Fiber reinforced polymer composites are widely used in aerospace， automotive， shipbuilding， rail transportation， and other fields. With the development of lightweight high-speed aerospace and precision instrument automation， vibration problems are increasingly prominent， and it is necessary to develop new structural-damping composites with high mechanical properties and high vibration damping performance. Based on the research of fiber reinforced polymer damping composites in the past decade， the damping mechanism of the material was described， and the influence of polymer matrix， reinforced fiber， interface and other factors on the damping performance of fiber reinforced polymer composites was summarized， providing a reference for further developing fiber reinforced polymer composites with the required damping performance. Finally， the existing problems and development directions of fiber reinforced polymer damping composites are discussed， such as the development of new materials， new methods，new mechanisms， the co-optimization of damping properties of composite materials and mechanical/technological properties， and the corresponding relationship between the damping properties of components， materials and structures.

Thermosetting resins are widely used in the composition of carbon fiber-reinforced polymers （CFRPs）， which are insoluble and non-melting after curing， making thermosetting resins and carbon fibers （CFs） difficult to recycle and reuse.Vitrimer has the advantages of thermosetting and thermoplastic resins， which can achieve high-performance CFRPs preparation and non-destructive recovery of CFs. Moreover， the construction of vitrimer and its CFRPs by the bio-based materials， such as lignin and vanillin， is in line with the green development concept. The methods， properties， and their applications for the preparation of bio-based vitrimer from lignin and vanillin were summarized in this paper； the applications of vanillin-based vitrimer in the recyclable CFRPs were reviewed； the future development of lignin/vanillin-based vitrimer and its CFRPs were outlooked. This paper would provide a reference for the construction of high-performance lignin and its derivative vitrimer and CFRPs.

Fiber reinforced thermosetting composites exhibit high strength-weight ratio， high modulus-weight ratio， and good thermostability， and have been applied in many high-tech areas such as aerospace. However， these materials face extreme difficulty in reprocessing and recycling after the molding process. To solve the above problem， the dynamic covalent bonds are introduced into resin networks to design the dynamic covalent thermosets， exhibiting recyclability and remolding dynamic properties similar to thermoplastic polymers， providing an effective method. In this review， the development， characteristic， and network regulation strategies of thermosets with dynamic covalent bonds were introduced. The characteristics of fiber reinforced composites derived from these thermosets were summarized. Based on the classification of dynamic covalent bond type， the research progress of transesterification reactions， disulfide metathesis， imine metathesis， and other bond exchange thermosetting resins and fiber reinforced composites was reviewed. The development tendency and commercial applications of these composites were briefly overviewed. Finally， the future development direction and design suggestions of these thermosets and composites are concluded， providing ideas for the preparation and commercial application of these materials.

With domestic high-strength medium modulus CCF800H carbon fiber as the basic reinforcement material， CCM40J and CCM55J high modulus carbon fibers as the hybrid reinforcements， and AC631 high-temperature bismaleimide resin as the matrix， the in-plane hybrid prepregs with different fiber ratios were prepared. Combined with the autoclave molding process， the mechanical properties of five groups of composite materials with different carbon fiber hybrid ratios were prepared and characterized. According to the test results， the changes in the mechanical properties of different hybrid composite systems were analyzed， and three groups of typical hybrid ratio composite systems， CCF800H/CCM40J （5∶5）， CCF800H/CCM40J （4∶6）， and CCF800H/CCM55J （5∶5）， were obtained， all of which showed good mechanical properties. This can provide reference basic material performance data for developing aircraft composite structural parts.

An aramid fiber reinforced thermoplastic resin composite connector was developed for the connection of trenchless penetration repair lining pipe of ocean pipeline. The results of the hydrostatic burst test show that the failure mode under internal pressure is that the fiber of the pipe itself breaks and the connector remains intact. The tensile test results show that the tensile strength of the connector is higher than that of the lining pipe body， which meets the requirements of penetration construction. The internal pressure， tensile and folding models of the composite connector were established， and the ultimate strength， stress and strain distribution， and variation trend of the lining pipe and connector were predicted by finite element analysis. The finite element results show that the main bearing structure under internal pressure is the toroidal fiber， and the maximum strain occurs at the junction of the connector and the lining pipe body. The main load-bearing structure under tensile action is axial fiber， and the outer thermoplastic polyurethane edge has a large strain due to stress concentration， but it is still within the limit elastic strain range of the material. During the large deformation process of folding and unfolding， the maximum strain occurs in the folding stage， and the intermediate connector strain is close to the strain at lining pipe body. The intermediate connector of the pipe body developed in this study is convenient to manufacture， exhibits a high degree of compatibility with the lining pipe， and can be continuously coiled and folded， meeting the requirements of one-time long-distance repair of submarine pipelines.

