The present study demonstrated the fabrication of a sustainable, high-performance composite by upcycling waste denim fabric within a cyanoacrylate matrix reinforced with B4C micro-particles (4, 7, and 10 wt%). XRD and SEM analyses confirmed the successful integration of the ceramic filler and effective fiber encapsulation, with particle agglomeration identified at 10 wt% loading. The 7 wt% B4C composition exhibited the highest static mechanical performance, with a tensile strength of ~20.3 ± 1.3 MPa and Young’s modulus of 1.17 GPa—improvements of ~22.8% and ~41% over the unreinforced denim–cyanoacrylate composite—while at 10 wt% B4C the ultimate tensile strength declined below the unreinforced baseline and the Young’s modulus reverted to a comparable value, likely reflecting agglomeration-induced stress concentration as a major contributing factor. Under dynamic impact loading, the peak contact force increased monotonically from 0.34 kN to 1.31 kN with increasing B4C content yet remained well below the thresholds specified by international impact protection standard thresholds across all compositions. This divergence between static and dynamic responses indicates that the increase in contact force with B4C content reflects progressive stiffening and more direct load transfer rather than improved energy attenuation, whereas tensile performance depends critically on dispersion quality and fiber–matrix adhesion. Surface wettability analysis showed a marked increase in hydrophobicity, with the water contact angle rising from 105 ± 4° to 133 ± 4° (for the DSGB-7 wt% composite), consistent with a Cassie–Baxter wetting regime. These preliminary results suggest that B4C-reinforced waste denim–cyanoacrylate composites merit further investigation as candidate materials platform for protective textile applications, pending validation through larger-scale, standardized testing.

The recycling of cable scrap, particularly from discarded electrical wiring, is gaining significant attention due to the rising demand for copper and the need for sustainable management of electronic waste. Traditionally, mechanical and thermal processings have been used to recover copper and plastic from cables. However, these approaches are often energy-intensive, time-consuming, and costly in terms of equipment and labor. In this study, we present a simple and effective method for recovering materials from cable scrap using a domestic microwave oven. Cable pieces (2–2.5 cm long) were exposed to 700 W of microwave irradiation under rotation for 30 s, enabling the rapid and efficient separation of high-quality copper metal from the core wire, and activated carbon from the carbonized plastic sheath. Microwaves facilitate this process through Ohmic heating, which induces electrical resistance in the metal, generating heat that mechanically loosens the metal and carbonized plastic components. The process demonstrates high efficiency, achieving an 80% reduction in energy consumption compared to conventional processings. This fast and energy-efficient method shows strong potential for scaling up to industrial recycling, offering a cost-effective and environmentally friendly way to recover high-quality materials for further use or repurposing.

This study introduces a microwave-assisted technique for extracting critical minerals from LED electronic waste. The process begins with microwave irradiation, which thermally decomposes the LED’s plastic lens into a brittle, charred residue. During this stage, the LED chip undergoes deflagration—being rapidly ejected from the reflective cavity and becoming embedded within the decomposed lens material. Consequently, the chip is encapsulated in the resulting charred residue. This composite, consisting of the charred lens and the LED chip, can be easily separated from the metallic pins (Fe, Ni, Ag), which remain almost undamaged. Subsequent calcination of the charred material in air exposes the materials making up the LED chip, which contain critical metals (e.g., Ga, As, In, Y, Au). These metals are then extracted through a two-step acid leaching process involving aqua regia followed by hot concentrated hydrochloric acid, yielding them in potentially recoverable forms. The synergistic effect of microwave irradiation and acid treatment achieves an average extraction efficiency of 96% for critical metals. Notably, this approach enables complete and loss-free recovery of the LED chip, offering a practical and efficient solution for LED e-waste recycling.

