Defective Graphene Research Articles

Electromagnetic interference shielding of graphene/PMMA composites depending on growth temperature of CVD-graphene

The research on graphene, driven by its exceptional mechanical, electrical, and thermal properties, has garnered significant attention, making it a promising multi-functional material for electronics. In this study, we investigated the effect of the synthesis temperature on the crystalline quality and the electromagnetic interference (EMI) shielding performance of graphene. We performed graphene synthesis on Cu foil at different temperatures (from 900° to 1050°C) and subsequently analyzed the samples using Raman spectroscopy. The results showed that the crystalline quality of graphene increased with increasing synthesis temperature. We then fabricated a 100-layer graphene/poly(methyl methacrylate) (PMMA) composite (GPC) and evaluated its electrical, mechanical properties, and EMI shielding effectiveness (SE). Our findings revealed the GPC with high crystalline graphene had a higher electrical conductivity and tensile strength than the GPC with defective graphene. In addition, the GPC with high crystalline graphene had a higher EMI SE, with a total SE of 14.16 dB, which is 140 % higher than that value for a defective graphene structure.

Highly defective graphene quantum dots-doped 1T/2H-MoS2 as an efficient composite catalyst for the hydrogen evolution reaction

We present a new composite catalyst system of highly defective graphene quantum dots (HDGQDs)-doped 1T/2H-MoS2 for efficient hydrogen evolution reactions (HER). The high electrocatalytic activity, represented by an overpotential of 136.9 mV and a Tafel slope of 57.1 mV/decade, is due to improved conductivity, a larger number of active sites in 1T-MoS2 compared to that in 2H-MoS2, and additional defects introduced by HDGQDs. High-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) were used to characterize both the 1T/2H-MoS2 and GQDs components while Fourier-transform infrared spectroscopy (FTIR) was employed to identify the functional groups on the edge and defect sites in the HDGQDs. The morphology of the composite catalyst was also examined by field emission scanning electron microscopy (FESEM). All experimental data demonstrated that each component contributes unique advantages that synergistically lead to the significantly improved electrocatalytic activity for HER in the composite catalyst system.

Boosting Copper Biocidal Activity by Silver Decoration and Few-Layer Graphene in Coatings on Textile Fibers.

The outbreak of the Coronavirus disease 2019 (COVID-19) pandemic has highlighted the importance of developing antiviral surface coatings that are capable of repelling pathogens and neutralizing them through self-sanitizing properties. In this study, a novel coating design based on few-layer graphene (FLG) is proposed and silver-decorated micro copper flakes (CuMF) that exhibit both antibacterial and antiviral properties. The role of sacrificial anode surfaces and intrinsic graphene defects in enhancing the release of metal ions from CuMF embedded in water-based binders is investigated. In silico analysis is conducted to better understand the molecular interactions of pathogen-repelling species with bacterial or bacteriophage proteins. The results show that the optimal amount of CuMF/FLG in the coating leads to a significant reduction in bacterial growth, with reductions of 3.17 and 9.81 log for Staphylococcus aureus and Escherichia coli, respectively. The same coating also showed high antiviral efficacy, reducing bacteriophage phi6 by 5.53 log. The antiviral efficiency of the coating is find to be doubled compared to either micro copper flakes or few-layer graphene alone. This novel coating design is versatile and can be applied to various substrates, such as personal protective clothing and face masks, to provide biocidal activity against both bacterial and viral pathogens.

Flexible carbon film with local enlarged interlayer spacing for ultrafast and highly durable potassium storage

Carbon materials have drawn much attention as a rigid electrode for the reversible intercalation of K+ along with a high surface adsorption capacity for potassium-ion batteries (KIBs). However, it is a challenge to prepare flexible carbon film for freestanding KIBs anodes, which could promote the free transfer of electrolyte and allow sufficient interlayer spacing to relieve the tension generated by K+-intercalation. Herein, a flexible carbon film constructed by honeycomb-like porous nanofibers with local enlarged interlayer spacing is synthesized by an electrospinning method together with a metal-organic frameworks (MOFs)-derived strategy. The flexible carbon film improves the electrical conductivity of freestanding electrode, and the interconnected porous structure with local enlarged interlayer spacing facilitates the transfer of electrolyte to active sites fluently and relieves the K+-intercalation induced tension, which synergistically boosts the reaction kinetics and K+-storage capacity. The freestanding flexible carbon film delivers excellent potassium storage performance of 386.1 mAh g−1 at 0.1 A g−1 after 500 cycles and 190.1 mAh g−1 at 5 A g−1 after 2400 cycles. Moreover, density functional theory (DFT) calculation confirms the advantage of edge-N atoms at graphene defect in adsorbing the K+ with limited volume expansion, which could provide extra capacity beyond K+-intercalated contribution for KIBs.