Black phosphorus （BP） nanosheets have a special folded structure， which gives them an adjustable band gap， transmission anisotropy， and photoluminescence. These unique properties make BP nanosheets widely used in the construction of metal ion sensors and show great application potential in environmental monitoring and other research fields. In this paper， the preparation methods of BP nanosheets and their applications of different sensors in detecting heavy metal ions were introduced. Firstly， different preparation methods for BP nanosheets were introduced based on the “top-down” and “bottom-up” methods， and their advantages and disadvantages were summarized. Then， the research progress of BP nanosheets based field effect transistor （FET） sensors， electrochemical sensors， and photochemical sensors for the detection of heavy metal ions were described in detail. Among these sensors， the FET sensor shows an excellent detection limit， the electrochemical sensor has advantages of short response time and simple operation. The photochemical sensor shows a wider detection range than that of others. Furthermore， it is concluded that the types of heavy metal ions that BP nanosheets based sensors can detect are relatively limited， and the stability and selectivity need to be further improved. Finally， in view of the challenges faced by BP nanosheets for constructing different types of heavy metal ion sensors， we should develop low-cost and high-quality BP nanosheets preparation methods， and structure optimization and functional modification of BP nanosheets. In the aspect of expanding the application of BP nanosheets for the detection of heavy metal ions， it is expected to make a breakthrough in the practical applications by combining with novel technology.

The nickel-rich layered cathode materials LiNi _xM _{1- x} O₂ （x>0.8，M=Co，Mn，Al，etc.） have become the most promising cathode materials for hybrid electric vehicles and electric vehicle （EV） high energy density lithium-ion batteries in recent years due to its high specific capacity， high operating voltage， and low cost. The further development of electric vehicle technology requires the commercial application of lithium-ion batteries with a high energy density of approximately 350 Wh·kg^-1 and a range of 500 km. However， the rapid capacity decay and structural instability of nickel-rich layered cathode materials hinder their market application. In this paper， the fundamental issue of performance degradation in nickel-rich layered cathode materials was summarized， and the latest progress and perspectives in improving the cycling stability of nickel-rich layered cathode materials through element doping， element ratio，surface reconstruction， particle arrangement，interparticle filling，particle size， single crystal transformation，and other aspects were summarized. It is pointed out that efforts could be made to construct high structural strength nickel-rich cathode materials through the coordination of elements and structures to fundamentally solve the structural and thermal stability problems under deep delithiated state， providing modified new processes and methods for nickel-rich layered cathode materials.

Al-5%Fe-xNi alloys （x=0%，1.5%，5%，7.5%，10%， mass fraction，the same below） were prepared by the traditional casting method， and the morphology and size changes of the primary phase in the alloys after Ni addition were observed. The transformation of the solidification process of the alloys and the effect of Ni addition on the primary phase and eutectic structure were analyzed， and the influence of Ni content on the microstructure and thermal properties of the alloys was discussed. The results show that with the increase of Ni content， the primary phase changes from irregular bulk to needle-like. As the Ni content exceeds 5%， the eutectic structure decreases， and the primary phase changes to a regularly arranged Al₉FeNi phase. The addition of Ni significantly changes the solidification process of the alloys， resulting in the precipitation reaction of the primary phase from L→Al₁₃Fe₄ to L→Al₉FeNi or L+Al₁₃Fe₄→Al₉FeNi， and the eutectic precipitation reaction from L→α-Al+Al₁₃Fe₄ to L+Al₁₃Fe₄→α-Al+Al₉FeNi and L→Al₃Ni+α-Al+Al₉FeNi. With the increase of Ni content， the volume fraction of the precipitated phase increases， and the thermal conductivity and thermal expansion coefficient of the alloys decrease. The thermal expansion coefficient of the alloys decreases from 19.9×10^-6 K^-1 （@25-200 ℃） of Al-5%Fe to 17.6×10^-6 K^-1 （@25-200 ℃） of Al-5%Fe-10%Ni. The thermal conductivity and thermal expansion coefficient of the alloys are predicted by using the general effective medium theory （GEMT） model and the modified Turner model， respectively. It is found that the simulated values are in good agreement with the experimental values.

