Graphite Surface Research Articles

Dendrite/Volume Expansion-Free Lithium Deposition Inside the Enclosed Nanoscale Space of Electrochemically Modified Graphite

Though over-lithiation of graphite can increase the initial specific capacity of the anodes, the cycling stability is unsatisfactory as metallic lithium depositing on the surface of graphite has poor reversibility. In this work, we utilize electrochemical co-intercalation of Li+ and diethylene glycol dimethyl ether (DEGDME) to prepare [Li-DEGDME]+-graphite co-intercalation compounds ([Li-DEGDME]-Gr) from pristine graphite. The expanded d-spacing and abundant cross-layer voids in the interlayer structure of [Li-DEGDME]-Gr owing to the co-intercalation of [Li-DEGDME]+ complex ions and parasitic chemical reactions between solvent molecules and graphene layers promotes the migration of bare Li+ and provides sufficient interior space for extra lithium-storage. As a result, a much higher lithium-storage capacity of 810 mAh g−1 can be successfully achieved. The extra lithium-storage is proved to originate from the deposition of lithium metal inside the enclosed nanoscale space of the as modified graphite, which inhibits the formation of lithium dendrites, isolates lithium metal from electrolytes and avoids volumetric expansion, enabling the [Li-DEGDME]-Gr electrodes to exhibit better cycling stability with high specific capacity. This work proposes a new strategy to enhance the reversibility of lithium metal plating/stripping by accommodating lithium deposition inside modified carbon materials, thus effectively increasing the reversible capacity of graphite-based anode materials.

Experimental Parametric Investigation of Nanosecond Laser-Induced Surface Graphitization of Nano-Crystalline Diamond.

While nano-crystalline diamond (NCD) is a promising engineering composite material for its unique mechanical properties, achieving the ultrahigh surface quality of NCD-based components through conventional grinding and polishing is challenging due to its exceptional hardness and brittleness. In the present work, we experimentally investigate the nanosecond laser ablation-induced graphitization characteristics of NCD, which provides a critical pretreatment method of NCD for realizing its superlative surface finish. Specifically, systematic experimental investigations of the nanosecond pulsed laser ablation of NCD are carried out, in which the characteristics of graphitization are qualitatively characterized by the Raman spectroscopy detection of the ablated area of the microhole and microgroove. Subsequently, the influence of laser processing parameters on the degree and morphological characteristics of graphitization is evaluated based on experimental data and related interpretation, from which optimized parameters for maximizing the graphitization of NCD are then identified. The findings reported in the current work provide guidance for promoting the machinability of NCD via laser irradiation-induced surface modification.

Comparison of coarse-grained models for cis-1,4-polyisoprene-graphite system

ABSTRACT Structural and dynamical properties of cis-1,4-polyisoprene-graphite system were compared by four coarse-grained models. Coarse-graining of graphene layers replaced four carbon atoms by a single bead while four mapping schemes were used for the polymer. Pressure-correction was applied to the nonbonded part of the coarse-grained potential among coarse-grained polyisoprene beads. Among structural properties density profiles, bond orientation and conformation tensor as function of distance from the graphite surface were studied. Bulk values were achieved at around 2 nm from the graphite surface. Higher degree of coarse-graining showed comparatively larger fluctuations in data. Among dynamical properties mean square displacement and autocorrelation of end-to-end unit vectors for varied distances from the graphite surface were studied. Dynamics study indicated that pressure-correction method used to optimise pressure of the system resulted in slower dynamics for the higher degree of coarse-graining.

Electrolyte design for high power dual-ion battery with graphite cathode for low temperature applications

The design of electrolyte suitable for low-temperature use is of great significance to expand the applications of energy storage devices. Dual-ion battery (DIB) with fast ion transport kinetics is expected to be a nascent battery system that can deliver high power density both at room temperature and low temperatures. In this work, we design a 4.8 M lithium bis(fluorosulfonyl)imide in 2,2,2-trifluoroethyl acetate/dimethyl carbonate (LiFSI FEA/DMC) + 1 % LiPF6 electrolyte with a low melting point of about −93 °C, enabling graphite cathode in a DIB to achieve excellent fast charge/discharge capability with a high capacity of about 108 mAh g−1 and 80 mAh g−1 at 10 C at 25 °C and 0 °C, respectively. Even at −30 °C, the graphite cathode can still give a capacity of 69.2 mAh g−1 at 0.5 C. The graphite||Li DIB with 4.8 M LiFSI FEA/DMC + 1 % LiPF6 electrolyte also exhibits a stable cycle life with a capacity retention of 91.5 % at 5 C after 2000 cycles at 25 °C. The electrolyte forms a uniform cathode electrolyte interface film on the graphite surface, as confirmed by transmission electron microscopy and X-ray photoelectron spectroscopy, which enables the outstanding electrochemical performance of the graphite cathode in a wide working temperature range from −30 °C to 25 °C.

