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The development of green primary explosives has become a "holy grail" of energetic materials research. Cu-based 5-nitrotetrazolate is considered one of the most promising candidates due to its excellent blasting power and environmentally benign nature. However, synthesizing Cu-based 5-nitrotetrazolate controllably and securely remains highly challenging. Herein, room-temperature anodization of metallic Cu and a Cu(I)-imidazole nanowire array on copper substrates in a sodium 5-nitrotetrazolate electrolyte leads to in situ electrosynthesis of Cu(I) 5-nitrotetrazolate (DBX-1, CuNT) and its analogue, Cu(II) 5-nitrotetrazolate [Cu(NT)

In this paper, sheet-like porous CuO (p-CuO), which was prepared using a hydrothermal-annealing method, has been first selected as an oxidizer to prepare n-Al/p-CuO/GO nanoenergetic composites. The...

A porous CuN3 film has been facilely synthesized by a sustainable electroassisted azidation methodology using the template of porous Cu as a precursor. Such porous CuN3 films show excellent perform...

It is highly desired but still remains challenging to design a primary explosive-based nanoparticle-encapsulated conductive skeleton for the development of powerful yet safe energetic films employed in miniaturized explosive systems. Herein, a proof-of-concept electrochemical preparation of metal-organic frameworks (MOFs) derived porous carbon embedding copper-based azide (Cu(N

Colloidal lithography provides a rapid and low-cost approach to construct 2D periodic surface nanostructures. However, an impressive demonstration to prepare large-area colloidal template is still missing. Here, a high-efficient and flexible technique is proposed to fabricate self-assembly monolayers consisting of orderly-packed polystyrene spheres at air/water interface via ultrasonic spray. This "non-contact" technique exhibits great advantages in terms of scalability and adaptability due to its renitent interface dynamic balance. More importantly, this technique is not only competent for self-assembly of single-sized polystyrene spheres, but also for binary polystyrene spheres, completely reversing the current hard situation of preparing large-area self-assembly monolayers. As a representative application, hexagonal-packed silver-coated silicon nanorods array (Si-NRs@Ag) is developed as an ultrasensitive surface-enhanced Raman scattering (SERS) substrate with very low limit-of-detection for selective detection of explosive 2,4,6-trinitrotoluene down to femtomolar (10

The CuO micro/nanowires film has been prepared successfully on a Cu substrate using a combination of an electrochemical anodization and an annealing treatment. Its morphology and phase composition ...

Water splitting has been considered as one of the most promising strategies for renewable energy production. The process of water electrolysis is greatly influenced by the sluggish kinetics of the oxygen evolution reaction (OER). Therefore, it is necessary to develop a very effective catalyst for improving OER performances. The electronic properties and morphological structure of electrocatalysts can significantly affect their OER performance. Electrocatalysts with the morphology of dendrite can expose more active sites which would enhance the OER activity. Here, the 3D dendritic Ni@Ni(Fe)OOH core-shell material has been developed on nickel foam (NF) with a controllable morphology and composition using an extremely simple and fast method. The doping of Fe can effectively modulate the morphology and the electronic structure of Ni@NiO to improve the intrinsic activity of active sites. The porous dendritic core-shell structure could allow more active sites to grow and transport electrolyte faster. At the same time, the internal Ni core can work as fast electronic transfer networks. As a result, the optimized Ni@Ni(Fe)OOH/NF shows a great catalytic performance for OER with an overpotential of 226 mV cm−2 at 10 mA cm−2 and an excellent stability in alkaline solution. The results given in paper may bring important implications for the development of a series of hydrogen and oxygen catalysts.

The design and synthesis of highly efficient electrocatalysts for OER are important for energy storing applications. In this communication, Cu(TCNQ)2 nanorod arrays have been designed and synthesized successfully with a Cu(Fe)OOH nanosheet shell by using a short oxidation process of Cu(TCNQ)2 and subsequently an ultrafast ion exchange reaction. They are expected to combine a variety of desired merits including a simple and rapid preparation process, a large specific surface area, high conductivity and multiple electrocatalytic active sites. All the worthy characteristics which make Cu(TCNQ)2@Cu(Fe)OOH are endowed with an excellent OER catalytic performances with the required overpotential of 261 mV at 25 mA cm−2 only. The present work not only produces a good OER catalyst but also provides us a new idea to design efficient OER electrocatalysts.

