Search Results (270)

With the global energy structure transitioning towards clean and low-carbon alternatives, electrochemical energy storage technologies have emerged as pivotal enablers for achieving efficient renewable energy utilization and carbon neutrality objectives. However, conventional electrode materials remain constrained by inherent limitations, including low specific surface area, sluggish ion diffusion kinetics, and insufficient mechanical stability, which fundamentally hinder the synergistic fulfillment of high energy density, superior power density, and prolonged cycling durability. Three-dimensional printing technology offers a revolutionary paradigm for designing and fabricating carbon-based electrochemical energy storage devices. By enabling precise control over both the microstructural architecture and macro-scale morphology of electrode materials, this additive manufacturing approach significantly enhances energy/power densities, as well as cycling stability. Specifically, 3D printing facilitates biomimetic topological designs (e.g., hierarchical porous networks, vertically aligned ion channels) and functional hybridization strategies (e.g., carbon/metal oxide hybrids, carbon/biomass-derived composites), thereby achieving synergistic optimization of charge transfer kinetics and mechanical endurance. This review systematically summarizes recent advancements in 3D-printed carbon-based electrodes across major energy storage systems, including supercapacitors, lithium-ion batteries, and metal–air batteries. Particular emphasis is placed on the design principles of carbon-based inks, multiscale structural engineering strategies, and process optimization methodologies. Furthermore, we prospect future research directions focusing on smart 4D printing-enabled dynamic regulation, multi-material integrated systems, and artificial intelligence-guided design frameworks to bridge the gap between laboratory prototypes and industrial-scale applications. Through multidisciplinary convergence spanning materials science, advanced manufacturing, and device engineering, 3D-printed carbon electrodes are poised to catalyze the development of next-generation high-performance, customizable energy storage systems. Full article

Hydrogen generation has become a popular research subject in light of currently pressing issues, such as the rapidly increasing environmental pollution, the depleting fossil fuel reserves, and the looming energy crisis. Sustainable electrochemical water splitting is regarded as one of the most desirable methods for obtaining green hydrogen. Considering this state of affairs, the water splitting electrocatalytic activity of glassy carbon electrodes modified with birnessite-type K₂Mn₄O₈ and mixed-valence iron phosphate Fe₃(PO₃OH)₄(H₂O)₄ materials were evaluated in electrolyte solutions having different pH values. Both compounds were characterized by X-ray diffraction and FT-IR spectroscopy in order to analyze their phase purity and their structural features. The most catalytically active birnessite-type K₂Mn₄O₈-based electrode was manufactured using a catalyst ink containing only the electrocatalyst dispersed in ethanol and Nafion solution. In 0.1 M H₂SO₄, it exhibited an oxygen evolution reaction (OER) overpotential of 1.07 V and a hydrogen evolution reaction (HER) overpotential of 0.957 V. The Tafel slopes obtained in the OER and HER experiments were 0.180 and 0.142 V/dec, respectively. The most catalytically active mixed-valence iron phosphate Fe₃(PO₃OH)₄(H₂O)₄-based electrode was obtained with a catalyst ink containing the specified material mixed with carbon black and dispersed in ethanol and Nafion solution. In a strongly alkaline medium, it displayed a HER overpotential of 0.515 V and a Tafel slope value of 0.122 V/dec. The two electrocatalysts have not been previously investigated in this way, and the acquired data provide insights into their electrocatalytic activity and improve the scientific understanding of their properties and applicative potential. Full article

Settlement on the Moon will require full exploitation of its resources if such settlements are to be permanent. Such in situ resource utilisation (ISRU) has primarily been focused on accessing water ice at the lunar poles and the use of raw lunar regolith as a compressive building material. Some work has also examined the extraction of metals, but there has been little consideration of the many useful ceramics that can be extracted from the Moon and how they may be fabricated. We introduce a strategy for full lunar industrialisation based on a circular lunar industrial ecology and examine the contribution of ceramics. We review ceramic fabrication methods but focus primarily on 3D printing approaches. The popular direct ink writing method is less suitable for the Moon and other methods require polymers which are scarce on the Moon. This turns out to be crucial, suggesting that full industrialisation of the Moon cannot be completed until the problem of ceramic fabrication is resolved, most likely in conjunction with polymer synthesis from potential carbon sources. Full article

