In industrial applications, the amination of long-chain fatty alcohols to synthesize fatty amines still faces challenges such as unstable reaction rates and low product yields. Therefore, developing a catalyst for the amination of long-chain fatty alcohols that achieves high yields remains a significant challenge. Herein, we report that a series of Ni-Re/Al2O3 catalysts were synthesized and characterized for the continuous gas-phase reductive amination of 1-octanol with ammonia under atmospheric pressure. The results indicate that the presence of Re not only promotes hydrogen spillover and accelerates the reduction of Ni species but also weakens Ni-O-Al interactions and reconstructs the surface acid-base properties. The resulting balanced distribution of weakly basic, moderately basic, and strongly basic sites regulates primary amine selectivity, with yield exhibiting a volcano-shaped relationship with Re content. Under the optimal conditions, the Ni-2Re/Al2O3 catalyst achieves 99.5% conversion and 64% monoamine selectivity. This study reveals the synergistic effect of Re in regulating metal-support interactions and acid-base sites, which provides a rational design strategy for non-noble catalysts in the reductive amination of long-chain alcohols.

MXenes, as new two-dimensional transition metal compounds, has become promising sensing materials due to the excellent metal conductivity, abundant adsorption sites and the terminal groups of -O, -OH and -F. In this study, we report the well-etched accordion-like Ti3C2Tx by removing Al layer in Ti3AlC2, where T-x represents a wealth of terminal functional groups (-OH, -F, -O, etc.). In addition, unique hierarchical self-assembly ZnO/Ti3C2Tx nanocomposites are synthesized by hydrothermal method. The Brunauer-Emmett-Teller Method investigation also shows that the ZnO/Ti3C2Tx nanocomposites has a specific surface area of about 22.08 m(2)/g, and the pore size is mainly located at 11.1 nm. The innovative nanostructure is conducive to the adsorption and response of gas molecules. By investigating the gas sensitive properties of the sensors, it is found that the response of the ZnO/Ti3C2Tx sensor to triethylamine (TEA) is improved by 66 times and 1.58 times over that of pure Ti3C2Tx and ZnO, and the optimal operating temperature is 60degree celsius lower than that of pure ZnO. In addition, the LOD (Low Of Detection) of about 32.7 ppb indicates that the ZnO/Ti3C2Tx sensor is suitable for the detection of low concentrations TEA. The sensing performances of the ZnO/Ti3C2Tx sensor at a high humidity of 75 % RH verifies the strong sensing performance in high humidity environment. Furthermore, the composite sensor stabilize in 6 repetitive tests and present slight decrease in response value over 30 days. The excellent TEA sensitive properties indicate that the ZnO/Ti3C2Tx nanocomposite sensor may have promising applications in the gas sensitive field.

Both the 3-fluorooxindole and germinal bisphosphonate structural motifs are prevalent in bioactive molecules because of their associated biological activities. We describe an approach to accessing 3,3-disubstituted 3-fluorooxindoles bearing a geminal bisphosphate fragment through a highly enantioselective Michael addition reaction between 3-fluorooxindoles and vinylidene bisphosphonates. These reactions are catalyzed by a commercially available cinchona alkaloid catalyst, have a broad substrate scope concerning 3-fluorooxindoles, and provide the corresponding addition products in a yield of up to 95% with an enantiomeric excess of up to 95%. A reasonable reaction pathway to explain the observed stereochemistry is also proposed.

Excessive emission of volatile organic compounds (VOCs) has caused serious harm to the ecological environment and human survival. It is necessary to develop gas sensors with high response, outstanding selectivity, and low power consumption to provide basic protection for human health environment. In this work, BaTiO3 nanospheres are prepared by solution method, and BaTiO3/ZnO composites are further synthesized based on facile hydrothermal technique. The gas sensitive investigations show that the response of BaTiO3/ZnO composite sensor to 100 ppm ethanol is reach up to 94, and the optimal operating temperature is significantly reduced. The response time of BaTiO3/ZnO is reduced to 66s, and full recovery can be achieved within 162s. In general, the performance of BaTiO3/ZnO nanocomposite sensors is better than that of pure BaTiO3 nanospheres and ZnO nanosheets, which may be related to the unique morphology, improved surface properties of BaTiO3/ZnO composites and the n-n heterojunction effect. Finally, the gas-sensing mechanism of the as-prepared BaTiO3/ZnO semiconductor in air and ethanol is discussed in detail.

