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Carbon dots (CDs), novel luminescent zero-dimensional carbon nanomaterials, have been widely applied due to their low toxicity, optimal optical properties, and easy modification. However, the current controllable equipment and mechanism explanation of CDs are relatively vague and require urgent resolution. Full-color emission CDs, an essential CDs category, have attracted people's attention given their light and color-tunable properties. In addition to a wider range of biological and optoelectronic device applications, full-color emission CDs have similar structures and significantly affected the fluorescence mechanism of CDs. At present, few studies have reported on the summary research of CDs emitted by its full color, which greatly limits the development of CDs mechanisms and applications. As such, the present review detailed the full-color CDs development status, to which a suitable method for preparing full-color CDs was presented and the existing fluorescence emission mechanism of full-color CDs was summarized. Herein, we comprehensively introduced full-color CDs applications in biology and optoelectronics. Finally, we made an outlook on the development and potential applications of full-color CDs. The present review aims to contribute novel insights and methods for understanding full-color CDs.

Chiral molecules are widely prevalent in nature and biological systems, and artificial chiral nanoparticles have drawn enormous interest owing to their unique optical and physical properties. Howev...

It is a viable approach to tailor the optical and catalytic properties of noble-metal nanocrystals by controlling their geometric shapes. Among various shapes, rhombic dodecahedra are considered pa...

Blue-emitting room-temperature phosphorescence (RTP) materials have always been one of the major challenges in the field of RTP materials. Deep-blue (430 nm) RTP emitting silica microparticles were prepared via a one-step hydrothermal reaction from a single raw material of 3-aminopropyltriethoxysilane (APTES). APTES provided amino groups and ethyl groups as a nitrogen and carbon source, which was further condensed to be nitrogen-contained carbon dots (CDs). Besides, the siloxane side of APTES was hydrolyzed and formed silica microparticles. The CDs with the potential chromophores (C═O and C-N etc.) were connected to SiO2 via Si-C bonds of APTES. The covalent bonds and the rigid silica network effectively restricted the motions of potential chromophores of the CDs and reduced the energy gap between the singlet state and triplet state, which was favorable to the RTP. It was believed that this work will guide researchers to realize other blue or deep-blue RTP materials.

Halide perovskite single crystals (HPSCs) provide a unique platform to study the optoelectronic properties of such emerging semiconductor materials, while the temperature induced crystal growth method often has an increased solute integration speed and/or unavoidable solute consumption, resulting in a soaring or slumping crystal growth rate of HPSCs. Here, we developed a universal and facile solvent-volatilization-limited-growth (SVG) strategy to finely control the crystal growth rate by the fine-control-valve for high quality crystal grown through solution processes. The grown HPSCs by SVG method exhibited a record low trap density of 2.8 × 108 cm−3 and a high charge carrier mobility-lifetime product (μτ product) of 0.021 cm2/V, indicating the excellent crystal quality. The crystal surface defects were further passivated by oxygen suppliers as Lewis base, which led to a reduction of surface leakage current by two times when using for low dose rate X-ray detection. Such HPSC X-ray detector displayed a high sensitivity of 1274 µC/(Gyair cm2) with a lowest detectable dose rate of 0.56 μGyair/s under 120 keV hard X-ray. Further applications including alloy composition analysis and metal flaw detection by HPSC detectors were also demonstrated, which not only shows the bright future for product quality inspection and non-destructive materials analysis, but also paves the way for growing high quality single crystals and fabricating polycrystalline films.

Miniaturized solid-state lasers with a single longitudinal mode are vital for various photonic applications. Here we prepare red-emissive carbon dots (CDs) with a photoluminescence quantum yield (PLQY) of 65.5 % by combining graphitic nitrogen doping and surface modification. High-concentration doping alters the CDs' emission from blue to red, while the electron-donating groups and polymer coating on their surfaces improve the PLQY and photostability. The CDs exhibit excellent stimulated emission characteristics, with a low threshold of amplified spontaneous emission (ASE) and long gain lifetime. A planar microcavity with only one resonant mode, which fitted with the CDs' ASE peak, was constructed. Combining the CDs and microcavity produced a solid-state laser with a single longitudinal mode, a linewidth of 0.14 nm and a signal-to-noise ratio of 14.8 dB (Q∼4600). Our results will aid the development of colorful solid-state micro/nano lasers with potential use in practical photonics.