C─N Coupling Enabled by N─N Bond Breaking for Electrochemical Urea Production

AbstractUrea electrosynthesis under mild conditions has emerged as a promising alternative strategy to replace the harsh industrial HaberBosch process, which is however limited by sluggish CN coupling and low selectivity. Here, a novel mechanism based on the synergistic effect of NN bond cleavage and CN coupling for highly efficient urea production is proposed. It is found that dual vanadium atoms anchoring onto defective graphene (V2N6) can activate the adsorbed *N2, in which the stable N≡N bond can be gradually weakened until being broken after two protonation steps, with superior thermodynamic and kinetic feasibility. CO molecules can be easily adsorbed on the dissociated *NH, followed by an exothermic CN coupling to form the urea precursor *NHCONH with a low kinetic energy barrier of 0.20 eV. The dual‐atom V2N6 not only exhibits superior intrinsic activity for urea formation, with a limiting potential of −0.26 V, but also can significantly suppress the competitive N2 reduction and hydrogen evolution reactions. This study presents a new avenue for developing novel mechanisms and efficient catalysts for urea electrochemical synthesis.

Novel synthesis of low-loading Pt/graphene via thermal expansion and its superior ORR performance

In this paper, graphene with low platinum loading was prepared using the thermal expansion method, resulting in uniform dispersion of ultrafine Pt nanoparticles. The synthesized Pt/graphene exhibits a large specific surface area, abundant graphene defects, and homogeneous Pt particles. In 0.1 M KOH, the catalyst exhibits a half-wave potential of 0.84 V (vs. RHE), a limiting current density of 5.66 mA cm−2, and an electron transfer number of 3.9. The performance is close to that of the commercial 20 wt% Pt/C and outperforms the 10 wt% Pt/C. Moreover, it demonstrates better charge transfer kinetics and exceptional stability compared to the commercial 20 wt% Pt/C. This provides a promising avenue for the development of novel Pt-based catalysts.

Proton penetration mechanism and selective hydrogen isotope separation through two-dimensional biphenylene.

Hydrogen isotope separation is of prime significance in various scientific and industrial applications. Nevertheless, the existing technologies are often expensive and energy demanding. Two-dimensional carbon materials are regarded as promising candidates for cost-effective separation of different hydrogen isotopes. Herein, based on theoretical calculations, we have systematically investigated the proton penetration mechanism and the associated isotope separation behavior through two-dimensional biphenylene, a novel graphene allotrope. The unique non-uniform rings with different sizes in the biphenylene layer resemble the topological defects of graphene, serving as proton transmission channels. We found that a proton can readily pass through biphenylene with a low energy barrier in some specific patterns. Furthermore, large kinetic isotope effect ratios for proton-deuteron (13.58) and proton-triton (53.10) were observed in an aqueous environment. We thus conclude that biphenylene would be a potential carbon material used for hydrogen isotope separation. This subtle exploitation of the natural structural specificity of biphenylene provides new insight into the search for materials for hydrogen isotope separation.

Effects of graphene pull‐out on the interfacial mechanical properties of alumina/graphene nanocomposite ceramic tool materials: Molecular dynamics analysis and material preparation

AbstractThe interfacial mechanical properties of the alumina/graphene (Al2O3/GR) nanocomposite ceramic tool materials were studied by molecular dynamic simulations. The effects of pull‐out velocity of graphene, system temperature, vacancy defect, and wrinkled graphene on the interfacial mechanical properties were investigated. Results show that a large interfacial shear stress (382 MPa) exists between the Al2O3/GR interface. The maximum pull‐out force and interfacial shear stress increase with increasing graphene pull‐out velocity. The increase of temperature reduces the maximum pull‐out force and interfacial shear stress. Moreover, the load transfer capacity is reduced and the creep of the matrix occurs. These factors reduce the fracture toughness of the Al2O3/GR nanocomposites. A moderate amount of vacancy defects in graphene increases the interfacial pull‐out force and shear stress of Al2O3/GR nanocomposite ceramic tool. Compared with Al2O3/GR nanocomposite ceramic tools, the interfacial interaction energy and shear stress of pleated graphene and Al2O3 were increased by 13.87% and 41.08% respectively, with better toughening and reinforcement. The results are of significance in further understanding of the interfacial mechanical properties at the nanoscale and then beneficial to improve the mechanical properties and engineering performance of Al2O3/GR composite ceramic materials.

