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Carbon dots are zero‐dimensional carbon nanomaterials with quantum confinement effects and edge effects, which have aroused great interests in many disciplines such as energy, chemistry, materials, and environmental applications. They can be prepared by chemical oxidation, electrochemical synthesis, hydrothermal preparation, arc discharge, microwave synthesis, template method, and many other methods. However, the raw materials' high cost, the complexity and environmental‐unfriendly fabrication process limit their large‐scale production and commercialization. Herein, we review the latest developments of coal‐based carbon dots about selecting coal‐derived energy resources (bituminous coal, anthracite, lignite, coal tar, coke, etc.) the developments of synthesis processes, surface modification, and doping of carbon dots. The coal‐based carbon dots exhibit the advantages of unique fluorescence, efficient catalysis, excellent water solubility, low toxicity, inexpensive, good biocompatibility, and other advantages, which hold the potentiality for a wide range of applications such as environmental pollutants sensing, catalyst preparation, chemical analysis, energy storage, and medical imaging technology. This review aims to provide a guidance of finding abundant and cost‐effective precursors, green, simple and sustainable production processes to prepare coal‐based carbon dots, and make further efforts to exploit the application of carbon dots in broader fields.

With the popularity of stereo printing technology, 3D printers are widely used in industry, manufacturing, medicine, and other industries to quickly manufacture small devices. Before 3D printing, it is necessary to plan the printing path. Unreasonable printing path will not only increase the time consumption of printing products, but also cause printing failure due to the accumulation of stress and deformation in the printing process. In order to overcome the superimposed stress and deformation in the process of printing thin-walled complex devices, this article introduces the idea of balanced stress based on the basic damage of the path planning based on the potential field method. In the printing process, the ring path, island path and cross path are added to overcome the stress deformation phenomenon and improve the printing quality. Finally, the 3D printer is used to manufacture thin-walled complex devices, and the feasibility of the balanced potential field method is verified by physical comparison.

Under the public spotlight, uranyl (UO22+) ions has attracted considerable attention for the extreme radioactive and chemical toxicity to ourselves and our environment. Herein, we present a simple and effective ratiometric fluorescence imaging method for the visualizing and quantitative detection UO22+ ions by cellphone-based optical platform. The sensing solution was prepared by mixing label-free red carbon dots (r-CDs) and blue carbon dots (b-CDs) together with a fixed photoluminescence intensity ratio of 4:1. When UO22+ ions were added, the fluorescence of r-CDs can be selectively quenched, while the fluorescence of b-CDs remains stable without spectral changes. With the gradually increase the amounts of UO22+ ions, the different response of dual-color CDs resulted in a signification color evolution from deep red to dark purple under the ultraviolet (UV) light illumination. Then, a cellphone-based optical platform was constructed for directly imaging the color change of the samples, and the built-in Colorpicker APP quickly output the red, green and blue (RGB) channel values of these images within one second. Interesting, there was a linear relationship between the ratio of red and blue (R/B) channel values and UO22+ ions concentration from 0 μmol/L to 30.0 μmol/L (R2 = 0.92804) with the detection limit of ∼8.15 μmol/L (signal-to-noise ratio of 3). In addition, the optical platform has also been applied to the quantification of UO22+ ions in tap water and river water sample. With the advantage of low-cost, portable, easy to operation, we anticipate that this method would greatly improve the accessibility of UO22+ ions detection even in resource-limited areas.

Metal–organic frameworks (MOFs) are a new type of porous crystal materials that have been widely used in various fields. Owing to their adjustable porous structure, MOF photocatalysts with high catalytic activity have become a research hotspot. In this study, NH2-MIL-125/CoSx samples were investigated as a novel visible light-responsive catalyst for the removal of organic dye. The NH2-MIL-125/CoSx-20 composites showed the best photodegradation efficiency, where photodegradation of the rhodamine B reached 95.4% in 45 min. CoSx was able to effectively extend the wavelength absorption range of NH2-MIL-125 and effectively separate the photogenerated electrons and holes and that could lead to the improved photocatalytic performance of the composites. The reactive superoxide radical (·O2−) was identified as the main active species using reactive species capture experiments, and a reasonable photocatalytic mechanism was proposed. This paper is intended to guide the development of organic–inorganic hybrid materials for environmental remediation.