Shale pore architecture governs gas storage capacity, permeability, and production potential in reservoirs. Therefore, this study systematically investigates the pore structure features and influencing factors of the Niutitang Formation shale from the QX1 well in northern Guizhou using field emission scanning electron microscopy (FE-SEM), high-pressure mercury intrusion (HPMI), low-temperature nitrogen adsorption (LTNA), and nuclear magnetic resonance (NMR) experiments. The results show that ① The pore size of the QX1 well’s Niutitang Formation shale is primarily in the nanometer range, with pore types including intragranular pores, intergranular pores, organic matter pores, and microfractures, with the former two types constituting the primary pore network. ② Pore shapes are plate-shaped intersecting conical microfractures or plate-shaped intersecting ink bottles, ellipsoidal, and beaded pores. ③ The pore size distribution showed a multi-peak distribution, predominantly mesopores, followed by micropores, with the fewest macropores. ④ The fractal dimension D₁ > D₂ indicates that the shale pore system is characterized by a rough surface and some connectivity of the pore network. ⑤ Carbonate mineral abundances are the main controlling factors affecting the pore structure of shales in the study area, and total organic carbon (TOC) content also has some influence, while clay mineral content shows negligible statistical correlation. Full article

Dry Turkish oak (Quercus cerris) sawdust, untreated and treated with three activators, (H₃PO₄, NaOH and H₂O₂) was pyrolyzed under limited-oxygen conditions to obtain biochar samples. The electrochemical properties of these samples were tested and compared to the properties of several commercial carbon blacks. The electrochemical characterization was performed via cyclic voltammetry, analyzing the response toward two commonly used redox probes, [Fe(CN)₆]^3−/−4− and [Ru(NH₃)₆]^2+/3+. The influence of the scan rate on this response was investigated, and the resulting data were used to obtain the values of the heterogenous charge transfer constant, k₀. Higher k₀ values were observed for carbon blacks than for investigated biochar samples. The detection of 4-nitrophenol and heavy metal ions was used to assess the applicability of biochars for electroanalytical purposes. The response of untreated biochar was comparable with the response of Vulcan carbon black, which showed the best response of all analyzed carbon blacks. Full article

Single-walled carbon nanotube (SWCNT) inks were prepared by mixing SWCNTs with ethanol and varying the amplitude of ultrasonic dispersion. When the SWCNT inks were prepared by dispersion amplitudes at 60% (nominal value of 200 W), the SWCNT inks had low viscosity and a small variation of the particle size. The SWCNT films fabricated under this dispersion condition had well-distributed SWCNT bundles and exhibited the highest power factor. However, when the dispersion amplitude was excessive, the viscosity of the SWCNT ink increased due to the reduced contact between the SWCNTs owing to over-dispersion, and the crystallinity of the SWCNT films decreased, exhibiting a lower power factor. When the optimized SWCNT films at 60% were applied to heat-source-free water-floating SWCNT-TEGs, an output voltage of 2.0 mV could be generated under sunlight irradiation. These findings are useful for preparing various electronic devices with SWCNT films to improve the film quality using ultrasonic dispersion. Full article

