Hydrogen (H2) is one of the most important clean and renewable energy sources for future energy sustainability. Nowadays, photocatalytic and electrocatalytic hydrogen evolution reactions (HERs) from ...water splitting are considered as two of the most efficient methods to convert sustainable energy to the clean energy carrier, H2. Catalysts based on transition metal dichalcogenides (TMDs) are recognized as greatly promising substitutes for noble‐metal‐based catalysts for HER. The photocatalytic and electrocatalytic activities of TMD nanosheets for the HER can be further improved after hybridization with many kinds of nanomaterials, such as metals, oxides, sulfides, and carbon materials, through different methods including the in situ reduction method, the hot‐injection method, the heating‐up method, the hydro(solvo)thermal method, chemical vapor deposition (CVD), and thermal annealing. Here, recent progress in photocatalytic and electrocatalytic HERs using 2D TMD‐based composites as catalysts is discussed.
Transition‐metal dichalcogenide (TMD)‐based catalysts have great promise as substitutes for noble‐metal‐based catalysts for hydrogen‐evolution reactions. Recent strategies regarding the various kinds of TMD‐based composites for photocatalytic and electrocatalytic hydrogen evolution are summarized here. In addition, the challenges and opportunities are provided.
Transition‐metal dichalcogenides (TMDs) have attracted considerable attention in recent years because of their unique properties and promising applications in electrochemical energy storage and ...conversion. However, the limited number of active sites as well as blocked ion and mass transport severely impair their electrochemical performance. The construction of three‐dimensional (3D) architectures from TMD nanomaterials has been proven to be an effective strategy to solve the aforementioned problems as a result of their large specific surface areas and short ion and mass transport distances. This Review summarizes the commonly used routes to build 3D TMD architectures and highlights their applications in electrochemical energy storage and conversion, including batteries, supercapacitors, and electrocatalytic hydrogen evolution. The challenges and outlook in this research area are also discussed.
Electrochemistry in 3D: Three‐dimensional transition‐metal dichalcogenide architectures have shown great promise for electrochemical energy storage and conversion. This Review summarizes the commonly used strategies for the construction of such architectures, as well as their application in rechargeable batteries, supercapacitors, and electrocatalytic hydrogen evolution.
C‐dots on hand: Luminescent carbon nanodots were synthesized and were shown to be biocompatible, have low toxicity, and distinctive photoluminescence properties. These C‐dots are inexpensive to ...synthesize and could potentially be used for versatile applications, such as anticounterfeiting, information encryption, and information storage.
Hydrogels that electronically respond to mechanical changes can be used as strain sensors. However, these systems usually require external power to convert changes in strain into electrical signals. ...Here, a self-powered strain sensor is developed based on a gelatin-based hydrogel and a galvanic cell. In the hydrogel matrix, hydrophobic interactions and hydrogen bonding between tannic acid and gelatin give the prepared hydrogel great potential for elongation (1600%). The hydrogel also has a rapid self-healing ability (within 0.65 s) and high self-healing efficiency (95%). The hydrogel operates as an efficient electrolyte material and forms a hydrogel battery when assembled with a thin layer of zinc and an air electrode. This device had excellent tolerance to large compressional strain without sacrificing open-circuit voltage. On the basis of this hydrogel battery, we fabricated a self-powered strain sensor by connecting the hydrogel battery to a fixed resistor to form a closed loop. By converting its chemical energy into electrical energy, the self-powered sensor efficiently converted resistance changes, caused by stretching or compression of the hydrogel, into changes in the voltage output signals without external power. Owing to the stretchability of the hydrogel, the self-powered sensor exhibited good response and flexibility. Self-healing and continuous cycling tests confirmed the long-term stability of the device. These properties suggest that our self-powered sensor has a potential for applications to portable and wearable electronic devices.
Two‐dimensional (2D) metal–organic framework (MOF) nanosheets are attracting increasing research interest due to their unique properties originating from their ultrathin thickness and large surface ...area with highly accessible active sites. Here, the aim is to provide recent advances in the synthesis of 2D MOF nanosheets by using the top‐down and bottom‐up methods, including sonication exfoliation, interfacial synthesis, three‐layer synthesis, and surfactant‐assisted synthesis methods. In addition, the recent progress in 2D‐MOF‐nanosheet‐based nanocomposites is also introduced. The synthesis of 2D MOF nanosheets should lead to new kinds of functional nanomaterials for a wide range of applications.