The in-situ EBSD analysis method was used to systematically study the effect of retained austenite characteristics on the phase transformation behavior of ferritic stainless steel after the quenching and partitioning （Q&P） process. The results show that the phase transformation behavior of retained austenite during deformation is related to its grain size， distribution， and morphology， and its influence degree is arranged in descending order. Compared with inter-martensitic austenite and inter-martensite-ferrite austenite， the trigeminal and twin austenite are more prone to martensitic transformation in the early stage of deformation. This is closely related to the different strains or stresses applied to different distributed retained austenites during deformation. Compared with large-sized austenite， small-sized austenite begins to transform in the later stage of deformation， which is helpful to prolong the uniform elongation. This may be due to the higher interfacial energy and average C content of small-sized austenite， and the need for larger macroscopic stress/strain to induce martensitic transformation due to the strengthening effect of fine grains. The elongated/equiaxed austenite is easy to transform in the early stage of deformation， while the transformation of thin film-retained austenite is mainly concentrated in the later stage of deformation， which is helpful to further improve plasticity. The different transformation behaviors are due to the differences in C and N content， as well as the presence of defects such as stacking faults， dislocations， and slip.

The microstructure evolution of the interface in the simulated heat affected zone （HAZ） of G115 steel was characterized by electron backscatter diffraction （EBSD） and high resolution transmission electron microscopy （HRTEM）. The results show that the size of precipitated M ₂₃C₆ in the fine grain zone is smaller than that in the coarse grain and the critical zone， which is only about 100 nm， and the precipitation strengthening effect is obvious. With the increase in peak temperature， the number of small angle grain boundary increases， hence the grain boundary strengthening effect increases. The highest geometrical dislocation density is 3.19×10¹⁴ m^-2 in the coarse-grained zone. The recovery of the critical dislocation， the pinning of the fine MX precipitates and the appearance of the subgrains make the G115 steel maintain the durable strength for a long time at high-temperature. For the microstructure of the fine grain zone， the increase of welding heat input promotes the transformation of martensitic lath substructure into martensite block substructure， the dislocations are annihilated， the formation of subgrain is inhibited， and the yield strength decreases from 1115 MPa to 947 MPa. When the welding heat input is 14.4 kJ/cm， the microstructure of the fine grain welding heat affected zone has both good strength and toughness.

Utilizing Ca and TiH₂ as the thickening agent and blowing agent， respectively， Al-0.16Sc， Al-0.21Sc， and Al-0.16Sc-0.17Zr cellular foams with porosity of （72±0.5）% were successfully fabricated by the melt-foaming method. The microstructure and compressive strength of the foams with isochronal aging treatment were investigated. The results show that during isochronal aging between 200 ℃ and 600 ℃， Al-0.16Sc and Al-0.21Sc foams achieve their peak yield strengths （about 21.4 MPa and 26.8 MPa， respectively） at 325 ℃ due to the precipitation strengthening of Al₃Sc/Al₃（Sc_{1- x} Ti _x ）. Unlike the Al-Sc foam， the yield strength of the Al-0.16Sc-0.17Zr alloy foam reaches 23.7 MPa at 325 ℃ and 24.7 MPa at 400 ℃， representing an increase of 100.8% and 109% than those of the cast alloy， respectively. Zr addition not only significantly enhances the strength of the Al-Sc foams， but also effectively affects the coarsening of the Al₃Sc/Al₃（Sc_{1- x} Ti _x ） precipitate.

The C/C-SiC composite materials combustion chamber layer was tested with liquid ramjet engines with solid particles or without solid particles separately at different oxygen contents. The ablation amount， ablative behavior and mechanical properties of the material after ablation in critical and general areas were studied under two test conditions. The results show that under the condition of containing solid particles， the amount of ablation in the critical ablation area is large， and the amount of ablation in the general area is also large， which is larger than that of the corresponding areas without solid particles. The surface coating of C/C-SiC composites undergoes oxidation reaction first， and the resulting SiO₂ glassy film covers the surface of the coating， blocking the entry of oxygen and effectively protecting the matrix material. As the temperature rises， active oxidation of the material occurs， and the process is accelerated by air erosion and scouring， making it difficult for SiO₂ to adhere to the inner surface of the product， and the SiC matrix and carbon fiber are lost without protection. The fibers become thinner， the strength decreases gradually， and the toughening effect of the fibers is reduced greatly， so the bending strength and shear strength of the C/C-SiC composites decrease under two test conditions， and the mechanical property loss of the material is more serious under particles scouring.