The interface layer is responsible for the outward migration of oxygen atoms, which subsequently leads to an adjustment in the energetic performance of nanothermite films. In this study, sandwich-structured CuO@Ni/Al and CuO@NiO/Al nanowire thermite films were successfully prepared to investigate the effects of the interface layer on the heat-release, ignition, and combustion performance. The effects of the Ni and NiO interface layers are extremely different on the heat-release performance and combustion properties of the CuO/Al nanowire thermite film. Herein, the introduced Ni layer decreased the heat release (1979.7 J/g), reactivity (Ea = 177.3 kJ/mol), and maximum pressure (2.32 MPa) compared with the CuO/Al composite. Al/Ni alloys can be formed at the interface to prevent oxygen from diffusing between CuO and Al. Moreover, the incorporation of the Ni interface layer into the CuO/Al systems results in a heat drop due to its heat-absorption capability as well as its blockage of heat transfer from the thermite reaction. The deposition of the NiO layer between CuO and Al leads to an increase in the heat release (3014.2 J/g) and a decrease in the activation energy (Ea = 178.6 kJ/mol). The NiO layer endows the CuO/Al system with a high energy-release rate and chemical reactivity. NiO can participate in a thermite reaction, which promotes the reaction of CuO/Al and induces the condensed phase.

In this study, CoFe2O4 is selected for the first time to synthesize CoFe2O4/Al nanothermite films via an integration of nano-Al with CoFe2O4 nanowires (NWs), which can be prepared through a facile hydrothermal-annealing route. The resulting nanothermite film demonstrates a homogeneous structure and an intense contact between the Al and CoFe2O4 NWs at the nanoscale. In addition, both thermal analysis and laser ignition test reveal the superb energetic performances of the prepared CoFe2O4/Al NWs nanothermite film. Within different thicknesses of nano-Al for the CoFe2O4/Al NWs nanothermite films investigated here, the maximum heat output has reached as great as 2100 J&middot, g&minus, 1 at the optimal thickness of 400 nm for deposited Al. Moreover, the fabrication strategy for CoFe2O4/Al NWs is also easy and suitable for diverse thermite systems based upon other composite metal oxides, such as MnCo2O4 and NiCo2O4. Importantly, this method has the featured advantages of simple operation and compatibility with microsystems, both of which may further facilitate potential applications for functional energetic chips.

Direct ink writing promotes ink formulation design gradually become a hotspot in the application research of nanothermite. In order to obtain an energetic ink with a certain mechanical strength and formability, it is necessary to compound the energetic material with an inert binder. The inert component will not only reduce the sensitivity and energy release efficiency of energetic systems, but also affect its application in micro ignition devices. Based on the thermal gelation behavior of hydroxypropyl methylcellulose (HPMC), the nAl/pCuO/HPMC ink was prepared by HPMC, nano aluminum powder (nAl), and sheet-like porous CuO (pCuO). It has found out that the energetic ink has a favorable printing accuracy when the HPMC content is 7 wt%. To compare the influence from the size and morphology of copper oxide and aluminum on ink printing and reaction performances, the mAl/pCuO/HPMC, nAl/nCuO/HPMC and nAl/mCuO/HPMC inks have been prepared using the same way. Due to the large particle size of the components, nAl/mCuO/HPMC cannot be printed continuously during the printing process. For the mAl/pCuO/HPMC, it cannot form self-sustaining combustion on the glass substrate when the ink is a single layer. The activation energy results show that nAl/pCuO/HPMC has the smallest value (68.39 kJ/mol). The calculated burning rate of nAl/pCuO/HPMC (32.56 cm/s) is about 6 times than that of nAl/nCuO/HPMC system (5.28 cm/s). The ignition performance test shows that only the nAl/pCuO/HPMC system can be successfully ignited by a SCB micro igniter when the HPMC content is 7 wt%. Meanwhile, the pressure test indicates that the nAl/pCuO/HPMC system (7 wt% HPMC, Ф=1.4) has the shortest pressure rising time (46.7 μs), but the largest pressurization rate (1661.7 GPa/s).

