Geometric Morphology Research Articles

Flower-like NiO to flower-like NiO/Ni@C microspheres: An effective strategy to comprehensively improve the loss capabilities

It was well recognized that the penetrated electromagnetic (EM) wave could be dissipated by means of magnetic loss, polarization loss and conduction loss. In order to improve their loss capacities and take full advantage of flower-like geometrical morphology, in this study, we proposed a simple route for the production of flower-like core@shell structure NiO/Ni@C microspheres through the carbon thermal reaction using NiO microflowers as precursor. The obtained results revealed that our proposed strategy successfully synthesized the core@shell structure magnetic carbon-based multicomponent nanocomposites without destroying the geometrical morphology of precursor. By regulating the annealing temperature, the as-prepared NiO/Ni@C microspheres with different contents of Ni and degrees of graphitization could be selectively synthesized, which effectively boosted their magnetic loss, polarization loss and conduction loss capabilities. Therefore, the elaborately designed NiO/Ni@C microspheres displayed the superior microwave absorption performances including strong absorption capability, broad absorption bandwidth and thin matching thicknesses compared to the NiO precursor. In summary, our findings not only provided a simple route to design and synthesize flower-like core@shell structure magnetic carbon-based nanocomposites as novel microwave absorbers, but also presented an effective strategy to comprehensively improve their loss capacities.

Microstructure evolution, mechanical properties of FeCrNiMnAl high entropy alloy coatings fabricated by laser cladding

In this work, FeCrNiMnAl high entropy alloy (HEA) coatings under different laser energy density (Led, 50–92 J/mm2) were fabricated on 17-4PH stainless steel by laser cladding (LC). The influence of different laser energy density on the geometric morphology, microstructure, microhardness and tribological properties of HEA coating was investigated. To obtain the specific solidification parameters (temperature gradient and solidification rate), the finite element model was established to express the transient change of molten pool temperature field. The columnar-to-equiaxed transition (CET) corresponding to different zones of HEA coating was revealed. The result showed that the geometric parameters increased with the rise of Led because of the Marangoni convection. Equiaxed crystals and columnar crystals were distributed on the top and bottom zones of HEA coatings respectively, and the CET behavior was observed. Higher temperature gradient and lower solidification rate were conducive to the growth of columnar-crystals. Furthermore, at the Led of 92 J/mm2, HEA coatings showed relatively high crack sensitivity. HEA coatings significantly improved the tribological properties owing to metal oxide particles generated by oxidation. In the mechanical properties test, the maximum microhardness of prepared HEA coating (1800 W) was 587.83 HV0.2, which was 1.63 times that of 17–4PH substrate. Metal oxide particles generated a flat wear-resistant enamel layer which protected the coating surface. The tribological properties was optimal at the Led of 64 J/mm2, the average friction coefficient and wear rate were 0.4654 and 7.026 × 10−8 mm2/N, respectively.

A stable and quantitative method for dimensionality reduction of aortic centerline.

Aortic dissection (AD) is a fatal aortic disease with high mortality. Assessing the morphology of the aorta is critical for diagnostic and surgical decisions. Aortic centerline projection methods have been used to evaluate the morphology of the aorta. However, there is a big difference between the current model of primary plane projection (PPP) and the actual shape of individuals, which is not conducive to morphological statistical analysis. Finding a method to compress the three-dimensional information of the aorta into two dimensions is helpful to clinical decision-making. In this paper, the evaluation parameters, including contour length (CL), enclosure area, and the sum of absolute residuals (SAR), were introduced to objectively evaluate the optimal projection plane rather than artificial subjective judgment. Our results showed that the optimal projection plane could be objectively characterized by the three evaluation parameters. As the morphological criterion, SAR is optimal among the three parameters. Compared to the optimal projection plane selected by traditional PPP, our method has better AD discrimination in the analysis of aortic tortuosity, and is conducive to the clinical operation of AD. Thus, it has application prospects for the preprocessing techniques for the geometric morphology analysis of AD.

Stress state at the root of variable-wall-thickness pipeline welded joint

In this study, root notch defects in the application of variable wall thickness designs of pipeline welded joints were analyzed. Considering variable-wall-thickness pipelines, various finite element models of butt-welded joints were established by changing the joint geometric parameters such as variable-wall-thickness ratio, butt misalignment, or variable wall thickness transition angle. This was followed by applying different internal working pressures of the pipeline to calculate the stress triaxiality and maximum principal stress near the root notch of the welded joints. The influence of the weld section shape and internal working pressure on the calculation results is summarized, and the corresponding fracture risk of the root notch is evaluated. Based on the aforementioned analysis, it was found that the root notch in the variable-wall-thickness joint reduced the safety of the welded joint. A greater irregularity of the joint geometric morphology results in a higher the stress triaxiality and maximum principal stress near the root notch, further severely increasing the brittle fracture risk of the joint.