In this study, we present a microwave-assisted method for recycling and recovering critical minerals from LED e-waste. This new approach uses microwave irradiation to convert first the plastic lens of LED into a brittle charred residue that encapsulates the LED chip. This residue is then mechanically separated from the metallic pins (Fe, Ni, Ag), which remain intact. Further calcination of the charred residue in air exposes the materials making up the LED chip, which contain critical metals (e.g., Ga, As, In, Y, Au). A follow up two-step acid treatment using aqua regia and hot concentrated HCl, selectively leaches out the other metals ultimately resulting in gallium enrichment. The proposed combination of microwave heating with acid treatment improves significantly the recovery of Ga and provides a practical approach to remediate LED e-waste.

Aluminum-coated plastics, such as CDs and snack bags, are widely used and consumed around the world. Since millions of CDs and trillions of snack bags end up in landfills and oceans as plastic waste every year, we suggest here an easy, fast, and cost-effective method for transforming this significant volume of garbage into added-value carbon using microwave technology. The proposed method differs from existing time- and energy-consuming pyrolytic processes employed in the traditional carbonization of this sort of waste. Conceptually, direct irradiation of the aluminum-coated plastic items in a domestic microwave oven heats up the metallic coating, thus triggering carbonization of the plastic substrate. The resulting carbon, which is characterized by means of X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) techniques, has structural similarities to carbons produced from CDs and snack bags using pyrolytic methods. In other words, the microwave technique produces similar effect, but it is faster and more energy efficient. We finally demonstrate some practical uses of the derived materials in gunpowder production, carbothermal production of metals and grey paint formulations.

Nowadays, interest in the circular-economy has established biomass valorisation as a sustainable approach to develop activated carbons (ACs) for energy and environmental applications. Until a few years ago, biomass-derived ACs were regarded as hydrophobic with high adsorption capacity towards organic molecules. Recent studies indicated that this AC’s hydrophobic nature is not mandatory, and this nature depends on several parameters such as the kind of activator. In this study we present the synthesis of a hydrophobic AC host matrix derived from spent coffee via a simple pyrolysis and chemical activation process, and the characterization of it. This material was compared with a commercial hydrophilic AC which was derived from pine-needles biomass. To prove that the biomass origin significantly affects the hydrophilic or not nature of the produced activated carbon, the capacity of all materials in one hydrophilic (H2S adsorption-removal) and one hydrophobic (paraffin loading) process was investigated. Our findings highlight that ACs produced by different biomass sources and via different processes exhibit different properties. Hydrophilic or lipophilic nature is one of the key factors for such materials effectiveness in different processes. This study offers new insights on surface chemistry and polarity modification of biomass derived activated carbons and paves the way for practical applications by exploiting these properties. Furthermore, it offers results for biomass-derived ACs’ capacity in Phase Changing Materials (PCMs) encapsulation and H2S adsorption-removal processes.

We report the first synthesis of metal nanoparticles and supported metal nanoparticles on carbon by using hypergolic reactions. Specifically, we report the synthesis of noble metal nanoparticles (Pt, Ag, and Au) using sodium hydride (NaH) as both an ignition trigger and a reducing agent for the corresponding metal salt precursors. In addition, we report the one-step, in situ synthesis of Pt nanoparticles supported on carbon by adding sucrose as the carbon source. The hypergolically synthesized nanoparticles display elliptical morphology and are more crystalline compared with those conventionally synthesized in solution using sodium borohydride (NaBH4). When tested as electrocatalysts, the hypergolic Pt nanoparticles exhibit more than 2 times higher specific electrochemical active surface area (ECSA) and a higher half-wave potential (E-1/2) of 0.94 V vs the reversible hydrogen electrode (RHE) compared to the conventionally synthesized ones. In addition, the electrocatalyst based on the in situ synthesized carbon that was decorated with the Pt nanoparticles synthesized hypergolically outperforms an analogous, state of the art, commercial PtC system. For example, the former shows an attractive E-1/2 (0.94 V) compared with 0.9 V for the commercial PtC. Accelerated durability tests (ADT) in an alkaline environment add another advantage. After 10 000 cycles, the hypergolically synthesized system shows a smaller reduction of E-1/2 and less degradation compared to the commercial PtC (10 mV compared to similar to 30 mV). The work described here represents the first reported synthesis using hypergolic reactions of metal nanoparticles as well as supported metal nanoparticles. The properties of the resulting electrocatalysts demonstrate the versatility and promise of the new approach in materials synthesis and open new avenues for further investigation as electrocatalysts.