Color-tunable semiconductor quantum dots (QDs) are highly attractive for a wide range of applications including imaging, sensing, and lighting. Herein, we reported a facile synthesis of copper-doped zinc sulfide quantum dots (ZnS:Cu QDs) with tunable emission colors, using a microwave-assisted one-pot reaction. 3-mercaptopropionic acid (MPA) was used as a stabilizer agent and sulfide source for the formation of ZnS:Cu QDs. The photoluminescence of ZnS:Cu QDs showed a clear red-shift as increasing Cu concentration, which can be controlled by microwave irradiation time. As increasing the irradiation time, the emission color (peak) of ZnS:Cu QDs changed from blue (500 nm) to green (540 nm), yellow (580 nm), and to orange-red (595 nm). The obtained ZnS:Cu QDs were highly luminescent, as evidenced by their high quantum yields. The potential utility of ZnS:Cu QDs as a novel lighting source was demonstrated in a near-UV chip-based white light-emitting diode.

We reported integration of conductivity, chirality, and porosity into MIL-101@chiral-PANI composite for synchronous chiral recognition, adsorption, and sensing toward enantiomers. The core-shell structure of MIL-101@chiral-PANI was characterized in detail by Fourier transform infrared and circular dichroism spectroscopy as well as scanning electron microscopy and transmission electron microscopy. Adsorption behaviors of carvone enantiomers over chiral PANI and MIL-101@chiral-PANI are satisfied with pseudo-first-order fitting. In comparison with chiral PANI, MIL-101@c-PANI exhibits a better enantioselectivity and much higher (5-fold) adsorption amount over l-carvone than d-carvone. And MIL-101@c-PANI is able to recognize the chirality of carvone via electrochemical sensing, taking advantage of the electric conductivity of chiral PANI. Our result demonstrated the feasibility of applying achiral MOF for enantioselective sensing and adsorption via installing chiral and conductive gates. And this chiral polymer modification strategy represents a universal way to entitle achiral MOFs with chiral functions.

We reported an example of metal–organic framework (MOF)-based porous liquid by dispersing ZIF-8 ({Zn(mim)2}, mim = 2-methylimidazole) nanocrystallites in ionic liquid (IL) of [Bpy][NTf2] (N-butyl pyridinium bis(trifluoromethyl sulfonyl)imide). Two essential challenges, stable colloid formation and porosity retention, have been overcome to prepare MOF-based porous liquid. Preventing ZIF-8 nanocrystals from aggregation before dispersing is vital to form a stable ZIF-8 colloid in IL via enhancing the interaction between ZIF-8 and IL. The resultant ZIF-8–[Bpy][NTf2] colloid is able to be stable over months without precipitating. [Bpy][NTf2] with larger ion sizes cannot occupy pores in ZIF-8, leaving the ZIF-8 cage empty for enabling access by guest molecules. The porosity of this porous liquid system was verified by positron (e+) annihilation lifetime spectroscopy and I2 adsorption in ZIF-8 in the colloid. MOF-based porous liquids could provide a new material platform for liquid-bed-based gas separations.

We demonstrated a facile and efficient method for the preparation of a magnetic and porous Ni@MOF-74(Ni) [Ni 2 (DOBDC), DOBDC = 2, 5-dihydroxyterephthalate] composite by one-step solvothermal reaction of Raney Ni and DOBDC. Ni in the reaction not only acted as the core of the composite, but also provided metal source for the formation of MOF-74(Ni). The Ni@MOF-74(Ni) composite exhibits both magnetic characteristics and high porosity, enabling it an efficient candidate for dye removal and target drug delivery system. The adsorption amount of rhodamine b reached up to 177.8 mg g −1 , and 4.1 mg g −1 for ibuprofen.

This paper presents a study on the durability of the ternary cementitious system (TCS) containing ordinary Portland cement, calcium aluminate cement and calcium sulfate with different content of ground granulated blast furnace slag (GGBS) when subjected to 5% NaCl, 5% Na2SO4, and 5% NaCl–5% Na2SO4 attacks. The results showed that the partial replacement of TCS by GGBS increased bound chloride, enhanced compressive strength, and decreased apparent porosity. Besides, the presence of chloride mitigated sulfate attack. The presence of sulfate decreased the contents of free and total chloride, and limited the formation of Friedel’s salt.

Open-cell Mg-xGd-2Zn (x = 4, 6 and 8 wt.%) foams were fabricated. The phase compositions, microstructures and element distributions of the foams with different amounts of added Gd were studied by X-ray diffraction, optical microscopy, scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The compressive properties of the foams were evaluated by compressive testing at the temperatures ranging from room temperature (RT) to 300 °C. The experimental results show that an increase in the Gd content refines the microstructures of the foams and promotes the formation of long periodic stacking ordered phase. An increased temperature results in the reduction in the compressive strength and the energy absorption capacity of the foams. Additionally, the compressive strength and energy absorption capacity at each testing temperature increase with increasing Gd content. The mechanisms underlying these effects are discussed based on the relationship between the compressive properties and the Gd content of the foams.