3D reconstruction and characterization of reef limestone pores based on optical and acoustic microscopic images

The pore network in reef limestone provides an important resource for fluid storage and flow. Three-dimensional (3D) reconstruction and characterization of the spatial structure of reef limestone pores offers a valuable way of identifying its physical and mechanical properties. This paper reports on a study where optical and acoustic microscope images were used to combine the advantages of the high resolution of optical testing with the high penetration capabilities of acoustic testing. This overcomes existing problems with multi-scale structural imaging of the pores in reef limestone caused by the small penetration depth of traditional optical imaging and the low resolution of ultrasonic imaging. First of all, a correlation function between the shallow and deep pore structure of reef limestone is established. This draws on high-resolution data from shallow optical microscopic images and deep acoustic microscopic images with a multi-layered cross-section. The contours of the shallow and deep pore structure are then digitized. After this, horizontal section control points and vertical transition contours are constructed that enable a deep integration of information about the multi-dimensional geometric morphology of the pore structure to be realized, providing in turn for a fine-grained 3D reconstruction of the pore structure at different scales. Finally, factors governing the characterization of contour similarity and center deviation are proposed that make it possible to generate spatial representations of the pore structure across multiple dimensions. A real-world case analysis is then used to verify the feasibility and reliability of the proposed method. The results show that the method can provide abundant data for the establishment of a reef limestone pore network and physical model, making it possible to improve the quality of 3D reconstructions of the pore structure and improve the 3D imaging of reef limestone pore networks. The proposed method can underpin new approaches to analysis of the pore structure of reef limestone and support a wide range of potential applications in the field of pore visualization and characterization.

Microstructure and tribological behavior of plasma spray Ni60 alloy coating deposited on ZL109 aluminum alloy substrate

This paper investigated the microstructure and tribological behavior of Ni60 alloy coating prepared on the surface of aluminum alloy (ZL109) by plasma spray. The ANSYS software was applied to compare the deformation and temperature of nickel-based alloy coating deposited on aluminum alloy piston with the thickness of 300 µm, 400 µm and 500 µm. X-ry diffraction (XRD) and Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray Spectroscopy (EDS) were used to characterize the phase, microstructure and chemical composition of Ni60 alloy coating. Besides, fractal theory was used to study the geometric morphology of materials. The tribological properties of the coating were investigated under oil-lubrication at 100 °C through the circular cyclic test with Si3N4. The result shows that the piston skirt deformation was the smallest when the coating thickness was 300 µm. Multiple phases such as chromium carbide and Ni3Fe phases were contained in the coating, and Si element was dispersed in the Ni60 alloy powders with the form of silicon oxide, which enhanced the hardness and oxidation resistance of the coating. The porosity of the coatings prepared under three power conditions (P = 40 kW, P = 50 kW and P = 45 kW) were 1.58%, 1.47% and 0.97%, respectively. When the load increased from 80 N to 100 N, the depth and width of the wear scar increased and the wear volume added from 1.54 × 108 μm3 to 3.45 × 108 μm3. The friction coefficient of the coating increased with the increment of load. By comparison, the coating with moderate spraying power has less weight loss and better wear resistance under higher wear load.

Podocarpium (Fabaceae) from the late Eocene of central Tibetan Plateau and its biogeographic implication

Podocarpium is an extinct genus in Fabaceae with rich fossil records in Eurasia dating back to the Eocene. However, the diversification and biogeographic histories of Podocarpium are poorly known due to a lack of fossils in some key regions, such as the Tibetan Plateau, an area recently shown to be crucial for floristic exchanges worldwide in the geological past. Here, we describe well-preserved fossil pods of Podocarpium from the late Eocene (~35 Ma) of the Lunpola Basin, central Tibetan Plateau, China. Together with detailed morphological observation and geometric morphology analysis, these fossil pods are named Podocarpium tibeticum W.-C. Li, J. Huang et T. Su sp. nov., characterized by asymmetrical elliptical valves, olecranon fruit beak, and a clearly oblique base. This material comprises the oldest fossil record of Podocarpium from the Tibetan Plateau and adjacent regions. The discovery of P. tibeticum shows Podocarpium was present in central Tibet by the late Eocene. Together with previous fossil records, it indicates that Podocarpium may have originated in East Asia, migrated into the central valley of Tibet in the late Eocene, and then spread westward to Europe through a low-latitude path of island chains along the Neotethys. Results of paleoecological niche modeling demonstrate that Podocarpium had an almost worldwide potential distribution range in the Eocene, but this sharply contracted thereafter until by the Pliocene it was restricted to a small area of East Asia. Generally, this finding further supports the idea that what is now the central Tibetan Plateau was a globally significant hub for Paleogene floristic exchange.

