The properties and applications of molybdenum oxides are reviewed in depth. Molybdenum is found in various oxide stoichiometries, which have been employed for different high‐value research and ...commercial applications. The great chemical and physical characteristics of molybdenum oxides make them versatile and highly tunable for incorporation in optical, electronic, catalytic, bio, and energy systems. Variations in the oxidation states allow manipulation of the crystal structure, morphology, oxygen vacancies, and dopants, to control and engineer electronic states. Despite this overwhelming functionality and potential, a definitive resource on molybdenum oxide is still unavailable. The aim here is to provide such a resource, while presenting an insightful outlook into future prospective applications for molybdenum oxides.
Molybdenum is found in various oxide stoichiometries, which have been employed for different high‐value research and commercial applications. The variations in oxidation states allow the manipulation of crystal structure, morphology, oxygen vacancies, and dopants, to control and engineer the electronic states, which makes them versatile and highly tunable for incorporation in optical, electronic, catalytic, bio, and energy systems.
Layered transition metal dichalcogenides (TMDs) are important members in the family of two-dimensional (2D) materials. The large surface-to-volume ratio, combined with the fascinating tunable ...electronic and optical properties, low toxicity, unique van der Waals layered structure, and engineerable surface structure, renders 2D TMDs highly valuable for next-generation biosensing applications. Herein, the recent progress in the development of 2D TMDs-based biosensors is comprehensively reviewed, with special focus on the implementation of the structural, electronic and optical properties of 2D TMDs in the realization of high-performance biosensors with different configurations for a wide spectrum of bioanalytes and bio-species. In addition, the comparison on biosensing performances with graphene as the currently most studied 2D candidate is critically discussed. Finally, future perspectives are provided along the development progress of 2D TMDs-based biosensors which are currently undergoing an intense study. This work will lead researchers to explore more novel sensing candidates within the category of TMDs with exotic chemical composition, structure, morphologies, dimensionalities, and properties.
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•Structure-property relationship in transition metal dichalcogenides (TMDs).•The merits and demerits of two-dimensional TMDs when compared with graphene.•Solid-, liquid-, and vapor-phase-based synthesis of TMDs.•Fabrication of optical and electrical sensing platform based on TMDs.•Future perspectives and challenges of TMDs-based biosensors.
Components with self-propelling abilities are important building blocks of small autonomous systems and the characteristics of liquid metals are capable of fulfilling self-propulsion criteria. To ...date, there has been no exploration regarding the effect of electrolyte ionic content surrounding a liquid metal for symmetry breaking that generates motion. Here we show the controlled actuation of liquid metal droplets using only the ionic properties of the aqueous electrolyte. We demonstrate that pH or ionic concentration gradients across a liquid metal droplet induce both deformation and surface Marangoni flow. We show that the Lippmann dominated deformation results in maximum velocity for the self-propulsion of liquid metal droplets and illustrate several key applications, which take advantage of such electrolyte-induced motion. With this finding, it is possible to conceive the propulsion of small entities that are constructed and controlled entirely with fluids, progressing towards more advanced soft systems.
The intriguing properties of two‐dimensional transition metal dichalcogenides (2D TMDCs) have led to a significant body of fundamental research and rapid uptake of these materials in many ...applications. Specifically, 2D TMDCs have shown great potential in biological systems due to their tunable electronic characteristics, unique optical properties, stability in aqueous environments, large surface area that can be manipulated and functionalized as well as an intercalatable layered structure, and low levels of toxicity. Here, the characteristics and use of 2D TMDCs for biological applications are reviewed and future possibilities for these materials in biological systems are outlined.
Two‐dimensional transition metal dichalcogenides demonstrate a plethora of unique properties, including tunable electronic and optical characteristics, stability in aqueous environments, large surface areas that can be manipulated and functionalized, and intercalatable layered structures. Relatively low levels of toxicity and facile synthesis routes make these materials suitable for future biological systems.