Wettability, imbibition and interdiffusion of lithium-based water-in-salt electrolytes in nanoporous carbon in relation to energy storage: A neutron radiography study

Superconcentrated lithium salt electrolytes, or lithium-based Water-in-Salt (WiS) electrolytes emerge as alternative electrolytes in supercapacitors and advanced batteries, such as the Li–O2 ones, especially when combined with a mesoporous carbon with very high surface area. In this work, we analyze the wettability, imbibition, and diffusivity of very concentrated lithium salts in a bimodal mesoporous carbon with pores of 5 nm and 25 nm in diameter. For the first time a neutron radiography technique is used to determine the imbibition and interdiffusion of lithium salts in mesoporous carbon. We found that a 20 m LiTFSI aqueous solution wets the surface of graphite and mesoporous carbon better than water. As a consequence, this WiS electrolyte is embedded rather fast in the mesoporous carbon by the action of capillary forces, exhibiting an intrinsic permeability K = (1.16 ± 0.03).10−18 m2. Finally, by resorting to the different cross-section of the 6Li and 7Li isotopes for the neutron capture, we could analyze the diffusion of LiCl in D2O confined in the mesoporous carbon. The interdiffusion coefficient of the confined LiCl is 5.0 10−7 cm2 s−1, corresponding to a tortuosity coefficient τ = 1.32. This moderate confinement effect results from the strong ion association of the LiCl that precludes the electrostatic interactions of Li+ ions with the negative charge on the pore walls. In summary, the combined properties of the lithium-based WiS electrolytes and the mesoporous carbon allow us to glimpse their use in supercapacitors and Li–O2 batteries.

Catalytic decomposition of ethylene carbonate by pyrrolic-N to stabilize solid electrolyte interphase on graphite anode under extreme conditions

Despite the dominated anode materials of graphite for lithium-ion batteries (LIBs), the poor rate capability and inferior cyclability restain their applications under extreme conditions due to their deficient interfacial chemistry. Herein, an ultrathin but Li2CO3-rich solid electrolyte interphase (SEI) is manipulated by the decomposition of ethylene carbonate (EC) on graphite anode with nitrogenous amorphous carbon coating (denoted as GMIB-2P). Specifically, Li2CO3 can enable a decreased charge transfer resistance and faster Li+ diffusion capability. In addition, we demonstrate the catalytic effect of pyrrolic-N on graphite surface with prominent wettability induces the rapid decomposition of EC with low reaction energy barrier through density function theory (DFT) calculation. Consequently, GMIB-2P delivers an outstanding capacity retention ratio of 90.82% after 300 cycles at 1 C and an improved initial Coulombic efficiency (ICE, 90.77% vs. 85.35%). More importantly, GMIB-2P possesses durable-cycling capability even with lean electrolytes of 5 μL mg-1 and as well as 85.68% capacity retention for over 300 cycles at 60 ℃. Our work highlights the key role of EC in tailoring interfacial chemistry from structure regulations and provides new guidelines to design more reliable anodes for LIBs under extreme conditions.

Effect of Anchoring Dynamics on Proton-Coupled Electron Transfer in the Ru(bda) Coordination Oligomer on a Graphitic Surface.

The oligomeric ruthenium-based water oxidation catalyst, Ru(bda), is known to be experimentally anchored on graphitic surfaces through CH-π stacking interactions between the auxiliary bda ([2,2'-bipyridine]-6,6'-dicarboxylate) ligand bonded to ruthenium and the hexagonal rings of the surface. This anchoring provides control over their molecular coverage and enables efficient catalysis of water oxidation to dioxygen. The oligomeric nature of the molecule offers multiple anchoring sites at the surface, greatly enhancing the overall stability of the hybrid catalyst-graphitic surface anode through dynamic bonding. However, the impact of this dynamic anchoring on the overall catalytic mechanism is still a topic of debate. In this study, a crucial proton-coupled electron transfer event in the catalytic cycle is investigated using DFT-based molecular dynamics simulations plus metadynamics. The CH-π stacking anchoring plays a critical role not only in stabilizing this hybrid system but also in facilitating the proton-coupled electron transfer event with possible vibronic couplings between the anchoring bonds motion and charge fluctuations at the catalyst - graphitic surface interface. Furthermore, this computational investigation displays the presence of a quartet spin state intermediate that can lead to the experimentally observed and thermodynamically more stable doublet spin state.