Recent progress on artificial propeller chirality and related circular dichroism engineering

<p indent="0mm">Chirality, a geometric asymmetry in which a structure cannot coincide with its own mirror image through rotation and translation, is one of the basic properties of nature. It has been involved in all aspects of our life, such as art, architectural design, medicine, pesticides, life, information, chiral optoelectronic functional materials and devices. The interactions of chiral substances with light can differ for left- and right-handed circularly polarized (LCP and RCP) light and rely on the handedness of the enantiomers. Since scientists discovered the optical activity of chiral matter in the 19th century, the study of chiral light-matter interactions has become one of the most cutting-edge research fields in optics. Circular dichroism (CD) is the difference in absorption of LCP and RCP light by chiral substances. Since the chiral optical response of natural chiral matter is weak and difficult to tune, researchers have creatively designed various artificial chiral structures to enhance chiral light-matter interactions and realize many novel physical phenomena. The most common example is the helical configuration, which can be seen as the result of the stretched superposition of multiple split resonator rings. It can obtain much larger CD than natural materials. However, the three-dimensional fabrication process of micro/nanoscale helical structures faces challenges, which limit its application research. Different from common helical chiral structures and based on the nano-kirigami fabrication technique, this review focuses on a new type of artificial propeller-like chiral micro/nanostructures and their applications in chiral optics. This artificial propeller chirality is quite different from the traditional chiral structure in terms of geometric morphology and physical responses, such as the novel out-of-plane stereo twist and the chiral competition mechanism enabled by the hybridization of unit cells with two different chiral centers. The CD responses can be significantly enhanced by the chiral Fano resonance that is caused by the surface lattice resonances (SLRs). The chiral SLRs are formed by the coupling of chiral electric quadrupole modes to the diffractive lattice mode (Rayleigh anomaly). These unique features enable outstanding advantages in the flexible manipulation of optical CD, including the sensitive changes in intensity, sign and wavelength upon structural perturbations. Specially, the counterintuitive sign reversal of CD can be realized under minor structural changes without inverting the handedness of artificial propeller chirality. The work in this review provides a novel design idea for new artificial chiral micro/nanostructures and an ideal platform for in-depth study of chiral physics.

The discriminative potential of palatal geometric analysis for sex discrimination and human identification.

Previous 3D superimposition studies of digital scans of the human palate, using geometric and surface morphology comparisons, have shown its usefulness in assisting in the identification process, including its ability to distinguish identical twins. This study aimed to evaluate the discriminative potential when only simple geometric analysis is used. Its aim is not only to determine if geometric comparison alone is sufficient not only to assist in identification but if it supports the hypothesis of assisting in sex discrimination when no other comparative data is available. The palates of 64 monozygotic (M.Z.T.) and 39 dizygotic (D.Z.T.) twins were digitized three times using a scanner. Digital smoothing was used to remove the rugae, and palatal height, depth, and width were measured. The study confirmed that the smoothing function had little effect on the discriminatory function since the Mean Absolute Distance (MAD) between M.Z.T. (0.430 ± 0.018 mm versus 0.425 ± 0.022 mm p=0.061) or D.Z.T. (0.621 ± 0.058 mm versus 0.586 ± 0.053 mm, p=0.284) scans show little change. By combining the height, depth, and width into a discriminative function, the sex correctly correlated 83.9% of the time, identity by 91.2% sensitivity, and twining by 68.5%. The difference in the 3D palatal model between twin siblings is primarily due to palate geometrics. Since geometric comparison requires far less computation time, geometric comparison alone can be used as an adjunct metric for limiting the possible matches in a dental 3D database in determining both sex and identity, especially if no other evidence is available.