Celiac disease (CD), a human leukocyte antigen-associated disorder, is caused by gluten sensitivity and is characterized by mucosal alterations in the small intestine. Currently, its diagnosis involves the determination of serological markers. The traditional method for clinically determining these markers is the enzyme-linked immunosorbent assay. However, immunosensors offer sensitivity and facilitate the development of miniaturized and portable analytical systems. This work focuses on developing an amperometric immunosensor for the quantification of IgA antibodies against tissue transglutaminase (IgA anti-TGA) in human serum samples, providing information on a critical biomarker for CD diagnosis. The electrochemical device was designed on a polyimide substrate using a novel solid ink of wax and carbon nanofibers (CNFs). The working electrode microzone was defined by incorporating aminofunctionalized TiO₂ nanoparticles (TiO₂NPs). The interactions and morphology of CNFs/wax and TiO₂NPs/CNFs/wax electrodes were assessed through different characterization techniques. Furthermore, the device was electrochemically characterized, demonstrating that the incorporation of CNFs into the wax matrix significantly enhanced its conductivity and increased the active surface area of the electrode, while TiO₂NPs contributed to the immunoreaction area. The developed device exhibited remarkable sensitivity, selectivity, and reproducibility. These results indicate that the fabricated device is a robust and reliable tool for the precise serological diagnosis of CD. Full article

An electrochemical aptasensor was developed for the rapid and sensitive detection of ciprofloxacin (CPX) in milk samples. The device was fabricated on a polyethylene terephthalate (PET) substrate using a screen-printing technique with carbon-based conductive ink. Gold nanoparticles (AuNPs) were incorporated to enhance aptamer immobilization and facilitate electron transfer at the electrode surface. The sensor’s analytical performance was optimized by adjusting key parameters, including AuNP volume, DNA aptamer concentration, and incubation times for both the aptamer and the blocking agent (6-mercapto-1-hexanol, MCH). Differential pulse voltammetry (DPV) measurements demonstrated a linear response ranging from 10 to 50 nmol L⁻¹ and a low detection limit of 3.0 nmol L⁻¹. When applied to real milk samples, the method achieved high recovery rates (101.4–106.7%) with a relative standard deviation below 3.1%, confirming its robustness. This disposable and cost-effective aptasensor represents a promising tool for food safety monitoring, with potential for adaptation to detect other pharmaceutical residues in dairy products. Full article

Patient-specific scaffolds for tissue and organ regeneration are still limited by the difficulty of simultaneously shaping complex geometries, preserving hierarchical porosity, and guaranteeing sterility. Additive technologies represent a promising approach for addressing problems in tissue engineering, with the potential to develop personalized matrices for the growth of tissue and organ cells. The utilization of supercritical technologies, encompassing the processes of drying and sterilization within a supercritical fluid environment, has demonstrated significant opportunities for obtaining highly effective matrices for cell growth based on biocompatible materials. We present a comprehensive methodology for fabricating intricately structured, sterile aerogels based on alginate–chitosan polyelectrolyte complexes. The target three-dimensional macrostructure is achieved through (i) direct ink writing or (ii) heterophase printing, enabling the deposition of inks with diverse rheological profiles (viscosities ranging from 0.8 to 2500 Pa·s). A coupled supercritical carbon dioxide drying–sterilization regimen at 120 bar and 40 °C is employed to preserve the highly porous architecture of the printed constructs. The resulting aerogels exhibit 96 ± 2% porosity, a BET surface area of 108–238 m² g⁻¹, and complete sterility. The proposed integration of 3D printing and supercritical processing yields sterile, intricately structured aerogels with substantial potential for the fabrication of patient-specific scaffolds for tissue and organ regeneration. Full article

Monitoring posture and movement accurately and efficiently is essential for both physical therapy and athletic training evaluation and interventions. Motion Tape (MT), a self-adhesive wearable skin-strain sensor made of piezoresistive graphene nanosheets (GNS), has demonstrated promise in capturing low back posture and movements. However, to address some of its limitations, this work explores alternative materials by replacing GNS with multi-walled carbon nanotubes (MWCNT). This study aimed to characterize the electromechanical properties of MWCNT-based MT. Cyclic load tests for different peak tensile strains ranging from 1% to 10% were performed on MWCNT-MT made with an aqueous ink of 2% MWCNT. Additional tests to examine load rate sensitivity and fatigue were also conducted. After characterizing the properties of MWCNT-MT, a human subject study with 10 participants was designed to test its ability to capture different postures and movements. Sets of six sensors were made from each material (GNS and MWCNT) and applied in pairs at three levels along each side of the lumbar spine. To record movement of the lower back, all participants performed forward flexion, left and right bending, and left and right rotation movements. The results showed that MWCNT-MT exceeded GNS-MT with respect to consistency of signal stability even when strain limits were surpassed. In addition, both types of MT could assess lower back movements. Full article

