Robustly integrated electrodes constructed by well‐organized building blocks of active materials are appealing in versatile electrochemical systems. Herein, orderly oriented nanowire arrays (NWAs) of ...multiple molybdenum‐based compounds (MoXn, MoXn = MoP, MoS2, Mo2C, MoN, and MoO2) on carbon fiber paper (CFP) are generally fabricated by topotactic transformations from molybdenum‐containing precursor NWAs. Extensive structural characterizations reveal that these MoXn nanowires are composed of either closely interconnected nanoparticles or edge‐rich nanosheets. When being used as self‐supported electrodes, these MoXn NWAs/CFP exhibit excellent catalytic activities and stabilities toward hydrogen evolution reaction (HER) in pH‐universal electrolytes. Especially, the best‐performed MoP NWAs/CFP shows comparable or even superior HER performance over platinum benchmark, which holds great promises in HER‐related energy technologies. This work presents a simple yet effective approach toward general synthesis of self‐supported Mo‐based NWAs on CFP, which also possesses huge application prospects in other fields, such as supercapacitors, batteries, and sensors.
Nanowire arrays (NWAs) of MoP, MoS2, Mo2C, MoN, and MoO2 are generally synthesized through topotactic transformation from molybdenum‐containing precursor NWAs mounted on carbon fiber paper. Benefiting from the structural advantages, these self‐supported molybdenum‐based NWAs electrodes exhibit excellent electrocatalytic performance toward HER in pH‐universal electrolytes.
Catalysts were prepared and utilized in the hydrotreatment of vegetable oil and FAME to produce diesel-like hydrocarbons. Mo2C/AC catalyst displayed the higher catalytic activity with 100.00% ...conversion and 21.01% cracking ratio, compared to MoO/Al2O3 (85.64%, 25.79%), MoS2/Al2O3 (83.46%, 11.88%), Mo/Al2O3 (67.99%, 33.19%), NiP/Al2O3 (48.72%, 3.49%), Ni/Al2O3 (18.12%, 0.00%), and MoO/AC (56.05%, 18.55%). The reaction condition was also optimized, and the bio-diesel achieved 100.00% conversion, 9.67% cracking ratio and 0.73 HDO/DC ratio over Mo2C/AC under the optimal condition. The conversion over Mo2C/AC dropped from 100.00% to 87.08% and 71.06% with cycles. The results of XRD, XPS and N2 adsorption–desorption demonstrated that the coke deposited on the surface of catalyst and the formation of MoO2 and MoO3 led to the deactivation. After regeneration, the catalyst recovered and achieved 99.36% conversion.
Bacterial infections have become a major danger to public health because of the appearance of the antibiotic resistance. The synergistic combination of multiple therapies should be more effective ...compared with the respective one alone, but has been rarely demonstrated in combating bacterial infections till now. Herein, oxygen‐vacancy molybdenum trioxide nanodots (MoO3−x NDs) are proposed as an efficient and safe bacteriostatic. The MoO3−x NDs alone possess triple‐therapy synergistic efficiency based on the single near‐infrared irradiation (808 nm) regulated combination of photodynamic, photothermal, and peroxidase‐like enzymatic activities. Therein, photodynamic and photothermal therapies can be both achieved under the excitation of a single wavelength light source (808 nm). Both the photodynamic and nanozyme activity can result in the generation of reactive oxygen species (ROS) to reach the broad‐spectrum sterilization. Interestingly, the photothermal effect can regulate the MoO3−x NDs to their optimum enzymatic temperature (50 °C) to give sufficient ROS generation in low concentration of H2O2 (100 µm). The MoO3−x NDs show excellent antibacterial efficiency against drug‐resistance extended spectrum β‐lactamases producing Escherichia coli and methicillin‐resistant Staphylococcus aureus (MRSA). Animal experiments further indicate that the MoO3−x NDs can effectively treat wounds infected with MRSA in living systems.
An oxygen‐deficiency molybdenum trioxide nanodots (MoO3−x NDs) are proposed as efficient and safe bacteriostatic for combating multidrug‐resistant bacterial infections. They are single‐component but with triple‐therapy synergistic effects of near‐infrared regulated combination of photodynamic therapy, photothermal therapy, and peroxidase‐like enzymatic activity.
Hollow silica confined defective molybdenum oxide catalysts showed excellent catalytic activity and the desulfurization efficiency reached 100% with H2O2 as an oxidant.
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•Hollow silica ...confined defective molybdenum oxide catalyst was synthesized successfully.•Compared with solid silica supported catalyst, the confined catalyst has better catalytic performance.•Deep desulfurization of DBT and 4-DMDBT can be achieved under mild conditions.•The confined catalyst can be recycled at least for five times.
Hollow nanomaterials are considered to be excellent carriers due to the nanoreactor confinement effect, which can improve the performance of the supported catalysts. In this work, a hollow silica confined defective molybdenum oxide catalyst (MoOx/HS) was obtained by using phosphomolybdic acid grafted polystyrenes as the templates. Compared with solid silica-supported catalyst (MoO3/SS), MoOx/HS could make better use of active components to achieve complete desulfurization. The calculated turnover value (TON) of MoOx/HS was 1.37 mol/mol, which is three times more than that of MoO3/SS. The presence of oxygen defects also facilitated the oxidation reaction. In addition, the catalyst MoOx/HS had good stability and selectivity, and the desulfurization rate of dibenzothiophene (DBT) remained 95.3% after being recycled for 5 times.