Energetic thin films have been widely used in the field of microscale energy-demanding systems. In this work, a novel energetic metal–organic frameworks [Cd5(Mtta)9]n film is fabricated on the copper substrate through an in situ synthesis method for the first time. A 5-methyl tetrazole/copper complex is deposited to modify the copper substrate through an electrochemical-assisted strategy. The [Cd5(Mtta)9]n film is then integrated on the surface of modified copper substrate by an in situ reaction of acetonitrile with sodium azide and cadmium nitrate. The morphological, structural and compositional information of the [Cd5(Mtta)9]n film is characterized by field emission scanning electron microscopy, X-ray diffraction and infrared spectrum. The thermostabilities of the [Cd5(Mtta)9]n film are studied by differential scanning calorimetry and thermogravimetry. In addition, the preliminary laser ignition test is conducted by using pulsed Nd:YAG laser. The results show that the as-prepared [Cd5(Mtta)9]n film possesses a rod-like topography. The flame height and ignition duration of [Cd5(Mtta)9]n film reach 9.0 mm and 220 µs, respectively, revealing that [Cd5(Mtta)9]n film is an excellent ignition material. This research opens up a new avenue for the preparation of novel energetic films, which provides potential applications on microelectromechanical systems to achieve functional nanoenergetics-on-a-chip.

NiCo2O4 has been selected as an oxidizer to realize the nanothermite film for the first time in this study. The NiCo2O4/Al core-shell nanowires (NWs) thermite film has been fabricated using a facile hydrothermal-annealing synthesis method and a controllable magnetron sputtering process. The as-obtained NiCo2O4/Al NWs thermite film shows a uniform structure and distribution on the substrate, with a favorable interfacial contact between the bimetallic oxide and the fuel at the nanoscale. It is found that the quantity of Al plays a key role in the total heat release magnitude. The maximal heat release of the NiCo2O4/Al nanothermite film has reached 2076.0 J/g at the optimal Al deposited thickness of 450 nm with the obtained optimum Al/NiCo2O4 molar ratio of 4.9. Moreover, this design strategy is highly compatible with microelectromechanical systems (MEMs) and it can be applied to realize other nanothermites composed by bimetallic oxide and fuel. Keywords: NiCo2O4/Al, Core-shell nanowires structure, Nanothermite film, Heat release, Magnetron sputtering

The energy performance of nanothermites in aqueous conditions is commonly restricted by the rapid heat dissipation and corrosion of nano-Al. Here we report studies on the fabrication and submerged ignition for the super-hydrophobic nanothermite film based upon the Co3O4/Al core/shell nanowires (NWs). The Co3O4 NWs arrays, which are synthesized using a facile hydrothermal-annealing method, serve as templates for the deposition of Al shells by magnetron sputtering. The super-hydrophobic surface is subsequently realized by the fluoroalkylsilane coating. The tests of the laser-induced underwater ignition reveal that the super-hydrophobic modification effectively could lead to the ignition of the nanothermite film. Furthermore, the anti-aging behaviors of the obtained super-hydrophobic nanothermite film in aqueous conditions are investigated in detail to compare the heat-release and ignition characteristics at different submersion times. Impressively, the resultant super-hydrophobic composite could still hold about 50% of the original energy even after an underwater storage of 2 days.

Co 3 O 4 nanowires (NWs) arrays were successfully fabricated via a facile hydrothermal-annealing method. The component, structure and morphology of the Co 3 O 4 NWs arrays were characterized. The slim Co 3 O 4 NWs consist of interconnected nanocrystals and have a specific surface area of 26.6 m 2 g −1 . The obtained materials have exhibited an excellent catalytic performance on the thermal decomposition of ammonium perchlorate (AP). In addition, catalytic activities of the prepared Co 3 O 4 mainly depend on the content of catalyst. Impressively, an addition of 9 wt% Co 3 O 4 NWs arrays to AP exhibited the most significant catalytic effect in lowering the decomposition temperature from 404 to 288 °C, increasing the decomposition heat from 502 to 930 J g −1 and decreasing the activation energy from 201 to 168 kJ mol −1 . Furthermore, the catalytic mechanism of the Co 3 O 4 NWs arrays based on electron transfer processes was discussed.

