Lack of effective strategies to regulate the internal activity of MoS2 limits its practical application for hydrogen evolution reactions (HERs). Doping of heteroatoms without forming aggregation or ...an edge enrichment is still challenging, and its effect on the HER needs to be further explored. Herein, a two‐step method is developed to obtain multi‐metal‐doped H‐MoS2, which includes intercalation of the layered MoO3 precursor with a following sulfurization. Benefiting from the capability of the intercalation method to uniformly and simultaneously introduce different elements into the van der Waals gap, this method is universal to obtain multi‐heteroatoms co‐doped MoS2 without forming clusters, phase separation, and an edge enrichment. It is demonstrated that the doping of adjacent cobalt and palladium monomers on MoS2 greatly enhances the HER catalytic activity. The overpotential at 10 mA cm−2 and Tafel slope of Co and Pd co‐doped MoS2 is found to be 49.3 mV and 43.2 mV dec−1, respectively, representing a superior acidic HER catalytic activity. This intercalation‐assisted method also provides a new and general strategy to synthesize uniformly doped transition metal dichalcogenides for various applications.
An intercalation‐assisted method is developed to obtain multi‐metal‐doped H‐MoS2, which is proven to be a universal method. The doping of adjacent cobalt and palladium monomers on MoS2 greatly enhances the HER catalytic activity. The overpotential at 10 mA cm−1 and Tafel slope of Co‐Pd‐MoS2 are 49.3 mV and 43.2 mV dec−1, respectively.
The efficient interconversion of chemicals and electricity through electrocatalytic processes is central to many renewable-energy initiatives. The sluggish kinetics of the oxygen reduction reaction ...(ORR) and the oxygen evolution reaction (OER)
has long posed one of the biggest challenges in this field, and electrocatalysts based on expensive platinum-group metals are often required to improve the activity and durability of these reactions. The use of alloying
, surface strain
and optimized coordination environments
has resulted in platinum-based nanocrystals that enable very high ORR activities in acidic media; however, improving the activity of this reaction in alkaline environments remains challenging because of the difficulty in achieving optimized oxygen binding strength on platinum-group metals in the presence of hydroxide. Here we show that PdMo bimetallene-a palladium-molybdenum alloy in the form of a highly curved and sub-nanometre-thick metal nanosheet-is an efficient and stable electrocatalyst for the ORR and the OER in alkaline electrolytes, and shows promising performance as a cathode in Zn-air and Li-air batteries. The thin-sheet structure of PdMo bimetallene enables a large electrochemically active surface area (138.7 square metres per gram of palladium) as well as high atomic utilization, resulting in a mass activity towards the ORR of 16.37 amperes per milligram of palladium at 0.9 volts versus the reversible hydrogen electrode in alkaline electrolytes. This mass activity is 78 times and 327 times higher than those of commercial Pt/C and Pd/C catalysts, respectively, and shows little decay after 30,000 potential cycles. Density functional theory calculations reveal that the alloying effect, the strain effect due to the curved geometry, and the quantum size effect due to the thinness of the sheets tune the electronic structure of the system for optimized oxygen binding. Given the properties and the structure-activity relationships of PdMo metallene, we suggest that other metallene materials could show great promise in energy electrocatalysis.
Monolayer transition metal dichalcogenides (TMDs) have become essential two-dimensional materials for their perspectives in engineering next-generation electronics. For related applications, the ...controlled growth of large-area uniform monolayer TMDs is crucial, while it remains challenging. Herein, we report the direct synthesis of 6-inch uniform monolayer molybdenum disulfide on the solid soda-lime glass, through a designed face-to-face metal-precursor supply route in a facile chemical vapor deposition process. We find that the highly uniform monolayer film, with the composite domains possessing an edge length larger than 400 µm, can be achieved within a quite short time of 8 min. This highly efficient growth is proven to be facilitated by sodium catalysts that are homogenously distributed in glass, according to our experimental facts and density functional theory calculations. This work provides insights into the batch production of highly uniform TMD films on the functional glass substrate with the advantages of low cost, easily transferrable, and compatible with direct applications.
