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Electronic switches have been considered to be one of the most important components of contemporary electronic circuits for processing and storing digital information. Fabricating functional devices with building blocks of atomic/molecular switches can greatly promote the minimization of the devices and meet the requirement of high integration. This review highlights key developments in the fabrication and application of molecular switching devices. This overview offers valuable insights into the switching mechanisms under various stimuli, emphasizing structural and energy state changes in the core molecules. Beyond the molecular switches, typical individual metal atomic switches are further introduced. A critical discussion of the main challenges for realizing and developing practical molecular/atomic switches is provided. These analyses and summaries will contribute to a comprehensive understanding of the switch mechanisms, providing guidance for the rational design of functional nanoswitch devices toward practical applications. [ABSTRACT FROM AUTHOR]

Single molecules, the smallest independently stable units in the material world, serve as the fundamental building blocks of matter. Among different branches of single-molecule sciences, single-molecule chemical reactions, by revealing the behavior and properties of individual molecules at the molecular scale, are particularly attractive because they can advance the understanding of chemical reaction mechanisms and help to address key scientific problems in broad fields such as physics, chemistry, biology and materials science. This review provides a timely, comprehensive overview of single-molecule chemical reactions based on various technical platforms such as scanning probe microscopy, single-molecule junction, single-molecule nanostructure, single-molecule fluorescence detection and crossed molecular beam. We present multidimensional analyses of single-molecule chemical reactions, offering new perspectives for research in different areas, such as photocatalysis/electrocatalysis, organic reactions, surface reactions and biological reactions. Finally, we discuss the opportunities and challenges in this thriving field of single-molecule chemical reactions. [ABSTRACT FROM AUTHOR]

In recent decades, there has been a significant increase in the application of single‐molecule electrical analysis platforms in studying proteins and peptides. These advanced analysis methods have the potential for deep investigation of enzymatic working mechanisms and accurate monitoring of dynamic changes in protein configurations, which are often challenging to achieve in ensemble measurements. In this work, the prominent research progress in peptide and protein‐related studies are surveyed using electronic devices with single‐molecule/single‐event sensitivity, including single‐molecule junctions, single‐molecule field‐effect transistors, and nanopores. In particular, the successful commercial application of nanopores in DNA sequencing has made it one of the most promising techniques in protein sequencing at the single‐molecule level. From single peptides to protein complexes, the correlation between their electrical characteristics, structures, and biological functions is gradually being established. This enables to distinguish different molecular configurations of these biomacromolecules through real‐time electrical monitoring of their life activities, significantly improving the understanding of the mechanisms underlying various life processes. [ABSTRACT FROM AUTHOR]

