Interface electron collaborative migration of Co–Co3O4/carbon dots:Boosting the hydrolytic dehydrogenation of ammonia borane

Ammonia borane(AB)is an excellent candidate for the chemical storage of hydrogen.However,its practical utilization for hydrogen production is hindered by the need for expensive noble-metal-based catalysts.Herein,we report Co-Co3O4 nanoparticles(NPs)facilely deposited on carbon dots(CDs)as a highly efficient,robust,and noble-metal-free catalyst for the hydrolysis of AB.The incorporation of the multiinterfaces between Co,Co3O4 NPs,and CDs endows this hybrid material with excellent catalytic activity(rB=6816 mLH2 min^-1 gCo^-1)exceeding that of previous non-noble-metal NP systems and even that of some noble-metal NP systems.A further mechanistic study suggests that these interfacial interactions can affect the electronic structures of interfacial atoms and provide abundant adsorption sites for AB and water molecules,resulting in a low energy barrier for the activation of reactive molecules and thus substantial improvement of the catalytic rate.

Carbon dots-confined CoP-CoO nanoheterostructure with strong interfacial synergy triggered the robust hydrogen evolution from ammonia borane

Ammonia borane(NH_(3)BH_(3),AB) is promising for chemical hydrogen sto rage;however,current systems for rapid hydrogen production are limited by the expensive noble metal catalysts required for AB hydrolysis.Here we report the design and synthesis of a highly efficient and robust non-noble-metal catalyst for the hydrolysis of AB at 298 K(TOF=89.56 molH_(2) min^(-1) molCo^(-1)).Experiments and density functional theory calculations were performed to explore the catalyst’s hybrid nanoparticle heterostructure and its catalytic mechanism.The catalyst comprised nitrogen-doped carbon dots confining CoO and CoP,and exhibited strong interface-induced synergistic catalysis for AB hydrolysis that effectively decreased the energy barriers for the dissociation of both AB and water molecules.The co-doping of N and P introduced numerous defects,and further regulated the reactivity of the carbon layers.The heterogeneous interface design technique presented here provides a new strategy for developing efficient and inexpensive non-noblemetal catalysts that may be applicable in other fields related to energy catalysis.

Biomass-Derived Carbon Dots and Their Applications

Carbon dots(CDs) have received much attention due to their superior properties including water solubility, low toxicity, biocompatibility, small size,fluorescence, and ease of modification. The use of a more environmentally friendly method to prepare high-quality CDs is still an urgent question waiting for solve. The use of renewable, inexpensive, and green biomass resources not only meets the urgent need for large-scale synthesis biomass CDs(BCDs), but also promotes the development of sustainable applications.In this article, we summarize the representative methods for synthesizing BCDs in green and simple ways using biomass as a carbon source, including hydrothermal carbonization, and microwave, pyrolysis. The prepared BCDs have a uniform particle size distribution and a relatively high throughput,which provide a method to scale up industrial production. Moreover, the integration of specific optical properties, that is, tunable photoluminescence and up-photoluminescence, has led to remarkable use in bioimaging, sensing,and drug delivery. But the current review is not particularly comprehensive for BCDs. Therefore, we now provide a review focusing on the synthesis,properties, and recent advances in BCDs in biosensing, bioimaging,optoelectronics, and catalytic applications.

Generation and Selection of Driver-Behavior-Based Transferable MotionPrimitives

To integrate driver experience and heterogeneous vehicle platform characteristics in a motion-planning algorithm,based on the driver-behavior-based transferable motion primitives(MPs), a general motion-planning framework for offline generation and online selection of MPs is proposed. Optimal control theory is applied to solve the boundary value problems in the process of generating MPs, where the driver behaviors and the vehicle motion characteristics are integrated into the optimization in the form of constraints. Moreover, a layered, unequal-weighted MP selection framework is proposed that utilizes a combination of environmental constraints, nonholonomic vehicle constraints,trajectory smoothness, and collision risk as the single-step extension evaluation index. The library of MPs generated offline demonstrates that the proposed generation method realizes the effective expansion of MP types and achieves diverse generation of MPs with various velocity attributes and platform types. We also present how the MP selection algorithm utilizes a unique MP library to achieve online extension of MP sequences. The results show that the proposed motion-planning framework can not only improve the efficiency and rationality of the algorithm based on driving experience but can also transfer between heterogeneous vehicle platforms and highlight the unique motion characteristics of the platform.