Two-dimensional transition metal carbides/nitrides (MXenes) show great potential in volatile organic compound (VOC) sensors owing to their exceptional electrical properties, numerous active sites, and abundant terminal functional groups. However, pure MXene Ti3C2Tx is prone to oxidative degradation under ambient environment, and the insufficient response and poor stability are still grand challenges. Hereby, by deliberately introducing metal oxide semiconductor in multilayer Ti3C2Tx, a promising Ti3C2Tx/SnO2 sensor with excellent long-term stability and outstanding selectivity is developed for VOC monitoring. The research shows that the Ti3C2Tx/SnO2 hybrid sensor implements efficient detection of hydrogen-bonded gases and is especially highly efficient with ethanolamine (EA). The sensitivity of the hybrid sensor to EA is improved by over 10-fold in comparison with pristine Ti3C2Tx, besides the good selectivity to over 12 different VOCs. The synergistic effects of n-n nanoheterojunctions, the large specific surface area of 45.186 m2/g and mesoporous-rich hierarchical structure, and the functional terminal groups together facilitate the EA-sensitive properties. In addition, the innovative preparation of the Ti3C2Tx/SnO2 sensor, which takes advantage of terpinol, contributes to the close contact of Ti3C2Tx/SnO2 on the ceramic tubes, thus improving the sensor sensitivity. The scientific findings of this work may provide valuable ideas for the exploration of innovatively composite gas sensors.

It is a novel-effective process for realizing high-efficiency sensing and continuous gas monitoring by introducing precious metals into metal–oxide–semiconductors (MOSs). In this study, Ag is exploited to prepare surface functionalized SnO2 nanoparticles (NPs) and innovative xAg@SnO2/CsPbBr3, activating and catalyzing the gas sensing reactions on semiconductors. The results show that the precious metal Ag NPs promote the directional transport of carriers, thus improving the gas sensing performances. In addition, innovative xAg@SnO2/CsPbBr3 composites originated from Ag@SnO2 NPs and 3-mercaptopropionic acid treated all-inorganic perovskite CsPbBr3 are constructed to further accelerate electron transfer on heterointerfaces, enabling continuous and efficient monitoring of ethanolamine (EA) at room temperature. The sensing properties of Ag@SnO2/CsPbBr3 on various volatile organic compounds are investigated. Compared with pure CsPbBr3, the EA response of as-prepared 2Ag@SnO2/CsPbBr3 is obviously improved by about sevenfold. The response/recovery time is greatly shortened, besides the good stability. Another interesting result for xAg@SnO2/CsPbBr3 is the lower limit of detection of 44.43 ppb. The work demonstrates that Ag modification facilitates the adsorption/desorption rate and the response. Furthermore, the catalytic activation of noble metal Ag NPs and the synergistic interaction of SnO2/CsPbBr3 nano-heterojunctions promote EA sensing performances at room temperature.

In this work, two ZSM-12 zeolites with stellar morphology and dendritic morphology were synthesized from the synthesis system containing nanorod-aggregated hexagonal prism seed and microrod seed, respectively, in the presence of CTAB. The stellar ZSM-12 zeolite was composed of core and branches, while the dendritic ZSM-12 zeolite consisted of stem and branches. For the two zeolites, the branches grew on {310} planes of seed and were in twin relation with the seed. The c-axes of branch and seed were parallel to each other, while the b-axes of them exhibited the angular relation of 65°. The crystallization process of the two zeolites were investigated by using XRD, SEM, and TEM characterizations. It was demonstrated that the branched growth on seeds was controlled by two factors: diffusion of reactive species and adsorption of CTAB. The Mullins-Sekerka instability occurred under the diffusion-limited condition, resulting in the formation of branches on seed. The adsorption of CTAB on side facets of branches inhibited the occurrence of secondary branching.

High-surface-area α-Al2O3 with abundant hydroxyls is synthesized by a ball-milling method. It demonstrates high catalytic activity and excellent stability for the CO oxidative coupling to dimethyl oxalate reaction.