In-situ construction of energetics-on-a-chip by the microcharge technique has recently received much attention by researchers. In this study, a novel integrated CuN3/CL-20 explosive train film was fabricated in-situ on a Cu substrate. The porous CuN3 film, which was synthesized by facile electrochemical azidation of porous Cu, served as a skeleton for the integration of CL-20 by means of spin-coating and recrystallization. In this architecture, the introduction of CL-20 endowed the resultant explosive train film with a greater charge density and an enhanced energy output than a single CuN3 film. In particular, the tunability of exothermic capacity could be controlled by adjusting the loading amount of CL-20. Additionally, the embedded CL-20 and CuN3 film jointly ensured violent explosive behavior upon laser stimulation. Given these advantages, this CuN3/CL-20 explosive train film exhibits great potential for application in functional energetic chips.

The electric initiating explosive devices (EIEDs) are playing an increasingly important role in both military and civilian applications. With respect to good electrical conductivity and flexural strength, carbon paper can be endowed with primary explosive so that it serves as an independent module just like an ignition component in the EIEDs to satisfy the modular integration of EIEDs. But a traditional primary explosive cannot meet the need of sustainably developed devices. New energetic films need to be designed for EIEDs. The heat release and activation energy of the CA-CP film are 1402 J·g−1 and 104 kJ·mol−1, respectively. The electrostatic sensitivity of the CA film, whose E50 reaches up to 4.81 mJ, has been well improved due to its interweaved fibers. Moreover, the cuprous azide film could be successfully ignited under water after a hydrophobicity treatment. Herein, the CA-loaded carbon paper has been successfully integrated with the Ni-Cr bridge EIEDs for a greatly improved ignition performance, which will subsequently lead to a vast enhancement in the ability of EIEDs to ignite the secondary explosives or devices.

In this work, for the first time, we have successfully prepared energetic metal-organic framework [Cu(ntz)]n films by integrating electrochemical deposition and solvothermal growth. With its excellent energy, stability and ignition performances, the [Cu(ntz)]n film has potential application in microelectromechanical systems (MEMS) to achieve functional nanoenergetics-on-a-chip.

In order to enhance the ignition ability and reliability of traditional electronic initiators, a novel electronic initiator has been designed to integrate with a nanothermite multilayer film and an electrode plug. The Al/CuO x nanothermite multilayer film with different thickness is deposited on the surface of the electrode plug by magnetron sputtering which uses Pt–W wire as electronic resistance. The exothermicity of Al/CuO x nanothermite multilayer film is so favourable that the ignition ability of electronic initiator is significantly improved. The full firing-voltage sensitivity of the electronic initiator is 10.8 V. The thickness of Al/CuO x multilayer film has negligible effects on the ignition time and ignition energy, but leads to great impacts on the function time, the maximum length of combustion flame and ignition ability. The electrical ignition experiments have exhibited outstanding ignition ability, since the electronic initiator can easily fire the insensitive ignition composition of boron-potassium nitrate (B-KNO 3 ) tablet in a gap of 20.35 mm. It proves that this novel proposal of remoulding the traditional electronic ignition devices will distinctly improve the ignition ability and reliability of electronic initiator.