With the purpose of oil energy recovery as well as achieving efficiency of oil/water separation, hydrophobic mesh materials have attracted extensive attention. However, fabrication of the current methods is not environmentally friendly, has high energy consumption, and creates serious pollution. Inspired by lotus leaves and rose petals, a biomimetic superhydrophobic surface was fabricated prepared on a stainless steel mesh by an in situ chemical reduction method with simple operation and mild conditions. The results of SEM, XRD, and XPS demonstrated that the mesh shows a stable and uniform moss-like rough structured surface. The SSM/Ag/ODA mesh, which was modified by moss-like Ag nanoclusters and low surface energy agents, has excellent superhydrophobicity with an excellent oil/water separation efficiency that reached up to 99.8%. The silver mirror phenomenon formed by the Ag nanoclusters further confirmed that silver ions were reduced and attached to the surface of the mesh. Moreover, the mesh can maintain superhydrophobicity under harsh conditions, such as a high concentration of a salty solution, organic solvents, alkaline, acidic solution, and even long-time UV irradiation, etc. More importantly, the modified mesh has excellent physical stability, in which the water contact angle on the mesh can be maintained above 150° after harsh mechanical wear. The hydrophobic mesh showed great potential to be applied for highly efficient oil/water separation and oil energy recovery even under complex and harsh conditions.

Iron-based alloy coatings were deposited on grey cast iron through plasma transfer arc welding. Results showed that the iron-based alloy coatings are composed of pearlite, martensite, austenite, an...

Carbon dots (CDs), as a kind of carbon nanomaterials, have attracted widespread attention due to their unique structure and excellent optical properties, and they are low-cost, environmentally friendly and biocompatible. However, the development of near-infrared (NIR) emission CDs remains a challenge. In this study, we successfully prepared CDs with a maximum emission of 714 nm using citric acid as the carbon source, thiourea and ammonium fluoride as the dopant source, and N,N-dimethylformamide as the solvent. The quantum yield (QY) is as high as 22.64%. Interestingly, the prepared CDs self-oxidize in the presence of oxygen, resulting in a blue shift of their emission. Therefore, they can be used to prepare white light-emitting diodes (WLEDs) without adding other fluorescent substances. Notably, the work presented herein constitutes the first report of WLEDs preparation from single CDs.

Carbon dots (CDs) have attracted much attention due to their excellent photoelectric properties and potential applications. Although previous studies have shown that almost all organic molecules can be converted into CDs via chemical carbonization, the mechanism of the conversion process remains unclear. The hydrothermal/solvothermal method commonly used to prepare CDs is complicated and leads to the generation of many by-product CDs with similar structures. Considering that the purification of the synthesized by-products is difficult, the process of CDs formation cannot be readily analyzed and understood. Herein, we use ethanol as a carbon source to synthesize white-emitting CDs (W-CDs). Column chromatography separation shows that the synthesized W-CDs are composed of blue-, cyan-, and yellow-emitting CDs that fluoresce at wavelengths corresponding to the three emission centers of W-CDs. Although the samples have similar graphitic structure, they exhibit different surface states due to variations in the degree of oxidation and carbonization. Therefore, the red-shift in their emission peaks is attributed to an increased degree of carbonization in their polymer structure. Theoretical calculations verify the experimental results, and the prepared CDs are successfully used to develop multi-color and white light-emitting diodes (LEDs).

Diabetic foot ulcers (DFUs) are hard-healing chronic wounds and susceptible to bacterial infection. Conventional hydrogel dressings easily lose water at high temperature or freeze at low temperature, making them unsuitable for long-term use or in extreme environments. Herein, a temperature-tolerant (-20 to 60 °C) antibacterial hydrogel dressing is fabricated by the assembly of polyacrylamide, gelatin, and e-polylysine. Owing to the water/glycerin (Gly) binary solvent system, the resultant hydrogel (G-PAGL) displayed good heat resistance and antifreezing properties. Within the wide temperature range (-20 to 60 °C), all the desirable features of the hydrogel, including superstretchability (>1400%), enduring water retention, adhesiveness, and persistent antibacterial property, are quite stable. Remarkably, the hydrogel wound dressing displayed lasting and broad antibacterial activity against Gram-positive and Gram-negative bacteria. Satisfactorily, the double-network (DN) G-PAGL hydrogel dressing could effectively promote the healing of DFUs by accelerating collagen deposition, promoting angiogenesis, and inhibiting bacterial breed. As far as we know, this is the first time that the extensive temperature-tolerant DN hydrogel with antibacterial ability is developed to use as DFU wound dressing. The G-PAGL hydrogel provides more choices for DFU wound dressings that could be used in extreme environments.

