Nanjing Tech University

About: Nanjing Tech University is a education organization based out in Nanjing, China. It is known for research contribution in the topics: Catalysis & Membrane. The organization has 21827 authors who have published 21794 publications receiving 364050 citations. The organization is also known as: Nangongda & Nánjīng Gōngyè Dàxúe.

Lanthanide-Activated Phosphors Based on 4f-5d Optical Transitions: Theoretical and Experimental Aspects.

Abstract: The synthesis of lanthanide-activated phosphors is pertinent to many emerging applications, ranging from high-resolution luminescence imaging to next-generation volumetric full-color display. In particular, the optical processes governed by the 4f-5d transitions of divalent and trivalent lanthanides have been the key to enabling precisely tuned color emission. The fundamental importance of lanthanide-activated phosphors for the physical and biomedical sciences has led to rapid development of novel synthetic methodologies and relevant tools that allow for probing the dynamics of energy transfer processes. Here, we review recent progress in developing methods for preparing lanthanide-activated phosphors, especially those featuring 4f-5d optical transitions. Particular attention will be devoted to two widely studied dopants, Ce3+ and Eu2+. The nature of the 4f-5d transition is examined by combining phenomenological theories with quantum mechanical calculations. An emphasis is placed on the correlation of hos...

Amphiphilic Egg-Derived Carbon Dots: Rapid Plasma Fabrication, Pyrolysis Process, and Multicolor Printing Patterns

Abstract: Carbon-based photoluminescent nanoparticles have recently received increased interest, owing to their favorable optical properties along with their biocompatibility and low toxicity. Such nascent nanomaterials, the so-called carbon dots (CDs or C-dots), are a promising alternative to more toxic metal-based semiconductor quantum dots (QDs) for applications such as bioimaging. Recent advances in the synthesis of CDs allow them to be formed from fine carbon structures (like graphene and multi-wall carbon nanotubes) by topdown methods, or from chemical precursors (like ammonium citrate and ethylenediaminetetraacetic acid) by bottom-up approaches. Typically, these CDs require surface oxidation and/or further passivation to emit fluorescence, which also makes them hydrophilic. Alternatively, some one-step strategies to fabricate surface-passivated CDs have also been shown. We reported a one-step synthesis of multicolor CDs from pyrolysis of epoxy-enriched polystyrene photonic crystals and their potential for use in light-emitting diodes. Herein, we present a simple and rapid strategy to fabricate CDs from cheap and natural carbon sources and further extend their application as printing “inks”. The fluorescent CDs developed herein have the following notable characteristics: 1) one-step generation in minutes from low-cost, natural, edible chicken eggs by plasma-induced pyrolysis; 2) good amphiphilicity with high solubility in a broad range of aqueous and organic solvents; 3) resistance to acids and bases; 4) versatile applications as fluorescent carbon inks for luminescent patterns. Figure 1 shows the fabrication of egg-derived fluorescent CDs and their application as “inks” for luminescent patterns using inkjet or silk-screen printing. We chose chicken eggs as the starting material to maintain low toxicity and affordability of the final product. Low-temperature plasma with highenergy, inherently charged particles (electrons or cations) and excited neutral species was used to create an active chemical environment for the synthesis of the nanostructures. As shown in Figure 1, the egg was separated into egg white and egg yolk, using an egg-separator, prior to use. A glass dish filled with egg white or yolk was placed between two quartz slides (height= 1.5 cm) of the plasma generator. Subsequently, intense and uniform plasma beams generated from the upper electrode (voltage= 50 V, current= 2.4 A) irradiated the egg samples for 3 min to yield dark black products, referred to as CDpew and CDpey for the plasma-treated egg white and yolk, respectively. The yield of CDs from the egg sample was calculated to be approximately 5.96%. Elemental analysis showed an increase in the carbon content of the products (62.42% for CDpey and 56.75% for CDpew) in comparison to that of the starting material (57.55% for egg yolk and 43.50% for egg white), implying carbonization occurs during the plasma treatment (Supporting Information, Table S1). Significantly, solutions of CDpew and CDpey display bright blue fluorescence under UV light (lex= 302 nm). Figure 2 shows high-resolution transmission electron microscope (HRTEM) images of the CDs. CDpey had uniform dispersion without apparent aggregation and a mean particle diameter (Dp) of 2.15 nm (Figure 2a and Figure S2). Detectable rings in the selected-area electron-diffraction (SAED) pattern revealed the crystalline structure of CDpey (Figure 2a inset). Well-resolved lattice fringes with an interplanar spacing of 0.208 nm were observed (Figure 2b), which is close to the (100) facet of graphite. On the other hand, CDpew was well distributed (Dp= 3.39 nm) and appeared Figure 1. Digital photographs of plasma-induced fabrication of eggderived CDs and their application as fluorescent carbon inks. Egg white or yolk, after a few minutes of plasma treatment under ambient conditions, were transformed into well-defined CDs with bright blue emission under UV light. The CD solutions can also be used as inks for making luminescent patterns by inkjet or silk-screen printing.