Two-dimensional (2D) transition metal oxide and chalcogenide (TMO&C)-based photocatalysts have recently attracted significant attention for addressing the current worldwide challenges of energy ...shortage and environmental pollution. The ultrahigh surface area and unconventional physiochemical, electronic and optical properties of 2D TMO&Cs have been demonstrated to facilitate photocatalytic applications. This review provides a concise overview of properties, synthesis methods and applications of 2D TMO&C-based photocatalysts. Particular attention is paid on the emerging strategies to improve the abilities of light harvesting and photoinduced charge separation for enhancing photocatalytic performances, which include elemental doping, surface functionalization as well as heterojunctions with semiconducting and conductive materials. The future opportunities regarding the research pathways of 2D TMO&C-based photocatalysts are also presented.
Nanoporous Nb2O5 hydrogen gas sensor Rani, Rozina Abdul; Zoolfakar, Ahmad Sabirin; Ou, Jian Zhen ...
Sensors and actuators. B, Chemical,
January 2013, 2013, 2013-01-00, 20130101, Letnik:
176
Journal Article
Recenzirano
Odprti dostop
This work presents the development of gas sensors based on nanoporous niobium oxide (Nb2O5) films for hydrogen gas sensing. Nanoporous Nb2O5 films were successfully synthesized by the anodization of ...niobium foil in fluoride-organic solvent containing a small percentage of water at 50°C. These conditions helped to obtain nanovein-like networks with pore diameters of 30–50nm. After annealing at 440°C an orthorhombic phase of Nb2O5 was obtained. Contacts of the sensors were then established using platinum (Pt) that also acted as catalytic layers. The gas sensing properties of these nanoporous contacts were investigated for hydrogen gas sensing at different film thicknesses and temperatures.
Metal oxides are the key ingredients for the development of many advanced functional materials and smart devices. Nanostructuring has emerged as one of the best tools to unlock their full potential. ...Tungsten oxides (WOx) are unique materials that have been rigorously studied for their chromism, photocatalysis, and sensing capabilities. However, they exhibit further important properties and functionalities that have received relatively little attention in the past. This Feature Article presents a general review of nanostructured WOx, their properties, methods of synthesis, and a description of how they can be used in unique ways for different applications.
Tungsten oxides (WOx) are unique functional materials that can be obtained in a vast variety of nanostructured forms. This Feature Article presents a comprehensive review on the properties of WOx that goes beyond chromism and photocatalysis, for which they are usually investigated for. This is followed by a survey of their synthesis methods and implementations for different applications.
Polydimethylsiloxane (PDMS) composites with different weight amounts of multi-walled carbon nanotubes (MWCNT) were synthesised as membranes to evaluate their gas separation properties. The ...selectivity of the membranes was investigated for the separation of H2 from CH4 gas species. Membranes with MWCNT concentrations of 1% increased the selectivity to H2 gas by 94.8%. Furthermore, CH4 permeation was almost totally blocked through membranes with MWCNT concentrations greater than 5%. Vibrational spectroscopy and X-ray photoelectron spectroscopy techniques revealed that upon the incorporation of MWCNT a decrease in the number of available Si–CH3 and Si–O bonds as well as an increase in the formation of Si–C bonds occurred that initiated the reduction in CH4 permeation. As a result, the developed membranes can be an efficient and low cost solution for separating H2 from larger gas molecules such as CH4.
•PDMS nanocomposite membranes of different MWCNT concentrations were synthesized.•The membranes were investigated for separating H2 and CH4 gas molecules.•Si–CH3, Si–O, and Si–C bonds played important roles in the membranes' performance.•More than 1wt% of MWCNT in membranes selectively attenuated the permeation of CH4.•MWCNT emerged as an effective additive for tuning H2/CH4 membranes' selectivity.
Two-dimensional (2D) oxides have a wide variety of applications in electronics and other technologies. However, many oxides are not easy to synthesize as 2D materials through conventional methods. We ...used nontoxic eutectic gallium-based alloys as a reaction solvent and co-alloyed desired metals into the melt. On the basis of thermodynamic considerations, we predicted the composition of the self-limiting interfacial oxide. We isolated the surface oxide as a 2D layer, either on substrates or in suspension. This enabled us to produce extremely thin subnanometer layers of HfO₂, Al₂O₃, and Gd₂O₃. The liquid metal–based reaction route can be used to create 2D materials that were previously inaccessible with preexisting methods. The work introduces room-temperature liquid metals as a reaction environment for the synthesis of oxide nanomaterials with low dimensionality.
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