The development of nanothermites with adjustable reactivity has always been the research hotspot in the field of energetic materials, and its key issue is to control the interfacial contact extent and diffusion length between fuel and oxidizer. Here, the 3DOM CuO/Al, 3DOM CuO/Al-NPs and CuO-NPs/Al-NPs nanothermites, which show a gradual decrease in contact extents between reactants, were firstly prepared simultaneously using magnetron sputtering, P4VP self-assembly and ultrasonic mixing, respectively. The DSC thermograms show that the heat release of the 3DOM CuO/Al (sputtering 200 nm Al) can reach 2541.4 J/g, much larger than either value of the prepared 3DOM CuO/Al-NPs and CuO-NPs/Al-NPs. The activation energies of these CuO/Al systems also exhibit the similar results as the heat releases. However, the 3DOM CuO/Al-NPs can lead to the highest combustion pressure (24.6 MPa), the shortest pressure rise time (0.067 ms), and the fastest pressurization rate (647.98 GPa/s), followed orderly in corresponding values by the CuO-NPs/Al-NPs and 3DOM CuO/Al. All data indicate that the contact extent between CuO and Al plays a great effect on the overall reactivity, and their differences in structure and volume are responsible for the diverse combustion pressure performance. Furthermore, the presence of reaction voids between components can promote the O diffusion to enhance the continuous mass and heat transfer for an efficacious reaction. Hence, it is believed that similar methods can be used to improve the contact extent and diffusion length between fuels and oxidants so as to achieve an adjustment in reactivity for various nanothermites.

The huge energy release and highly adjustable combustion characteristics of nanoporous silicon (nPS) make it one of the most attractive inorganic energetic materials. However, nPS will be oxidized slowly from its surface when it is left in ambient air to be aged. Explanations vary as to the aging mechanism, and the corresponding anti-ageing strategy remains to be fully investigated. The present study provides an efficient strategy of a thermal-induced hydrosilylation to improve the long-term chemical stability of H-terminated nPS. The nPS of 75 μm in depth was etched with a pore diameter of 52.5 nm and a gravimetry-determined porosity of 79.6%. The DSC and FTIR data confirm that oxygen is able to infiltrate the H-terminated layer and preferentially attack the weak Si-Si over Si-H bonds. The prime oxidizer is not sodium perchlorate but oxygen from the air to cause a backbond oxidation. After a modification, the heat of reaction is determined to be 1436 J·g−1. Interestingly, this value is of almost no detectable change to be 1402 J·g−1 and 1387 J·g−1 when aged for 24 or 48 h, respectively. All the evidences suggest that the alkyl-terminated nPS exhibits an excellent anti-oxidation ability to ambient air, which is well consistent with a high-speed video analysis from the combustion behavior of nPS impregnated with NaClO4·H2O. This work suggests that only one step may be away from a practical application of nPS energetic materials.

In order to enhance the ignition ability and reliability of traditional electronic initiators, a novel electronic initiator has been designed to integrate with a nanothermite multilayer film and an electrode plug. The Al/CuOx nanothermite multilayer film with different thickness is deposited on the surface of the electrode plug by magnetron sputtering which uses Pt–W wire as electronic resistance. The exothermicity of Al/CuOx nanothermite multilayer film is so favourable that the ignition ability of electronic initiator is significantly improved. The full firing-voltage sensitivity of the electronic initiator is 10.8 V. The thickness of Al/CuOx multilayer film has negligible effects on the ignition time and ignition energy, but leads to great impacts on the function time, the maximum length of combustion flame and ignition ability. The electrical ignition experiments have exhibited outstanding ignition ability, since the electronic initiator can easily fire the insensitive ignition composition of boron-potassium nitrate (B-KNO3) tablet in a gap of 20.35 mm. It proves that this novel proposal of remoulding the traditional electronic ignition devices will distinctly improve the ignition ability and reliability of electronic initiator.

The traditional gas-solid synthesis of copper azide (CA) always requires rigorous conditions, such as the use of hazardous HN3 gas, and time-consuming preparation processes (>12 h). Both disadvantages impede its eco-friendly large-scale production and result in high safety risks for the practical synthesis. Here, a safe and efficient (

In this study, a new method was reported for the fabrication of the nanostructured CuO/Al thermite film on a Cu substrate. The CuO nanorod (NR) arrays grew vertically from the Cu surfaces by electrochemical anodization processes, followed by the deposition of an Al layer on the CuO NRs via magnetron sputtering to form a core/shell CuO/Al nanothermite film, whose component, structure and morphology were subsequently characterized. In addition, the energy-release characteristics of the obtained nanothermite film were investigated using thermal analyses and laser ignition tests. All evidence demonstrates that the obtained CuO/Al is of a uniform structure and has superb energy performance. Impressively, the resulting material is potentially useful in applications of functional energetic chips due to its easy integration with microelectromechanical systems (MEMS) technologies.