Single-molecule non-volatile memories can be designed as high-density memories and memristors. The latter, enabling real-time data processing by performing computations directly within the memory unit, holds the potential to surpass the limitations predicted by the Von Neumann architecture. This article provides an overview of the research progress on non-volatile memories associated with functional centers of single molecules. Single-molecule devices with bistable or even multistable switching characteristics have been used to achieve storage and memory resistance functions. This review aims to summarize strategies for achieving non-volatile resistance switching using single-molecule devices, including the design of functional molecules and device construction. It uncovers the physical and chemical mechanisms by which single-molecule non-volatile memories realize multistable conductance states, such as conformational transformations, tautomerisms, intramolecular motions, spin changes, and charge changes. Furthermore, it discusses the potential developments and challenges of single-molecule non-volatile memories, including the diversity in device construction, the challenges of device integration, and the possibility of achieving the high performance, while proposing potential solutions. The objective of this review is to provide readers with fresh research insights and avenues for further exploration, thereby introducing new perspectives in the field of single-molecule non-volatile memories. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) materials, consisting of atomically thin crystal layers bound by the van der Waals force, have attracted much interest because of their potential in diverse technologies, including electronics, optoelectronics and catalysis.sup.1-10. In particular, solution-processable 2D semiconductor (such as MoS.sub.2) nanosheets are attractive building blocks for large-area thin-film electronics. In contrast to conventional zero- and one-dimensional nanostructures (quantum dots and nanowires, respectively), which are typically plagued by surface dangling bonds and associated trapping states, 2D nanosheets have dangling-bond-free surfaces. Thin films created by stacking multiple nanosheets have atomically clean van der Waals interfaces and thus promise excellent charge transport.sup.11-15. However, preparing high-quality solution-processable 2D semiconductor nanosheets remains a challenge. For example, MoS.sub.2 nanosheets and thin films produced using lithium intercalation and exfoliation are plagued by the presence of the metallic 1T phase and poor electrical performance (mobilities of about 0.3 square centimetres per volt per second and on/off ratios of less than 10).sup.2,12, and materials produced by liquid exfoliation exhibit an intrinsically broad thickness distribution, which leads to poor film quality and unsatisfactory thin-film electrical performance (mobilities of about 0.4 square centimetres per volt per second and on/off ratios of about 100).sup.14,16,17. Here we report a general approach to preparing highly uniform, solution-processable, phase-pure semiconducting nanosheets, which involves the electrochemical intercalation of quaternary ammonium molecules (such as tetraheptylammonium bromide) into 2D crystals, followed by a mild sonication and exfoliation process. By precisely controlling the intercalation chemistry, we obtained phase-pure, semiconducting 2H-MoS.sub.2 nanosheets with a narrow thickness distribution. These nanosheets were then further processed into high-performance thin-film transistors, with room-temperature mobilities of about 10 square centimetres per volt per second and on/off ratios of 10.sup.6 that greatly exceed those obtained for previous solution-processed MoS.sub.2 thin-film transistors. The scalable fabrication of large-area arrays of thin-film transistors enabled the construction of functional logic gates and computational circuits, including an inverter, NAND, NOR, AND and XOR gates, and a logic half-adder. We also applied our approach to other 2D materials, including WSe.sub.2, Bi.sub.2Se.sub.3, NbSe.sub.2, In.sub.2Se.sub.3, Sb.sub.2Te.sub.3 and black phosphorus, demonstrating its potential for generating versatile solution-processable 2D materials.By intercalating large ammonium molecules to exfoliate MoS.sub.2 with preservation of the 2H-phase, highly uniform solutionprocessable 2D semiconductor nanosheets are obtained for the scalable fabrication of large-area thin-film electronics., Author(s): Zhaoyang Lin [sup.1] , Yuan Liu [sup.2] [sup.3] , Udayabagya Halim [sup.1] , Mengning Ding [sup.2] , Yuanyue Liu [sup.4] , Yiliu Wang [sup.1] , Chuancheng Jia [sup.2] , [...]

Owing to rapid property degradation after ambient exposure and incompatibility with conventional device fabrication process, electrical transport measurements on air‐sensitive 2D materials have always been a big issue. Here, for the first time, a facile one‐step polymer‐encapsulated electrode transfer (PEET) method applicable for fragile 2D materials is developed, which showed great advantages of damage‐free electrodes patterning and in situ polymer encapsulation preventing from H2O/O2 exposure during the whole electrical measurements process. The ultrathin SmTe2 metals grown by chemical vapor deposition (CVD) are chosen as the prototypical air‐sensitive 2D crystals for their poor air‐stability, which will become highly insulating when fabricated by conventional lithographic techniques. Nevertheless, the intrinsic electrical properties of CVD‐grown SmTe2 nanosheets can be readily investigated by the PEET method instead, showing ultralow contact resistance and high signal/noise ratio. The PEET method can be applicable to other fragile ultrathin magnetic materials, such as (Mn,Cr)Te, to investigate their intrinsic electrical/magnetic properties. [ABSTRACT FROM AUTHOR]

Single‐atom catalysts based on noble metals provide efficient atomic utilization along with enhanced reactivity. Herein, a convenient strategy to construct atomically dispersed palladium catalyst on layered potassium titanate (KTO), which has enhanced interaction between the TiO6 layer and the palladium atoms, is presented. Due to the presence of K+ ions in the interlayers of KTO, the TiO6 octahedron layers have negative charge, which increases the interaction between Pd atoms and the substrate, thus preventing their agglomeration. In addition, the provision of charge of K+ ion makes the molecular oxygen in the system easier to be activated and promotes catalytic oxidation activity. [ABSTRACT FROM AUTHOR]