Nanohybrids with tunable band gap and low electron effective mass: Graphenes doped by multiple boron nitrogen domains

Two-dimensional (2-D) hexagonal boron–nitrogen–carbon (h-BNC) has long been considered as an important candidate material for the next generation of semiconductor electronic devices. Nevertheless, simply controlling the concentration of BN cannot effectively regulate the electronic properties. It is highly required to develop a more efficient doping strategy with the involvement of the geometrical morphology and arrangement of the BN domain. Inspired by recent experimental evidence that BN dopants preferentially form regularly shaped BN nanodomains on graphene by controlling precursors and high-temperature environments, in this work, for the first time, we investigate the effects of embedded BN domains of different shapes, sizes, and numbers on the electrical properties and thermodynamic stability of 2-D h-BNC nanohybrids using density functional theory.It is demonstrated that a doping mode with multiple small BN domains can effectively achieve a wide range of tunable band gap engineering of graphene, better than routinelysingle large BN domain.Meanwhile, multiple BN domain-modified graphene can maintain the excellent carrier mobility of intrinsic graphene.This unique behavior can be attributed to more boundary B/N atoms in the multiple BN domain doping h-BNC structures. Our simulation provides new conceptual insight into the doping configuration design for 2-D nanomaterials.

Facile generation of crumpled polymer strips by immersion electrospinning for oil spill cleanups

The fabrication of electrospun products with desired structures and improved oil sorption capacities has attracted increasing attention in recent years; however, the overall geometry of electrospun products has rarely been investigated. Herein, we report a promising and competitive strategy for the preparation of novel electrospun polystyrene (PS) strips with advanced crumpled geometries for oil spill cleanups. The crumpled PS strips were prepared by immersion electrospinning, in which the nozzle and collector were simultaneously immersed in a coagulation bath. By controlling the processing parameters such as applied voltage and polymer concentration, the geometric morphology of the crumpled strips was precisely regulated. Benefiting from the crumpled structure, the crumpled strips demonstrated oil sorption capacities of approximately 83, 77, and 72 g/g for silicone, canola, and mineral oils, respectively. These values significantly higher than the values exhibited by the straight conventional electrospun fibers. The reported strategy offers a novel perspective on the rational design of electrospun products for oil sorption applications.

Far-Field and Non-Intrusive Optical Mapping of Nanoscale Structures.

Far-field high-density optics storage and readout involve the interaction of a sub-100 nm beam profile laser to store and retrieve data with nanostructure media. Hence, understanding the light–matter interaction responding in the far-field in such a small scale is essential for effective optical information processing. We present a theoretical analysis and an experimental study for far-field and non-intrusive optical mapping of nanostructures. By a comprehensive analytical derivation for interaction between the modulated light and the target in a confocal laser scanning microscopy (CLSM) configuration, it is found that the CLSM probes the local density of states (LDOSs) in the far field rather than the sample geometric morphology. With a radially polarized (RP) light for illumination, the far-field mapping of LDOS at the optical resolution down to 74 nm is obtained. In addition, it is experimentally verified that the target morphology is mapped only when the far-field mapping of LDOS coincides with the geometric morphology, while light may be blocked from entering the nanostructures medium with weak or missing LDOS, hence invalidating high-density optical information storage and retrieval. In this scenario, nanosphere gaps as small as 33 nm are clearly observed. We further discuss the characterization for far-field and non-intrusive interaction with nanostructures of different geometric morphology and compare them with those obtainable with the projection of near-field LDOS and scanning electronic microscopic results.

An Investigation on Local Shearing Mechanisms of Irregular Dentate Rock Joints Using the PFC

Joint surfaces are widely distributed in natural rock mass, and their shear mechanical properties play an important role in determining the safety and stability of rock mass. Previous studies rarely discussed the contribution degree of different joint protrusions to resisting shear stress. In this study, seven irregular dentate joint profiles were proposed to represent the geometric morphology of natural joints. Joint samples were subjected to direct shear tests under constant normal stress using the particle flow code (PFC). First, the reliability of the research scheme was verified by routine test results. Secondly, based on the microcrack tracking module and the force chain analysis, the local failure modes of the joint sample after and during the shearing process are discussed in detail. The relationship between the shear stress and the number of microcracks was studied. Finally, based on the measuring circle function, the variation law of the mean stress at different joint protrusions during the shearing process was tracked. The maximum stress of each protrusion before the shear stress peak was introduced to quantitatively describe the contribution of local protrusions to shear stress. There was an important link between the size of the protrusion and the stress it can withstand. During the shearing process, the local shearing mechanism of the joint surface is controlled by the distribution of joint protrusions. The research results of this paper can provide a good idea for the follow-up joint surface research.