Recent advances in the synthesis of 2D metal–organic framework (MOF) nanosheets using the top‐down and bottom‐up methods are summarized, including sonication exfoliation, interfacial synthesis, three‐layer synthesis, and surfactant‐assisted synthesis methods. In addition, the recent progress in 2D‐MOF‐nanosheet‐based nanocomposites is also introduced.
•Adsorption of organic compounds on GO and RGO.•Adsorption of metal ions on GO and RGO.•Adsorption of oil spills on GO and RGO.•Application of GO and RGO in chromatography.•Application of GO and RGO ...in solid-phase extraction.
Graphene, a single layer of carbon atoms densely packed into a honeycomb crystal lattice with unique electronic, chemical, and mechanical properties, is the 2D allotrope of carbon. Owing to the remarkable properties, graphene and graphene-based materials are likely to find potential applications as a sorbent in analytical chemistry. The current review focuses predominantly on the recent development of graphene-based materials and demonstrates their enhanced performance in adsorption of organic compounds, metal ions, and solid phase extraction as well as in separation science since mostly 2012.
A facile surfactant‐assisted bottom‐up synthetic method to prepare a series of freestanding ultrathin 2D M‐TCPP (M = Zn, Cu, Cd or Co, TCPP = tetrakis(4‐carboxyphenyl)porphyrin) nanosheets with a ...thickness of sub‐10 nm is developed. As a proof‐of‐concept application, some of them are successfully used as new platforms for DNA detection. The Cu‐TCPP nanosheet‐based sensor shows excellent fluorescent sensing performance and is used for the simultaneous detection of multiple DNA targets.
Two-dimensional (2D) metal–organic framework (MOF) nanosheets are attracting increasing research interest. Here, for the first time, we report the facile synthesis of 2D porphyrin paddlewheel ...framework-3 (PPF-3) MOF nanosheets with thickness of ca. 12–43 nm. Through the simultaneous sulfidation and carbonization of PPF-3 MOF nanosheets, we have prepared the 2D nanocomposite of CoS1.097 nanoparticles (NPs) and nitrogen-doped carbon, referred to as CoSNC, in which the CoS1.097 NPs with size of ca. 10 nm are embedded in the nitrogen-doped carbon matrix. As a proof-of-concept application, the obtained 2D CoSNC nanocomposite is used as an electrode material for a supercapacitor, which exhibits a specific capacitance of 360.1 F g–1 at a current density of 1.5 A g–1. Moreover, the composite electrode also shows high rate capability. Its specific capacitance delivered at a current density of 30.0 A g–1 retains 56.8% of the value at 1.5 A g–1.
Inspired by the multiple functions of natural multienzyme systems, a new kind of hybrid nanosheet is designed and synthesized, i.e., ultrasmall Au nanoparticles (NPs) grown on 2D metalloporphyrinic ...metal‐organic framework (MOF) nanosheets. Since 2D metalloporphyrinic MOF nanosheets can act as the peroxidase mimics and Au NPs can serve as artificial glucose oxidase, the hybrid nanosheets are used to mimic the natural enzymes and catalyze the cascade reactions. Furthermore, the synthesized hybrid nanosheets are used to detect biomolecules, such as glucose. This study paves a new avenue to design nanomaterial‐based biomimetic catalysts with multiple complex functions.
Inspired by the multiple functions of natural multienzyme systems, hybrid nanosheets are designed and synthesized, i.e., ultrasmall Au nanoparticles are grown on 2D metalloporphyrinic metal‐organic framework nanosheets. Since nanosheets can act as the peroxidase mimics and Au nanoparticles can serve as artificial glucose oxidase, the hybrid nanosheets are used to mimic the natural enzymes and catalyze the cascade reactions.
Similar to heterostructures composed of different materials, possessing unique properties due to the synergistic effect between different components, the crystal‐phase heterostructures, one variety ...of hetero‐phase structures, composed of different crystal phases in monometallic nanomaterials are herein developed, in order to explore crystal‐phase‐based applications. As novel hetero‐phase structures, amorphous/crystalline heterostructures are highly desired, since they often exhibit unique properties, and hold promise in various applications, but these structures have rarely been studied in noble metals. Herein, via a one‐pot wet‐chemical method, a series of amorphous/crystalline hetero‐phase Pd nanosheets is synthesized with different crystallinities for the catalytic 4‐nitrostyrene hydrogenation. The chemoselectivity and activity can be fine‐tuned by controlling the crystallinity of the as‐synthesized Pd nanosheets. This work might pave the way to preparing various hetero‐phase nanostructures for promising applications.
Amorphous/crystalline heterophase Pd nanosheets exhibit crystallinity‐dependent chemoselectivity and catalytic activity.
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