State-of-the-art of biomass-derived carbon dots: Preparation, properties, and applications

Carbon dots (CDs) have attracted considerable attention as a new type of fluorescent carbon nanomaterial because of their excellent optical properties, biocompatibility, and high electrical conductivity. Research on CDs has been conducted for nearly two decades and has focused on numerous precursors, various synthesis conditions and properties and applications of CDs. Biomass is critical in the green development of CDs because of its low cost, environmental friendliness, and sustainable properties. This review focuses on the advantages and applications of biomass-derived CDs. In addition, the challenges of photobleaching, toxicity, and stability of biomass-based CDs are discussed in detail. Lastly, the prospects and challenges of biomass-derived CDs are highlighted.

Bionic soft robotic gripper with feedback control for adaptive grasping and capturing applications

Robots are playing an increasingly important role in engineering applications.Soft robots have promising applications in several fields due to their inherent advantages of compliance,low density,and soft interactions.A soft gripper based on bio-inspiration is proposed in this study.We analyze the cushioning and energy absorption mechanism of human fingertips in detail and provide insights for designing a soft gripper with a variable stiffness structure.We investigate the grasping modes through a large deformation modeling approach,which is verified through experiments.The characteristics of the three grasping modes are quantified through testing and can provide guidance for robotics manipulation.First,the adaptability of the soft gripper is verified by grasping multi-scale and extremely soft objects.Second,a cushioning model of the soft gripper is proposed,and the effectiveness of cushioning is verified by grasping extremely sharp objects and living organisms.Notably,we validate the advantages of the variable stiffness of the soft gripper,and the results show that the soft robot can robustly complete assemblies with a gap of only 0.1 mm.Owing to the unstructured nature of the engineering environment,the soft gripper can be applied in complex environments based on the abovementioned experimental analysis.Finally,we design the soft robotics system with feedback capture based on the inspiration of human catching behavior.The feasibility of engineering applications is initially verified through fast capture experiments on moving objects.The design concept of this robot can provide new insights for bionic machinery.

Origin and geological control of desorbed gas in multi-thin coal seam in the Wujiu depression, Hailar Basin, China

To understand the natural gas characteristics of multi-thin coal seam,this study selected the desorbed gas of coal seams in different layers of Well A in the Wujiu depression,Hailar Basin in northeast Inner Mongolia.The results show that the heavy hydrocarbon content of desorbed gas increases significantly with the increasing depth.Methane carbon(δ13C_(1))and ethane carbon(δ13C_(2))isotope values are vertically become heavier downwards,while the δ13 values did not change significantly.The kerogen is close to the III–II mixed type with the source rocks mainly deposited in a shore/shallow lake or braided-river delta front,and the gas produced has certain characteristics of oil associated gas.However,the characteristics of oil associated gas produced by the organic formed in the shallow-water environment(braided-river delta plain)are not obvious.The sandstone pore and fracture systems interbedded with multi-thin coal seam are well developed.And it is conducive to the migration of methanogenic micro-organisms to coal seams via groundwater,making it easier to produce biogenic gas under this geological condition.During the burial evolution of coal-bearing strata in the study area,when the burial depth reaches the maximum,there are significant differences in the paleotemperature experienced by different vertical coal seams,caused by a high-paleogeothermal gradient,increasing the δ13C_(2) of desorbed gas with increasing depth.The above research indicates that there is less biogenic gas in the multi-thin coal seams with relatively developed mudstone,and the multi-thin coal seams with relatively developed sandstones have obvious biogenic gas characteristics.Therefore,for the exploration and development of biogenic gas in low-rank multi-thin coal seams,it is necessary to give priority to the layer with high sandstone content.

人工智能与多组学时代基于生物网络的肿瘤精准防治

Cancer is recognized as a leading cause of deaths nowadays,accounting for 10 million annual deaths worldwide and resulting in heavy health and economic burdens[1].Reducing cancer incidence through precision prevention is thus of great scientific and clinical value.Gastric cancer(GC)is one of the most common cancers in China.Pathologically,the onset of GC,especially the intestinal-type ones,would usually suffer a series of premalignant lesions,including atrophic gastritis,intestinal metaplasia,and low-grade dysplasia(LGD),which is known as the process of gastritis-induced tumorigenesis(GIGT)[2].Epidemiological studies have shown that GIGT has exhibited the characteristics of longterm and low-probability,that is,only a small number of gastritis patients would develop into GC after a long period.Therefore,it has become the key challenge for GC precision prevention that how to uncover the biological mechanism underlying GIGT,followed by accurately identifying the critical time point at which effective diagnosis and treatment strategies could be developed to prevent GC.Of note,this is also a common challenge for the precision prevention of other cancer types,such as liver and colon cancers.