In this work, ZnO nanocrystals (NCs) are innovatively decorated on the hierarchically porous microflowers (MFs) of BiOBr. The preparation is accompanied by the construction of n-n nano-heterojunctions. The crystallographic information, microstructure, oxygen vacancy, and gas sensing performances of BiOBr/ZnO composites are investigated. The BiOBr/ZnO sensor presents excellent response characteristics to triethylamine (TEA). Compared with BiOBr MFs and pure ZnO NCs, the BiOBr/ZnO composite sensor exhibits a higher response (Ra/Rg) of about 20.57 to 100 ppm TEA at 200 degrees C. The sensor also shows good selectivity and durable long-term stability, besides the low detection limit of 112 ppb. Even more appealingly, the response time is only 4 s. The improved TEA sensing performance of BiOBr MFs modified with ZnO NCs can be mainly attributed to the unique hierarchical heterogeneous microstructure. Furthermore, the construction of n-n BiOBr/ZnO heterostructures leads to a large specific surface area and effective electron transport, which facilitate the surface reaction and diffusion of TEA molecules. The BiOBr/ZnO composite sensor based on n-n nano-heterojunctions may provide a valuable strategy for the detection of volatile organic compounds.

3,3-Disubstituted oxindoles bearing a stereogenic 3-fluorinated carbon center are privileged structural motifs present in many bioactive molecules. The straightforward functionalization of 3-fluorooxindoles constitutes a powerful method for the synthesis of 3-fully substituted 3-fluorooxindoles, taking advantage of the ease of preparation of 3-fluorooxindoles with different substitution patterns and the atom efficiency of chemical reactions. In the past decade, many papers have appeared on the synthesis of 3-fully substituted 3-fluorooxindoles from 3-fluorooxindoles. Importantly, many asymmetric catalytic methods have been developed for the enantioselective synthesis of these valuable compounds. This review summarizes the achievements in this area, and overviews synthetic opportunities that still exist.

A highly selective TMG-catalyzed beta-addition of (arylsulfonyl)fluoromethane derivatives to allenoates has been developed. Cyano, nitro, and ester-functionalized (arylsulfonyl)fluoromethanes are all suitable substrates, giving a series of structurally diverse beta-addition products bearing a stereogenic fluorinated carbon center. A possible reaction pathway is also presented.

Considering the different electron structure-related physical properties and their own sensing advantages of MoS2 and SnO2, we report a novel n-n heterogeneous MoS2/SnO2 nanotubes and the excellent triethylamine (TEA) sensing performances. MoS2/SnO2 hollow nanotubes were prepared using electrospinning combined with hydrothermal treatment. The crystal structure, morphology features and microstructure were characterized by XRD, SEM and TEM, etc. Gas sensing investigations show that MoS2/SnO2 sensor exerts preeminent selectivity and high response to TEA at 200 degrees C. The heterogeneous composite sensor could effectively detect TEA concentration as low as 1 ppm. The response and recovery time to 100 ppm TEA are about 62 s and 153 s, respectively. The sensing mechanism caused by the synergistic effect of n-n type heterojunctions and unique tubular nanostructure are discussed.

2D transition-metal dichalcogenides (TMDs) have attracted much attention for promising application in gas sensors. Edges of the layered nanostructures are well known as highly reactive sites, besides the low working temperature. However, TMD sensors still suffer from the bottlenecks of low response and slow reaction kinetics. We propose an innovative use of porous carbon nanostructures originated from zeolitic imidazolate frameworks. In this work, multi-layered MoS2 nanoplates are confined in nanoscale porous carbon nanocages (PCNCs) by a facile hydrothermal technique. The carefully designed MoS2/PCNC sensor exhibits good triethylamine (TEA) sensing performances. Compared with pure MoS2, the response (Ra/Rg) of the MoS2/PCNC composite sensor to 100 ppm TEA is as high as 53. The theoretical TEA detection limit is estimated to be as low as 12 ppb. In addition, the investigation proves good stability and reproducibility. The possible sensing mechanism for the improved performances is discussed too. The innovative strategy for the controlled design of MoS2/PCNC nanostructures may provide valuable application in designing high-performance TEA sensors.

All-inorganic halide perovskites, as a dominant member of the perovskite family, have been proven to be excellent semiconductors due to the great successes for solar cells, light-emitting diodes, photodetectors, and nanocrystal photocatalysts. Despite the remarkable advances in those fields, there are few research studies focusing on gas and humidity-sensing performances, especially for pure CsPbBr3 and heterogeneous CsPbBr3@MoS2 composites. Here, we first report a valuable CsPbBr3 sensor prepared by electrospinning, and the excellent gas sensing performances are investigated. The CsPbBr3 sensor can quickly and effectively detect ethanolamine at room temperature. The response time is only 16 s, and the response to 100 ppm ethanolamine is as high as 29.87, besides the excellent repeatability and good stability. The theoretical detection limit is estimated to be 21 ppb. Furthermore, considering the irreplaceable role of heterostructures in regulating the electronic structure and supporting rich reaction boundaries, we also actively explored the EA sensitivity of inorganic CsPbBr3-based heterogeneous composites CsPbBr3@MoS2. At the same time, the roles of the critical capping agents OA and OAm are systematically investigated. This work demonstrates the great potential of all-inorganic halide perovskites in promising volatile organic compound detection.