The self-healing capability of cracks plays an important role in improving the durability of concrete. This study investigated the the self-healing capability of mortar with crystalline admixture and fly ash under three conditions. The compressive strength, water absorption, and surface crack pattern were used to evaluate self-healing capability of mortar, and the composition of the healing products was analyzed by x-ray diffraction and scanning electron microscopy. The results indicated that the crystalline admixture could improve the self-healing capability of cementitious materials but caused a negative effect if adding too great an amount of fly ash (≥20%). The specimen that was immersed in water showed favorable self-healing capability of cracks. The healing products in cracks are mainly composed of CaCO3.

We present a facile and one-step synthesis of N-decorated porous carbon (NPC) material via direct heating dicyanobenzene in presence of ZnCl2, free from any pre- and post-treatments. The resultant NPC material features with graphite-like monolayers with thickness of ca. 1.4 nm as proved by microscopy technology. Highly porous NPC shows a BET surface area of 3038.5 m2 g-1 and a narrow pore size distribution centered at 0.51 nm. As a consequence, NPC displays a high H2 uptake up to 2.96 wt% at 77 K and CO2 adsorption capability of 23.4 wt% at 278 K and 1 bar. N-doping leads to optical absorption of NPC extended into near infrared (NIR) region. This N-decorated carbon material, as first example of NIR-triggered carbon photocatalyst, exhibits a pronounced H2 production capability. Carbonization of aromatic multi-nitriles would be a general and facile approach to prepare multifunctional N-doped carbon materials for gas storage and full solar spectrum-driven photocatalysts.

We report a stable and semiconductive heteropolyoxotitanate of [Ti12Cr6O18(OOCC6H5)30] (denoted as POTi12Cr6), which exhibits a pronounced photocatalytic hydrogen evolution rate, photothermal effect, and photocurrent under full solar spectrum, including near-infrared (NIR) irradiation, moreover, with high stability in both acid and base aqueous solution. Crystallinity and photocatalytic activity of POTi12Cr6 remain unchanged under cycling photocatalysis tests. This work demonstrates an approach to overcome the common restriction of low stability and limited solar absorption capability in polyoxotitanate- and TiO2-based materials. The result will open up heteropolyoxotitanate as a novel type of semiconductor material for the full solar spectrum, especially NIR energy utilization including photothermal transformation, photocurrent response, and photocatalytic H2 evolution.

We present a novel strategy to improve the stability and optical absorption of polyoxotitanates (POTs) via concurrently fully carboxylate-coordinating and hetero-metal-doping, and illustrate the strategy by an indium doped hetero-polyoxotitanate (h-POT) of a [Ti12In6O18(OOCC6H5)30] (POTi12In6) nanocluster, which possesses ultrahigh stability in both acid and base aqueous solutions. The nanocluster structurally features a core–shell double wheel structure and a polar cavity. Both experiments and theoretical calculations confirm the semiconductive properties of the nanocluster. Under visible irradiation the POTi12In6 nanocluster can produce pronounced photocurrent, and reactive oxygen species for pollutant degradation. Without using any cocatalyst, POTi12In6 exhibits important visible-light-driven photocatalytic activity for H2 evolution in an aqueous system. This work could render a polyoxotitanate as a new type of visible-photoactive photocatalyst.

Two new chromium and manganese bimetallic nanoclusters, [Cr8−xMnx(OH)8−x(H2O)x(OOCC6H5)16, x = 1.11] (1) and [Cr4Mn4O4(OOCC6H5)12·3CH3CN·H2O] (2), have been synthesized in a one-pot solvothermal reaction in this work. Under visible irradiation, cluster 1 can produce an increased photocurrent and exhibits significant visible-light-driven photocatalytic activity for H2 evolution in an aqueous system. Most importantly, it exhibits ultrahigh stability in both acid and base aqueous solutions, making it an excellent synthon for preparing functional materials.

