoparticles exhibited the cubic AgBiS2 crystal structure, regardless of the reaction temperature.The Ag/Bi ratio in the preparation also changed the particle size of obtained AgBiS2 nanoparticles as well as their chemical composition. By reacting precursors with Ag/(Ag+Bi) = 0.33 at 423 K, almost stoichiometric AgBiS2 nanoparticles were formed, that is, Ag: Bi: S = 1: 1: 2. In contrast, when Ag/(Ag+Bi) ratio in preparation was decreased from 0.5 to 0.25, the Ag fraction in nanoparticles decreased from the stoichiometric value of Ag/Bi=1, that is, non-stoichiometric AgBiS2 nanoparticles were formed. The particle size tended to decrease with a decrease in the Ag/(Ag+Bi) ratio in preparation.We carried out the photoelectrochemical measurement of AgBiS2 nanoparticles immobilized on ITO electrodes. Anodic or cathodic photocurrents were detected, depending on the Ag fraction in nanoparticles. The energy levels of AgBiS2 nanoparticles were determined by measuring the photoelectron yield spectroscopy in air. The onset potentials of photocurrent generation were significantly different from the levels of conduction band minimum or valence band maximum, suggesting that the thus-obtained AgBiS2 nanoparticles contained the large amount of defect sites which acted as a carrier recombination site. Acknowledgments This work is supported by the New Energy and Industrial Technology Development Organization (NEDO). References (1) S. Chen, D. Huang, P. Xu, W. Xue, L. Lei, M. Cheng, R. Wang, X. Liu, and R. Deng., J. Mater. Chem. A, 8, 2286 (2020).(2) G. H. Carey, A. L. Abdelhady, Z. Ning, S. M. Thon, O. M. Bakr, and E. H. Sargent, Chem. Rev., 115, 12732 (2015).(3) H. Lee, H. J. Song, M. Shim, and C. Lee, Energy Environ. Sci., 13, 404 (2020).(4) F. M. Winnik and D. Maysinger, Acc. Chem. Res., 46, 672 (2013).(5) M. Bernechea, N. Miller, G. Xercavins, D. So, A. Stavrinadis, and G. Konstantatos, Nat. Photonics, 10, 521 (2016).(6) S. N. Guin and K. Biswas, Chem. Mater., 25, 3225 (2013).

AuPd nanoparticles functionalized core–shell Co3O4/ZnO@ZnO for ultra-sensitive toluene detection

In this work, core–shell AuPd nanoparticles (NPs) sensitized Co3O4/ZnO@ZnO ellipsoid nanoparticles was successfully synthesized via a simple liquid phase synthesis method. SEM and TEM characterization results showed that the as-prepared samples have core–shell ellipsoid morphology and the size of the nanoparticles were uniform. Systematic gas sensing characterization was carried out to obtain the gas sensing property of AuPd NPs decorated Co3O4/ZnO@ZnO. It was found that the gas sensing property could be significantly enhanced after noble metal decoration with Au, Pd and AuPd NPs, respectively. The optimal gas sensing performance was achieved by AuPd NPs functionalized Co3O4/ZnO@ZnO based gas sensor. The maximum response reached 256–100 ppm toluene at 250 °C, which is 50 °C lower than pure ZnO. The detection limit of AuPd functionalized Co3O4/ZnO@ZnO was as low as 100 ppb. The enhanced sensing mechanism was mainly attributed to the synergistic effect of Au and Pd, which was detailly discussed in gas sensing mechanism part.

Liquid-phase synthesis of Li2S and Li3PS4 with lithium-based organic solutions

Sulfide solid electrolytes are widely regarded as one of the most promising technical routes to realize all-solid-state batteries (ASSBs) due to their high ionic conductivity and favorable deformability. However, the relatively high price of the crucial starting material, Li2S, results in high costs of sulfide solid electrolytes, limiting their practical application in ASSBs. To solve this problem, we develop a new synthesis route of Li2S via liquid-phase synthesis method, employing lithium and biphenyl in 1, 2-dimethoxyethane (DME) ether solvent to form a lithium solution as the lithium precursor. Because of the comparatively strong reducibility of the lithium solution, its reaction with sulfur proceeds effectively even at room temperature. This new synthesis route of Li2S starts with cheap precursors of lithium, sulfur, biphenyl and DME solvent, and the only remaining byproduct (DME solution of biphenyl) after the collection of Li2S product can be recycled and reused. Besides, the reaction can proceed effectively at room temperature with mild condition, reducing energy cost to a great extent. The as-synthesized Li2S owns uniform and extremely small particle size, proved to be feasible in synthesizing sulfide solid electrolytes (such as the solid-state synthesis of Li6PS5Cl). Spontaneously, this lithium solution can be directly employed in the synthesis of Li3PS4 solid electrolytes via liquid-phase synthesis method, in which the centrifugation and heat treatment processes of Li2S are not necessary, providing simplified production process. The as-synthesized Li3PS4 exhibits typical Li+ conductivity of 1.85×10−4 S⋅cm−1 at 30 °C.

Metal-organic framework-derived ZnO decorated with CuO for ultra-high response and selectivity H2S gas sensor

Fast response recovery time and high response value are very necessary indicators for H2S sensors in the past few years. As H2S is a toxic gas that has great threat to human life, research on H2S gas sensors has received widespread attention. In this work, H2S gas sensors with high response value, excellent selectivity and fast response/recovery time were prepared by liquid phase synthesis method. Firstly, ZIF-8 (zeolite imidazolate framework-8) metal-organic framework derived ZnO was synthesized. Then high performance CuO/ZnO sensing materials modified with different amounts of CuO were synthesized using ZnO as the pristine material and CuO as the sensitizing material. Furthermore, the gas sensing test was conducted and the results show that the synthesized CuO/ZnO has significantly enhanced sensing performance to H2S. The highest response to 10 ppm H2S is 941 at a relatively low working temperature of 175 °C, which is 80 times higher than that of ZIF-8 derived ZnO. Moreover, the sensor based on CuO sensitized ZnO also showed excellent selectivity, fast response/recovery property and good moisture resistance. The enhanced gas sensing performance is mainly attributed to the formation of p-n heterojunction and the strong chemical affinity and catalytic performance of CuO for H2S.

Highly Efficient Photocatalytic Degradation of Methyl Orange by SnO2/Carbon/PANI Composite

Polyaniline (PANI) modified carbon-containing SnO2 composites (SnO2/Carbon/PANI) have been successfully synthesized via a simple liquid phase synthesis method. The compositions, structures and properties of as-synthesized samples were characterized by XRD, FT-IR, BET, XPS, SEM and TEM. Meanwhile, the degradation mechanism of the photocatalysts was put forward. The photocatalytic tests showed that the SnO2/Carbon/PANI composites have excellent photocatalytic activity for methyl orange (MO) degradation under visible light irradiation and the MO can be degraded to 98% within 10 min. The photocatalytic activity is still excellent after three cycles and as-synthesized samples have emerged as powerful foundation for further industrial application.