Prediction of molten pool temperature and processing quality in laser metal deposition based on back propagation neural network algorithm

Stability of molten pool temperature directly affects the dimensional accuracy, metallurgical defects, solidification microstructure and mechanical properties of formed parts manufactured by laser metal deposition technology. Therefore, the optimization of the macroscopic morphology and microstructure of the formed parts through the stable control of the molten pool temperature has been intensively studied. In this study, three models, based on the back propagation neural network (BPNN), random forest (RF) algorithms and response surface methodology (RSM) approach, respectively, were used to establish prediction relationships between the deposition input parameters and processing status parameters, geometric morphology and mechanical property parameters. Then, the processing temperature and molten pool characteristics of thirty groups of 316L stainless steel single-track cladding layers were analyzed. The prediction results show that the average prediction error (APE) of the prediction of molten pool temperature, track width, track height and micro-hardness of the deposited layer based on BPNN model are 0.5%, 1.3%, 2.9% and 0.1%, respectively, which are better than the prediction results of RF and RSM models. Then, BPNN model was further used to predict the molten pool temperature and processing quality of the deposited layer under the combination of five new process parameters groups. Objective of this study was to lay the foundation for the subsequent design of the molten pool temperature control system to improve the morphology accuracy and mechanical properties of formed parts.

Unraveling trajectories of diffusive particles on networks

The analysis of single-particle trajectories plays an important role in elucidating dynamics within complex environments such as those found in living cells. However, the characterization of intracellular particle motion is often confounded by confinement of the particles within nontrivial subcellular geometries. Here we focus specifically on the case of particles undergoing Brownian motion within a network of narrow tubules, as found in some cellular organelles. A computational unraveling algorithm is developed to uncouple particle motion from the confining network structure, allowing for an accurate extraction of the underlying one-dimensional diffusion coefficient, as well as differentiating between Brownian and fractional Langevin motion. We validate the algorithm with simulated trajectories and then highlight its application to an example system: analyzing the motion of membrane proteins confined in the tubules of the peripheral endoplasmic reticulum in mammalian cells. We show that these proteins undergo diffusive motion and provide a quantitative estimate of their diffusion coefficient. Our algorithm provides a generally applicable approach for disentangling geometric morphology and particle dynamics in networked architectures.

Population Genetic Structure and Geometric Morphology of Codling Moth Populations from Different Management Systems

Codling moth (CM), Cydia pomonella L., is an important pest of apples worldwide. CM resistance to insecticides is a serious problem in apple production. For effective management and control, monitoring of resistant CM populations is absolutely necessary. Therefore, in this study, we investigated whether it is possible to find a reliable pattern of differences in CM populations related to the type of apple control method. The genetic results showed low estimated value of the pairwise fixation index, FST = 0.021, which indicates a lack of genetic differentiation and structuring between the genotyped populations. Different approaches were used to analyze the genetic structure of codling moth populations: Bayesian-based model of population structure (STRUCTURE), principal component analysis (PCA), and discriminant analysis of principal components (DAPC). STRUCTURE grouped the CM genotypes into two distinct clusters, and the results of PCA were consistent with this. The DAPC revealed three distinct groups. However, the results showed that population genetic differentiation between organic and integrated orchards was not significant. To confirm the genetic results, the forewing morphology of the same CM individuals was examined using geometric morphometric techniques based on the venation patterns of 18 landmarks. The geometric results showed higher sensitivity and separated three distinct groups. Geometric morphometrics was shown to be a more sensitive method to detect variability in genotypes due to pest control management. This study shows the possibility of using a novel method for a strategic integrated pest management (IPM) program for CM that is lacking in Europe.

Leakage performance of CFRP laminate under cryogenic temperature: Experimental and simulation study

Leakage rate prediction of carbon fiber reinforced polymer (CFRP) composites for cryogenic propellant tanks has been a challenge for the research community. In this paper, the leakage properties of CFRP laminates with various lay-up configurations are experimentally assessed by measuring their leakage rates under different loads and temperatures. The effects of temperature, cooling conditions and loading on the leakage rates of the above laminate composites are discussed. Meanwhile, in-situ micro X-ray computed tomography (μCT) testing is performed to characterize the internal microstructure evolution of the composites under tension. The geometric morphology and parameters of defects are investigated as well. The propagation of internal cracks in the composites under loading is carefully monitored. A novel 3D image-based model is developed using μCT scans to predict the leakage properties of the composites under various loads. The initiation and propagation leakage rates of laminates, whose values are found to be within the same order of magnitude as experimental ones. The proposed simulation method allows one to quickly calculate the image-based leakage model suitable for the prediction of leakage performance and the lay-up design of composite cryogenic propellant tanks under cryogenic temperatures.