The efficient evolution of hydrogen through electrocatalysis is considered a promising approach to the production of clean hydrogen fuel. Platinum (Pt)‐based materials are regarded as the most active ...hydrogen evolution reaction (HER) catalysts. However, the low abundance and high cost of Pt hinders the large‐scale application of these catalysts. Active, inexpensive, and earth‐abundant electrocatalysts to replace Pt‐based materials would be highly beneficial to the production of cost‐effective hydrogen energy. Herein, a novel organoimido‐derivatized heteropolyoxometalate, Mo4‐CNP, is designed as a precursor for electrocatalysts of the HER. It is demonstrated that the carbon, nitrogen, and phosphorus sources derived from the Mo4‐CNP molecules lead to in situ confined carburization, phosphorization, and chemical doping on an atomic scale, thus forming nitrogen‐doped porous molybdenum carbide and phosphide hybrids, which exhibit remarkable electrocatalytic activity for the HER. Such an organically functionalized polyoxometalate‐assisted strategy described here provides a new perspective for the development of highly active non‐noble metal electrocatalysts for hydrogen evolution.
A novel organoimido‐derivatized heteropolyoxometalate, Mo4‐CNP, is designed as a precursor for hydrogen evolution reaction (HER) electrocatalysts. It is demonstrated that the carbon, nitrogen, and phosphorous sources derived from the Mo4‐CNP molecules lead to in situ and confined carburization, phosphorization, and chemical doping on the atomic scale, forming nitrogen‐doped porous molybdenum carbide and phosphide hybrids with remarkable electrocatalytic HER activity.
Molybdenum disulfide (MoS
) nanosheets have been found to exhibit intrinsic peroxidase-like activity that could be applied in colorimetric sensing platforms. However, their poor conductivity and few ...exposed edge sites often lead to poor catalytic activity, impeding the application of MoS
nanosheets in enzyme-like catalysis. Here, a novel strategy was developed to selectively deposit Fe-doped MoS
nanosheets on polypyrrole microtubes to obtain Fe-MoS
@PPy microtubes to address these issues. In the synthesized Fe-MoS
@PPy microtubes, PPy microtubes can not only be used as a conductive support to promote the electron transfer, but also greatly alleviate the aggregations of MoS
nanosheets, and thus improve the enzyme-like activity. Meanwhile, additional active sites, formed by Fe doping, also endow the catalyst with excellent activity in enzyme-like catalysis. Notably, in the process of sulfidation, the dissolution, redistribution and diffusion result in the disappearance of MoO
@FeOOH cores and the formation of Fe doped MoS
nanosheets, which significantly facilitate the deposition of Fe-doped MoS
nanosheets on PPy microtubes. On the basis of the high peroxidase-like catalytic efficiency of the Fe-MoS
@PPy microtubes, a simple and convenient colorimetric strategy for the rapid and sensitive detection of L-cysteine has been developed. This strategy introduces both the PPy layer and Fe doping to increase the conductivity and the density of active sites of MoS
nanosheets, thus enhancing the catalytic activity and stability. More importantly, Fe-MoS
@PPy microtubes could be used as a good support for loading other materials such as Au and Ag nanoparticles (NPs), forming ternary Fe-MoS
/Ag, Au@PPy nanotubes. This work offers an opportunity to develop low-cost and highly active MoS
-based nanocomposites for promising potential applications in electrochemical energy conversion and medical diagnostics.
The Z selectivity of the catalysts seems to be a consequence of the bulky, freely rotating monodentate ligand - in the reaction intermediate that leads to the formation of an alkene product, this ...ligand orients other bulky chemical groups so that they adopt the Z rather than the E arrangement in the product (Fig. 1c). To achieve this, they chose alkene reactants that included chemical groups that would bias the reactivities of the alkylidene intermediates through electronic and steric effects (repulsion that occurs when bulky groups are brought too closely together).
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We fabricated large-area atomically thin MoS2 layers through the direct transformation of crystalline molybdenum trioxide (MoO3) by sulfurization at relatively low temperatures. The obtained MoS2 ...sheets are polycrystalline (~10–20 nm single-crystal domain size) with areas of up to 300 × 300 µm2, 2–4 layers in thickness and show a marked p-type behavior. The synthesized films are characterized by a combination of complementary techniques: Raman spectroscopy, X-ray diffraction, transmission electron microscopy and electronic transport measurements.
As a remarkable class of plasmonic materials, two dimensional (2D) semiconductor compounds have attracted attention owing to their controlled manipulation of plasmon resonances in the visible light ...spectrum, which outperforms conventional noble metals. However, tuning of plasmonic resonances for 2D semiconductors remains challenging. Herein, we design a novel method to obtain amorphous molybdenum oxide (MoO3) nanosheets, in which it combines the oxidation of MoS2 and subsequent supercritical CO2‐treatment, which is a crucial step for the achievement of amorphous structure of MoO3. Upon illumination, hydrogen‐doped MoO3 exhibits tuned surface plasmon resonances in the visible and near‐IR regions. Moreover, a unique behavior of the amorphous MoO3 nanosheets has been found in an optical biosensing system; there is an optimum plasmon resonance after incubation with different BSA concentrations, suggesting a tunable plasmonic device in the near future.
Better off amorphous: Amorphous MoO3 nanosheets were fabricated through the oxidation of MoS2 and subsequent treatment with supercritical CO2. Hydrogen‐doped MoO3 formed via a facile solar‐light‐driven process exhibits surface plasmon resonances (SPR) in the visible and NIR regions. In an optical biosensing system the SPR correlates with bovine serum albumin concentrations.
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