Tunable plasmon resonances in suspended 2D molybdenum oxide flakes are demonstrated. The 2D configuration generates a large depolarization factor and the presence of ultra-doping produces ...visible-light plasmon resonances. The ultra-doping process is conducted by reducing the semiconducting 2D MoO sub(3) flakes using simulated solar irradiation. The generated plasmon resonances can be controlled by the doping levels and the flakes' lateral dimensions, as well as by exposure to a model protein.
Hydrogen (H
) represents a promising avenue for reducing carbon emissions in energy systems. However, achieving its widespread adoption requires more effective and scalable synthesis methods. Herein, ...we investigated the isothermal carburization process of the MoO
catalyst. This reaction was carried out at a constant temperature of 700 °C in a 60% CO/He stream, with hold reaction times varying (60-min, 90-min, and 120-min). This investigation was conducted using a micro-reactor Autochem with the aim of enhancing the yield of H
. The study focused on evaluating the chemical reduction and carburization behavior of the MoO
catalyst through X-ray diffraction (XRD), transmission electron microscopy (TEM), and CHNS elemental analysis. The XRD analysis revealed the formation of carbides, Mo
C, and MoO
, serving as active sites for subsequent H
production in the thermochemical water splitting (TWS) process. The carburization at a 60-min hold time exhibited enhanced H
production, generating approximately ~ 6.60 µmol of H
with a yield of up to ~ 32.90% and a conversion rate of ~ 54.83%. This finding emphasizes the essential role played by the formation of carbides, particularly Mo
C, in the carburization process, contributing significantly to the facilitation of H
production. These carbides serve as exceptionally active catalytic sites that actively promote the generation of hydrogen. This study underscores that the optimized duration of catalyst exposure is a key factor influencing the successful carburization of MoO
catalysts. This emphasizes how important carbide species are to increasing H
efficiency. Additionally, it is noted that carbon formation on the MoO
active sites can act as a potential poison to the catalysts, leading to rapid deactivation after prolonged exposure to the CO precursor.
Electronic synaptic devices are important building blocks for neuromorphic computational systems that can go beyond the constraints of von Neumann architecture. Although two‐terminal memristive ...devices are demonstrated to be possible candidates, they suffer from several shortcomings related to the filament formation mechanism including nonlinear switching, write noise, and high device conductance, all of which limit the accuracy and energy efficiency. Electrochemical three‐terminal transistors, in which the channel conductance can be tuned without filament formation provide an alternative platform for synaptic electronics. Here, an all‐solid‐state electrochemical transistor made with Li ion–based solid dielectric and 2D α‐phase molybdenum oxide (α‐MoO3) nanosheets as the channel is demonstrated. These devices achieve nonvolatile conductance modulation in an ultralow conductance regime (<75 nS) by reversible intercalation of Li ions into the α‐MoO3 lattice. Based on this operating mechanism, the essential functionalities of synapses, such as short‐ and long‐term synaptic plasticity and bidirectional near‐linear analog weight update are demonstrated. Simulations using the handwritten digit data sets demonstrate high recognition accuracy (94.1%) of the synaptic transistor arrays. These results provide an insight into the application of 2D oxides for large‐scale, energy‐efficient neuromorphic computing networks.
All‐solid‐state synaptic transistors based on 2D α‐MoO3 nanosheets are fabricated. The operation mechanism is based on the gate voltage–induced reversible intercalation of Li‐ion dopants into α‐MoO3 channel lattice, which engenders bidirectional, near‐linear analog modulation of channel conductance in an ultralow conductance regime (<75 nS). The essential functionalities of synapses and neuromorphic computing for image recognition are demonstrated.
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.
•We analyzed and modeled spectral envelopes of complex molybdenum oxides.•Molybdenum oxide films of varying valence and crystallinity were synthesized.•MoO3 and MoO2 line shapes from experimental ...data were created.•Informed amorphous sample model (IASM) developed.•Amorphous molybdenum oxide XPS envelopes were interpreted.
Accurate elemental oxidation state determination for the outer surface of a complex material is of crucial importance in many science and engineering disciplines, including chemistry, fundamental and applied surface science, catalysis, semiconductors and many others. X-ray photoelectron spectroscopy (XPS) is the primary tool used for this purpose. The spectral data obtained, however, is often very complex and can be subject to incorrect interpretation. Unlike traditional XPS spectra fitting procedures using purely synthetic spectral components, here we develop and present an XPS data processing method based on vector analysis that allows creating XPS spectral components by incorporating key information, obtained experimentally. XPS spectral data, obtained from series of molybdenum oxide samples with varying oxidation states and degree of crystallinity, were processed using this method and the corresponding oxidation states present, as well as their relative distribution was elucidated. It was shown that monitoring the evolution of the chemistry and crystal structure of a molybdenum oxide sample due to an invasive X-ray probe could be used to infer solutions to complex spectral envelopes.
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.
Plasmonic materials have drawn emerging interest, especially in nontraditional semiconductor nanostructures with earth‐abundant elements and low resistive loss. However, the actualization of highly ...efficient catalysis in plasmonic semiconductor nanostructures is still a challenge, owing to the presence of surface‐capping agents in their synthetic procedures. To fulfill this, a facile non‐aqueous procedure was employed to prepare well‐defined molybdenum oxide nanosheets in the absence of surfactants. The obtained MoO3‐x nanosheets display intense absorption in a wide range attributed to the localized surface plasmon resonances, which can be tuned from the visible to the near‐infrared region. Herein, we demonstrate that such plasmonic semiconductor nanostructures could be used as highly efficient catalysts that dramatically enhance the hydrogen‐generation activity of ammonia borane under visible light irradiation.