Herein, a ratiometric fluorescence sensing strategy coupled with smartphone imaging-based sensing platform was proposed for the on-site determination of fluoride ion (F−) with high sensitivity and accuracy. The principle of sensing strategy is based on the fluoride-promoted Si–O bond cleavage of 2-(tert-butyldiphenylsilyloxy)phenol (2-TBDPSP) to release 2-hydroxyphenolate, which rapidly auto-oxidized to ortho-quinone. As excellent electron acceptor, these quinone species covalently bonded on the surface of dual-emission amino-modified quantum dots (QDs) nanohybrid via a Michael's type adduction, quenching the fluorescence of green-emitting QDs on the surface of the nanohybrid, while not affecting the fluorescence of red-emitting QDs embedding silica nanospheres. Upon exposure to different amounts of F−, the variations of dual emission intensity ratios display continuous color changes from green to red, which could be directly observed by naked eyes. Then a smartphone imaging-based sensing platform was constructed by 3D-printing technology. The smartphone camera acquired the images of fluorescence derived from samples, and the Color Picker APP installed in smartphone continued to read out the Red, Green and Blue (RGB) channel values of these images. There was a linear relationship between the ratio of Red and Green (R/G) and F− concentration in the range of 0–70.0 μM. The limit of detection (LOD) was estimated to be 2.0 μΜ, much lower than the allowable level of F− (~63.16 μM) in drinking water set by World Health Organization. This methodology reported here is low-cost, portable, easy-operation, and thus potentially attractive for F− determination without the need of elaborate equipment.

This experiment investigates the effect of time on the quality of the film during the micro-arc oxidation of magnesium alloys. The micro-arc oxidation surface morphology, the thickness of the film layer, and the influence on the corrosion resistance of the magnesium alloy were studied at different times. The experiment found that when the micro-arc oxidation time is controlled at 9 minutes, the surface quality of the film layer is the best, and the improvement of the corrosion resistance is more obvious.

Self-healing properties of cementitious materials is an important way to improve the durability of concrete. The effect of various granulated blast furnace slag (GBFS) contents on the self-healing properties of mortar with crystalline admixture (CA) were studied. The compressive strength recovery rate, water absorption rate and visual crack healing were used to evaluate the early age and structural cracks self-healing capability, and the self-healing products were studied by X-ray diffraction (XRD), scanning electron microscopy and energy spectrum analysis (SEM-EDS). The results show that CA ensures the self-healing properties, the mortar with CA and 10 wt. % GBFS has the highest self-healing capability, and the healing product is mainly composed of calcium carbonate.

The open-cell Mg-xSi (x = 1, 5, 9 wt%) foams reinforced by in-situ Mg2Si compounds were prepared by pressure infiltration process. The optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) were used to investigate the microstructure, chemical components and phase compositions of the foams, respectively. Compressive strength and energy absorbing characteristics of the foams containing varied Si additions were assessed via compressive test. The experimental results exhibit that the microstructure of the foams is depending on Si content. Mg 1Si foams are mainly composed of eutectic Mg2Si and α-Mg, while Mg 5Si and Mg 9Si foams mainly consist of the primary Mg2Si, eutectic Mg2Si and α-Mg. The compressive strength of the foams is elevated initially and then decreased when the Si content is increased from 1 to 9 wt%, but the energy absorption capacity is reduced with the increase of Si content. The related mechanism was discussed and a schematic diagram was drawn to reflect the role of coarse primary Mg2Si in fracture behavior of the foams.

Correlated X-ray scattering (CXS) which was explored to study the conformations of biological macromolecules in solution was studied further in this paper. In our experiment, three kinds of solution sample such as the Peg solution, the linear DNA from salmon sperm and the plasmid DNA were scattered by X-ray Free Electron Laser in Spring8 in Japan. And the X-ray scattering patterns with low rate of signal and noise were obtained. In order to improve the correlated signal, a cluster data filtering method for billions of scattering patterns was put forward. Finally, some of the scattering patterns with high artifacts which were related with potential sources of experimental set-up had been characterized and removed. In addition, different clusters were clarified so as to compute and analyze the angular autocorrelation of different clusters more effectively.

Surface-enhanced Raman scattering (SERS) has been proven to be a powerful analytical tool for the detection of trace molecules because of its integration of high sensitivity, unique spectroscopic fingerprint, and non-destructive data acquisition. However, the lack of reliable, stable, well-defined, and uniform SERS substrates impedes their further practical applications. Herein, we have developed a SERS-active substrate based on a flexible and stable polymer (PDMS) film loaded with nanoparticles for ultrasensitive Raman signal readout and trace detection of pesticide residues in agricultural products and environments. By controlling the deposition of Ag nanoparticles, tremendous Raman enhancement can be achieved due to numerous hot spots generated among the Ag nanoparticles on the PDMS composite film. The flexible SERS film can be employed to detect rhodamine 6G (R6G) with an enhancement factor (EF) of 3.37 × 1011 and the pesticide thiram in commercial grape juice with a detection limit of as low as 0.1 μm (0.03 ppm), which is considerably lower than the maximum residue limit (MRL) of 7 ppm in fruit prescribed by the U.S. Environmental Protection Agency (EPA). Furthermore, spiked detection indicated that the AgNP–PDMS flexible film can be used to monitor thiram in commercial grape juice and natural lake water without further treatment. Therefore, the AgNP–PDMS flexible film enhanced Raman spectroscopic technique offers great potential for practical applications in the on-site monitoring and assessment of pesticide residues in agricultural products and environments.