Facile synthesis of dense SiBCN coatings with excellent compactness, smoothness, and high-temperature inertness on defective graphite surfaces

SiBCN ceramics possess extreme high-temperature stability among engineering ceramics; however, their application is constrained by the difficulty in achieving large continuous products at low cost. This work exhibits the possibility of fabricating SiBCN continuous coatings on graphite substrates to improve their surface integrity, hardness, and inertness. The ceramic coatings were fabricated simply by spin coating, curing, and pyrolysis. The key innovations are the synthesis of the precursor, polyborosilazane (PBSZ), that derives continuous ceramic films after pyrolysis, and the finding that the xylene solution of PBSZ can achieve a very good spinning performance on various surfaces, especially the low-quality graphite surfaces with holes. The fabricated SiBCN coatings, characterized to be networks of Si–C, Si–N, C–C, and B–N bonds, possessed smooth and hard surfaces with roughness below 9 nm and a hardness of 7.3 GPa. The coating thickness can be well controlled in the range of 1.4 – 2.1 μm as the latter is linearly dependent on the concentration of PBSZ in the solution. Detailed observations of surface morphologies and physisorption experiments reveal that the coating surfaces are crack-free and highly dense, rendering a significant reduction in specific surface areas when a defective graphite face is coated.

Synergistic engineering of palladium-cobalt nanoalloys on graphite sheet for efficient and sustainable hydrogen evolution reaction

The electrochemical hydrogen evolution reaction (HER)—a carbon-free route for hydrogen (H2) production—is of the utmost importance for H2-economy. Currently, HER performance is mainly restricted by the lack of promising alternatives to Pt-based electrocatalysts. In this study, we developed bimetallic PdCo alloy thin films with outstanding catalytic properties for the HER under acidic conditions. A simple aerosol-assisted chemical vapor deposition technique designed in-house was used to produce bimetallic alloy thin films on graphite sheets. The thin-film morphological patterns were significantly changed by varying the deposition time from 30 to 90 min. The optimized PdCo catalyst deposited for 30 min had a unique nanostructure with numerous active sites and exhibited faster HER kinetics than its analogs and pure Pd. As-prepared PdCo-30 electrode produced current densities of 10 and 1000 mA cm−2 at overpotentials of 41 and 161 mV, respectively, along with a Tafel slope of 42 mV/dec, high conductivity (0.28 Ω), and catalytic stability of ∼24 h in 0.5 M H2SO4. The excellent HER activity of the PdCo alloy was attributed to the synergy between the noble transition metal and the thin nanostructured layer of the bimetallic catalyst, which promoted formation of extensive electroactive sites on the conductive graphite surface. Density functional theory calculations confirmed the experimental findings. The Gibbs free energy (ΔGH*) of the PdCo alloy (−0.43 eV) was significantly lower than that of pure Pd (−0.57 eV), confirming the enhancement in HER activity due to the introduction of Co into the Pd lattice.

High‐Safety Anode Materials for Advanced Lithium‐Ion Batteries

Lithium‐ion batteries (LIBs) play a pivotal role in today's society, with widespread applications in portable electronics, electric vehicles, and smart grids. Commercial LIBs predominantly utilize graphite anodes due to their high energy density and cost‐effectiveness. Graphite anodes face challenges, however, in extreme safety‐demanding situations, such as airplanes and passenger ships. The lithiation of graphite can potentially form lithium dendrites at low temperatures, causing short circuits. Additionally, the dissolution of the solid‐electrolyte‐interphase on graphite surfaces at high temperatures can lead to intense reactions with the electrolyte, initiating thermal runaway. This review introduces two promising high‐safety anode materials, Li4Ti5O12 and TiNb2O7. Both materials exhibit low tendencies towards lithium dendrite formation and have high onset temperatures for reactions with the electrolyte, resulting in reduced heat generation and significantly lower probabilities of thermal runaway. Li4Ti5O12 and TiNb2O7 offer enhanced safety characteristics compared to graphite, making them suitable for applications with stringent safety requirements. This review provides a comprehensive overview of Li4Ti5O12 and TiNb2O7, focusing on their material properties and practical applicability. It aims to contribute to the understanding and development of high‐safety anode materials for advanced LIBs, addressing the challenges and opportunities associated with their implementation in real‐world applications.