Making MoO3‐x, and hydrogen too: Well‐defined molybdenum oxide nanosheets (MoO3‐x) were prepared by a facile surfactant‐free nonaqueous process. With strong localized surface plasmon resonances, these MoO3‐x nanostructures could be used as highly efficient catalysts, and showed dramatically enhanced activity for hydrogen evolution from ammonia borane under visible‐light irradiation.
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•MoO3 nanoshapes.•Electrochemical energy.•Electrocatalysis.•Device operation.
We introduce a simple room-temperature (25–27 °C) solution process-inspired approach for obtaining ...sharp-edged nanoshapes like nanocubes, nanorods and nanoparticles of molybdenum oxide (MoO3) on a stainless-steel conducting substrate for supercapacitor and electrocatalysis applications. The nanoshape of MoO3 has strikingly been changed from nanocubes to nanopaticles dependig on HCl concentration. The MoO3 electrodes of different morphologies are systematically characterized by various characterization techniques for confirming phase, structure, and surface elementals. The electrochemical studies exhibit significant enhancement in specific capacitance and oxygen evolution reaction (OER) activity for MoO3 nanorod-based electrode. The specific capacitance of 2561.53 F g−1 for MoO3 nanorods is much higher than 608.20 F g−1 and 400.28 F g−1 for nanocubes and nanoparticles, respectively. Besides, with the 98.59% capacitance retention up to 2000 cycles, the electrode consisting nanorods is found to be highly stable. In the commercial point of view, the as-fabricated MoO3//MoO3 symmetric device adduces excellent energy/power density (69.06 Wh kg−1/1336.63 W Kg−1) at current density of 1 A g−1. The laboratory panel, Center for Nanomaterials & Energy Devices, containing nearly 42 LEDs has been ignited with full intensity using MoO3//MoO3 symmetric device as the practical demonstration of electrode material. From supercapacitor study, the MoO3 nanorod-based electrode endows excellent OER activity (overpotential of 246 mV; Tafel slope of 36 mV dec-1). In both cases, the MoO3 nanorod-based electrode produces excellent chemical and cyclic stability. Overall electrochemical results demonstrate that the MoO3 nanorod-based electrode would be excellent electrode material for supercapacitor as well as OER applications. The proposed room-temperature solution synthesis process is valuable and well effective in view of trouble-free, cost-effective, and scalability for commercial benefits.
Planar 2D materials are possibly the ideal channel candidates for future field effect transistors (FETs), due to their unique electronic properties. However, the performance of FETs based on 2D ...materials is yet to exceed those of conventional silicon based devices. Here, a 2D channel thin film made from liquid phase exfoliated molybdenum oxide nanoflake inks with highly controllable substoichiometric levels is presented. The ability to induce oxygen vacancies by solar light irradiation in an aqueous environment allows the tuning of electronic properties in 2D substoichiometric molybdenum oxides (MoO3−x). The highest mobility is found to be ≈600 cm2 V−1 s−1 with an estimated free electron concentration of ≈1.6 × 1021 cm−3 and an optimal IOn/IOff ratio of >105 for the FETs made of 2D flakes irradiated for 30 min (x = 0.042). These values are significant and represent a real opportunity to realize the next generation of tunable electronic devices using electronic inks.
Electronic inks of 2D MoO3−x flakes based on a solar light irradiation in liquid‐phase exfoliated method are used for developing channels FETs for future high‐performance printed nanoelectronic devices. It is shown that the carrier concentration, energy band, and carrier charge mobility in 2D MoO3−x‐based FETs can be tuned and the optimal substoichiometric value with the maximum transconductance is obtained.
MoS2 has emerged as a promising alternative electrocatalyst for the hydrogen evolution reaction (HER) due to high intrinsic per‐site activity on its edge sites and S‐vacancies. However, a significant ...challenge is the limited density of such sites. Reducing the size and layer number of MoS2 and vertically aligning them would be an effective way to enrich and expose such sites for HER. Herein, a facile self‐limited on‐site conversion strategy for synthesizing monolayer MoS2 in a couple of nanometers which are highly dispersed and vertically aligned on 3D porous carbon sheets is reported. It is discovered that the preformation of well‐dispersed MoO3 nanodots in 1–2 nm as limited source is the key for the fabrication of such an ultrasmall MoS2 monolayer. As indicated by X‐ray photoelectron spectroscopy and electron spin resonance data, these ultrasmall MoS2 monolayers are rich in accessible S‐edge sites and vacancies and the smaller MoS2 monolayers the more such sites they have, leading to enhanced electrocatalytic activity with a low overpotential of 126 mV at 10 mA cm−2 and 140 mV at 100 mA mg−1 for HER. This state‐of‐the‐art performance for MoS2 electrocatalysts enables the present strategy as a new avenue for exploring well‐dispersed ultrasmall nanomaterials as efficient catalysts.
An ultrasmall MoS2 monolayer well‐dispersed and vertically aligned on porous carbon is developed via a self‐limited on‐site fabrication strategy. It exhibits excellent and size‐dependent electrocatalytic performance for hydrogen evolution with an ultralow overpotential of 126 and 140 mV at 10 mV cm−2 and 100 mA mg−1, respectively.
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