This study introduces a novel magnetic nanohybrid material consisting of ferromagnetic (FM) bcc Fe–Co nanoparticles (NPs) grown on nanodiamond (ND) nanotemplates. A combination of wet chemistry, which produces chemical precursors and their subsequent thermal treatment under vacuum, was utilized for its development. The characterization and study of the prepared samples performed with a range of specialized experimental techniques reveal that thermal treatment of the as-prepared hybrid precursors under a range of annealing conditions leads to the development of Co-rich Fe–Co alloy NPs, with average sizes in the range of 6–10 nm, that exhibit uniform distribution on the surfaces of the ND nanotemplates and demonstrate FM behavior throughout a temperature range from 2 K to 400 K, with maximum magnetization values ranging between 18.9 and 21.1 emu/g and coercivities ranging between 112 and 881 Oe. Moreover, 57Fe Mössbauer spectroscopy reveals that apart from the predominant bcc FM Fe–Co phase, iron atoms also participate in the formation of a secondary martensitic-type Fe–Co phase. The emergence of this distinctive phase is attributed to the diffusion of carbon atoms within the Fe–Co lattices during their formation at elevated temperatures. The source of these carbon atoms is related to the unique morphological properties of the ND growth matrices, which facilitate surface sp2 formations. Apart from their diffusion within the Fe–Co NP lattice, the carbon atoms also reconstruct layered graphitic-type nanostructures enveloping the metallic alloy NPs. These non-typical nanohybrid materials, reported here for the first time in the literature, hold significant potential for use in applications related, but not limited to, biomedicine, biopharmaceutics, catalysis, and other various contemporary technological fields.

Hypergolic reactions have emerged as a new synthetic approach enabling the rapid production of a diverse set of materials at ambient conditions. While hypergolic reactions bear several similarities to the well-established flame spray pyrolysis (FSP), the former has only recently been demonstrated as a viable approach to materials synthesis. Here we demonstrate a new pathway to 2D materials using hypergolic reactions and expand the gallery of nanomaterials synthesized hypergolically. More specifically, we demonstrate that ammonia borane complex, NH _3 BH _3 , or 4-fluoroaniline can react hypergolically with fuming nitric acid to form hexagonal boron nitride/fluorinated carbon nanosheets, respectively. Structural and chemical features were confirmed with x-ray diffraction, infrared, Raman, XPS spectroscopies and N _2 porosimetry measurements. Electron microscopy (SEM and TEM) along with atomic force microscopy (AFM) were used to characterize the morphology of the materials. Finally, we applied Hansen affinity parameters to quantify the surface/interfacial properties using their dispersibility in solvents. Of the solvents tested, ethylene glycol and ethanol exhibited the most stable dispersions of hexagonal boron nitride (h-BN). With respect to fluorinated carbon (FC) nanosheets, the suitable solvents for high stability dispersions were dimethylsulfoxide and 2-propanol. The dispersibility was quantified in terms of Hansen affinity parameters ( δ _d , δ _p , δ _h ) = (16.6, 8.2, 21.3) and (17.4, 10.1, 14.5) MPa ^1/2 for h-BN and FC, respectively.

We report a family of carbon sorbents synthesized by integrating hypergolics with activation reactions on a templated substrate. The materials design leads to nanoporous carbons with a BET area of 4800 m2 g-1 with an impressive total pore volume of 2.7 cm3 g-1. To the best of our knowledge, this BET area value is the highest reported in the literature. Electron spin resonance (ESR) measurements determined the number of radicals in an effort to provide a mechanistic understanding of the formation of ultrahigh surface area carbons. In combination with XPS, we propose a mechanism based on the synergistic effect between rim-based pentagonal rings and carbon radicals, which we believe can be exploited to produce other highly porous carbons. The CO2 capture capacity of the hyperporous carbon tested under dynamic CO2 capture conditions was ∼1.25 mmol g-1 versus 0.66 mmol g-1 of a conventionally activated carbon under similar conditions. The CO2 capture kinetics were extremely fast and reached 99% of the total capacity within 120 s. Lastly, supercapacitor electrodes deliver a high volumetric energy density of ∼60 W h L-1 and a volumetric power density of 1 kW L-1, which is the highest reported value for activated carbon.

