Mengmeng Fan

Bio: Mengmeng Fan is an academic researcher from Nanjing University of Science and Technology. The author has contributed to research in topics: Graphene & Bacterial cellulose. The author has an hindex of 12, co-authored 28 publications receiving 467 citations. Previous affiliations of Mengmeng Fan include Nanjing University & Rice University.

Improving the Catalytic Activity of Carbon‐Supported Single Atom Catalysts by Polynary Metal or Heteroatom Doping

Abstract: Single atom catalysts (SACs) are widely researched in various chemical transformations due to the high atomic utilization and catalytic activity. Carbon-supported SACs are the largest class because of the many excellent properties of carbon derivatives. The single metal atoms are usually immobilized by doped N atoms and in some cases by C geometrical defects on carbon materials. To explore the catalytic mechanisms and improve the catalytic performance, many efforts have been devoted to modulating the electronic structure of metal single atomic sites. Doping with polynary metals and heteroatoms has been recently proposed to be a simple and effective strategy, derived from the modulating mechanisms of metal alloy structure for metal catalysts and from the donating/withdrawing heteroatom doping for carbon supports, respectively. Polynary metals SACs involve two types of metal with atomical dispersion. The bimetal atom pairs act as dual catalytic sites leading to higher catalytic activity and selectivity. Polynary heteroatoms generally have two types of heteroatoms in which N always couples with another heteroatom, including B, S, P, etc. In this Review, the recent progress of polynary metals and heteroatoms SACs is summarized. Finally, the barriers to tune the activity/selectivity of SACs are discussed and further perspectives presented.

Atomic Ru Immobilized on Porous h-BN through Simple Vacuum Filtration for Highly Active and Selective CO2 Methanation

Abstract: As CO2 emissions are sharply increasing, processes for converting CO2 into value-added products are becoming more desirable. Ruthenium-based catalysts are the most active for CO2 methanation; howev...

Doping Nanoscale Graphene Domains Improves Magnetism in Hexagonal Boron Nitride.

Abstract: Carbon doping can induce unique and interesting physical properties in hexagonal boron nitride (h-BN). Typically, isolated carbon atoms are doped into h-BN. Herein, however, the insertion of nanometer-scale graphene quantum dots (GQDs) is demonstrated as whole units into h-BN sheets to form h-CBN. The h-CBN is prepared by using GQDs as seed nucleations for the epitaxial growth of h-BN along the edges of GQDs without the assistance of metal catalysts. The resulting h-CBN sheets possess a uniform distrubution of GQDs in plane and a high porosity macroscopically. The h-CBN tends to form in small triangular sheets which suggests an enhanced crystallinity compared to the h-BN synthesized under the same conditions without GQDs. An enhanced ferromagnetism in the h-CBN emerges due to the spin polarization and charge asymmetry resulting from the high density of CN and CB bonds at the boundary between the GQDs and the h-BN domains. The saturation magnetic moment of h-CBN reaches 0.033 emu g-1 at 300 K, which is three times that of as-prepared single carbon-doped h-BN.

Recent progress in 2D or 3D N-doped graphene synthesis and the characterizations, properties, and modulations of N species

Abstract: Nitrogen (N)-doped graphene (N-substituted or nitrogenated graphene) (NG) has become a new class of graphene material due to its modified properties such as the tunable work function, n-type semiconductivity, increasing biocompatibility, and, in particular, the synergistic function with various functional materials. However, the preparation of NG by a simple and effective method is still lacking. The modification of NG mainly depends on the N species and the N content. Thus, we focus on the recent progress in preparing methods of 2D NG and the respective key modulating parameters to modulate the N species and the N content. Furthermore, many effective charactering techniques are covered to accurately analyze the properties of N species, and the distribution and topography of N atoms. Also, we review the effect of N species on graphene, especially, the optical and electronic properties. Since constructing 3D structure is considered a promising strategy to prevent the restacking of 2D NG, the summary for preparing 3D NG is made on the basis of methodology of 2D NG. In a word, this review provides a reference for preparing 2D or 3D NG, modulating and characterizing N species, which are greatly contributed to the NG application.

Emerging Two-Dimensional Nanomaterials for Electrocatalysis

Abstract: 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, ...

Electronic and Optical Properties of 2D Transition Metal Carbides and Nitrides (MXenes).

Abstract: 2D transition metal carbides, carbonitrides, and nitrides, known as MXenes, are a rapidly growing family of 2D materials with close to 30 members experimentally synthesized, and dozens more studied theoretically. They exhibit outstanding electronic, optical, mechanical, and thermal properties with versatile transition metal and surface chemistries. They have shown promise in many applications, such as energy storage, electromagnetic interference shielding, transparent electrodes, sensors, catalysis, photothermal therapy, etc. The high electronic conductivity and wide range of optical absorption properties of MXenes are the key to their success in the aforementioned applications. However, relatively little is currently known about their fundamental electronic and optical properties, limiting their use to their full potential. Here, MXenes' electronic and optical properties from both theoretical and experimental perspectives, as well as applications related to those properties, are discussed, providing a guide for researchers who are exploring those properties of MXenes.

Graphene based metal and metal oxide nanocomposites: synthesis, properties and their applications

Abstract: Graphene, an atomically thin two-dimensional carbonaceous material, has attracted tremendous attention in the scientific community, due to its exceptional electronic, electrical, and mechanical properties. Indeed, with the recent explosion of methods for a large-scale synthesis of graphene, the number of publications related to graphene and other graphene based materials has increased exponentially. Particularly the development of easy preparation methods for graphene like materials, such as highly reduced graphene oxide (HRG) via reduction of graphite oxide (GO), offers a wide range of possibilities for the preparation of graphene based inorganic nanocomposites by the incorporation of various functional nanomaterials for a variety of applications. In this review, we discuss the current development of graphene based metal and metal oxide nanocomposites, with a detailed account of their synthesis and properties. Specifically, much attention has been given to their wide range of applications in various fields, including electronics, electrochemical and electrical fields. Overall, by the inclusion of various references, this review covers in detail the aspects of graphene-based inorganic nanocomposites.