A new synthetic approach has recently been developed for the fabrication of freestanding crystalline perovskite oxide nanomembranes, which involves the epitaxial growth of a water-soluble sacrificial layer. By utilizing an ultrathin capping layer of SrTiO3, here we show that this sacrificial layer, as grown by pulsed laser deposition, can be stabilized in air and therefore be used as transferrable templates for ex situ epitaxial growth using other techniques. We find that the stability of these templates depends on the thickness of the capping layer. On these templates, freestanding superconducting SrTiO3 membranes were synthesized ex situ using molecular beam epitaxy, enabled by the lower growth temperature which preserves the sacrificial layer. This study paves the way for the synthesis of an expanded selection of freestanding oxide membranes and heterostructures with a wide variety of ex situ growth techniques.

Gold nanoring arrays are widely applied in various fields benefitting from their localized surface plasmon resonance (LSPR) properties. A key advantage of gold nanoring arrays is that the dipole resonance peak can be systematically tuned by changing the dimensions of gold nanoring arrays. However, most of the currently reported methods for preparing gold nanoring arrays cannot conveniently control the heights of the nanorings at a low cost. Here we introduce a facile method for preparing gold nanoring arrays with tunable plasmonic resonances using colloidal lithography. The dimensions of the nanorings including diameters, lattice constants, even the heights of the nanorings can be conveniently varied. Fourier transform near-infrared (FT-NIR) absorption spectroscopy was used to obtain the plasmonic resonance spectra of the nanoring arrays. All the prepared gold nanoring arrays exhibited a strong NIR or infrared (IR) plasmonic resonance which can be tuned by varying the nanoring dimensions. This versatile method can also be used to fabricate other types of plasmonic nanostructures, such as gold nanocone arrays. The obtained gold nanoring arrays as well as nanocone arrays may have potential applications in surface-enhanced spectroscopy or plasmonic sensing.

Non-rutile polymorphs of binary iridium oxide such as columbite IrO2 (α-IrO2) are promising candidates for highly active acid-stable oxygen evolution reaction (OER) catalysts, yet their synthesis h...

Solution-processed perovskites as emerging semiconductors have achieved unprecedented milestones in sensor optoelectric devices. Stability along with the device noise issues are the major obstacle for photodetectors to compete with the traditional devices. Here, we demonstrated that l-ascorbic acid (l-AA) as a polyhydroxy ester can coordinate with the amino group of formamidine cations (FA+) through multiple hydrogen bond interactions to stabilize the perovskite, which protect the FA+ ions from nucleophile attack and effectively suppress the degradation of FA+ ions, improving the perovskite stability and suppressing the device noise to below 0.3 pA Hz-1/2 with a large linear dynamic range of 239 dB. The dual functions of l-AA enable the perovskite photodetector to have a high detectivity of 1012 Jones. The self-powered device works with no energy consumption and maintains an undegraded performance over 1200 h of inspection at ambient conditions, which is promising for infrastructure construction, signal sensing, and real-time information delivery.

To mitigate the slagging, fouling and high-temperature corrosion problems caused by alkali metals during coal combustion process, measurement of time-resolved alkali metals release is very important. The paper proposed an in-situ approach for measuring sodium (Na) release in coal combustion by Flame Emission Spectroscopy (FES). Through the analysis of spontaneous emission spectra and a calibration procedure, the concentration of gas phase Na, temperature and thermal radiation can be obtained. Firstly, experimental measurement of Zhundong coal particles burning in a flat flame burner was done. Two kinds of Zhundong coal with similar proximate and ultimate analyses, but different ash composition were used. The Na-release history measured by FES was compared with that by LIBS. Results showed that the Na-release at the devolatilization, char, and ash stages can be distinguished by FES. The higher Si/Al content in ash can suppress the Na-release at the ash stage. Moreover, FES method was extended to the measurement of Na-release in four industrial boiler furnaces of two Zhundong coal-fired power plants. Results showed the Na-release measured by FES can reflect the change of fuel and load, and both temperature and thermal radiation play key roles in Na-release in coal combustion.