Sonoelectrochemical nitrided graphene nanosheets with vacancies and their applications for catalysis and sensing of uric acid oxidation

A sonoelectrochemical method for preparing N-doped defective graphene nanosheets (N/O-dGNs) with point defects and 5-9 or 5-8-5 vacancies and oxygen-containing groups was successfully demonstrated. In this one-pot approach, the N-bonding configuration and N content of N/O-dGNs were finely tuned by the ultrasonic power (192, 320, and 640 W). The N content in atomic percentage (at%) for N/O-dGN (N/O-dGN320W) with point defects and 5-8-5 vacancy prepared at 320 W power was 5.6 at%, greater than 3.0 at% and 2.6 at% for N/O-dGN with point defects and 5-9 vacancies at 192 W and 640 W power (N/O-dGN192W and N/O-dGN640W), respectively. N-bonding sites on N/O-dGN320W were dominantly amine N (2.1 at%) and pyrrolic N (2.4 at%). Additionally, the electrocatalytic activity of N/O-dGN192W, N/O-dGN320W, and N/O-dGN640W was successfully demonstrated for the sequential uric acid (UA) oxidation reaction (UOR), in which N/O-dGN320W displayed a significant mass activity (2.51 A/g). As in the transient catalysis of UOR, N/O-dGN320W with amine N showed 400.8 μA mM−1 cm−2 in sensitivity within a wide linear analysis range (1.5 × 10–2–6 mM) for amperometrically sensing UA. The results of real sample experiments using serum samples further demonstrated the potential of N/O-dGN320W as a non-enzymatic UA sensor.

Synthesis and characterization of graphene via electrochemical exfoliation technique and study its electrochemical properties

In this study, we present a one-pot approach for the large-scale synthesis of multilayer to few-layer graphene nanosheets in an aqueous medium that is cost-effective, environmentally friendly, high-yielding, and simple. This electrochemical exfoliation method produces low defect and high yield graphene nanosheet products and is more efficient than chemical exfoliation methods. Two highly oriented pyrolytic graphite plates (HOPG) are utilized as the anode and cathode in this method, which also incorporates two electrode geometry configurations. XRD, HRTEM, AFM, XPS, and Raman spectroscopy are used to describe graphene nano-sheets. Raman characterization supports graphene’s inherent qualities. By using cyclic voltammetry, the electrochemical performance of the produced nano-sheets is evaluated.

Insights into the mechanism of electric field regulating hydrogen adsorption on Li-functionalized N-doped defective graphene: A first-principles perspective

The hydrogen storage properties of lithium functionalized graphene under external electric fields have been studied in this work employing density functional theory (DFT) calculations. Lithium modified nitrogen doped double-vacancy graphene (Li_NDVG) was constructed as hydrogen storage material. It is examined in terms of the system’s electronic properties, H2 adsorption energy, and stable configuration. The results demonstrate that Li atoms can be distributed on the substrate surface and incorporated into defect centers without producing metal clusters. In comparison to pristine graphene, the adsorption energy of H2 on Li_NDVG is four times higher. The Coulomb force between Li atom and H2 molecule grows as the positive electric field’s strength increases, and the adsorption distance shrinks. On the contrary, the H2 adsorption energy decreases as the negative electric field’s strength increases, and the adsorption distance expands. Furthermore, adsorption occurs spontaneously within the range of 0–300 K and 1–100 atm, and the promoting effect of a positive electric field on adsorption only occurs in the temperature range of 0–140 K. Hydrogen storage properties of functionalized graphene modified with lithium trimer and tetramer respond to the electric field in the same way as single atom. And the presence of clusters and positive electric field increases the bond length of the H2 molecule, causing a tendency for the H2 molecule to dissociate.