The initial sticking of high velocity water onto graphite under non-equilibrium supersonic flow conditions.

In this paper, we present a combined experimental and theoretical study that explored the initial sticking of water on cooled surfaces. Specifically, these ultra-high vacuum gas-surface scattering experiments utilized supersonic molecular beam techniques in conjunction with a cryogenically cooled highly oriented pyrolytic graphite crystal, giving control over incident kinematic conditions. The D2O translational energy spanning 300-750meV, the relative D2O flux, and the incident angle could all be varied independently. Three different experimental measurements were made. One involved measuring the total amount of D2O scattering as a function of surface temperature to determine the onset of sticking under non-equilibrium gas-surface collision conditions. Another measurement used He specular scattering to assess structural and coverage information for the interface during D2O adsorption. Finally, we used time-of-flight (TOF) measurements of the scattered D2O to determine how energy is exchanged with the graphite surface at surface temperatures above and near the conditions needed for gaseous condensation. For comparison and elaboration of the roles that internal degrees of freedom play in this process, we also did similar TOF measurements using another mass 20 incident particle, atomic neon. Enriching this study are precise molecular dynamics simulations that elaborate on gas-surface energy transfer and the roles of molecular degrees of freedom in gas-surface collisional energy exchange processes. This study furthers our fundamental understanding of energy exchange and the onset of sticking and ultimately gaseous condensation for gas-surface encounters occurring under high-velocity flows.

Enhancing Electrochemical Sensing through Molecular Engineering of Reduced Graphene Oxide-Solution Interfaces and Remote Floating-Gate FET Analysis.

Two-dimensional nanomaterials such as reduced graphene oxide (rGO) have captured significant attention in the realm of field-effect transistor (FET) sensors due to their inherent high sensitivity and cost-effective manufacturing. Despite their attraction, a comprehensive understanding of rGO-solution interfaces (specifically, electrochemical interfacial properties influenced by linker molecules and surface chemistry) remains challenging, given the limited capability of analytical tools to directly measure intricate solution interface properties. In this study, we introduce an analytical tool designed to directly measure the surface charge density of the rGO-solution interface leveraging the remote floating-gate FET (RFGFET) platform. Our methodology involves characterizing the electrochemical properties of rGO, which are influenced by adhesion layers between SiO2 and rGO, such as (3-aminopropyl)trimethoxysilane (APTMS) and hexamethyldisilazane (HMDS). The hydrophilic nature of APTMS facilitates the acceptance of oxygen-rich rGO, resulting in a noteworthy pH sensitivity of 56.8 mV/pH at the rGO-solution interface. Conversely, hydrophobic HMDS significantly suppresses the pH sensitivity from the rGO-solution interface, attributed to the graphitic carbon-rich surface of rGO. Consequently, the carbon-rich surface facilitates a denser arrangement of 1-pyrenebutyric acid N-hydroxysuccinimide ester linkers for functionalizing capturing probes on rGO, resulting in an enhanced sensitivity of lead ions by 32% in our proof-of-concept test.

Graphite sheet-supported bimetallic RhNi thin film alloys for enhanced and durable hydrogen evolution in acidic environments

Noble metal-based materials are excellent catalysts for hydrogen production from water electrolysis, but their high cost and limited availability hinder widespread use. However, precious metals can be effectively utilized in catalysts by forming alloys with low-cost 3d transition metals, thereby reducing the need for precious metals, while enhancing the performance. In this study, aerosol-assisted chemical vapor deposition was employed to deposit bimetallic rhodium-nickel (RhNi) alloy thin films on a graphite sheet for hydrogen evolution reaction (HER) catalysis in a 0.5 M H2SO4 solution. Thin-film morphological patterns were significantly changed as the deposition time varied from 45 to 135 min. The RhNi alloy fabricated for 90 min outperformed its counterparts, displaying lower overpotential of 40 and 197 mV at 10 and 1000 mA cm−2, small Tafel kinetics (54 mV dec−1), high conductivity (0.57 Ω) and large electrochemical surface area (3312 cm2), and extended stability (48 h) compared to pure Rh metal and other reported catalysts. The superior HER performance arises from the synergistic effects between Rh and Ni metals, coupled with a uniform layer of spherical particles that enhance conductive properties and reaction rates by providing maximized active sites on graphite surface. This work provides valuable guidelines for efficiently preparing highly active and durable thin-film electrocatalyst within short time span and applying directly in fuel cell for hydrogen production.

