Enhancing the Combustion of Magnesium Nanoparticles via Low-Temperature Plasma-Induced Hydrogenation.

The hydrogenation of metal nanoparticles provides a pathway toward tuning their combustion characteristics. Metal hydrides have been employed as solid-fuel additives for rocket propellants, pyrotechnics, and explosives. Gas generation during combustion is beneficial to prevent aggregation and sintering of particles, enabling a more complete fuel utilization. Here, we discuss a novel approach for the synthesis of magnesium hydride nanoparticles based on a two-step aerosol process. Mg particles are first nucleated and grown via thermal evaporation, followed immediately by in-flight exposure to a hydrogen-rich low-temperature plasma. During the second step, atomic hydrogen generated by the plasma rapidly diffuses into the Mg lattice, forming particles with a significant fraction of MgH2. We find that hydrogenated Mg nanoparticles have an ignition temperature that is reduced by ∼200 °C when combusted with potassium perchlorate as an oxidizer, compared to the non-hydrogenated Mg material. This is due to the release of hydrogen from the fuel, jumpstarting its combustion. In addition, characterization of the plasma processes suggests that a careful balance between the dissociation of molecular hydrogen and heating of the nanoparticles must be achieved to avoid hydrogen desorption during production and achieve a significant degree of hydrogenation.

Magnesium-Induced Strain and Immobilized Radical Generation on the Boron Oxide Surface Enhances the Oxidation Rate of Boron Particles: A DFTB-MD Study.

Despite their high gravimetric and volumetric energy densities, boron (B) particles suffer from poor oxidative energy release rates as the boron oxide (B2O3) shell impedes the diffusivity of O2 to the particle interior. Recent experiemental studies have shown that the addition of metals with a lower free energy of oxidation, such as Mg, can reduce the oxide shell of B and enhance the energetic performance of B by ∼30-60%. However, the exact underlying mechanism behind the reactivity enhancement is unknown. Here, we performed DFTB-MD simulations to study the reaction of Mg vapor with a B2O3 surface. We found that the Mg becomes oxidized on the B2O3 surface, forming a MgBxOy phase, which induces a tensile strain in the B-O bond at the MgBxOy-B2O3 interface, simultaneously reducing the interfacial B and thereby developing dangling bonds. The interfacial bond straining creates an overall surface expansion, indicating the presence of a net tensile strain. The B with dangling bonds can act as active centers for gas-phase O2 adsorption, thereby increasing the adsorption rate, and the overall tensile strain on the surface will increase the diffusion flux of adsorbed O through the surface to the particle core. As the overall B particle oxidation rate is dependent on both the O adsorption and diffusion rates, the enhancement in both of these rates increases the overall reactivity of B particles.

Electrochemical Modulation of the Flammability of Ionic Liquid Fuels.

Flammability and combustion of high energy density liquid propellants are controlled by their volatility. We demonstrate a new concept through which the volatility of a high energy density ionic liquid propellant can be dynamically manipulated enabling one to (a) store a thermally insensitive oxidation resistant nonflammable fuel, (b) generate flammable vapor phase species electrochemically by applying a direct-current voltage bias, and (c) extinguish its flame by removing the voltage bias, which stops its volatilization. We show that a thermally stable imidazolium-based energy dense ionic liquid can be made flammable or nonflammable simply by application or withdrawal of a direct-current bias. This cycle can be repeated as often as desired. The estimated energy penalty of the electrochemical activation process is only ∼4% of the total energy release. This approach presents a paradigm shift, offering the potential to make a "safe fuel" or alternatively a simple electrochemically driven fuel metering scheme.

Enhanced Decomposition of Ammonium Perchlorate-Ethyl Cellulose-Molybdenum Disulfide Nanocomposites.