(Digital Presentation) Deconstructing Proton Transport through Atomically Thin Monolayer CVD Graphene Membranes

Selective proton (H+) permeation through the atomically thin lattice of graphene and other 2D materials offers new opportunities for energy conversion/storage and novel separations. Practical applications necessitate scalable synthesis via approaches such as chemical vapor deposition (CVD) that inevitably introduce sub-nanometer defects, grain boundaries and wrinkles, and understanding their influence on H+ transport and selectivity for large-area membranes is imperative but remains elusive. Using electrically driven transport of H+ and potassium ions (K+) we probe the influence of intrinsic sub-nanometer defects in monolayer CVD graphene across length-scales for the first time. At the micron scale, the areal H+ conductance of CVD graphene (∼4.5–6 mS cm−2) is comparable to that of mechanically exfoliated graphene indicating similarly high crystalline quality within a domain, albeit with K+ transport (∼1.7 mS cm−2). However, centimeter-scale Nafion|graphene|Nafion devices with several graphene domains show areal H+ conductance of ∼339 mS cm−2 and K+ conductance of ∼23.8 mS cm−2 (graphene conductance for H+ is ∼1735 mS cm−2 and for K+ it is ∼47.6 mS cm−2). Using a mathematical-transport-model and Nafion filled polycarbonate track etched supports, we systematically deconstruct the observed orders of magnitude increase in H+ conductance for centimeter-scale CVD graphene. The mitigation of defects (>1.6 nm), wrinkles and tears via interfacial polymerization results in a conductance of ∼1848 mS cm−2 for H+ and ∼75.3 mS cm−2 for K+ (H+/K+ selectivity of ∼24.5) via intrinsic sub-nanometer proton selective defects in CVD graphene. We demonstrate atomically thin membranes with significantly higher ionic selectivity than state-of-the-art proton exchange membranes while maintaining comparable H+ conductance. Our work provides a new framework to assess H+ conductance and selectivity of large-area 2D membranes and highlights the role of intrinsic sub-nanometer proton selective defects for practical applications.

Van der Waals Interaction Mediated Redox on Graphene Electrode

Graphene, unlike (defective) graphene oxide, is generally not considered to be a highly efficient electrochemical electrode except for activity at the edges. This is because, graphene forms a highly stable hydration bilayer that screens the electric field emanating from the electrode to drive the electrochemical process. A remarkable electrochemical electrode property of graphene is discovered and explored. The property emerges from graphene’s single crystal, aromatic structure. The redox behavior of an aromatic compound, methylene blue (MB) and non-aromatic compounds, such as , potassium ferric cyanide are compared. The electrochemical behavior on monolayer of graphene is quantitatively measured by a novel opto-electrochemical instrument for both electrochemical and structural information. The instrument called, the Scanning Electrometer for electrical Double-layer (SEED) allows local measurement of redox on a 10 micron laser spot to exclusively measure redox signal away from the edges of graphene. Two distinct peaks for both reduction and oxidation during conventional cyclic voltametric (CV) waveform are observed by SEED (Figure 1). The two peaks were attributed to two distinct orientation of MB chemisorption on graphene and subsequent electron transfer. One of the peak depended on precise orientation of the MB on single crystal graphene surface indicating pi-pi interaction mediated chemisorption (Figure 2). The other peak is independent of graphene orientation. MB redox on Au showed a single peak (Figure 1) and was independent of orientation (Figure 2). The effect of the two modes of chemisorption on ionic strength was studied and compared with MB redox on pure gold performed on the same chip. The two peaks were not distinguishable by CV or differential pulse voltammetry (DPV) measured on the same sample under similar conditions. This indicated the sensitivity of SEED to obtain structural information and its ability to measure electrochemical activity on micro-spot. All the three measurements, SEED, DPV and CV were performed without taking the sample out of the solution. The redox of non-aromatic compounds showed no orientation effect. The distinct van der Waals interaction mediated chemisorption by pi-pi stacking on graphene electrode may have distinct advantage to design highly sensitive and specific sensors and biosensors in future, for example, in DNA and RNA sensing. Figure 1

Nitrogen amended graphene catalyses fast reduction of vinyl chloride by nano zerovalent iron