Nonradical reactions in environmental remediation processes: Uncertainty and challenges

Abstract: Recent discoveries of nonradical oxidation in aqueous-phase advanced oxidation processes (AOPs) have induced tremendous interest in environmental remediation of wastewater, whereas different findings from a variety of investigations have also raised severe controversies in the occurrence and mechanism of the nonradical reaction. Hence, critical understandings of the nonradical reaction will significantly advance the knowledge and its application for catalytic oxidation and wastewater treatment. In this review, we would like to present state-of-the-art research on nonradical pathways in persulfate-based AOPs, with emphases on the controversial methodologies for identifying the oxygen reactive species (ROS), ambiguous reaction mechanisms, intrinsic impacts of metal/carbon catalysts and organic substrates in the nonradical-based catalytic oxidation reactions. Moreover, further research directions on mechanistic investigation of the nonradical pathway with rational experimental design and advanced strategies, as well as the potential applications of the nonradical system are proposed.

Energy decomposition analysis

Abstract: The energy decomposition analysis (EDA) is a powerful method for a quantitative interpretation of chemical bonds in terms of three major components. The instantaneous interaction energy ΔEint between two fragments A and B in a molecule A–B is partitioned in three terms, namely (1) the quasiclassical electrostatic interaction ΔEelstat between the fragments; (2) the repulsive exchange (Pauli) interaction ΔEPauli between electrons of the two fragments having the same spin, and (3) the orbital (covalent) interaction ΔEorb which comes from the orbital relaxation and the orbital mixing between the fragments. The latter term can be decomposed into contributions of orbitals with different symmetry which makes it possible to distinguish between σ, π, and δ bonding. After a short introduction into the theoretical background of the EDA we present illustrative examples of main group and transition metal chemistry. The results show that the EDA terms can be interpreted in chemically meaningful way thus providing a bridge between quantum chemical calculations and heuristic bonding models of traditional chemistry. The extension to the EDA–Natural Orbitals for Chemical Valence (NOCV) method makes it possible to breakdown the orbital term ΔEorb into pairwise orbital contributions of the interacting fragments. The method provides a bridge between MO correlations diagrams and pairwise orbital interactions, which have been shown in the past to correlate with the structures and reactivities of molecules. There is a link between frontier orbital theory and orbital symmetry rules and the quantitative charge- and energy partitioning scheme that is provided by the EDA–NOCV terms. The strength of the pairwise orbital interactions can quantitatively be estimated and the associated change in the electronic structure can be visualized by plotting the deformation densities. For further resources related to this article, please visit the WIREs website.

Stretchable Ti3C2Tx MXene/Carbon Nanotube Composite Based Strain Sensor with Ultrahigh Sensitivity and Tunable Sensing Range

Abstract: It remains challenging to fabricate strain-sensing materials and exquisite geometric constructions for integrating extraordinary sensitivity, low strain detectability, high stretchability, tunable sensing range, and thin device dimensions into a single type of strain sensor. A percolation network based on Ti3C2Tx MXene/carbon nanotube (CNT) composites was rationally designed and fabricated into versatile strain sensors. This weaving architecture with excellent electric properties combined the sensitive two-dimensional (2D) Ti3C2Tx MXene nanostacks with conductive and stretchable one-dimensional (1D) CNT crossing. The resulting strain sensor can be used to detect both tiny and large deformations with an ultralow detection limit of 0.1% strain, high stretchability (up to 130%), high sensitivity (gauge factor up to 772.6), tunable sensing range (30% to 130% strain), thin device dimensions ( 5000 cycles). The versatile and scalable Ti3C2Tx MXene/CNT strain sens...