碳点光致发光机理的新见解:进展与展望

碳点由于其优异的光学性能、高生物相容性和低毒性,在生物成像、发光二极管和传感等许多领域具有潜在的应用价值.它们的光致发光机制已经得到了广泛的研究,了解这一机制对于指导可调谐光致发光碳点的合成和促进其应用具有重要意义.然而,光致发光的内在机制尚不清楚,由于粒子结构的不同,尚未找到统一的机制.本综述概括了碳点的类别,指出了它们的结构多样性,概述了与结构差异有关的三种类型的发光机制:内部因素主导发射(包括共轭效应、表面态和二者的协同效应)、外部因素主导发射(包括分子态和环境效应)和交联增强发射,并简要介绍了碳点的光学应用.最后,对发光机制研究的发展前景进行了讨论,指出了未来工作的主要挑战和发展方向.

Near-infrared emissive carbon dots with 33.96% emission in aqueous solution for cellular sensing and light-emitting diodes

Near-infrared emissive carbon dots(CDs) were synthesized by hydrothermal method. The as-prepared CDs exhibited a relatively high quantum yield(QY) of 33.96% in an aqueous solution, and the peak toward the near-infrared fluorescence reached 685 nm. The CDs exhibited pH-sensitive characteristics under strong acidic conditions. Even at pH = 0, the as-prepared CDs retained a high fluorescence intensity,which proved that they possessed good acid resistance. More importantly, the CDs were sensitive to the Fe3+changes in living cells. In addition, they could also be used for white and red emissive LEDs.This discovery will expand the use of aqueous-phase high QY CDs in the field of living cell sensing and imaging.

Superior trichloroethylene removal from water by sulfide-modified nanoscale zero-valent iron/graphene aerogel composite

Sulfide-modified nanoscale zero-valent iron(S-nZVI) is a promising material for removal of organic pollutants from water, but S-nZVI nanoparticles(NPs) easily agglomerate and have poor contact with organic contaminants.Herein, we propose a new S-nZVI/graphene aerogel(S-nZVI/GA) composite which exhibits superior removal capability for trichloroethylene(TCE) from water.Three-dimensional porous graphene aerogel(GA) can improve the efficiency of electron transport, enhance the adsorption of organic pollutants and restrain the agglomeration of the core-shell S-nZVI NPs.The TCE removal rates of Fe S, nZVI, GA and S-nZVI were 27.8%, 42%, 63% and 75% in 2 hr, respectively.Furthermore, TCE was completely removed within 50 min by S-nZVI/GA.The TCE removal rate increased with increasing p H and temperature, and TCE removal followed the pseudo-first-order kinetic model.The results demonstrate the great potential of S-nZVI/GA composite as a low-cost,easily separated and superior monolithic adsorbent for removal of organic pollutants.

Ethanol-derived white emissive carbon dots:The formation process investigation and multi-color/white LEDs preparation

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).

High production-yield solid-state carbon dots with tunable photoluminescence for white/multi-color light-emitting diodes

Plastic waste is generally resistant to natural degradation and has become a major environmental pollution problem globally. The pollution of ecosystems seriously affects the health and survival of organisms,including humans. Much attention has been paid to finding suitable ways to convert plastic waste into high-value-added carbon materials. To this end, we report the high production yield(60%–85%) of carbon dots(CDs) for solid-state fluorescence(SSF) obtained by a one-step solvothermal method using waste expanded polystyrene as the precursor. The SSF mechanism of the CDs was also explored. Their emission wavelength, with a large full width at half maximum of 150–200 nm, exhibited tunable photoluminescence from white to yellow and orange. CDs powder was used to fabricate single-component white and multi-colour light-emitting diodes on UV chips. Overall, plastic waste was converted into tunable solid-state fluorescent CDs powder, which has promising applications in carbon-based lighting, by a simple solvothermal method that provides a viable method for recycling plastic waste.

Kilogram-scale synthesis of carbon quantum dots for hydrogen evolution, sensing and bioimaging

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 CQD s 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,Fe^3+ sensing and bioimaging.It showed remarkable electrocatalytic activity,Fe^3+ 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.

Electron-phonon coupling-assisted universal red luminescence of o-phenylenediamine-based carbon dots

Due to the complex core-shell structure and variety of surface functional groups,the photoluminescence(PL)mechanism of carbon dots(CDs)remain unclear.o-Phenylenediamine(oPD),as one of the most common precursors for preparing red emissive CDs,has been extensively studied.Interestingly,most of the red emission CDs based on oPD have similar PL emission characteristics.Herein,we prepared six different oPD-based CDs and found that they had almost the same PL emission and absorption spectra after purifiication.Structural and spectral characterization indicated that they had similar carbon core structures but diffferent surface polymer shells.Furthermore,single-molecule PL spectroscopy confirmed that the multi-modal emission of those CDs originated from the transitions of different vibrational energy levels of the same PL center in the carbon core.In addition,the phenomenon of"spectral splitting"of single-particle CDs was observed at low temperature,which confirmed these oPD-based CDs were unique materials with properties of both organic molecules and quantum dots.Finally,theoretical calculations revealed their potential polymerization mode and carbon core structure.Moreover,we proposed the PL mechanism of red-emitting CDs based on oPD precursors;that is,the carbon core regulates the PL emission,and the polymer shell regulates the PL intensity.Our work resolves the controversy on the PL mechanism of oPD-based red CDs.These findings provide a general guide for the mechanism exploration and structural analysis of other types of CDs.