Vinyl chloride (VC) is a dominant carcinogenic residual in many aged chlorinated solvent plumes, and it remains a huge challenge to clean it up. Zerovalent iron (ZVI) is an effective reductant for many chlorinated compounds but shows low VC removal efficiency at field scale. Amendment of ZVI with a carbonaceous material may be used to both preconcentrate VC and facilitate redox reactions. In this study, nitrogen-doped graphene (NG) produced by a simple co-pyrolysis method using urea as nitrogen (N) source, was tested as a catalyst for VC reduction by nanoscale ZVI (nZVI). The extent of VC reduction to ethylene in the presence of 2 g/L of nZVI was less than 1% after 3 days, and barely improved with the addition of 4 g/L of graphene. In contrast, with amendment of nZVI with NG produced at pyrolysis temperature (PT) of 950 °C, the VC reduction extent increased more than 10-fold to 69%. The reactivity increased with NG PT increasing from 400 °C to an optimum at 950 °C, and it increased linearly with NG loadings. Interestingly, N dosage had little effect on reactivity if NG was produced at PT of 950 °C, while a positive correlation was observed for NG produced at PT of 600 °C. XPS and Raman analyses revealed that for NG produced at lower PT (<800 °C) mainly the content of pyridine-N-oxide (PNO) groups correlates with reactivity, while for NG produced at higher PT up to 950 °C, reactivity correlates mainly with N induced structural defects in graphene. The results of quenching and hydrogen yield experiments indicated that NG promote reduction of VC by storage of atomic hydrogen, thus increasing its availability for VC reduction, while likely also enabling electron transfer from nZVI to VC. Overall, these findings demonstrate effective chemical reduction of VC by a nZVI-NG composite, and they give insights into the effects of N doping on redox reactivity and hydrogen storage potential of carbonaceous materials.

Adsorption of Tunable aryl alkyl ionic liquids (TILs) on the graphene and Defective graphene nanosheets: A DFT Study

Optical and electronic characteristics of the graphene nanosheets (GNS) could be altered by some structural defects such as double-vacancy and Stone-Wales ones. The physisorption manner of [MPI][BF4], [MPT1][BF4], [MPT2][BF4], and [MPTT][BF4] ionic liquids on intact and defective GNS surfaces were investigated using M06-2X/cc-pVDZ computational method. Capability for adsorption on the DV and SW graphene surfaces by TILs is increased by about 1.0–4.3 and 0.4–2.0 kcal/mol respectively. The electrostatic potential of the GNS-DV surface is more negative than the GNS-SW one which enables it to interact with cation parts of the adsorbed TILs so extensively. The highest adsorption energy belongs to the [MPI][BF4]/GNS-DV system. Adsorption of the TILs on the GNS surfaces leads to a decrease in the energy of the LUMO molecular orbital as well as their energy gap of them. Results revealed that the electrical conductivity, as well as absorption spectra of the GNS surfaces, are affected by TILs adsorption and defect nature.

Proton transport through nanoscale corrugations in two-dimensional crystals

Defect-free graphene is impermeable to all atoms1–5 and ions6,7 under ambient conditions. Experiments that can resolve gas flows of a few atoms per hour through micrometre-sized membranes found that monocrystalline graphene is completely impermeable to helium, the smallest atom2,5. Such membranes were also shown to be impermeable to all ions, including the smallest one, lithium6,7. By contrast, graphene was reported to be highly permeable to protons, nuclei of hydrogen atoms8,9. There is no consensus, however, either on the mechanism behind the unexpectedly high proton permeability10–14 or even on whether it requires defects in graphene’s crystal lattice6,8,15–17. Here, using high-resolution scanning electrochemical cell microscopy, we show that, although proton permeation through mechanically exfoliated monolayers of graphene and hexagonal boron nitride cannot be attributed to any structural defects, nanoscale non-flatness of two-dimensional membranes greatly facilitates proton transport. The spatial distribution of proton currents visualized by scanning electrochemical cell microscopy reveals marked inhomogeneities that are strongly correlated with nanoscale wrinkles and other features where strain is accumulated. Our results highlight nanoscale morphology as an important parameter enabling proton transport through two-dimensional crystals, mostly considered and modelled as flat, and indicate that strain and curvature can be used as additional degrees of freedom to control the proton permeability of two-dimensional materials.

