Since the discovery of mechanically exfoliated graphene in 2004, research on ultrathin two-dimensional (2D) nanomaterials has grown exponentially in the fields of condensed matter physics, material science, chemistry, and nanotechnology. Highlighting their compelling physical, chemical, electronic, and optical properties, as well as their various potential applications, in this Review, we summarize the state-of-art progress on the ultrathin 2D nanomaterials with a particular emphasis on their recent advances. First, we introduce the unique advances on ultrathin 2D nanomaterials, followed by the description of their composition and crystal structures. The assortments of their synthetic methods are then summarized, including insights on their advantages and limitations, alongside some recommendations on suitable characterization techniques. We also discuss in detail the utilization of these ultrathin 2D nanomaterials for wide ranges of potential applications among the electronics/optoelectronics, electrocat...

Recent Advances in Ultrathin Two-Dimensional Nanomaterials

We present the science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems, targeting an evolution in technology, that might lead to impacts and benefits reaching into most areas of society. This roadmap was developed within the framework of the European Graphene Flagship and outlines the main targets and research areas as best understood at the start of this ambitious project. We provide an overview of the key aspects of graphene and related materials (GRMs), ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries. We also define an extensive list of acronyms in an effort to standardize the nomenclature in this emerging field.

/pdf/science-and-technology-roadmap-for-graphene-related-two-4q9m7czlkc.pdf

Science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems

Metal oxide nanostructures are promising electrode materials for lithium-ion batteries and supercapacitors because of their high specific capacity/capacitance, typically 2-3 times higher than that of the carbon/graphite-based materials. However, their cycling stability and rate performance still can not meet the requirements of practical applications. It is therefore urgent to improve their overall device performance, which depends on not only the development of advanced electrode materials but also in a large part "how to design superior electrode architectures". In the article, we will review recent advances in strategies for advanced metal oxide-based hybrid nanostructure design, with the focus on the binder-free film/array electrodes. These binder-free electrodes, with the integration of unique merits of each component, can provide larger electrochemically active surface area, faster electron transport and superior ion diffusion, thus leading to substantially improved cycling and rate performance. Several recently emerged concepts of using ordered nanostructure arrays, synergetic core-shell structures, nanostructured current collectors, and flexible paper/textile electrodes will be highlighted, pointing out advantages and challenges where appropriate. Some future electrode design trends and directions are also discussed.

Recent Advances in Metal Oxide-based Electrode Architecture Design for Electrochemical Energy Storage

We developed two-step solution-phase reactions to form hybrid materials of Mn3O4 nanoparticles on reduced graphene oxide (RGO) sheets for lithium ion battery applications. Mn3O4 nanoparticles grown selectively on RGO sheets over free particle growth in solution allowed for the electrically insulating Mn3O4 nanoparticles wired up to a current collector through the underlying conducting graphene network. The Mn3O4 nanoparticles formed on RGO show a high specific capacity up to ~900mAh/g near its theoretical capacity with good rate capability and cycling stability, owing to the intimate interactions between the graphene substrates and the Mn3O4 nanoparticles grown atop. The Mn3O4/RGO hybrid could be a promising candidate material for high-capacity, low-cost, and environmentally friendly anode for lithium ion batteries. Our growth-on-graphene approach should offer a new technique for design and synthesis of battery electrodes based on highly insulating materials.

Mn3O4-Graphene Hybrid as a High Capacity Anode Material for Lithium Ion Batteries

Over the past few decades, the design and development of advanced electrocatalysts for efficient energy conversion technologies have been subjects of extensive study. With the discovery of graphene, two-dimensional (2D) nanomaterials have emerged as some of the most promising candidates for heterogeneous electrocatalysts due to their unique physical, chemical, and electronic properties. Here, we review 2D-nanomaterial-based electrocatalysts for selected electrocatalytic processes. We first discuss the unique advances in 2D electrocatalysts based on different compositions and functions followed by specific design principles. Following this overview, we discuss various 2D electrocatalysts for electrocatalytic processes involved in the water cycle, carbon cycle, and nitrogen cycle from their fundamental conception to their functional application. We place a significant emphasis on different engineering strategies for 2D nanomaterials and the influence these strategies have on intrinsic material performance, ...

Emerging Two-Dimensional Nanomaterials for Electrocatalysis

We report the direct growth of atomically thin WS2 nanoplates and nanofilms on the SiO2/Si (300 nm) substrate by vapor phase deposition method without any catalyst. The WS2 nanostructures were systematically characterized by optical microscopy, scanning electron microscopy, Raman microscopy and atomic force microscopy. We found that growth time and growth temperature play important roles in the morphology of WS2 nanostructures. Moreover, by using Kelvin probe force microscopy, we found that the WS2 nanoplates exhibit uniform surface and charge distributions less than 10 mV fluctuations. Our results may apply to the study of other transition metal dichalcogenides by vapor phase deposition method.

/pdf/synthesis-characterization-and-electrostatic-properties-of-59u6d21wzt.pdf

Synthesis, characterization and electrostatic properties of WS2 nanostructures

Electronic and Magnetic Properties of Monolayer and Bilayer Phosphorene Doped with Transition‐Metal Atoms

2D layered material Bi2O2Se nanosheets, due to its high carrier mobility, near-ideal subthreshold swing, and high air-stability, which have shown great potential for applications in high-performance field-effect transistors and photodetector. Here, we have been successfully synthesized Bi2O2Se nanosheets via a facile one-step hydrothermal method. The Bi2O2Se nanosheets were characterized by scanning electron microscopy (SEM), Raman spectra and X-ray diffraction (XRD) patterns, which confirm an excellent crystallized of Bi2O2Se nanosheets. The as-prepared Bi2O2Se nanosheets were used to fabricate electrodes for a self-powered photodetector and exhibit preferable photoresponse activity. At 0 V, the photoeletrochemical (PEC) tests demonstrate that the responsivity and the response time of Bi2O2Se nanosheets can reach up to 20 μA W−1 and 0.12 s. Furthermore, the time stability and cycle stability also were measured. After a long time of testing, the photocurrent of Bi2O2Se nanosheets remained around 300 nA, and after processing 100 and 200 cycles, the photocurrent exhibits slight distinction. These findings indicate that Bi2O2Se nanosheets have great prospects for future applications in self-powered photodetector devices.

High-performance self-powered photodetector based on Bi 2 O 2 Se nanosheets

The successful synthesis of large-area SnSe films on SiO2/Si substrate through vapor transport is reported. Based on this we fabricated photodetectors that exhibited a fast response from ultraviolet (UV) to near infrared (NIR) wavelengths. By decorating the SnSe film with graphene oxide quantum dots (GO QDs) the photocurrent and photoresponse time were enhanced significantly over the whole spectrum. Our results indicate that GO functionalised SnSe is a promising material for broadband photodetection.

/pdf/enhanced-photoresponse-of-graphene-oxide-functionalised-snse-ompp6m9pzu.pdf

Xiang Qi

Papers

Synthesis, characterization and electrostatic properties of WS2 nanostructures

Electronic and Magnetic Properties of Monolayer and Bilayer Phosphorene Doped with Transition‐Metal Atoms

High-performance self-powered photodetector based on Bi 2 O 2 Se nanosheets

Enhanced photoresponse of graphene oxide functionalised SnSe films

Fermi level shift in topological insulator-silicon heterostructures