Nowadays, the scientific interest is focused more and more on the development of new strategies in recycling of waste products as well as on the development of clean technologies due to the increased environmental pollution. In this work we studied the valorization of an expired cheese-tomato flavor corn snack, which is polysaccharide food product, by producing advanced hybrid magnetic materials for environmental remediation purposes. The carbonization-chemical activation of this snack using potassium hydroxide leads to a microporous activated carbon with high surface area (SgBET ~800 m2/g). The magnetic hybrid material was synthesized via an in-situ technique using iron acetate complex as the precursor to produce iron based magnetic nanoparticles. The resulting material retains a fraction of the microporous structure with surface area SgBET ~500 m2/g. Such material consists, of homogenously dispersed magnetic isolated zero valent iron nanoparticles and of iron carbides (Fe3C), into the carbon matrix. The magnetic carbon exhibited high adsorption capacity in Cr(VI) removal applications following a pseudosecond order kinetic model. The maximum adsorption capacity was 88.382 mgCr(VI)/gAC at pH = 3. Finally, oxidation experiments, in combination with FT-IR, Mössbauer, and VSM measurements indicated that the possible Cr6+ removal mechanism involves oxidation of iron phases and reduction of Cr6+ to Cr3+.

Hypergolic reactions have been recently introduced from our group as a radically new preparative tool in materials science, namely hypergolic materials synthesis, allowing the fast and spontaneous synthesis of several nanomaterials at ambient conditions in an energy-liberating manner. Although the majority of the examples given from our group in this context have been mainly referred to carbon, hypergolic materials synthesis can be, in principle, extended to the synthesis of inorganic materials as well. For instance, in previous works we have illustrated that metallocenes and metallocene dichlorides in combination with fuming nitric acid HNO3 are versatile organometallic reagents towards the hypergolic synthesis of a wide range of inorganic material. In our search for additionally new precursors towards the hypergolic synthesis of inorganic materials, here we take another step-forward to show the great potential of metal (IV) dimethylamides with fuming nitric acid HNO3 or of low melting point, hydrated transition metal salts (chlorides or nitrates) with sodium hydride NaH, in the synthesis of inorganic materials with peculiar morphologies through the corresponding hypergolic reactions. In particular, we show that titania TiO2 nanoparticles with twin structure can be derived by ignition of titanium (IV) dimethylamide with fuming nitric acid HNO3, whereas thin maghemite γ-Fe2O3 nanosheets by ignition of molten iron (III) chloride hexahydrate FeCl3•6H2O with sodium hydride NaH. The method can be equally applied to other metal (IV) dimethylamides or low melting point, hydrated transition metal salts with fuming nitric acid HNO3 or sodium hydride NaH, respectively, thus emphasizing the generality and simplicity of this new type of precursors in the hypergolic synthesis of inorganic materials.

Carbon is an energetic, plentiful, cheap, non-toxic and non-corrosive material that is however scarcely used as solid fuel in hypergolic propellants for rocket engines, probably due to the luck of hypergolicity and ignition difficulties. Taking into consideration that carbon hypergolicity is a rare phenomenon in the literature, herein is presented a new type of carbon-containing hypergolic compositions based on water-ignitable C-NaH mixtures. In these formulations, carbon might be fullerenes C60, multiwall carbon nanotubes MWNTs, charcoal or active carbon, whereas sodium hydride NaH and water react exothermically upon contact to trigger carbon combustion and ignition of the mixtures at ambient conditions. Hence, carbon allotropes appear as potentially new solid fuels in hypergolic propellant compositions, meriting further attention in this direction.