In urgent demand for high-performance cryogenic titanium alloy for the heavy-lift launch vehicle， a novel 1500 MPa Ti-Al-V-Zr-Mo-Nb cryogenic titanium alloy （CT1400） was designed. Alloy bars and powder metallurgy materials of CT1400 were fabricated， and the microstructure， tensile properties， and cryogenic tensile deformation mechanism were also observed and analyzed. The results indicate that the CT1400 cryogenic titanium alloy mainly consists of α phase and a small quantity of β phase， which shows a typical near-α type cryogenic titanium alloy. CT1400 alloy bars display the apparent equiaxed fine-grain microstructure characteristic， and the powder metallurgy materials show the dominating lamellar microstructure combing with the “network” structure characteristic. CT1400 titanium alloys display excellent room and cryogenic tensile properties， which can stably reach cryogenic stress of 1500 MPa resulting from dislocation strengthening and grain boundary strengthening mechanisms. Furthermore， the twinning deformation at the cryogenic temperature of 20 K could additionally improve the cryogenic plastic deformation capacity of CT1400 titanium alloy by coordinating crystal orientation， promoting strain hardening， making it represent excellent coupling of strength and ductility at cryogenic temperatures.

The defects on TB6 titanium alloy were repaired using pulsed TIG（tungsten inert gas） additive manufacturing technology， and the effects of process parameters （pulse current and pulse time） and heat treatment on the microstructure and mechanical properties of the repaired TB6 titanium alloy were studied to determine the optimal heat treatment process parameters. The results show that the mechanical properties are relatively better in the as-repaired state when the pulse current is 50 A and the pulse time is 40 ms， with a tensile strength of 1113 MPa and an elongation of 5.26%. These samples are sequentially subjected to solid solution and aging heat treatment. When the samples are solid solution treated for 2 h under different temperatures （740， 760， 780 ℃）， the primary α phase is increasingly dissolved， while the β phase gradually grows and evenly distributes in the matrix. After water quenching， the growth of the β phase is inhibited， and acicular rhombic martensite α'' phase is precipitated in β grains， resulting in a decrease in tensile strength and a remarkable increase in elongation. Under different aging temperatures （500， 520， 540 ℃） for 8 h， the α'' phase continuously grows and gradually transforms to equiaxial grain， and the mechanical properties are greatly improved. The optimal microstructure and mechanical properties are achieved under the conditions of 780 ℃/2 h WC+520 ℃/8 h AC， with a tensile strength of 1119 MPa and an elongation of 7.36%.

The 6061-T6 ultra-thin aluminum alloy with a thickness of 0.5 mm was welded using micro-joint friction stir welding technology. The effects of three kinds of stirring heads with different shaft shoulder morphology on the forming quality， microstructure， mechanical properties， welding thermal cycle， and force process of the 6061-T6 thin-wall butt joint were studied. The flow behavior characteristics of the plastic metal in the three welding cross-sections were analyzed in sequence. The results show that the forming effect of the weld surface is significantly affected by welding heat input. The hardness distribution trend of the joint cross-section formed by three kinds of stirring heads with different shaft shoulder morphology is a “W” shape. The highest hardness values in the center of the nucleation zone and the lowest hardness values in the thermo-mechanical affected zone of the needle-free three-involute diversion groove shaft shoulder welded joint are the highest among the three shaft shoulder welded joints. The mechanical properties of the joint formed by the three-involute guide groove with the needle shaft shoulder are outstanding， and the tensile strength， yield strength， and elongation after fracture are higher than those of the other two. The three tensile fracture forms are mainly ductile fractures. The process parameters of the thermal cycle and force can accurately reflect the changing trend of the welding state. The energy required to maintain the weld metal softening is from the heat generated by friction between the shaft shoulder and the workpiece and the work done by the axial and forward forces of the shaft shoulder. The axial force and forward force changed with the softening degree of the welded metal， playing a dynamic regulating role in the migration of plastic metal in the weld. The shoulder surface has a strong effect on the upper part of the weld， driving the plastic metal migration between the forward side and the backward side. The needle of the stirring head promotes the interaction between the plastic metal and the backing plate， providing a driving force for the flow of the upper and lower parts of the weld metal. The optimal heat generation potential is the combined result of the stirring needle and the involute groove， which work together to form a well-formed weld.