Exploring sustainable and highly active electrocatalysts for the oxygen reduction reaction (ORR) is vital for the development and application of energy conversion technologies. Here, we prepared Fe-isolated single atomic site (ISAs)-supported hollow mesoporous carbon nanocages (Fe-ISAs/H-CNs). Using zeolitic imidazolate framework (ZIF-8) as the templates, the iron precursor was used as the Fe source for doping, and also acted as the initiator to promote the polymerization of pyrrole for constructing the shell. In addition, the H cations released by pyrrole polymerization diffused into the interior of ZIF-8 through the pores and further broke the structure of ZIF-8, resulting in porous MOF–polymer nanocomposites (ZIF-8/Fe@PPy). After thermal treatment, the obtained Fe-ISAs/H-CN exhibited a higher half-wave potential (E1/2 = 0.87 V), exceptional kinetic current density (Jk = 32.82 mA cm−2 at 0.80 V), high stability, and superior tolerance to methanol crossover, exceeding those of commercial Pt/C catalyst and most previously reported non-precious-metal catalysts in alkaline media. The excellent catalytic behavior was attributable to hollow carbon nanocages and the feature of Fe single atoms with the Fe–N4 configuration, which provided more active sites and was beneficial to create highly interconnected electron connection channels that facilitated oxygen exchange, reactant diffusion, and electron conduction, thus changing the reaction kinetics.

Graphite has been widely used as the anode material in lithium-ion batteries (LIBs) due to its good conductivity, layered crystal structure, high charging–discharge potential, and other characteristics. With the rapid development of the LIB industry, the graphite industry has also developed into a mode of high production capacity. The anode graphite of spent LIBs has the characteristics of large layer spacing and ease of being intercalated and peeled due to the reduction of the interlamination force after repeated charge and discharge cycles. In this study, we present a facile freeze–thaw ultrasonic assisted circulation method to prepare two-dimensional low-layer graphite flakes (GFs) using anode graphite from spent LIBs. Characterizations of GFs were carried out by SEM, TEM, XRD and Raman spectroscopy. The results indicate that GFs prepared by graphite of spent LIBs have a better morphology than that prepared by purchased graphite. Furthermore, the GF-filled ethylene glycol (EG) nanofluids exhibit higher thermal conductivity and conductive heat transfer coefficient than base fluids, of which the maximum enhancements are 10.5% and 30%, respectively. The freeze–thaw ultrasonic assisted circulation method is not only an effective method for the reuse of anode graphite from spent LIBs, but also a reference for the synthesis of two-dimensional materials. Furthermore, GF-filled nanofluids could be a potential heat transfer working medium.

Synthetic nanofibrillar hydrogels resembling a natural extracellular matrix have emerged as a promising material in the biomedical field; however, achievement of multifunctional nanofibrillar hydro...

Carbon dots (CDs), as a new type of carbon-based nanomaterial, have attracted broad research interest for years, because of their diverse physicochemical properties and favorable attributes like good biocompatibility, unique optical properties, low cost, ecofriendliness, abundant functional groups (e.g., amino, hydroxyl, carboxyl), high stability, and electron mobility. In this Outlook, we comprehensively summarize the classification of CDs based on the analysis of their formation mechanism, micro-/nanostructure and property features, and describe their synthetic methods and optical properties including strong absorption, photoluminescence, and phosphorescence. Furthermore, the recent significant advances in diverse applications, including optical (sensor, anticounterfeiting), energy (light-emitting diodes, catalysis, photovoltaics, supercapacitors), and promising biomedicine, are systematically highlighted. Finally, we envisage the key issues to be challenged, future research directions, and perspectives to show a full picture of CDs-based materials., Carbon dots possessing various appealing properties such as good biocompatibility, high quantum yield, strong absorption, show promising optical, energy, and biomedicine applications.

Recently, the room-temperature phosphorescence (RTP) properties of carbon dots (CDs) have attracted significant interest. However, the regulation of RTP emission faces great challenges because of untunable emissive lifetime and wavelength. Here, ultrahigh-yield acrylamide-based N-doped carbonized polymer dots (AN-CPDs) with ultralong RTP lifetime are synthesized by a one-step hydrothermal addition polymerization and carbonization strategy. The RTP lifetime and wavelength of the proposed AN-CPDs can be regulated by changing the carbonization degree. Thus, the AN-CPDs' RTP lifetimes are in the range of 61.4-466.5 ms, while the RTP emission wavelengths vary from 485 to 558 nm. Further experiment and theoretical calculation proved that RTP can be attributed to the polymer/carbon hybrid structure and nitrous functional groups as the molecular state related emission centers. Supramolecular cross-linking in the aggregated state is vital for the RTP emission of the AN-CPDs by restricting the nonradiative transition of the triplet excitons. AN-CPDs of different RTP lifetimes can be applied to time-resolved multistage information encryption and multistage anticounterfeiting. This work facilitates the optical regulation and application potential of CDs and provides profound insights into the effect of the polymer/carbon hybrid structure on the properties of CDs.