Chemical vapour deposition of two-dimensional materials typically involves the conversion of vapour precursors to solid products in a vapour–solid–solid mode. Here, we report the vapour–liquid–solid ...growth of monolayer MoS2, yielding highly crystalline ribbons with a width of few tens to thousands of nanometres. This vapour–liquid–solid growth is triggered by the reaction between MoO3 and NaCl, which results in the formation of molten Na–Mo–O droplets. These droplets mediate the growth of MoS2 ribbons in the ‘crawling mode’ when saturated with sulfur. The locally well-defined orientations of the ribbons reveal the regular horizontal motion of the droplets during growth. Using atomic-resolution scanning transmission electron microscopy and second harmonic generation microscopy, we show that the ribbons are grown homoepitaxially on monolayer MoS2 with predominantly 2H- or 3R-type stacking. Our findings highlight the prospects for the controlled growth of atomically thin nanostructure arrays for nanoelectronic devices and the development of unique mixed-dimensional structures.
As a typical advanced oxidation technology, the Fenton reaction has been employed for the disinfection, owing to the strong oxidizability of hydroxyl radicals (·OH). However, the conventional Fenton ...system always exhibits a low H2O2 decomposition efficiency, leading to a low production yield of ·OH, which makes the disinfection effect unsatisfactory. Herein, we develop a molybdenum sulfide (MoS2) co-catalytic Fenton reaction for rapid and highly efficient inactivation of Escherichia coli K-12 (E. coli) and Staphylococcus aureus (S. aureus). As a co-catalyst in the Fe(II)/H2O2 Fenton system, MoS2 can greatly facilitate the Fe(III)/Fe(II) cycle reaction by the exposed Mo4+ active sites, which significantly improves the H2O2 decomposition efficiency for the ·OH production. As a result, the MoS2 co-catalytic Fenton system can reach up to 83.37% of inactivation rate of E. coli just in 1 min and 100% of inactivation rate within 30 min, which increased by 2.5 times than that of the conventional Fenton reaction. Furthermore, the ·OH as the primary reactive oxygen species (ROS) in MoS2 co-catalytic Fenton reaction was measured and verified by electron paramagnetic resonance (EPR) and photoluminescence (PL). It is demonstrated an increased amount of ·OH generated from the decomposition of H2O2 in the presence of MoS2, which is responsible for the rapid and efficient inactivation of E. coli and S. aureus. This study provides a new perspective for rapid and highly efficient inactivation of bacteria in environmental remediation.
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•MoS2 co-catalytic Fenton reaction was employed for the disinfection for the first time.•Inactivation rate of Escherichia coli K-12 can reach 83.37% in 1 min and 100% in 30 min.•MoS2 can increase the H2O2 decomposition efficiency from 17.5% to 61.5% in Fenton reaction.•The ·OH is the primary reactive oxygen species (ROS) for the disinfection.•MoS2 co-catalytic Fenton system has obvious advantages in bactericidal effect and reaction rate.
Graphene Analogues of Inorganic Layered Materials Rao, C. N. R.; Ramakrishna Matte, H. S. S.; Maitra, Urmimala
Angewandte Chemie (International ed.),
December 9, 2013, Letnik:
52, Številka:
50
Journal Article
Recenzirano
The discovery of graphene has created a great sensation in chemistry, physics, materials science, and related areas. The unusual properties of graphene have aroused interest in other layered ...materials, such as molybdenum sulfide and boron nitride. In the last few years, single‐ as well as few‐layer as well as chalcogenides and other inorganic materials have been prepared and characterized by a variety of methods. These materials possess interesting properties, and some have potential applications. This Review provides an up‐to‐date account of these emerging two‐dimensional nanomaterials. Not only are the synthesis and characterization covered, but also important aspects such as spectroscopic and optical properties, magnetic and electrical properties, as well as applications. Salient features of the composites formed from the layered inorganic structures with graphene and polymers are presented along with a brief description of borocarbonitrides.