Structural color is a kind of natural color that widely exists in nature. The ordered microstructure of nano materials can absorb or reflect light of specific wavelength, thus showing colorful colors. Structural color is an ideal choice for color contact lens pattern pigment due to its good tinting degree, stability, and nontoxicity. This paper explores a method for synthesis of zinc oxide (ZnO) nanoparticles with a high refractive index and enhancement of the brightness of the structured colors by introducing carbon black nanoparticles. This method is convenient and successful to prepare ZnO ink, which can produce bright structural colors, and to produce color patterns through rubber pad printing. It is worth mentioning that ZnO nanoparticles can be self-assembled and arranged in contact lens ink without subsequent complicated processing. At the same time, the color only comes from ZnO and carbon black. While there is no other organic matter, the presence of nanoparticles plays a certain role in sterilization. Blue contact lenses prepared by this method have bright structural color, high oxygen permeability, and high hydrophilicity. At the same time, a cell viability test showed that the contact lenses prepared by this method had low adsorption capacity for lipids and proteins, reflecting the photonic crystal’s high biocompatibility. In summary, a trend for future research is to use high-refractive-index zinc oxide nanoparticles to produce structural colors rather than employing conventional contact lens pigments. Full article

Printed electronics employ established printing methods to create low-cost, mechanically flexible devices including batteries, supercapacitors, sensors, antennas and RFID tags on plastic, paper and textile substrates. This review focuses on the specific contribution of screen printing to that landscape, examining how ink viscosity, mesh selection and squeegee dynamics govern film uniformity, pattern resolution and ultimately device performance. Recent progress in advanced ink systems is surveyed, highlighting carbon allotropes (graphene, carbon nano-onions, carbon nanotubes, graphite), silver and copper nanostructures, MXene and functional oxides that collectively enhance mechanical robustness, electrical conductivity and radio-frequency behavior. Parallel improvements in substrate engineering such as polyimide, PET, TPU, cellulose and elastomers demonstrate the technique’s capacity to accommodate complex geometries for wearable, medical and industrial applications while supporting environmentally responsible material choices such as water-borne binders and bio-based solvents. By mapping two decades of developments across energy-storage layers and functional electronics, the article identifies the key process elements, recurring challenges and emerging sustainable practices that will guide future optimization of screen-printing materials and protocols for high-performance, customizable and eco-friendly flexible devices. Full article

The development of printable, conductive, and biocompatible hydrogels has emerged as a promising strategy for the next generation of flexible and soft sensor platforms. In this study, we present a systematic investigation of alginate-based hydrogels incorporating different carbonaceous materials, natural graphite, carbon black (Vulcan V3), and activated carbon (PCO1000C), to evaluate their suitability for sensor applications. Hydrogels were formulated with varying concentrations of sodium alginate and a fixed loading of carbon additives. Each composite was characterized in terms of electrical conductivity under compression, rheological behavior, and mechanical strength. Printability was assessed using a custom-designed extrusion platform that allowed for the precise determination of the minimum force and optimal conditions required to extrude each formulation through a standard 20G nozzle. Among all tested systems, the alginate–graphite hydrogel demonstrated superior extrudability, shear-thinning behavior, and shape fidelity, making it well-suited for 3D printing or direct ink writing. A simple conductivity-testing device was developed to verify the electrical response of each hydrogel in the hydrated state. The effects of different drying methods on the final conductivity were also analyzed, showing that oven drying at 50 °C yielded the highest restoration of conductive pathways. Mechanical tests on printed structures confirmed their ability to maintain shape and resist compressive forces. Finally, the biocompatibility of the printed alginate–graphite hydrogel was validated using a standard cytotoxicity assay. The results demonstrated high cell viability, confirming the material’s potential for use in biomedical sensing environments. This work offers a robust framework for the development of sustainable, printable, and biocompatible conductive hydrogels. The combined performance in printability, mechanical integrity, electrical conductivity, and cytocompatibility highlights their promise for flexible biosensors and wearable sensor technologies. Full article