Nanocomposite hydrogels based on carbon dots (CDs) and polymers have emerged as new materials with integrated properties of individual components, leading to their important applications in the field of soft nanomaterials. This perspective highlights recent advances in the development of nanocomposite hydrogels from CDs and polymers. We review the preparation methods of nanocomposite hydrogels based on CDs and polymers, and emerging applications of these nanocomposite hydrogels such as environmental remediation, energy storage, sensing, drug delivery and bioimaging. We conclude with the discussion of new research directions in the development of new type of nanocomposite hydrogels based on CDs and polymers.

As one of the most environmentally friendly photovoltaic (PV) conversion equipments, aqueous-processed CdTe nanocrystal solar cells (NC SCs) have attracted great interest in recent years because of their excellent properties such as high charge-carrier mobility and broad absorption. However, two issues including interfacial recombination and leakage current seriously restrict their performance. In this paper, insulating polymer poly(vinyl pyrrolidone) (PVP) is introduced into CdTe NC SCs to solve the problems. The experimental results of transmission electron microscopy (TEM), atomic force microscopy (AFM) and dark current measurements, etc., demonstrate the leakage current is effectively suppressed by introducing PVP. Through further designing device structure, the reduction of interfacial recombination after introducing PVP is confirmed. By strategically taking the advantages of PVP properties (e.g., water solubility and thermostability), the power conversion efficiency of the devices with PVP is enhanced by almost 37% compared to pure CdTe devices. This work demonstrates an effective and low-cost method to fabricate NC SCs via aqueous route. Moreover, it also proves that appropriate content of insulating polymer is of beneficial in promoting the PV performance.

2-dimensional (2D) lead halide perovskites are the junction of two hot areas of 2D materials and lead halide perovskites (LHPs), which possess unique chemical and physical properties and deserve in...

Straining an oxide membrane Perovskite manganites, such as La 0.7 Ca 0.3 MnO 3 , have complex phase diagrams with many competing states. Among the knobs that can be used to control their properties are magnetic field and strain. Hong et al. placed membranes of La 0.7 Ca 0.3 MnO 3 on a flexible polymer layer (see the Perspective by Beekman). Stretching the flexible layer resulted in large strains of up to 8% on the membrane. By varying the magnitude and direction of the strain, the researchers were able to explore the phase diagram of the system and influence its magnetic and transport properties. Science , this issue p. 71 ; see also p. 32

Residual bacteria and microleakage in a complicated root canal can often result in reinfection of the periapical tissues. To promote the antibacterial and sealing effects of a root canal filling, core-shell structured CaO/ZnO nanospheres were synthesized using a precipitation method based on a traditional root canal sealer, zinc oxide-eugenol(ZOE). The obtained CaO/ZnO particles had a size of 80–90 nm and a core-shell structure. The film thickness, flow rate, pH, and calcium ion release of the core-shell structured CaO/ZnO nanospheres-eugenol paste were tested. The pH and calcium ion release results showed a slight increase in the prepared nanospheres, with a flow rate of 24.22 mm and a formed film thickness of 30 µm, which are basically consistent with ISO 6876:2001 standards(regarding dental root canal sealing materials). Cytotoxicity tests showed that the cytocompatibility of the CaO/ZnO nanospheres-eugenol paste was much higher than that of the ZOE or iRoot SP groups(P

The development of effective and inexpensive hydrogen evolution reaction (HER) electrocatalysts for future renewable energy systems is highly desired. Carbon-based metal hybrid materials with unique edge sites, good chemical stability, high electrical conductivity, and synergetic effects exhibit great potential. However, there are few studies on the effect of the carbon-based support on catalytic performance. In this study, we explored the synergy between the carrier and metal (Ru), and studied the effect of the carrier and metal crystallinity on the catalytic performance of HER. The performance of Ru nanoparticles (Ru NPs) catalyst supported on carbon quantum dots (Ru@CQDs) was superior to that on other carbon supports. In addition, the HER performance of the Ru@CQDs catalyst was highly dependent on the crystallinity and confinement effects. Experimental results indicate that the Ru NPs were successfully anchored by strong coordination interactions between the d orbitals of Ru and the surface functional groups of CQDs, which is beneficial to the confinement of Ru NPs around the CQDs and to prevent their aggregation. The results will guide the design of inexpensive Ru-based HER electrocatalysts.