Ammonium perchlorate (AP) is commonly used in propulsion technology. Recent studies have demonstrated that two-dimensional (2D) nanomaterials such as graphene (Gr) and hexagonal boron nitride (hBN) dispersed with nitrocellulose (NC) can conformally coat the surface of AP particles and enhance the reactivity of AP. In this work, the effectiveness of ethyl cellulose (EC) as an alternative to NC was studied. Using a similar encapsulation procedure as in recent work, Gr and hBN dispersed with EC were used to synthesize the composite materials Gr-EC-AP and hBN-EC-AP. Additionally, EC was used because the polymer can be used to disperse other 2D nanomaterials, specifically molybdenum disulfide (MoS2), which has semiconducting properties. While Gr and hBN dispersed in EC had a minimal effect on the reactivity of AP, MoS2 dispersed in EC significantly enhanced the decomposition behavior of AP compared to the control and other 2D nanomaterials, as evidenced by a pronounced low-temperature decomposition event (LTD) centered at 300 °C and then complete high-temperature decomposition (HTD) below 400 °C. Moreover, thermogravimetric analysis (TGA) showed a 5% mass loss temperature (Td5%) of 291 °C for the MoS2-coated AP, which was 17 °C lower than the AP control. The kinetic parameters for the three encapsulated AP samples were calculated using the Kissinger equation and confirmed a lower activation energy pathway for the MoS2 (86 kJ/mol) composite compared to pure AP (137 kJ/mol). This unique behavior of MoS2 is likely due to enhanced oxidation-reduction of AP during the initial stages of the reaction via a transition metal-catalyzed pathway. Density functional theory (DFT) calculations showed that the interactions between AP and MoS2 were stronger than AP on the Gr or hBN surfaces. Overall, this study complements previous work on NC-wrapped AP composites and demonstrates the unique roles of the disperagent and 2D nanomaterial in tuning the thermal decomposition of AP.

In Situ Microscopic Studies on the Interaction of Multi-Principal Element Nanoparticles and Bacteria.

Multi-principal element nanoparticles are an emerging class of materials with potential applications in medicine and biology. However, it is not known how such nanoparticles interact with bacteria at nanoscale. In the present work, we evaluated the interaction of multi-principal elemental alloy (FeNiCu) nanoparticles with Escherichia coli (E. coli) bacteria using the in situ graphene liquid cell (GLC) scanning transmission electron microscopy (STEM) approach. The imaging revealed the details of bacteria wall damage in the vicinity of nanoparticles. The chemical mappings of S, P, O, N, C, and Cl elements confirmed the cytoplasmic leakage of the bacteria. Our results show that there is selective release of metal ions from the nanoparticles. The release of copper ions was much higher than that for nickel while the iron release was the lowest. In addition, the binding affinity of bacterial cell membrane protein functional groups with Cu, Ni, and Fe cations is found to be the driving force behind the selective metal cations' release from the multi-principal element nanoparticles. The protein functional groups driven dissolution of multielement nanoparticles was evaluated using the density functional theory (DFT) computational method, which confirmed that the energy required to remove Cu atoms from the nanoparticle surface was the least in comparison with those for Ni and Fe atoms. The DFT results support the experimental data, indicating that the energy to dissolve metal atoms exposed to oxidation and/or the to presence of oxygen atoms at the surface of the nanoparticle catalyzes metal removal from the multielement nanoparticle. The study shows the potential of compositional design of multi-principal element nanoparticles for the controlled release of metal ions to develop antibacterial strategies. In addition, GLC-STEM is a promising approach for understanding the nanoscale interaction of metallic nanoparticles with biological structures.

Perfluoroalkyl-Functionalized Graphene Oxide as a Multifunctional Additive for Promoting the Energetic Performance of Aluminum.

Aluminum (Al) is a widely used metal fuel for energetic applications ranging from space propulsion and exploration, and materials processing, to power generation for nano- and microdevices due to its high energy density and earth abundance. Recently, the ignition and combustion performance of Al particles were found to be improved by graphene-based additives, such as graphene oxide (GO) and graphene fluoride (GF), as their reactions provide heat to accelerate Al oxidation, gas to reduce particle agglomeration, and fluorine-containing species to remove Al2O3. However, GF is not only expensive but also hydrophobic with poor mixing compatibility with Al particles. Herein, we report a multifunctional graphene-based additive for Al combustion, i.e., perfluoroalkyl-functionalized graphene oxide (CFGO), which integrates the benefits of GO and GF in one material. We compared the effects of CFGO to GO and GF on the ignition and combustion properties of nAl particles using thermogravimetric analysis, differential scanning calorimetry, temperature-jump ignition), Xe flash ignition, and constant-volume combustion test. These experiments confirm that CFGO generates fluorine-containing species, heat, and gases, which collectively lower the ignition threshold, augment the energy release rate, and reduce the combustion product agglomeration of nanosized Al particles, outperforming both GO and GF as additives. This work shows the great potential of using multifunctionalized graphene as an integrated additive for enhancing the ignition and combustion of metals.

In-Situ Thermochemical Shock-Induced Stress at the Metal/Oxide Interface Enhances Reactivity of Aluminum Nanoparticles.