Heterogeneity of pore and fracture structures has become an important factor affecting the migration of methane and water in coal reservoirs. However, controlling factors of pore and fracture structure collected from coal seam 10 in Taliqike Formation, Kubai Coalfield, Xinjiang need to be studied. In this paper, carbon dioxide adsorption, cryogenic liquid nitrogen, and high-pressure mercury intrusion, as well as coal microscopic components, were used to study pore volumes and characterize pore diameter distribution heterogeneity. By the theory of single weight and multiple fractal formations, the heterogeneity of the pore fracture structure of coal reservoir is expressed, and the influencing factors of the heterogeneity of the pore fracture structure and the pore volume are also discussed. The results are as follows. (1) Micro-pore distribution presents a distinct bidirectional state, with the main peak at approximately 0.6 nm and 0.85 nm. R_o,max has an obvious influence on micro-pore volume. The single-fractal dimension of micro-pore is not affected by a micro-pore volume but is influenced by other factors such as R_o,max and microscopic composition. The heterogeneity of the low-value area controls the heterogeneity of micro-pore diameter distribution. (2) For lower R_o,max samples, mesopores of these samples are ink bottle-shaped pores, and the pore connectivity is poor. In contrast, meso-pore of higher thermal evolution coal samples are mostly simple pores, such as parallel plates. The main mesopores are 10–100 nm pores, accounting for 75% of the total meso-pore volume. For the single fractal dimension, D₁ is greater than D₂, which also shows that the heterogeneity of a pore structure greater than 4 nm is much stronger than that of a pore structure less than 4 nm in these samples. (3) For lower R_o,max samples, double S-shaped curves with distinct hysteresis loop are obtained, while samples of higher R_o,max samples show parallel curves, suggesting that macro-pore of this type of sample develops parallel plate-like pore. There is a positive relationship between D₋₁₀–D₀ and D₋₁₀–D₁₀, while D₀–D₁₀ and D₋₁₀–D₀ have a weak correlation. With the increase of 2–10 nm pore volume, pore distribution heterogeneity of lower value area (D₋₁₀–D₀) weakens. This indicates that pore volume is an important factor affecting the multifractal variation. Full article

Additive manufacturing (AM) has the potential to revolutionize the fabrication of continuous carbon fiber-reinforced polymer composites (CCFRPCs). Among AM techniques, direct ink writing (DIW) with ultraviolet (UV) curable resin shows promise for creating CCFRPCs with high manufacturing speed, high fiber volume fraction, and low energy consumption. However, issues such as incomplete curing and weak interfacial bonding, particularly in dense fiber bundles, limit the mechanical performance. This study addressed these challenges using pre-impregnated systems (PISs), which is a process developed to impregnate dry fiber bundles with partially cured resin before being used for DIW printing, to enhance resin-fiber adhesion and fiber–fiber bonding within fiber bundles. By optimizing resin viscosity and curing conditions in the PIS process, samples treated by PIS achieved improved mechanical properties. Tensile and bending tests revealed significant performance gains over non-PIS treated samples, with tensile stiffness increasing by at least 39% and bending stiffness by 45% in 3K fiber bundles. Tensile samples with thicker fiber bundles (6K and 12K) exhibited similar improvements. On the other hand, while all samples exhibit enhanced mechanical properties under bending deformation, the improvement of flexural stiffness and strength with thicker fiber bundles is shown to be less significant than those with 3K fiber bundles. Overall, composites made with PIS-treated fibers can enhance mechanical performance compared with those made with non-PIS-treated fibers, offering the scaling capability of printing thicker fiber bundles to reduce processing time while maintaining improved properties. It emphasizes the importance of refining the pre-processing strategies of large continuous fiber bundles in the AM process to achieve optimal mechanical properties. Full article