Long Chen

Bio: Long Chen is an academic researcher from Northeastern University. The author has contributed to research in topics: Sulfite & Perylene. The author has an hindex of 31, co-authored 102 publications receiving 4872 citations. Previous affiliations of Long Chen include La Trobe University & Tianjin University.

Three-Dimensional Nitrogen and Boron Co-doped Graphene for High-Performance All-Solid-State Supercapacitors

Abstract: carbide-derived carbon, [ 12 ] carbon nanotubes (CNTs), [ 14–17 ] and graphene, [ 6 , 7 , 10 , 18 , 19 ] possess notable features including high surface area, high electrical conductivity, and good chemical stability, and therefore they have been widely explored as thinfi lm electrode materials for ASSSs. However, the fabrication of ASSSs generally involves complex solution processing, highpressure pressing, high-temperature sintering, and sputtering techniques. [ 11 , 12 , 14–17 ] Moreover, polymer binders and conductive additives are required to enhance the adhesion between electrode materials and substrates as well as to improve the conductivity of the electrode, which unavoidably leads to decreased energy density of the devices. [ 6 , 20 ] Therefore, several challenges remain in developing ASSSs, such as to: i) explore high-performance electrode materials, ii) enhance the interfacial compatibility between electrode and solid-state electrolyte, and iii) simplify the device fabrication process. Graphene aerogels (GAs) represent a new class of ultralight and porous carbon materials that are associated with high

From Nanographene and Graphene Nanoribbons to Graphene Sheets: Chemical Synthesis

Abstract: Graphene, an individual two-dimensional, atomically thick sheet of graphite composed of a hexagonal network of sp2 carbon atoms, has been intensively investigated since its first isolation in 2004, which was based on repeated peeling of highly oriented pyrolyzed graphite (HOPG). The extraordinary electronic, thermal, and mechanical properties of graphene make it a promising candidate for practical applications in electronics, sensing, catalysis, energy storage, conversion, etc. Both the theoretical and experimental studies proved that the properties of graphene are mainly dependent on their geometric structures. Precise control over graphene synthesis is therefore crucial for probing their fundamental physical properties and introduction in promising applications. In this Minireview, we highlight the recent progress that has led to the successful chemical synthesis of graphene with a range of different sizes and chemical compositions based on both top-down and bottom-up strategies.

High-Performance Electrocatalysts for Oxygen Reduction Derived from Cobalt Porphyrin-Based Conjugated Mesoporous Polymers

Abstract: A cobalt-nitrogen-doped porous carbon that exhibits a ribbon-shape morphology, high surface area, mesoporous structure, and high nitrogen and cobalt content is fabricated for high-performance self-supported oxygen reduction electrocatalytsts through template-free pyrolysis of cobalt porphyrin-based conjugated mesoporous polymer frameworks.

On-surface synthesis of rylene-type graphene nanoribbons.

Abstract: The narrowest armchair graphene nanoribbon (AGNR) with five carbons across the width of the GNR (5-AGNR) was synthesized on Au(111) surfaces via sequential dehalogenation processes in a mild condition by using 1,4,5,8-tetrabromonaphthalene as the molecular precursor. Gold-organic hybrids were observed by using high-resolution scanning tunneling microscopy and considered as intermediate states upon AGNR formation. Scanning tunneling spectroscopy reveals an unexpectedly large band gap of Δ = 2.8 ± 0.1 eV on Au(111) surface which can be interpreted by the hybridization of the surface states and the molecular states of the 5-AGNR.

Beyond perylene diimides: synthesis, assembly and function of higher rylene chromophores

Abstract: Perylene diimides are among the most important chromophores in dyestuff chemistry. They do not only have excellent thermal, chemical and photochemical stability, high absorption coefficients and fluorescence quantum yields but also permit various chemical functionalizations. Over the last decades, academic and industrial interest in this class of chromophores has steadily increased due to their favourable properties and potential application in various research fields like organic electronics, biochemistry, photophysics and supramolecular chemistry. Higher rylene diimide dyes (e.g.2–6), however, are still in their infancy and must be further explored by combining more research efforts of chemists, physicists, biologists, and material scientists since these dyes possess unique optical, electrochemical, and electronic properties. One of the main obstacles in such rylene based dyes seems to be their synthetic challenges. Thus, in this feature article, we summarize the latest advances in the field of rylene diimide dyes focusing on synthetic strategies toward their preparation. The self-assembly behaviour and applications of larger rylene chromophores are discussed as well.

Recent Advances in Ultrathin Two-Dimensional Nanomaterials

Abstract: 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...

Electrochemical capacitors: mechanism, materials, systems, characterization and applications

Abstract: Electrochemical capacitors (i.e. supercapacitors) include electrochemical double-layer capacitors that depend on the charge storage of ion adsorption and pseudo-capacitors that are based on charge storage involving fast surface redox reactions. The energy storage capacities of supercapacitors are several orders of magnitude higher than those of conventional dielectric capacitors, but are much lower than those of secondary batteries. They typically have high power density, long cyclic stability and high safety, and thus can be considered as an alternative or complement to rechargeable batteries in applications that require high power delivery or fast energy harvesting. This article reviews the latest progress in supercapacitors in charge storage mechanisms, electrode materials, electrolyte materials, systems, characterization methods, and applications. In particular, the newly developed charge storage mechanism for intercalative pseudocapacitive behaviour, which bridges the gap between battery behaviour and conventional pseudocapacitive behaviour, is also clarified for comparison. Finally, the prospects and challenges associated with supercapacitors in practical applications are also discussed.

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

Abstract: 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.

Design and Mechanisms of Asymmetric Supercapacitors.

Abstract: Ongoing technological advances in diverse fields including portable electronics, transportation, and green energy are often hindered by the insufficient capability of energy-storage devices By taking advantage of two different electrode materials, asymmetric supercapacitors can extend their operating voltage window beyond the thermodynamic decomposition voltage of electrolytes while enabling a solution to the energy storage limitations of symmetric supercapacitors This review provides comprehensive knowledge to this field We first look at the essential energy-storage mechanisms and performance evaluation criteria for asymmetric supercapacitors to understand the wide-ranging research conducted in this area Then we move to the recent progress made for the design and fabrication of electrode materials and the overall structure of asymmetric supercapacitors in different categories We also highlight several key scientific challenges and present our perspectives on enhancing the electrochemical performance of future asymmetric supercapacitors