Although aluminum (Al) nanoparticles have been widely explored as fuels in energetic applications, researchers are still exploring approaches for tuning their energy release profile via microstructural alteration. In this study, we show that a nanocomposite (∼70 nm) of a metal ammine complex, such as tetraamine copper nitrate (Cu(NH3)4(NO3)2/TACN), coated Al nanoparticles containing only 10 wt. % TACN, demonstrates a ∼200 K lower reaction initiation temperature coupled with an order of magnitude enhancement in the reaction rate. Through time/temperature-resolved mass spectrometry and ignition onset measurements at high heating rates, we show that the ignition occurs due to a condensed phase reaction between Al and copper oxide (CuO) crystallized on TACN decomposition. TEM and XRD analyses on the nanoparticles at an intermediate stage show that the rapid heat release from TACN decomposition in-situ enhances the strain on the Al core with induction of nonuniformities in the thickness of its AlOx shell. The thinner region of the nonuniform shell enables rapid mass transfer of Al ions to the crystallized CuO, enabling their condensed phase ignition. Hence, the thermochemical shock from TACN coating induces stresses at the Al/AlOx interface, which effectively switches the usual gas phase O2 diffusion-limited ignition process of Al nanoparticles to become condensed phase Al ion transfer controlled, thereby enhancing their reactivity.

Vaporization-Controlled Energy Release Mechanisms Underlying the Exceptional Reactivity of Magnesium Nanoparticles.

Magnesium nanoparticles (NPs) offer the potential of high-performance reactive materials from both thermodynamic and kinetic perspectives. However, the fundamental energy release mechanisms and kinetics have not been explored due to the lack of facile synthetic routes to high-purity Mg NPs. Here, a vapor-phase route to surface-pure, core-shell nanoscale Mg particles is presented, whereby controlled evaporation and growth are utilized to tune particle sizes (40-500 nm), and their size-dependent reactivity and energetic characteristics are evaluated. Extensive in situ characterizations shed light on the fundamental reaction mechanisms governing the energy release of Mg NP-based energetic composites across particle sizes and oxidizer chemistries. Direct observations from in situ transmission electron microscopy and high-speed temperature-jump/time-of-flight mass spectrometry coupled with ignition characterization reveal that the remarkably high reactivity of Mg NPs is a direct consequence of enhanced vaporization and Mg release from their high-energy surfaces that result in the accelerated energy release kinetics from their composites. Mg NP composites also demonstrate mitigated agglomeration and sintering during reaction due to rapid gasification, enabling complete energy extraction from their oxidation. This work expands the compositional possibilities of nanoscale solid fuels by highlighting the critical relationships between metal volatilization and oxidative energy release from Mg NPs, thus opening new opportunities for strategic design of functional Mg-based nanoenergetic materials for tunable energy release.

High-Temperature Interactions of Metal Oxides and a PVDF Binder.

Interactions between energetic material relevant nanoscale metal oxides (SiO2, TiO2, MgO, Al2O3, CuO, Bi2O3) and poly(vinylidene fluoride) (PVDF) at high temperature were investigated by temperature-jump/time-of-flight mass spectrometry (T-jump/TOFMS) and thermogravimetric-differential scanning calorimetry (TGA-DSC). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the morphology of the compositions, while X-ray diffraction (XRD) was utilized to analyze the condensed phase crystalline species at temperatures of interest. The exergonicity and exothermicity of HF gas with hydroxyl-terminated metal oxide surfaces make HF the likely fluorine-bearing moiety and primary mode of the fluorinating reactions, where terminal OH- configurations are replaced by F- in the formation of a stronger metal-fluorine bond. However, not all compositions produce corresponding stable metal fluoride. The results show that while some of the investigated metal oxide-PVDF compositions enhance PVDF decomposition and release HF in larger quantities than PVDF, others release HF in smaller quantities than PVDF and even retard PVDF decomposition. The former compositions demonstrate exothermic, multistep mass loss modes prior to neat PVDF mass loss, and the relative intensity of HF gas increases as the temperature of the release point decreases, implying a correlation between HF release and the progression of exothermic behavior. An interplay dynamic where surface interactions both lower the onset of HF release and engage exothermically with HF gas subsequently is proposed.

Understanding Dimethyl Methylphosphonate Adsorption and Decomposition on Mesoporous CeO2.