Analytical techniques based on surface-enhanced Raman scattering (SERS) suffer from a lack of reproducibility and reliability, thus hampering their practical applications. Herein, we have developed SiO2@Ag nanospheres as an effective SERS detection platform through in situ loading Ag nanocontacts onto the SiO2 nanospheres, the well-designed and uniform nanocomposites provide highly enhanced effects for the tremendous SERS signal amplification. The huge enhanced effect might originate from the hot spots generated from the nanocontacts among the silver nanoparticles loaded onto the silica nanosphere, and also possibly from the nanogaps among the neighboring silver nanoparticles between the two silica nanospheres. The SERS enhancement factor of the SiO2@Ag nanospheres substrate is as high as 1016. Moreover, the as-fabricated SERS substrate can be employed to enhance the Raman signals of some chemicals that are harmful to environment including thiram, melamine and ethyl-parathion. The detection limits with the SERS platform are several orders of magnitude lower than the maximal residue limit (MRL) in fruit prescribed by U.S. Environmental Protection Agency (EPA). Therefore the surface lifting spectroscopic technique based on the SiO2@Ag nanosphere SERS platform offers great practical potential for the on-site assessment and identification of harmful chemicals with ultralow concentrations in agricultural products and environments.

We have developed a direct and scalable approach, based upon a thermal decomposition method under normal atmospheric pressure via an interface diffusion mechanism, for growing well-defined single-crystalline functional metal oxide nanobelts. Several metal oxide nanobelts including magnetic oxides, transparent conducting oxides, and other functional oxides can be synthesized on a large scale. The typical synthesis strategy involves the synthesis of the precursors via a solvothermal process and subsequently the fabrication of the nanobelts through thermal decomposition of the precursors at atmospheric pressure, and the sizes (the length and the width) of nanobelts can be easily tuned by modifying the heating temperature and the heating rate. This synthetic strategy might not only shed a new light on the facile, general synthesis and functional mechanisms of the functional metal oxide nanobelts, but also extend the practical applications of the nanobelts in a variety of fields.

The development and innovation of strategies for the fabrication of oriented nanostructures has been among the hot research topics in the field of nanoscience because of the novel properties of these nano-arrays, that differ drastically from their bulk counterparts, and their potential applications in many areas including the chemical, physical, biological and engineering fields. Herein, we have demonstrated an extremely simple procedure for the fabrication of a forest of oriented silver nanowires at ambient temperature in aqueous solution without a hard template. The oriented silver nanowire arrays exhibit better field emission performance than that of a single nanowire or non-oriented nanowires. By variation of the experimental parameters, the diameter and length of the oriented Ag nanowires can be tuned accordingly. The successful fabrication of a forest of the oriented nanowires under mild conditions without a template not only provides an efficient route to selectively control the preparation of oriented nano-arrays, but also provides new insights into the underlying surfactant-mediated mechanism of nano- and micro-architectures. This strategy might be extended to fabricate other metal and semiconductor nanocrystal arrays and widen their potential applications in many fields.

Molecular recognition events that occur at the interface between inorganic surfaces and organic molecules play a critical role in a wide field of technologically and scientifically relevant processes including heterogeneous catalysis, crystal growth, and the development of sensor systems based on functional materials. Herein, we have developed a general and versatile method for the controlled synthesis of nanosized silver crystals with different shapes ranging from microspheres assembled with nanoparticles, nanocubes, nanocones to one-dimensional (1D) nanostructures including nanobelts and nanohelixes. These well-defined morphologies were obtained by controlling the relative growth rate of the crystal plates by selective use of capping ligand mixtures. The method involves the slow chemical reduction of the silver precursor by amine molecules. It is known that certain amines function as weak (and thus slow) reductants and as metal coordination ligands for metal complexes in solution. Both these properties should contribute to a slow rate of crystal growth and hence to the formation of special shapes under different solutions. We have used dodecylamine (DA) in combination with other amine ligands under selected solvents for the synthesis of the silver nanocrystals with different shapes. By changing the composition of the amine ligand mixture, nanosized crystals with different feature shapes and sizes can be obtained. Our results suggest a general strategy for the morphology controlled synthesis of metallic nanocrystals with different feather shapes: utilization of molecular recognition at the crystallographic planes under slow-growth conditions.