Single and few‐layer MoS2, BN, and similar layered inorganic compounds are emerging as very interesting materials with numerous potential applications. This Review describes the synthesis and characterization of these graphene analogues and presents some of their physical properties and applications.
Molybdenum cofactor deficiency classically presents in neonates with intractable seizures; however, milder cases generally present before age 2 years with developmental delays and may go undiagnosed. ...Early diagnosis, and safe, US Food and Drug Administration-approved substrate replacement are critical to preserve neurologic function. This article discusses 2 children who presented with late-onset molybdenum cofactor deficiency type A.
To explore highly effective catalysts with low cost and earth abundant for the hydrogen evolution reaction (HER), in this work, a novel electrocatalyst of alpha-molybdenum carbide and molybdenum ...phosphide heterostructure embedded in N-doped carbon (α-MoC1-x-MoP/C) is synthesized via facile simultaneous carbonization and phosphorization strategy for the first time, which exhibits an excellent hydrogen evolution activity with a Tafel slope of 57 mV dec−1 in an acidic media. A strong electronic interaction between α-MoC1-x and MoP in the interfaces is verified experimentally and theoretically, which contributes to a mild free energy of H adsorption and smaller charge transfer resistance, resulting in an improved HER activity.
Ultra-scaled transistors are of interest in the development of next-generation electronic devices1-3. Although atomically thin molybdenum disulfide (MoS2) transistors have been reported4, the ...fabrication of devices with gate lengths below 1 nm has been challenging5. Here we demonstrate side-wall MoS2 transistors with an atomically thin channel and a physical gate length of sub-1 nm using the edge of a graphene layer as the gate electrode. The approach uses large-area graphene and MoS2 films grown by chemical vapour deposition for the fabrication of side-wall transistors on a 2-inch wafer. These devices have On/Off ratios up to 1.02 x 105 and subthreshold swing values down to 117 mV dec-1. Simulation results indicate that the MoS2 side-wall effective channel length approaches 0.34 nm in the On state and 4.54 nm in the Off state. This work can promote Moore's law of the scaling down of transistors for next-generation electronics.
As the dimensions of the semiconducting channels in field-effect transistors decrease, the contact resistance of the metal-semiconductor interface at the source and drain electrodes increases, ...dominating the performance of devices
. Two-dimensional (2D) transition-metal dichalcogenides such as molybdenum disulfide (MoS
) have been demonstrated to be excellent semiconductors for ultrathin field-effect transistors
. However, unusually high contact resistance has been observed across the interface between the metal and the 2D transition-metal dichalcogenide
. Recent studies have shown that van der Waals contacts formed by transferred graphene
and metals
on few-layered transition-metal dichalcogenides produce good contact properties. However, van der Waals contacts between a three-dimensional metal and a monolayer 2D transition-metal dichalcogenide have yet to be demonstrated. Here we report the realization of ultraclean van der Waals contacts between 10-nanometre-thick indium metal capped with 100-nanometre-thick gold electrodes and monolayer MoS
. Using scanning transmission electron microscopy imaging, we show that the indium and gold layers form a solid solution after annealing at 200 degrees Celsius and that the interface between the gold-capped indium and the MoS
is atomically sharp with no detectable chemical interaction between the metal and the 2D transition-metal dichalcogenide, suggesting van-der-Waals-type bonding between the gold-capped indium and monolayer MoS
. The contact resistance of the indium/gold electrodes is 3,000 ± 300 ohm micrometres for monolayer MoS
and 800 ± 200 ohm micrometres for few-layered MoS
. These values are among the lowest observed for three-dimensional metal electrodes evaporated onto MoS
, enabling high-performance field-effect transistors with a mobility of 167 ± 20 square centimetres per volt per second. We also demonstrate a low contact resistance of 220 ± 50 ohm micrometres on ultrathin niobium disulfide (NbS
) and near-ideal band offsets, indicative of defect-free interfaces, in tungsten disulfide (WS
) and tungsten diselenide (WSe
) contacted with indium alloy. Our work provides a simple method of making ultraclean van der Waals contacts using standard laboratory technology on monolayer 2D semiconductors.
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