Herein we present a micro-nanostructure integrated liquid pressure sensor, which features an ultra-high sensitivity of 16.71 mbar-1, a low-pressure regime of 2 mbar, a trace sample volume of less than 1.3 μL and a visible display element. The measurable pressure ranges of the sensors include not only from micro-scale fluids to bulk liquids but also from hydraulic pressures to blood pressures, opening a window for liquid pressure sensing in lab-on-chip platforms, point-of-care diagnostics, and even robotics.

Metal halide perovskites are promising candidates as photocatalysts due to their uniquely outstanding photophysical properties; however, the catalytic efficiency is limited by severe charge recombination. Herein, we show that carbonized polymer dots (CPDs) can act as an efficient charge modulator to stabilize photo-generated carriers in methylamine lead triiodide (MAPbI3) perovskites through ultra-fast hole transfer, and thus increase the rate of visible light-driven photocatalytic HI splitting 35-fold. The optimized CPD/MAPbI3/Pt hybrid photocatalytic system exhibits an impressive H2 evolution rate of 11 497 μmol h−1 g−1, a solar-to-hydrogen conversion efficiency of 2.15%, and an apparent quantum yield of 53.6% at 420 nm, which are among the highest values for metal halide perovskite photocatalysts. Moreover, the presented strategy of hole extraction via CPDs can be universally applied to improve the performance of previous electron-manipulated MAPbI3-based photocatalytic systems. The easy-to-prepare and bandedge-tunable CPDs with excellent charge-transfer ability may bring new insights in developing high-performance perovskite photocatalysts.

The research on advanced functional polymers is being driven by the fast-growing demand for new functional materials that can be used in revolutionary technologies. Polymers can be endowed with functions by using certain special preparation methods or by introducing functional groups or fillers into materials. These functions are either intrinsically possessed by materials or actuated by external stimuli. In this review, we present an overview of the recent developments made in the research hotspots of functional polymers, encompassing polymerization methodologies, luminescent polymers, photovoltaic polymers, other electronic and optical polymers (including low-k polyimides and second-order nonlinear optical polymers), biorelated polymers (particularly those for biomedical applications), supramolecular polymers, stimuli-responsive polymers, shape-memory polymers, separation polymer membranes, energy storage polymers, and covalent organic framework polymers. The concepts, design strategies at the molecular level, preparation methods, classifications, properties, potential applications, and recent progress made in such polymers are summarized. Challenges and future perspectives of each type of functional polymers are also addressed, including research efforts regarding the design and fabrication of functional polymers for serving the increasing demand for new materials.

Carbon dots (CDs) are a new class of luminescent carbon nanomaterials possessing small size, excellent water solubility, low toxicity, tunable light-emitting properties and good biocompatibility, which display bright prospects in catalysis, drug delivery, bioimaging, biosensing and energy conservation and storage. In the past several years, great achievements on the synthetic strategies, characterization techniques, unique optical properties and novel applications of a large variety of CDs have been realized. In this review, the brilliant optical properties of CDs-based nanomaterials via a series of spectroscopic techniques are summarized. After a brief introduction of the characteristic of CDs, we will focus on the optical properties of the CDs, including photoluminescence (PL), near-infrared (NIR) fluorescence, surface-enhanced Raman scattering (SERS), phosphorescence, chemiluminescence (CL), electrochemical luminescence (ECL), and chirality. The correlation between the structure of CDs and their optical properties has been discussed. In addition, some challenges and future prospects in the field of the optical properties of CDs have been highlighted. With the rapid development of their superior optical properties, it is anticipated that CDs will be applicable in a large number of research fields.