Microigniters play an important role for the reliable initiation of micro explosive devices. However, the microigniter is still limited by the low out-put energy to realize high reliability and safety. Integration of energetic materials with microigniters is an effective method to enhance the ignition ability. In this work, a Al/Co3O4 nanothermite film with a three-dimensionally ordered macroporous structure was prepared by the deposition of nanoscale Al layers using magnetron sputtering on Co3O4 skeletons that are synthesized using an inverse template method. Both the uniform structure and nanoscale contact between the Al layers and the Co3O4 skeletons lead to an excellent exothermicity. In order to investigate the ignition properties, a micro-energetic igniter has been fabricated by the integration of the Al/Co3O4 nanothermite film with a semiconductor bridge microigniter. The thermite reactions between the nanoscale Al layer and the Co3O4 skeleton extensively promote the intensity of the spark, the length in duration and the size of the area, which greatly enhance the ignition reliability of the micro-energetic igniter. Moreover, this novel design enables the micro-energetic igniter to fire the pyrotechnic Zr/Pb3O4 in a gap of 3.7 mm by capacitor discharge stimulation and to keep the intrinsic instantaneity high and firing energy low. The realization of gap ignition will surely improve the safety level of initiating systems and have a significant impact on the design and application of explosive devices.

An edge-connected multilayer graphene-based architecture has been rationally designed for the first time by a covalent/noncovalent one-pot strategy. The novel nanohybrid exhibits enhanced thermal stability and dispersibility simultaneously, indicating the generation of increasing interfacial interactions. The successful fabrication demonstrated that the steric hindrance of each component plays an important role in synthetic reactions based on graphene oxide.

Microigniters play an important role for the reliable initiation of micro explosive devices. However, the microigniter is still limited by the low out-put energy to realize high reliability and safety. Integration of energetic materials with microigniters is an effective method to enhance the ignition ability. In this work, a Al/Co

In this work, for the first time, we have successfully prepared energetic metal-organic framework [Cu(ntz)]

The performances of nanothermites largely rely on a meticulous design of nanoarchitectures and the close assembly of components. Three-dimensionally ordered macroporous (3DOM) NiO/Al nanothermite film has been successfully fabricated by integrating colloidal crystal template (CCT) method and controllable magnetron sputtering. The as-prepared NiO/Al film shows uniform structure and homogeneous dispersity, with greatly improved interfacial contact between fuel and oxidizer at the nanoscale. The total heat output of 3DOM NiO/Al nanothermite has reached 2462.27 J·g−1 at optimal the deposition time of 20 min, which is significantly more than the values of other NiO/Al structural systems that have been reported before. Intrinsic reduced ignition temperature (onset temperature) and less gas production render the wide applications of 3DOM NiO/Al nanothermite. Moreover, this design strategy can also be readily generalized to realize diverse 3DOM structured nanothermites. Keywords: Nanothermite, NiO/Al, Three-dimensionally ordered macroporous, Magnetron sputtering, Heat release

Three-dimensional ordered macroporous (3DOM) Al/NiFe2O4 nanothermite has been obtained by a colloidal crystal templating method combined with magnetron sputtering processing. Owing to the superior material properties and unique 3DOM structural characteristics of composite metal oxides, the heat output of the Al/NiFe2O4 nanothermite is up to 2921.7 J g−1, which is more than the values of Al/NiO and Al/Fe2O3 nanothermites in literature. More importantly, by comparison with the other two nanothermites, the onset temperature of about 300 °C from Al/NiFe2O4 is remarkably low, which means it can be ignited more easily. Laser ignition experiments indicate that the synthesized Al/NiFe2O4 nanothermite can be easily ignited by a laser. In addition, the preparation process is highly compatible with the MEMS technology. These exciting achievements have great potential to expand the scope of nanothermite applications.