The steam generator is subjected to the action of high temperature and high-pressure steam， and the flow induced vibration phenomenon of its heat transfer tube is caused by the secondary lateral flow. At the same time， the periodic loads cause fretting wear and fretting fatigue in the Inconel 690 alloy tube heat transfer tube and 403SS anti-vibration bar， which makes the heat transfer tube crack or even rupture and fail， and affects the safe operation of the nuclear power system. The friction and wear test of Inconel 690 alloy heat transfer tube and 403SS anti-vibration bar under different normal loads and displacement amplitudes was carried out by using fretting wear testing machine under normal temperature air and high-temperature air. The surface wear morphology and oxidation components of Inconel 690 alloy heat transfer tube were analyzed to reveal the wear failure mechanism of the heat transfer tube of the steam generator. The results show that with the increase of normal load at room temperature， debris accumulation and delamination appear on the surface of worn scars， and the degree of oxidation gradually intensifies. The fretting wear mechanism is mainly friction oxidation， abrasive wear， and delamination. Under the condition of high-temperature air， the peak friction force and the depth of worn scars increase， and the width of worn scars decrease. The plastic flow on the surface of the material is obvious， and the degree of oxidation and delamination deepens under the condition of high-temperature air. The fretting wear mechanism is mainly friction oxidation and delamination.

To investigate the relationship between calendaring temperature and the microstructure and performance of cathode for Li-ion batteries （LIBs）， two kinds of cathodes at calendaring temperatures of 25 ℃ and 150 ℃ were prepared by two-high rolling mill， respectively. The effects of calendaring temperature on microstructure， thickness consistency， mechanical， and electrochemical properties of cathode were studied. The results show that with the increasing calendaring temperature， the compaction density of cathode coating particles increases significantly， the pore size is smaller， the carbon adhesive phase is uniformly distributed on the active particles， the coating particles are broken， cracks， holes， and other defects decrease， and the cathode structure of conductive/bonding network is easier to form. Compared with the room-temperature calendaring cathode， the thickness consistency of hot calendaring cathode is improved， the rebound rate is reduced by 50%， and the pole sheet bond strength increases from 182.77 N/m to 237.37 N/m， increasing 29.87%. The tensile strength increases from 20.47 MPa to 24.44 MPa， increasing 19.39%. The electrode resistivity decreases from 158.05 Ω·cm to 119.41 Ω·cm， decreasing 24.45%. The electrical conductivity increases from 0.63 S/m to 0.84 S/m， increasing 33.33%. After being assembled as LIBs， the electrochemical performance of the hot calendaring cathode is better than that of the room-temperature calendaring cathode. The cycling capacity retention increases by 18.65%. The cathode performance can be improved moderately by adjusting the calendaring temperature and other technological parameters， providing a research basis for optimizing cathode performance during the LIBs electrodes industrial preparation.