Study on 2D Molecular Networks of Flexible Pentacarboxylic Acid Ligands Induced by Ether Bonds in Response to Selective Guest Inclusion.

The flexibility of ligands allows for their bending, twisting, or rotation to adopt various conformations, leading to distinct symmetries during the self-assembled process. Flexible aromatic acid ligands modified by ether bonds are a promising type of self-assembled module when it comes to surfaces. Here, two pentacarboxylic acid ligands (H5L1 and H5L2) with minor skeleton differences have successfully self-assembled into disparate porous networks on the graphite surface and demonstrated excellent potential for the inclusion of guest molecules. The H5L1 molecule's network structure only accommodates coronene (COR) molecules. With fewer COR molecules, H5L1 molecules act as a host template to accommodate the COR molecules. When there are too many COR molecules, COR molecules will induce H5L1 molecules to transform into a new host-guest nanostructure. Additionally, H5L2 molecules showed the ability to capture C70 molecules and exhibited cavity selectivity. However, the assembled network of H5L2 was slightly deformed in attempts to trap the COR molecules. To understand these phenomena more deeply, various assembled mechanisms were analyzed in combination with building theoretical models and energy analysis. These results reveal the great potential of flexible aromatic acid ligands in two-dimensional self-assembly and host-guest systems for their application in related fields.

Wetting and interfacial behavior of aqueous Deep eutectic solvents on Graphite, silica and calcite surfaces: Molecular dynamics study

Understanding the wetting behavior of liquids/fluids on solid surfaces at the nanoscale can help develop more effective and efficient technologies in various applications, including microfluidics, biomedical, enhanced oil recovery, and many others. Deep eutectic solvents (DESs) have recently gained attention due to their physical and chemical properties and tunability, making them useful in many applications. This article reports the investigation of the wetting behavior of aqueous deep eutectic solvent (DES) on graphite, silicon dioxide (SiO2), and calcite (CaCO3) using molecular dynamics (MD) simulation. The study's main objective is to understand the interfacial behavior of aqueous DES on these surfaces. In the current study, two different DESs, choline-chloride (ChCl) as hydrogen bond acceptor (HBA) and two different hydrogen bond donors (HBD), urea (U) and ethylene glycol (EG) with molar ratio 1:2are used. Aqueous DES has been studied for three different concentrations of10, 20, and 30 wt% of DES molecules to explore the effect of concentration.AqueousDES system on the graphite makes a finite contact angle for all concentrations of DES.In contrast, for SiO2 and CaCO3, droplets spread and attain a contact angle below ∼ 10° due to high hydrophilicity. We confirmed that our simulation had attained equilibrium by computing the interaction energy with the substrate and system molecules. The wetting behavior of aqueous DES thin film on the surfaceis characterizedby a density profile along the z-axis (normal to the surface). Furthermore, hydrogen bond (HB) analysisis performedto elucidate the structural relationship of these aqueous-DES systems. Overall, this study provides insights into the wetting behavior of nanodroplets/film of aqueous DES on different surfaces and illustrates the structural characteristics of these systems through various properties such as contact angle, density profiles, and hydrogen bonds.

Sublimation and oxidation measurements of graphite and carbon black at high temperatures in a shock tube using absorption imaging and thermal emission

Surface mass loss rates due to sublimation and oxidation at temperatures of 3000–7000 K have been measured in a shock tube for graphite and carbon black (CB) particles. Diagnostics are presented for measuring surface mass loss rates by diffuse backlit illumination extinction imaging and thermal emission. The surface mass loss rate is found by regression fitting extinction and emission signals with an independent spherical primary particle assumption. Measured graphite sublimation and oxidation rates are reported to be an order of magnitude greater than CB sublimation and oxidation rates. It is speculated that the difference between CB and graphite surface mass loss rates is largely due to the primary particle assumption of the presented technique which misrepresents the effective surface area of an aggregate particle where primary particles overlap and shield inner particles. Measured sublimation rates are compared to sublimation models in the literature, and it is seen graphite shows fair agreement with the models while CB underestimates, likely a result of the particle shielding affect not being considered in the sublimation model.

Electrografting of aryl amines on graphitic surfaces: An alternative to diazonium salts?