A surface is said to be isotropic in wettability when the contact angles measured in all direction are identical. On the contrary, once a surface shows distinct contact angles in “specific” but not random directions, the surface is considered to show anisotropic wetting, accompanied by anisotropic droplet spreading (in cases with greater wetting) or anisotropic droplet movement (in cases with greater anti-wetting). Anisotropic wetting occurs when the liquid contact line encounters physical asymmetry or chemical heterogeneity present on a solid surface. In recent years, anisotropic wetting surfaces have attracted wide scientific attention for both fundamental research and practical applications. Controllable directional liquid transportation, as a promising and important form of intelligent liquid manipulation, plays an important role in lots of fields. In nature, anisotropic wettability has been observed on a variety of biological surfaces, such as rice leaves, butterfly wings, desert beetle elytra, spider silks, cactus spines, and Nepenthes alata peristomes. Inspired by biological surfaces with anisotropic wetting properties, researchers have made great progress in the design and fabrication of micro-/nanostructures with the desired anisotropic wettability. This review focuses on typical and recent advances in the areas of natural and artificial anisotropic wetting surfaces, mainly based on micro-/nanostructures, and on their preparation methods and applications in liquid transportation, microfluidics, fog harvesting, and oil–water separation. Furthermore, potential applications of anisotropic wetting micro-/nanostructures in microreactors, biomedical devices, and sensors are presented.

Efficient pH-universal overall water splitting electrocatalysts are critical but remain challenging. Herein, a highly efficient, pH-universal overall water-splitting electrocatalyst, was reported by ingeniously controlling the bulk and surface electronic structures of Ru with Co-doping and interfacial incorporation of carbon dots (CDs), respectively. The developed RuCo@CD electrocatalyst present superior hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activities with great durability over a wide pH range, achieving a very low overpotential of 51 mV, 11 mV and 67 mV for HER, and 190 mV, 257 mV and 410 mV for OER at 10 mA cm−2 in 0.5 M H2SO4, 1.0 M KOH and neutral 1.0 M phosphate buffer solution (PBS), respectively. A modified chemical/valence state originating from the strong electronic coupling process among Co, Ru and CDs, is revealed by combined experimental and theoretical results, which contributes to the optimization of water dissociation kinetics. A RuCo alloy was unprecedentedly endowed with efficient and stable bi-functional activities for the first time through electronic coupling with CDs. This reflects the dependence of catalytic activity on chemical/valence states and electronic structures at the atomic level. The work provides a new approach for the design of excellent Ru-based overall water splitting electrocatalysts.

In the present study, a novel hybrid nanomaterial composed of core–shell structured Ag@carbon dot (CD) modified TiO2 nanofibers (NFs) was successfully fabricated via a simple two-step strategy for the first time. Herein, the Ag@CDs–TiO2 NFs are demonstrated to be an efficient SERS substrate. The strong LSPR-induced electromagnetic enhancement (EM) by Ag@CDs NPs and efficient charge transfer (CT) effect between Ag@CDs and TiO2 NFs synergistically contribute to the excellent SERS enhancement. In addition, the Ag@CDs–TiO2 NFs exhibit enhanced photocatalytic activity regarding the organic pollutant degradation under visible light irradiation because of the enhanced light absorption and improved separation of photo-generated electron–hole pairs. Thus, this new nanocomposite can be used as a sensitive SERS substrate for determining the catalytic activity and reaction kinetics during the photodegradation of methylene blue (MB). Compared with UV-vis spectroscopy, the SERS technique enables more accurate monitoring of the changes of adsorption molecules and actual catalytic process on the surface of the catalyst. These results are significant for the development of metal or semiconductor-based catalysts for ensuring optoelectronic, energy and environmental applications.

Crystallographic orientation control is an effective method to improve the photoelectrochemical water splitting efficiency of BiVO4 photoanodes. Herein, textured and transparent Mo–BiVO4 photoanodes are fabricated by spin-coating Mo-doped BiVO4 nanoparticles on FTO. The photoelectrodes exhibit a current density of 4.15 mA cm−2 and 2.50 mA cm−2 for sulfite and water oxidation, respectively. By connecting the photoelectrode with a CsPbBrI2 perovskite solar cell, a stand-alone tandem water splitting device with a current density of 2.13 mA cm−2 and an STH of 2.43% can be achieved.

The authors uncover an insulator-to-metal crossover in the magnetic-field-induced normal state of infinite-layer nickelate thin films, near the edge of its superconducting dome.