The increased risk of chemical warfare agent usage around the world has intensified the search for high-surface-area materials that can strongly adsorb and actively decompose chemical warfare agents. Dimethyl methylphosphonate (DMMP) is a widely used simulant molecule in laboratory studies for the investigation of the adsorption and decomposition behavior of sarin (GB) gas. In this paper, we explore how DMMP interacts with the as-synthesized mesoporous CeO2. Our mass spectroscopy and in situ diffuse reflectance infrared Fourier transform spectroscopy measurements indicate that DMMP can dissociate on mesoporous CeO2 at room temperature. Two DMMP dissociation pathways are observed. Based on our characterization of the as-synthesized material, we built the pristine and hydroxylated (110) and (111) CeO2 surfaces and simulated the DMMP interaction on these surfaces with density functional theory modeling. Our calculations reveal an extremely low activation energy barrier for DMMP dissociation on the (111) pristine CeO2 surface, which very likely leads to the high activity of mesoporous CeO2 for DMMP decomposition at room temperature. The two reaction pathways are possibly due to the DMMP dissociation on the pristine and hydroxylated CeO2 surfaces. The significantly higher activation energy barrier for DMMP to decompose on the hydroxylated CeO2 surface implies that such a reaction on the hydroxylated CeO2 surface may occur at higher temperatures or proceed after the pristine CeO2 surfaces are saturated.

Carbon Fibers Enhance the Propagation of High Loading Nanothermites: In Situ Observation of Microscopic Combustion.

A major challenge in formulating and manufacturing energetic materials lies in the balance between total energy density, energy release rate, and mechanical integrity. In this work, carbon fibers are embedded into ∼90 wt % loading Al/CuO nanothermite sticks through a simple extrusion direct writing technique. With only ∼2.5 wt % carbon fiber addition, the burn rate and heat flux were promoted >2×. In situ microscopic observation of combustion shows that the carbon fiber intercept ejected hot agglomerates near the burning surface and enhanced heat feedback to the unreacted material. This study outlines how these approaches may enhance the propagation and reduce the two-phase flow losses.

Magnetic-Field Directed Vapor-Phase Assembly of Low Fractal Dimension Metal Nanostructures: Experiment and Theory.

While gas-phase synthesis techniques offer a scalable approach to production of metal nanoparticles, directed assembly is challenging due to fast particle diffusion rates that lead to random Brownian aggregation. This work explores an electromagnetic-levitation technique to generate metal nanoparticle aggregates with fractal dimension (Df) below that of diffusion limited assembly. We demonstrate that in addition to levitation and induction heating, the external magnetic field is sufficient to compete with random Brownian forces, which enables the formation of altered fractals. Ferromagnetic metals (Fe, Ni) form chain-like aggregates, while paramagnetic Cu forms compact nanoparticle aggregates with higher Df values. We have also employed a Monte Carlo simulation to evaluate the necessary field strength to form linear chains in the gas phase.

Modelling and simulation of field directed linear assembly of aerosol particles.

Unlike liquid phase colloidal assembly, significantly changing the structure of fractal aggregates in the aerosol phase, is considered impractical. In this study, we discuss the possibility of applying external magnetic and electric fields, to tune the structure and fractal dimension (Df) of aggregates grown in the aerosol phase. We show that external fields can be used to induce dipole moments in primary nanoparticles. We found that an ensemble of particles with induced dipole moments will interact through directional attractive and repulsive forces, leading to the formation of linear, chain-like aggregates with Df ~ 1. The aggregate structure transition is dependent on the primary particle sizes, temperature and applied field strength which was evaluated by performing a hybrid ensemble/cluster-cluster aggregation Monte Carlo simulation. We demonstrate that the threshold magnetic field strength required to linearly assemble 10-500 nm particle sizes are practically achievable whereas the electric field required to assemble sub-100 nm particles are beyond the breakdown strength of most gases. To theoretically account for the enhanced coagulation rates due to attractive interactions, we have also derived a correction factor to both free molecular and transition regime coagulation kernel, based on magnetic dipolar interactions. A comparison has been made between the coagulation time-scales estimated by theory and simulation, with the estimated magnetization time-scales of the primary particles along with oscillation time period of the magnetic field, to demonstrate that sub-50 nm superparamagnetic primary particles can be magnetized and assembled at any temperature, while below the Curie temperature ferromagnetic particles of all sizes can be magnetized and assembled, given the applied field is higher than the threshold.