Constructing MoSe2/MoS2 and MoS2/MoSe2 inner and outer-interchangeable flower-like heterojunctions: A combined strategy of interface polarization and morphology configuration to optimize microwave absorption performance

Interfacial polarization and geometrical morphology play a significant role in the attenuation of electromagnetic (EM) wave. Herein, the two-dimensional (2D)/2D heterojunction with flower-like geometrical morphology is proposed and produced, which may simultaneously provide a large contact area for achieving strong interfacial polarization and activates more sites for the possible multiple EM wave reflection and scattering. By adopting a simple two-step hydrothermal method, MoSe2/MoS2and MoS2/MoSe2 inner and outer-interchangeable heterojunctions consisting of 2D MoSe2 and MoS2 nanosheets with flower-like geometrical morphology were successfully synthesized. The results revealed that the hydrothermal temperatures significantly impacted the flower-like geometrical morphology and MoS2 content. By optimizing the microstructures, the designed MoSe2/MoS2 and MoS2/MoSe2 heterojunctions presented enhanced comprehensive EM wave absorption properties (EMWAPs), possessing strong absorption capability, wide absorption bandwidth and thin matching thicknesses. Generally, this work demonstrates that the optimized EMWAPs of designed heterojunctions mainly originate from the special interfaces and morphology configuration, which also paves a new way for the designing and synthesis of transition metal dichalcogenides-based heterojunction as a novel and desirable candidate for high-performance microwave absorbers.

Ultrafast laser-induced integrated property–structure modulation of Ge2Sb2Te5 for multifunction and multilevel rewritable optical recording

Abstract In this paper, we report an approach for tuning the surface morphology and phase of Ge2Sb2Te5 (GST) by using an ultrafast laser in a one-step process. Four surface micro/nanostructures with specific phase states were sequentially formed by changing the pulse energy: the modified ripple structure, the completely crystallized structure, the ablated nanodots, and the ablated ripple structure. A high correlation existed between the surface micro/nanostructures and their property. Through integrated property–structure modulation, multifunctional optical recording could be achieved by using modified ripples with specific crystallized phase states. The geometric grating morphology caused by the volume shrinkage effect during crystallization enabled modified ripples to exhibit a structural color based on the grating’s diffraction effect. Moreover, the considerable change in the reflectivity of the crystallized area enabled easy grayscale identification. On the basis of the spatially resolved phase-transition threshold effect, the integrated modulation of the geometric nanograting proportion and degree of crystallization was conducted in multilevel states. Notably, different from the fixed ablated surface structures, the printed modified surface structures could be erased and rewritten by controlling its phase state. This paper presents a promising method for producing dynamic tunable metasurfaces, conducting optical anticounterfeiting, and achieving information storage.

Morphology and composition dependence of multicomponent Cu-based nanoreactor for tandem electrocatalysis CO2 reduction

Multicomponent heterogeneous catalysts present excellent catalytic performance attributed to the synergistic effect of multi-sites. Nevertheless, identifying the composition of the multi-sites and exploring the synergistic catalytic mechanisms for the multiple active sites in electrocatalytic CO2 reduction reaction (CO2RR) still lack intensive study. This work regulates the chemical composition of Cu-based nanoreactors readily by adjusting the geometrical morphology of metal-organic frameworks precursor. The obtained cuboctahedron nanoreactor containing Cu-N4/Cu2O/Cu multiple active sites exhibits excellent CO2RR selectivity towards deep reduction product (80%) with high current density. Moreover, the tandem catalytic mechanism of multicomponent active sites has been studied intensively. The CO2 molecule is firstly reduced in Cu-N4 sites to form CO and then the CO is transfered to Cu2O/Cu sites for further deep reduction. The high concentration of CO provided by Cu-N4 sites decreases the free energy of rate-determining step for CH4 products in Cu2O sites. This work provides a promising direction for designing and synthesizing multicomponent Cu-based tandem catalysts to access high efficiency and selectivity in the electrocatalytic CO2 reduction reaction.