Copper-chromium-zirconium alloy is a common alloy enhanced by precipitation， and it is extensively used in high-speed railway contact wires， lead frames， and heat exchange. The high-performance， complex-structured CuCrZr alloy produced by selective laser melting（LSM） has vast application potential in electronic components and heat exchangers. CuCrZr alloy powders were used as basic materials and manufactured by selective laser melting. Additionally， the effect of laser energy density on the microstructure and characteristics of SLM CuCrZr alloy was investigated. The results show that with the increase of laser energy density， the relative density of the alloy increases. At low energy density （119 J/mm³）， there are irregular holes on the surface of alloy sample， because the molten metal exhibits poor fluidity in the region surrounding the edge of the defect-prone molten pool. However， when the energy density increases to 267 J/mm³， the number of irregular holes decreases. Moreover， the relative density reaches the maximum value of 98.34% with the increasing energy density. Additionally， the electrical conductivity of the CuCrZr alloys with different process parameters is between 15.57%IACS and 18.68%IACS. Relative density is one of the variables that influence electrical conductivity， and the samples with great relative density have higher electrical conductivity than those with low relative density. Furthermore， there are significant differences in the strength and elongation properties of the samples with different process parameters. When the laser power is kept constant and the scanning speed and spacing are decreased， the strength of the alloy gradually increases. However， when the laser power increases and the scanning speed and spacing remain constant， the strength of the alloy increases accordingly. It can be concluded that the SLM process parameters have a great influence on the mechanical properties of the produced alloy. Density is intimately retated to the tensile characteristics of materials. Particularly， the greater the relative density is， the smaller the porosity of the material is， and the greater its strength is. With the increase in the bulk energy density， the degree of densification of the samples increases， and their tensile characteristics are enhanced. The SLM-5^# sample， manufactured with the parameters P=400 W， V=500 mm/s， and h=0.1 mm， shows the largest relative density and the highest ultimate tensile strength （330.63 MPa）， also has excellent plasticity， with the elongation of 30.81%. In addition， the sample exhibits ductile fracture properties， and the fracture surface has varying degrees of porosity and inclusion flaws. These are formed by the solidification of splash and unmelted particles generated during the SLM process， the pore size is between 3 μm and 100 μm， and tensile deformation traces in the form of wrinkles are dispersed around the inner walls of the holes， indicating that the samples generate significant amounts of plastic deformation during the tensile process. The presence of varying degrees of porosity and inclusion flaws on the fracture surface may disrupt the consistency of the internal structure of the molded components. The XRD spectrum indicates that the phase composition of the SLM CuCrZr alloy sample is α-Cu， and the Bragg peak of the sample significantly differs from that of the CuCrZr alloy powder. During the SLM process， the XY plane of the sample produces a strong ｛110｝ texture.The elongation at break of SLM CuCrZr alloy reaches 40.95%， and the tensile fracture morphology shows that defects such as unfused particles and holes are the key factors reducing the strength of the alloy.

The 316 stainless steel coatings with different thicknesses （SSC2， SSC4， SSC7， SSC10） were deposited on the magnesium alloy surface by using the HVOF method. The microstructures， deposition characteristics， residual stresses and immersion corrosion characteristics of the coating were investigated. The results reveal that due to the lower melting point and hardness of magnesium alloy， spray particles are prone to invade the substrate and melt its surface， causing particle escape or splashing， resulting in lower deposition efficiency； after depositing thinner coatings （SSC2 and SSC4）， the escape or splashing behavior of deposited particles reduces significantly， and the deposition efficiency increases； when the deposition thickness increases to SSC7 or above， the surface temperature of the deposition increases， particle splashing gradually increases， and the porosity and oxide content of the coating surface increase. Furthermore， as the coating thickness increases， the residual compressive stress of the coating decreases， the stress distribution becomes more uniform， and the number of penetrating pores in the coating decreases significantly， approaching zero. There are penetrating pores inside the SSC2 and SSC4 coatings， and the effective protection time is extremely short. The thick coatings （SSC7 and above） still have a protective effect after soaking in 3.5% （mass fraction） NaCl solution for 720 h.

The green fluorescent N-doped carbon dots （N-CDs） and （B，N）-doped carbon dots （B，N-CDs） were prepared from mint leaves by one-step hydrothermal method. The morphology structure， elementary composition，surface functional groups， and fluorescence properties of CDs were characterized by TEM， XRD，FT-IR，XPS， UV-Vis， and XRF. The results show that CDs are uniform in size and have hydrophilic groups such as —OH and —COOH on the surface. N-CDs and B，N-CDs are typical aromatic systems， with the maximum fluorescence emission peaks at 490 nm and 440 nm， respectively， exhibiting excitation light-dependent characteristics. After 120 min of simulated solar light， the degradation rate of methylene blue by N-CDs and B， N-CDs are 84% and 67%. The capture experiment result shows that h⁺，·O {}_{\mathrm{2}}^{-}，and e^- are the main active substances produced by N-CDs， and h⁺ and ·O {}_{\mathrm{2}}^{-} are the main active substances produced by B，N-CDs in the photocatalytic process. The type and intensity of reactive oxygen species are verified using electron spin resonance （ESR） spectroscopy， and ·O {}_{\mathrm{2}}^{-} is detected in both carbon dots. The photocatalytic process of N-CDs also produced more ¹O₂ than B， N-CDs， which resulted in a higher efficiency of N-CDs in photocatalytic degradation of MB than that of B， N-CDs.