Elucidating the dominant mechanisms in burn rate increase of thermite nanolaminates incorporating nanoparticle inclusions.

It was experimentally found that silica and gold particles can modify the combustion properties of nanothermites but the exact role of the thermal properties of these additives on the propagating combustion front relative to other potential contributions remains unknown. Gold and silica particles of different sizes and volume loadings were added into aluminum/copper oxide thermites. Their effects on the flame front dynamics were investigated experimentally using microscopic dynamic imaging techniques and theoretically via a reaction model coupling mass and heat diffusion processes. A detailed theoretical analysis of the local temperature and thermal gradients at the vicinity of these two additives shows that highly conductive inclusions do not accelerate the combustion front while poor conductive inclusions result in the distortion of the flame front (corrugation), and therefore produce high thermal gradients (up to 1010K.m-1) at the inclusion/host material interface. This results in an overall slowing down of the combustion front. These theoretical findings contradict the experimental observations in which a net increase of the flame front velocity was found when Au and SiO2particles are added into the thermite. This leads to the conclusion that the faster burn rate observed experimentally cannot be fully associated with thermal effects only, but rather on chemical (catalytic) and/or mechanical mechanisms: formation of highly-stressed zones around the inclusion promoting the reactant mixing. One additional experiment in which physical SiO2particles were replaced by voids (filled with Ar during experiment) to cancel the potential mechanical effects while preserving the thermal inhomogeneity in the thermite structure confirms the hypothesis that instead of pure thermal conduction, it is the mechanical mechanisms that dominate the propagation velocity in our specific Al/CuO multilayered films.

Revealing High-Temperature Reduction Dynamics of High-Entropy Alloy Nanoparticles via In Situ Transmission Electron Microscopy.

Understanding the behavior of high-entropy alloy (HEA) materials under hydrogen (H2) environment is of utmost importance for their promising applications in structural materials, catalysis, and energy-related reactions. Herein, the reduction behavior of oxidized FeCoNiCuPt HEA nanoparticles (NPs) in atmospheric pressure H2 environment was investigated by in situ gas-cell transmission electron microscopy (TEM). The reduction reaction front was maintained at the external surface of the oxide. During reduction, the oxide layer expanded and transformed into porous structures where oxidized Cu was fully reduced to Cu NPs while Fe, Co, and Ni remained in the oxidized form. In situ chemical analysis showed that the expansion of the oxide layer resulted from the outward diffusion flux of all transition metals (Fe, Co, Ni, Cu). Revealing the H2 reduction behavior of HEA NPs facilitates the development of advanced multicomponent alloys for applications targeting H2 formation and storage, catalytic hydrogenation, and corrosion removal.

Silicon Nanoparticles for the Reactivity and Energetic Density Enhancement of Energetic-Biocidal Mesoparticle Composites.

Biocidal nanothermite composites show great potential in combating biological warfare threats because of their high-energy-release rates and rapid biocidal agent release. Despite their high reactivity and combustion performance, these composites suffer from low-energy density because of the voids formed due to inefficient packing of fuel and oxidizer particles. In this study, we explore the potential of plasma-synthesized ultrafine Si nanoparticles (nSi, ∼5 nm) as an energetic filler fuel to increase the energy density of Al/Ca(IO3)2 energetic-biocidal composites by filling in the voids in the microstructure. Microscopic and elemental analyses show the partial filling of mesoparticle voids by nSi, resulting in an estimated energy density enhancement of ∼21%. In addition, constant-volume combustion cell results show that nSi addition leads to a ∼2-3-fold increase in reactivity and combustion performance, as compared to Al/Ca(IO3)2 mesoparticles. Oxidation timescale analyses suggest that nSi addition can promote initiation due to faster oxygen transport through the oxide shell of Si nanoparticles. At nSi loadings higher than ∼8%, however, slower burning characteristics of nSi and sintering effects lead to an overall degradation of combustion behavior of the composites.

In Situ Oxidation Studies of High-Entropy Alloy Nanoparticles.