Intermolecular charge transport plays a vital role in the fields of electronics, as well as biochemical systems. Here, we design supramolecular dimer junctions and investigate the effects of charge state and energy level alignment on charge transport under nanoconfinement. Incoherent tunneling caused by thermally‐induced vibrations is enhanced in positively charged systems. The transition between coherent and incoherent tunneling is associated with specific molecular vibration modes. Positively charged systems with smaller torsional barriers and vibrational frequencies result in lower transition temperatures. Multiple thermal effects have a great impact on the conductance in the off‐resonant tunneling, while thermally‐induced vibron‐assisted tunneling contributes more to the transport in the resonant tunneling. These investigations offer a deep mechanism understanding of intermolecular charge transport and facilitate the development of practical functional molecular devices. [ABSTRACT FROM AUTHOR]

Filter membrane technology has been extensively used for water purification. However, due to their high brittleness and biological fouling, filter membranes will gradually deteriorate. Here we develop a robust Cu/TiO2 ceramic filter membrane for water treatment, which has excellent inherent antibacterial activities both in the dark and under visible light irradiation. One-dimensional nanobelt TiO2 can be sintered into a nanoporous membrane structure by overlapping and interweaving with each other, thereby achieving high flux simultaneously and solving the problem of high brittleness of inorganic ceramics. Meanwhile, such one-dimensional TiO2 nanostructures can provide more deposition sites for Cu nanoparticles with inherent antibacterial activity in the dark. To realise the surface plasmon resonance-enhanced antibacterial activity under visible light, Cu/TiO2 heterostructures are used. [ABSTRACT FROM AUTHOR]

The photochemical reaction is a very important type of chemical reaction. Visualizing and controlling photo‐mediated reactions is a long‐standing goal and challenge. In this regard, single‐molecule electrical detection with label‐free, real‐time, and in situ characteristics has unique advantages in monitoring the dynamic process of photoreactions at the single‐molecule level. In this review, a valuable summary of the latest process of single‐molecule photochemical reactions based on single‐molecule electrical platforms is provided. The single‐molecule electrical detection platforms for monitoring photoreactions are displayed, including their fundamental principles, construction methods, and practical applications. The single‐molecule studies of two different types of light‐mediated reactions are summarized as below: i) photo‐induced reactions, including reversible cyclization, conformational isomerization, and other photo‐related reactions; ii) plasmon‐mediated photoreactions, including reaction mechanisms and concrete examples, such as plasmon‐induced photolysis of SS/OO bonds and tautomerization of porphycene. In addition, the prospects for future research directions and challenges in this field are also discussed. [ABSTRACT FROM AUTHOR]

Single-molecule optoelectronic devices promise a potential solution for miniaturization and functionalization of silicon-based microelectronic circuits in the future. For decades of its fast development, this field has made significant progress in the synthesis of optoelectronic materials, the fabrication of single-molecule devices and the realization of optoelectronic functions. On the other hand, single-molecule optoelectronic devices offer a reliable platform to investigate the intrinsic physical phenomena and regulation rules of matters at the single-molecule level. To further realize and regulate the optoelectronic functions toward practical applications, it is necessary to clarify the intrinsic physical mechanisms of single-molecule optoelectronic nanodevices. Here, we provide a timely review to survey the physical phenomena and laws involved in single-molecule optoelectronic materials and devices, including charge effects, spin effects, exciton effects, vibronic effects, structural and orbital effects. In particular, we will systematically summarize the basics of molecular optoelectronic materials, and the physical effects and manipulations of single-molecule optoelectronic nanodevices. In addition, fundamentals of single-molecule electronics, which are basic of single-molecule optoelectronics, can also be found in this review. At last, we tend to focus the discussion on the opportunities and challenges arising in the field of single-molecule optoelectronics, and propose further potential breakthroughs. [ABSTRACT FROM AUTHOR]

Single-molecule field-effect transistors (FETs) are promising to break the development bottleneck of device miniaturization, which is of great significance for realizing the development of more than Moore. However, the field-effect properties under gating need to be further improved. Here, we design an azulene-based single-molecule FET with two opposite dipole moments in a single molecule and ionic liquid gating. This kind of FET shows ambipolar characteristics and better gate controllability with a high on–off current ratio, which is about five times higher than that of single-molecule FET based on the naphthalene molecule. According to both experimental and theoretical research, the high efficiency of gate control is related to the inherent dipole moment of azulene, which results in a lower conductance in the off-state, higher polarizability of azulene, and an effective energy level shift of the molecule. These studies offer a proven method to build single-molecule FETs with high gating regulation efficiency, thus promoting the development of practical single-molecule electronic devices. [ABSTRACT FROM AUTHOR]