Radiator sludge is caused by hydrothermal corrosion of ferrous metals that make up the system, with more than 98 % being magnetite Fe3O4 (e.g., magnetite sludge). When hot circulating water reacts with metals such as the steel inside radiator, the build-up of sludge can be costly, leading to heating inefficiency or system breakdown through pipes blockage. Therefore, the sludge must be removed from radiator on a regular basis, ending up as waste to the environment without any further use. Taking into account the numerous applications of magnetic iron oxides, as well as the vast number of installed radiators existing worldwide, it becomes apparent that magnetite sludge makes a considerable yet cheap waste meriting further attention towards practical applications. In this work, we isolate and characterize magnetite sludge from radiator, providing evidence about the magnetic nature of the iron oxide phase for the first time. Following, we exploit the sludge as sorbent material towards hydrogen sulfide H2S removal. Due to trace amounts of catalytic elements in the sample from the steel body of radiator, this shows a high removal capacity of 2.68 mmol H2S per gram of sorbent at room temperature, thus surpassing literature-reported values of synthetic magnetite Fe3O4 nanoparticles (0.1-1.5 mmol H2S per gram of sorbent in the range 30-120 °C). This finding is important taking into consideration that there is an ever-increasing need towards an efficient removal of hydrogen sulfide H2S at room temperature by low-cost sorbents.

More than 14 billion pencils are manufactured and used globally every year. On average, a pencil is discarded after 60% of its original length has been depleted. In the present work we propose a simple and affordable way of converting this non-neglectable amount of waste into added value carbon product. In particular, we demonstrate the microwave synthesis of carbon from the wood pencil with and without chemical activation. This could be a process stage before the final recycling of the expensive graphite core. In the latter case, irradiation of the wood pencil in a domestic microwave oven heats up the pencil’s graphite core, thus inducing carbonization of its wood casing. The carbonized product consists of amorphous carbon nanosheets having relatively low surface area. However, if the wood pencil is soaked in 50% KOH aqueous solution prior to microwave irradiation, a significantly higher surface area of carbon is obtained, consisting of irregular-shaped porous particles. Consequently, the obtained carbon can easily decolorize a methylene blue aqueous solution, can be used to make pocket warmers or gunpowder, and lastly, serves as an excellent adsorbent towards Cr(VI) removal from water, showing a maximum adsorption capacity of 70–75 mg/g within 24 h at 23 °C, pH = 3.

Access to clean water for drinking, sanitation, and irrigation is a major sustainable development goal of the United Nations. Thus, technologies for cleaning water and quality-monitoring must become widely accessible and of low-cost, while being effective, selective, sustainable, and eco-friendly. To meet this challenge, hetero-bifunctional nanographene fluorescent beacons with high-affinity pockets for heavy metals are developed, offering top-rated and selective adsorption for cadmium and lead, reaching 870 and 450 mg g-1 , respectively. The heterobifunctional and multidentate pockets also operate as selective gates for fluorescence signal regulation with sub-nanomolar sensitivity (0.1 and 0.2 nm for Pb2+ and Cd2+ , respectively), due to binding affinities as low as those of antigen-antibody interactions. Importantly, the acid-proof nanographenes can be fully regenerated and reused. Their broad visible-light absorption offers an additional mode for water-quality monitoring based on ultra-low cost and user-friendly reagentless paper detection with the naked-eye at a limit of detection of 1 and 10 ppb for Pb2+ and Cd2+ ions, respectively. This work shows that photoactive nanomaterials, densely-functionalized with strong, yet selective ligands for targeted contaminants, can successfully combine features such as excellent adsorption, reusability, and sensing capabilities, in a way to extend the material's applicability, its life-cycle, and value-for-money.