Effects of carbon vacancies on the CO oxidation on Cu double atom catalyst supported by graphene

The activity of double metal atoms is closely related to their chemical coordination environments. In this work, CO oxidation on Cu double atom catalyst loaded on defective graphene with triple carbon vacancy (Cu2-TG) and quadruple carbon vacancy (Cu2-QG) has been comprehensively studied through DFT calculations. Empty Cu-3d orbital is created through charge transfer from Cu atom to carbon atom of graphene, which is parallel to the basal plane of graphene for one Cu atom and nearly perpendicular to the basal plane for the other Cu atom in Cu2-TG. While the empty Cu-3d orbital is parallel to the basal plane for both Cu atoms in Cu2-QG. The delocalized orientation of empty Cu-3d orbital in Cu2-TG makes it more convenient to accept electrons and more active. This is verified through the larger adsorption energies of -1.74 eV and -1.68 eV for O2 and CO molecules on Cu2-TG, as well as the smaller values of -0.20 eV and -0.40 eV on Cu2-QG, respectively. Because of the weak interactions between Cu2-QG and gas molecules, only Cu2-TG is further considered to catalyze the CO oxidation. The maximum barrier of CO oxidation along ER path is 1.75 eV on Cu2-TG, while that is only 0.39 eV along LH path, which indicates a smooth reaction progress on Cu2-TG. The electronic structures show that the Cu atom can accept electrons through its empty 3d orbital and lose electrons through its filled 3d orbital with an “acceptance and feedback” mechanism. Cu2-TG can move the 5σCO orbital downshift significantly, which causes the 5σCO/1πCO orbitals very close to 5σO2/1πO2 orbitals and facilitates the formation of OC-OO bond along LH path. These results indicate that the synergistic effects between the two Cu atoms and the triple carbon vacancy make Cu2-TG to be an efficient CO oxidation catalyst.

Defect effect of graphene on interface properties of copper/graphene/copper composite: A first-principles study

The introduction of defects in graphene will affect the mechanical and electrical properties of the composite interface. We investigate the effect of Stone–Wales (S-W), single-vacancy (S-V), and double-vacancy (D-V) defects on interface properties of copper/graphene/copper (Cu/Gr/Cu) sandwich models using the first-principles study. The results indicate that most defects forming in the Cu/Gr/Cu interface have lower formation energy than that in the free graphene slab. The introduction of defects is beneficial to enhance interface bonding while decreasing electrical properties due to electron scattering. By analyzing the differential charge density of all the Cu/Gr/Cu models with defects, we show that the defects cause changes in electron distribution and facilitate charge transfer between graphene and adjacent copper layers by altering the atomic layer distance.

Vacancies and Stone–Wales defects in twisted bilayer graphene – A comparative theoretical study

The combination of miss-alignment and point defects on the electronic structure of bilayer graphene can lead to special properties, which deserve a theoretical investigation, since they are scarcely studied up to now. Although most graphene layers are nominally free of defects, they can be introduced in a simple way to achieve the desired properties. By performing density functional theory calculations implemented in two different computational approaches (SIESTA and QuantumEspresso) and a tight-binding hybrid method (DFTB+), we analyze the effects of single vacancies and Stone-Wale defects on the electronic structure of Twisted Bilayer Graphene (tBLG). Our results show that both kinds of defects can induce flat bands near the Fermi energy of tBLG, even for rotation angles quite larger than the well-known magic angles associated with the superconductivity of these systems. Additionally, with the aim to provide a theoretical background to identify defects on tBLG during experimental characterization, we simulate scanning tunneling microscopy (STM) images of these systems. As expected, such simulated STM images are dramatically influenced by the van Hove Singularities associated to the flat bands induced by defects. The results of our theoretical study may have an influence on the targeted introduction of defects in tBLG for the future design of tBLG with particular properties for some technological applications.

Effect of vacancy defects of graphene on the interfacial bonding and strengthening mechanism of graphene/Al composite

The structure and properties of the graphene-Al interface change significantly when defects are present in graphene. However, the effect of defects on interfacial bonding lacks quantitative assessment, and the results of theoretical studies are also difficult to guide the design of interface structures. In this paper, the interfacial structure of graphene-Al with different vacancy defect types has been investigated by first-principle calculations, and the interfacial bonding was calculated by quantifying the interfacial shear strength. The interfacial shear strengths of defect-free, single-vacancy, and double-vacancy were 0.02 GPa, 6.8 GPa, and 8.5 GPa, respectively. Based on the first-principles data and the differential idea, the calculation model of shear strength of graphene-Al interface with different defect contents was established. The role of vacancy defects on the enhancement of graphene-Al interfacial bonding was elucidated. A method to estimate the shear strength of graphene-Al direct bonding interface based on Raman characterization of graphene defects was proposed. The influence of graphene defects on graphene strengthening efficiency was clarified, and an apparent strengthening model applicable to directly bonded interfacial graphene/aluminum composites was established. The model was validated by graphene/Al composites with directly bonding interface.