Aryl amines have recently been shown to be effectively grafted with the use of Lewis bases. Hence, they have been proposed as a potential alternative to aryl diazonium salts for the covalent modification of surfaces. In this work we compare grafting efficiencies of aryl amines, such as 4-bromoaniline (4-BA), with aryl diazonium salts, such as 4-bromobenzene diazonium (4-BBD), on carbon-based surfaces, namely highly oriented pyrolytic graphite (HOPG) and graphene. The Lewis base 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) was employed to improve the grafting of 4-BA to the surfaces. The systems were studied with a range of techniques to confirm grafting of the organic molecules to the carbon surfaces, such as cyclic voltammetry, atomic force microscopy, scanning tunnelling microscopy and Raman spectroscopy. Density functional theory calculations demonstrate that the C-C bond is more favoured than the C-N bond. The grafting density of the aryldiazonium salts on graphite and graphene surfaces is much higher compared to aryl amines with or without the use of a Lewis base. Consequently, selection of the appropriate precursor for efficient covalent functionalization of a surface is required.

Characterization and H2O2 production mechanisms study on self-oxidized graphite during the two-electron water oxidation electrochemical process

The 2e− water oxidation process is an eco-friendly way to produce H2O2 using water as the raw material. It avoids the low solubility of oxygen in water, unlike traditional oxygen reduction methods. However, electrocatalysts always suffer from self-oxidation during the oxidation reaction, leading to decreased activity. We solved this by using non-metal graphite electrocatalysts that undergo an evolution process to oxidized carboxylated graphite, which is even more active. A defect forms on the graphite surface that facilitates HCO3− adsorption. The –COOH group easily forms a –COOOH intermediate, which is advantageous for hydrogen peroxide generation. The hydrogen peroxide generation rate is 4.55 times higher than that of initial graphite. Graphite is an environmentally friendly catalyst that avoids the release of metal ions, making it more suitable for large-scale applications.

From waste corn straw to graphitic porous carbon: A trade-off between specific surface area and graphitization degree for efficient peroxydisulfate activation

Electron transfer pathways have been verified as overriding regimes when peroxydisulfate (PDS) was activated by porous carbon. The incorporation of graphitic structure into carbon matrix was favorable to the rapid electron transfer, but excessive graphitization would deteriorate the specific surface area (SSA), weakening the catalytic performance. The reasonable trade-off between SSA and graphitization degree was necessary and challenging for the preparation of efficient carbon based PS-activators. Herein, a series of graphitic porous carbon with discrepant SSA and graphitic structure were fabricated. The incorporation of graphitization tracks into ultra-thin edges on porous carbon film was verified by multifarious structural characterization. After trade-off, the optimum catalyst exhibited superior catalytic performance with degradation rate constant (kobs) exceeding that of ungraphitized precursor by up to 16.0 times. Mechanistic investigations substantiated that the sufficient SSA of catalyst provided favorable conditions for its affinity towards PDS and sulfadiazine (SDZ), resulting in the formation of PDS* complexes and SDZ adsorption, while the appropriate graphitization degree ensured the reinforced electron transfer rate, which collectively accelerated SDZ oxidation through electron-transfer pathway. The multivariate linear regression model linking kobs to SSA and graphitization degree was established providing basis to construct efficient catalysts for PDS activation.

Study on the picosecond laser surface treatment and tribological properties of 3D woven carbon fiber reinforced carbon matrix (Cf/C) composites

Carbon fiber reinforced carbon matrix (Cf/C) composites have demonstrated great significance in many fields, especially in aircraft and automobiles as brake materials. The surface physical/chemical states of Cf/C composites significantly affect their tribological properties. Although ultrafast laser machining technology has been proven to be an effective method for modifying material surfaces, there are some issues concerning the ultrafast laser surface treatment of Cf/C composites and the adjustment of their tribological properties by laser treatment. Here, the 3D woven Cf/C composites were treated with an infrared picosecond laser. The effects of machining parameters on the surface microscopic morphology, chemical compositions, and graphitization degree were investigated. The experiment results indicated that the ultrafast laser treatment could eliminate surface defects, improve surface quality, and reduce the porosity of the Cf/C composites due to photothermal-mechanical ablation. More importantly, the laser-induced photothermal effects led to a graphitization transformation of Cf/C composites from a disordered turbostratic structure into an ordered graphite structure with an increased graphitization degree. The abundant micro-nano structures and the graphitization transformation on the Cf/C composite surface contributed to forming a complete and dense friction film on the Cf/C composites. Therefore, the laser-treated Cf/C composites showed lower COF, higher wear rate, and more stable tribological properties. This study demonstrated a method to adjust the tribological properties of Cf/C composites by ultrafast laser surface treatment, which showed great significance for the surface treatment and tribological property enhancement of Cf/C composites.