In a previous work we have demonstrated the carbonization of biomass waste, such as stale bread, spent coffee and cardboard, in piranha solution towards the formation of hypergolic carbons that could be exploited as solid fuels in rocket engines. These cases simply aimed to provide some interesting examples of waste valorization towards a new class of carbon-based rocket fuels rather unique to the piranha solution treatment. In an effort to further strengthen this concept with additional examples herein we report the carbonization of waste tea in piranha solution towards the formation of hypergolic carbons at decent yield. Likewise bread, coffee and cardboard waste, spent tea is also produced in large quantities worldwide every year, thus meriting further attention in this context. Consistently with the previously reported results, the piranha solution-mediated carbonization of waste tea produces carbon nanosheets that spontaneously ignite upon contact with fuming nitric acid HNO3 at ambient conditions. Interestingly, intercalation of the nanosheets with certain ignitable molecules further boosts carbon hypergolicity upon contact with fuming nitric acid HNO3. These findings come to confirm the versatile character of the method in diverting biomass waste into valuable energetic carbons by piranha solution.

Lithium-Sulfur Batteries is promising energy storage systems due to their superior capacity and energy density. A promising solution for drawbacks such as low sulfur utilization and cycling stability is the use of porous carbon as sulfur carrier. On the other hand, cyclic economy and green ideas is of great importance nowadays. Carbon-sulfur cathodes from waste valorization, abundant, and low-cost precursors is an attractive approach. Herein, an activated carbon (AC-Poc) derived from "Posidonia oceanica" sea-waste, was studied as a matrix for the development of a novel carbon-sulfur composite cathode (AC-Poc/S) for the first time. AC-Poc can be used as an effective sulfur host, due to its high specific BET surface area (1264 m(2).g(-1)) hierarchical porous structure, and total pore volume 0.81 cm(3).g(-1). AC-Poc/S reveals an outstanding initial capacity of 1539 mAh.g(-1) as cathode material, combined with high reversible capacity at 0.2 C. Furthermore, the discharge capacity of 390 mAh/g at 2 C reveals good rate capability, even at increased C-rate. AC-Poc/S composite exhibits excellent sulfur utilization (92 %) alongside with sufficiently well electrochemical performance. These results combined with the easy synthesis method of the activated carbon from an abundant and low-cost precursor make AC-Poc/S a very promising material for LSBs applications.

In the present work we report for the first time the carbonization of biomass waste, such as stale bread and spent coffee, in piranha solution (H2SO4-H2O2) at ambient conditions. Carbonization is fast and exothermic, resulting in the formation of carbon nanosheets at decent yields of 25–35%, depending on the starting material. The structure and morphology of the nanosheets were verified by X-ray diffraction, Raman, X-ray photoelectron and microscopy techniques. Interestingly, the obtained carbon spontaneously ignites upon contact with fuming nitric acid HNO3 at ambient conditions, thus offering a rare example of hypergolicity involving carbon as the solid fuel (i.e., hypergolic carbon). Based on the relatively large interlayer spacing of the as-produced carbons, a simple structural model is proposed for the observed hypergolicity, wherein HNO3 molecules fit in the gallery space of carbon, thus exposing its basal plane and defect sites to a spontaneous reaction with the strong oxidizing agent. This finding may pave the way towards new type hypergolic propellants based on carbon, the latter exclusively obtained by the carbonization of biomass waste in piranha solution.

Hypergolic materials synthesis is a new preparative technique in materials science that allows a wide range of carbon (nanosheets, dots, hollow spheres, discs, fullerols, graphene/graphite) or inorganic (magnetic, photocatalytic, metallic or metal alloy) solids with useful properties to be obtained. Solely based on simple hypergolic reactions that lift-off rockets to space, the method not only allows the fast and spontaneous synthesis of several nanomaterials at ambient conditions, but also releases sizable amounts of energy that can be directly converted into useful work, such as chemical, mechanical, photovoltaic, thermoelectric or heating fluids. The present review aims to summarize the basic principles behind this new technique, to emphasize the general character and simplicity of the method by citing several paradigms of carbon and inorganic functional materials syntheses, as well as, to discuss some future prospects for large scale implementation based on rocket fuel engineering concepts.