Continuous monitoring of volatile organic compounds (VOCs) is an important challenge for human beings. All-inorganic halide perovskites (AIHPs) have attracted extensive attention because of their excellent semiconductor properties. Perovskite interfacial modulation engineering is considered as a key factor in the preparation of stable and high-performance AIHP devices. In this work, organic hydrophilic ligand 3-mercaptopropionic acid (MPA) is creatively introduced to regulate the nanostructure of CsPbBr3 and construct the ambient stable binary heterojunction of CsPbBr3 nanoparticles (NPs)/ZnO NPs. The microscopic morphology design shows that CsPbBr3 NPs with the optimal nano size have abundant sensitive gas adsorption sites and large specific surface area, which can effectively improve the sensitivity of the CsPbBr3-based sensor to ethanolamine (EA). Moreover, hydrophilic groups in MPA are good for the formation of hydrogen bonds and MPA network structures, which effectively improve the binding affinity of metal oxides on MPA surfaces, enhancing the stable anchoring of ZnO to halide perovskite CsPbBr3 and the heterojunction construction of CsPbBr3/ZnO. The CsPbBr3-2MPA/ZnO sensor displays the advantages of the lowest theoretical detection limit (DL, 31 ppb), excellent selectivity, a much shorter response time (50 s) than CsPbBr3, and significantly enhanced EA response (13.25, 100 ppm) at room temperature, besides the stable repeatability in more than 1 month. In addition, we propose a feasible sensing mechanism. The gas sensor based on CsPbBr3/ZnO nano-heterojunctions with efficient hydrophilic MPA modulation may provide constructive idea for the detection of VOCs.

In this work, the sodium halide, e.g., NaBr, NaCl, or NaF, was added into the synthesis system of ZSM-12 zeolite. The addition of sodium halide accelerated the crystallization of ZSM-12 zeolite, and the acceleration effect of different sodium halide increased in the order of NaBr < NaCl < NaF. To understand the acceleration mechanism of sodium halide, the crystallization process of ZSM-12 zeolite synthesized with and without sodium halide was studied comparatively by using XRD, SEM, TEM, TG and FTIR characterizations. Experimental results revealed that the accelerated crystallization of ZSM-12 zeolite arose from the combined effects of sodium cation and halide anion. The sodium cation induced the coagulation of colloidal particles of initial sol and avoided the formation of gel, resulting in the improved mass transfer. The halide anion promoted the combination of tetraethylammonium cation (as structure-directing agent) with the solid phase. A ZSM-12 zeolite with abundant mesopores was finally obtained from the synthesis system containing sodium halide. The Pt/ZSM-12 catalyst using the mesoporous zeolite as the support exhibited excellent activity and isomerization selectivity in the hydroisomerization of n-dodecane.

A highly selective phosphine-catalyzed β-addition of α-fluoro β-dicarbonyl compounds to allenoates has been developed. Both α-fluoro β-diketones and α-fluoro β-keto esters prove to be competent fluorocarbon nucleophiles, giving a series of the β-addition products bearing a fluorinated quaternary carbon center in good to excellent yields and with excellent regioselectivities. A plausible reaction pathway is presented.

Pr-doped SnO2 hollow beaded tubular nanostructure was synthesized by electrospinning technique, accompanied by using carbon spheres as sacrificial templates. The crystalline phase, morphology, microstructure, and element composition of the samples were explored and analyzed. The gas sensitivity test results show that Pr-doped SnO2 sensor exhibits high response value, excellent selectivity and rapid response-recovery ability to ethanol at 200 degrees C. The sensor can effectively detect ethanol vapor as low as 2 ppm. Response/recovery time to 100 ppm ethanol are about 12 s/8 s, respectively. The possible enhancement mechanism caused by the synergistic effect of the unique nanostructure, the carbon templates, and Pr dopant are discussed. The research may provide a better design of ethanol sensors.