The treatment of large segmental bone defects and complex types of fractures caused by trauma, inflammation, or tumor resection is still a challenge in the field of orthopedics. Various natural or synthetic biological materials used in clinical applications cannot fully replicate the structure and performance of raw bone. This highlights how to endow materials with multiple functions and biological properties, which is a problem that needs to be solved in practical applications. Hydrogels with outstanding biocompatibility, for their casting into any shape, size, or form, are suitable for different forms of bone defects. Therefore, they have been used in regenerative medicine more widely. In this review, versatile hydrogels are compounded with nanoparticles of different dimensions, and many desirable features of these materials in bone regeneration are introduced, including drug delivery, cell factor vehicle, cell scaffolds, which have potential in bone regeneration applications. The combination of hydrogels and nanoparticles of different dimensions encourages better filling of bone defect areas and has higher adaptability. This is due to the minimally invasive properties of the material and ability to match irregular defects. These biological characteristics make composite hydrogels with different dimensional nanoparticles become one of the most attractive options for bone regeneration materials.

Carbon dots (CDs) have excellent luminescence characteristics, such as good light stability, high quantum yield (QY), long phosphorescence lifetime, and a wide emission wavelength range, resulting in CDs' great success in optical applications. Understanding the structure-property relationships in CDs is essential for their use in optoelectronic applications. However, because of the complex nature of CD structures and synthesis processes, understanding the luminescence mechanism and structure-property relationships of CDs is a big challenge. This Perspective reviews the theoretical efforts toward the understanding of structure-property relationships and discusses the challenges that need to be overcome in future development of CDs.

We report a facile yet general in situ seed-mediated method for the synthesis of polymer-grafted gold nanoparticles with narrow size distributions (

The development of large-scale synthetic methods for high quality carbon quantum dots (CQDs) is fundamental to their applications. However, the macroscopic preparation and scale up synthetic of CQDs is still in its infancy. Here, we report a facile, green, kilogram-scale synthesis of high quality fluorescent CQDs derived from poplar leaves via a one-step hydrothermal method. Notably, the throughput of CQDs can reach a level up to as high as 1.4975 kg in one pot. The structure and properties of the as-prepared CQDs were assessed through TEM, XRD, XPS and various spectroscopic methods. The obtained high quality CQDs with a photoluminescent quantum yield of 10.64% showed remarkable stability in aqueous media, rich functional groups, high photostability, consistent photoluminescence within biological pH range and low cytotoxicity. On account of these good properties, we demonstrated the multifunctional application to electrocatalytic water splitting, Fe3+ sensing and bioimaging. It showed remarkable electrocatalytic activity, Fe3+ sensitivity and good biocompatibility. This study provides a green, facile, inexpensive and large-scale method for producing high quality CQDs, which provides application value for large-scale production of CQDs.

Nanolayered flaky Fe-based amorphous-nanocrystalline/graphite sheet composites with excellent microwave absorbing properties are fabricated by ball milling the Fe-based amorphous alloy and graphite. The obtained composites consist of Fe-based amorphous-nanocrystalline flakes and graphite sheet coating, which exhibit good impedance matching. The modified magnetic and dielectric properties, especially the large coercivity, high permeability and the interfacial polarization are responsible for the significantly improved microwave absorption properties with minimum reflection loss of −67.95 dB at thin thickness of 1.6 mm and bandwidth of 5.36 GHz. The facile composites with excellent microwave absorbing properties are potential materials for high-performance microwave absorbers.

Enhancement of permeability and the retention effect is one of the main pathways for the accumulation of nanomaterials in tumor sites, but poor cellular internalization and rapid clearance of nanomaterials always hamper the efficacy of imaging diagnosis and treatment. With the consideration of both high tumor accumulation and cellular internalization, positively charged nanomaterials can adhere to the tumor cell membrane by an electrostatic force, which is conducive to cellular internalization, but they are easily recognized and cleared during blood circulation. However, negatively charged nanomaterials show an enhanced stealth-like effect and possess a long blood circulation time, which is conducive to tumor accumulation. Therefore, in this work, on the basis of the shielding effect of citrate ions to positive charge and the protonation under an acidic tumor microenvironment, pH-sensitive sodium citrate-modified polyaniline nanoshuttles (NSs) with negative charge during blood circulation but positive charge in tumor sites are designed. With this hierarchical targeting strategy, the blood circulation half-life increases from 4.35 to 7.33 h, and the retention rate of NSs in tumors increases from 5.29 to 8.57% ID/g. Because the retention rate of NSs is increased, the magnetic resonance imaging resolution and signal intensity are significantly improved. A synergistic treatment of tumors is further achieved by means of photothermal therapy with laser irradiation and chemotherapy via heat-stimulated drug release.