Although high-entropy alloys (HEAs) have shown tremendous potential for elevated temperature, anticorrosion, and catalysis applications, little is known on how HEA materials behave under complex service environments. Herein, we studied the high-temperature oxidation behavior of Fe0.28Co0.21Ni0.20Cu0.08Pt0.23HEA nanoparticles (NPs) in an atmospheric pressure dry air environment by in situ gas-cell transmission electron microscopy. It is found that the oxidation of HEA NPs is governed by Kirkendall effects with logarithmic oxidation rates rather than parabolic as predicted by Wagner's theory. Further, the HEA NPs are found to oxidize at a significantly slower rate compared to monometallic NPs. The outward diffusion of transition metals and formation of disordered oxide layer are observed in real time and confirmed through analytical energy dispersive spectroscopy, and electron energy loss spectroscopy characterizations. Localized ordered lattices are identified in the oxide, suggesting the formation of Fe2O3, CoO, NiO, and CuO crystallites in an overall disordered matrix. Hybrid Monte Carlo and molecular dynamics simulations based on first-principles energies and forces support these findings and show that the oxidation drives surface segregation of Fe, Co, Ni, and Cu, while Pt stays in the core region. The present work offers key insights into how HEA NPs behave under high-temperature oxidizing environment and sheds light on future design of highly stable alloys under complex service conditions.

High-Temperature Pulse Method for Nanoparticle Redispersion.

Nanoparticles suffer from aggregation and poisoning issues (e.g., oxidation) that severely hinder their long-term applications. However, current redispersion approaches, such as continuous heating in oxidizing and reducing environments, face challenges including grain growth effects induced by long heating times as well as complex procedures. Herein, we report a facile and efficient redispersion process that enables us to directly transform large aggregated particles into nanoscale materials. In this method, a piece of carbon nanofiber film was used as a heater and high treatment temperature (∼1500-2000 K) is rapidly elevated and maintained for a very short period of time (100 ms), followed by fast quenching back to room temperature at a cooling rate of 105 K/s to inhibit sintering. With these conditions we demonstrate the redispersion of large aggregated metal oxide particles into metallic nanoparticles just ∼10 nm in size, uniformly distributed on the substrate. Furthermore, the metallic states of the nanoparticles are renewed during the heat treatment through reduction. The redispersion process removes impurities and poisoning elements, yet is able to maintain the integrity of the substrate because of the ultrashort heating pulse time. This method is also significantly faster (ca. milliseconds) compared to conventional redispersion treatments (ca. hours), providing a pragmatic strategy to redisperse degraded particles for a variety of applications.

Aerosol Synthesis of High Entropy Alloy Nanoparticles.

Homogeneously mixing multiple metal elements within a single particle may offer new material property functionalities. High entropy alloys (HEAs), nominally defined as structures containing five or more well-mixed metal elements, are being explored at the nanoscale, but the scale-up to enable their industrial application is an extremely challenging problem. Here, we report an aerosol droplet-mediated technique toward scalable synthesis of HEA nanoparticles with atomic-level mixing of immiscible metal elements. An aqueous solution of metal salts is nebulized to generate ∼1 µm aerosol droplets, which when subjected to fast heating/quenching result in decomposition of the precursors and freezing-in of the zero-valent metal atoms. Atomic-level resolution scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy analysis reveals that all metal elements in the nanoparticles are homogeneously mixed at the atomic level. We believe that this approach offers a facile and flexible aerosol droplet-mediated synthesis technique that will ultimately enable bulk processing starting from a particulate HEA.

Synergistically Chemical and Thermal Coupling between Graphene Oxide and Graphene Fluoride for Enhancing Aluminum Combustion.

Metal combustion reaction is highly exothermic and is used in energetic applications, such as propulsion, pyrotechnics, powering micro- and nano-devices, and nanomaterials synthesis. Aluminum (Al) is attracting great interest in those applications because of its high energy density, earth abundance, and low toxicity. Nevertheless, Al combustion is hard to initiate and progresses slowly and incompletely. On the other hand, ultrathin carbon nanomaterials, such as graphene, graphene oxide (GO), and graphene fluoride (GF), can also undergo exothermic reactions. Herein, we demonstrate that the mixture of GO and GF significantly improves the performance of Al combustion as interactions between GO and GF provide heat and radicals to accelerate Al oxidation. Our experiments and reactive molecular dynamics simulation reveal that GO and GF have strong chemical and thermal couplings through radical reactions and heat released from their oxidation reactions. GO facilitates the dissociation of GF, and GF accelerates the disproportionation and oxidation of GO. When the mixture of GO and GF is added to micron-sized Al particles, their synergistic couplings generate reactive oxidative species, such as CFx and CFxOy, and heat, which greatly accelerates Al combustion. This work demonstrates a new area of using synergistic couplings between ultrathin carbon nanomaterials to accelerate metal combustion and potentially oxidation reactions of other materials.