Advances, opportunities, and challenge for full-color emissive carbon dots

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.

Effects of local matrix environment on the spectroscopic properties of ensemble to single-particle level carbon dots

Carbon dots(CDs), because of their unique properties, are being rapidly developed as important luminescent materials for imaging, sensing, and use in photonic devices. However, most of the reported fundamental properties of the CDs are results of investigations conducted in the solution state, which may be completely different from those conducted in the solid state. In this work, we study the luminescence properties, photostability, and the dynamics of CDs in different matrix environments, from ensemble to the single-particle level. We observed that the properties associated with the emission centers and photostability of CDs were extremely sensitive to the local chemical environment. A better understanding of the dependence of the spectroscopic properties of CDs on the complex local chemical environment is an important step toward finding new ways of controlling the optical properties of CDs and optimizing their use in various applications.

Red-emitting,self-oxidizing carbon dots for the preparation of white LEDs with super-high color rendering index

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 of714 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.

Differences in hydrocarbon composition of shale oils in different phase states from the Qingshankou Formation, Songliao Basin, as determined from fluorescence experiments

The phase state of shale oil has a significant impact on its mobility.The mineral and organic matter in shale reservoirs play an important role in oil phase.This study attempts to evaluate the properties of shale oils in different phase states and to investigate how these differences are related to initial shale composition.Samples from the first member of the Qingshankou(Q1)Formation were analyzed using X-ray diffraction,total organic carbon content,rock pyrolysis solvent extraction and group component separation.Subsequently,fluorescence techniques were used to quantitatively determine the content and properties of the free oil(FO),the adsorbed oil associated with carbonate(ACO),and the adsorbed oil associated with silicate and clay-organic complexes(AKO).The results showed that non-hydrocarbons and asphaltenes are the primary fluorescing compounds on shale grain.FO is the dominant phase in the Q1 Formation.The quantitative grain fluorescence on extraction(QGF-E)and total scanning fluorescence(TSF)spectra of ACO and AKO show a significant redshift compared to the FO.The TSF spectra of FO have a characteristic skew to the left and a single peak distribution,suggesting a relatively light hydrocarbon component.The TSF spectra of ACO show a skew to the right and an even,double-peaked distribution.The TSF spectra of AKO show a single peak with a skew to the right,indicating that ACO and AKO hydrocarbons are heavier than FO hydrocarbons.In summary,enrichment of carbonate minerals in shale may result in mis-identification of“sweet spots”when using QGF.The normalized fluorescence intensity of QGF-E and TSF are effective indexes allowing oil content evaluation.As an additional complicating factor,hydrocarbon fractionation occurs during generation and expulsion,leading to a differentiation of oil composition.And FO has high relatively light hydrocarbon content and the strongest fluidity.

Cross-linking enhanced room-temperature phosphorescence of carbon dots

Currently,there is a strong drive to discover alternative materials that exhibit room-temperature phosphorescence(RTP)for displays,bioimaging,and data security.Ideally,these materials should be nontoxic,cheap,and possess controllable photoluminescent properties.Carbon dots(CDs)possess each of these characteristics,but to date,less attention has been paid to their RTP mechanism.Herein,we synthesized a series of CDs by self-crosslinking and carbonization of precursor.The resultant CDs were luminescent and exhibited a bright,micro-second afterglow lifetime.To increase the RTP,a second microwave processing step was used to coat the CDs with polyvinyl alcohol(PVA),polyacrylamide(PAM),or tetraethyl orthosilicate(TEOS),producing CDs@PVA,CDs@PAM,and CDs@TEOS composites.The core-shell structure acted to enhance crosslinking at the surface of the CDs to boost the RTP,creating abundant energy levels for intersystem crossover.In situ X-ray photoelectron spectroscopy verified electron transfer during luminescence.Finally,we present a design rule that can be used to tune the quantum yields and RTP lifetime of CDs,based on the effective stabilization of triplet excited states through the extent and strength of cross-linking.This simple strategy provides a flexible route for guiding the further development of CDs with tailored RTP properties for various applications.