Search Results (107)

Direct Air Capture (DAC) is emerging as a critical climate change mitigation strategy, offering a pathway to actively remove atmospheric CO₂. This comprehensive review synthesizes advancements in DAC technologies, with a particular emphasis on the pivotal role of nanostructured solid sorbent materials. The work critically evaluates the characteristics, performance, and limitations of key nanomaterial classes, including metal–organic frameworks (MOFs), covalent organic frameworks (COFs), zeolites, amine-functionalized polymers, porous carbons, and layered double hydroxides (LDHs), alongside solid-supported ionic liquids, highlighting their varied CO₂ uptake capacities, regeneration energy requirements, and crucial water sensitivities. Beyond traditional temperature/pressure swing adsorption, the review delves into innovative DAC methodologies such as Moisture Swing Adsorption (MSA), Electro Swing Adsorption (ESA), Passive DAC, and CO₂-Binding Organic Liquids (CO₂ BOLs), detailing their unique mechanisms and potential for reduced energy footprints. Despite significant progress, the widespread deployment of DAC faces formidable challenges, notably high capital and operational costs (currently USD 300–USD 1000/tCO₂), substantial energy demands (1500–2400 kWh/tCO₂), water interference, scalability hurdles, and sorbent degradation. Furthermore, this review comprehensively examines the burgeoning global DAC market, its diverse applications, and the critical socio-economic barriers to adoption, particularly in developing countries. A comparative analysis of DAC within the broader carbon removal landscape (e.g., CCS, BECCS, afforestation) is also provided, alongside an address to the essential, often overlooked, environmental considerations for the sustainable production, regeneration, and disposal of spent nanomaterials, including insights from Life Cycle Assessments. The nuanced techno-economic landscape has been thoroughly summarized, highlighting that commercial viability is a multi-faceted challenge involving material performance, synthesis cost, regeneration energy, scalability, and long-term stability. It has been reiterated that no single ‘best’ material exists, but rather a portfolio of technologies will be necessary, with the ultimate success dependent on system-level integration and the availability of low-carbon energy. The review paper contributes to a holistic understanding of cutting-edge DAC technologies, bridging material science innovations with real-world implementation challenges and opportunities, thereby identifying critical knowledge gaps and pathways toward a net-zero carbon future. Full article

The construction sector presently consumes about 40% of global energy and generates 36% of CO₂ emissions, making facade retrofits a priority for decarbonising buildings. This review clarifies how ventilated facades (VFs), wall assemblies that interpose a ventilated air cavity between outer cladding and the insulated structure, address that challenge. First, the paper categorises VFs by structural configuration, ventilation strategy and functional control into four principal families: double-skin, rainscreen, hybrid/adaptive and active–passive systems, with further extensions such as BIPV, PCM and green-wall integrations that couple energy generation or storage with envelope performance. Heat-transfer analysis shows that the cavity interrupts conductive paths, promotes buoyancy- or wind-driven convection, and curtails radiative exchange. Key design parameters, including cavity depth, vent-area ratio, airflow velocity and surface emissivity, govern this balance, while hybrid ventilation offers the most excellent peak-load mitigation with modest energy input. A synthesis of simulation and field studies indicates that properly detailed VFs reduce envelope cooling loads by 20–55% across diverse climates and cut winter heating demand by 10–20% when vents are seasonally managed or coupled with heat-recovery devices. These thermal benefits translate into steadier interior surface temperatures, lower radiant asymmetry and fewer drafts, thereby expanding the hours occupants remain within comfort bands without mechanical conditioning. Climate-responsive guidance emerges in tropical and arid regions, favouring highly ventilated, low-absorptance cladding; temperate and continental zones gain from adaptive vents, movable insulation or PCM layers; multi-skin adaptive facades promise balanced year-round savings by re-configuring in real time. Overall, the review demonstrates that VFs constitute a versatile, passive-plus platform for low-carbon buildings, simultaneously enhancing energy efficiency, durability and indoor comfort. Future advances in smart controls, bio-based materials and integrated energy-recovery systems are poised to unlock further performance gains and accelerate the sector’s transition to net-zero. Emerging multifunctional materials such as phase-change composites, nanostructured coatings, and perovskite-integrated systems also show promise in enhancing facade adaptability and energy responsiveness. Full article

Electrocatalytic urea oxidation reaction (UOR) is a promising dual-purpose approach for hydrogen production and wastewater treatment, addressing critical energy and environmental challenges. However, conventional anode materials often suffer from limited active sites and high charge transfer resistance, restricting UOR efficiency. To overcome these issues, a novel NiP@PNC/NF electrocatalyst was developed via a one-step thermal annealing process under nitrogen, integrating nickel phosphide (NiP) with phosphorus and nitrogen co-doped carbon nanotubes (PNCs) on a nickel foam (NF) substrate. This design enhances catalytic activity and charge transfer, achieving current densities of 50 mA cm⁻² at 1.34 V and 100 mA cm⁻² at 1.43 V versus the reversible hydrogen electrode (RHE). The electrode’s high electrochemical surface area (235 cm²) and double-layer capacitance (94.1 mF) reflect abundant active sites, far surpassing NiP/NF (48 cm², 15.8 mF) and PNC/NF (39.5 cm², 12.9 mF). It maintains exceptional stability, with only a 16.3% performance loss after 35 h, as confirmed by HR-TEM showing an intact nanostructure. Our single-step annealing technique provides simplicity, scalability, and efficient integration of NiP nanoparticles inside a PNC matrix on nickel foam. This method enables consistent distribution and robust substrate adhesion, which are difficult to attain with multi-step or more intricate techniques. Full article

Electrochemical water splitting is a feasible and effective method for attaining hydrogen, offering a mechanism for renewable energy solutions to combat the world’s energy crises due to the scarcity of fossil fuels. Evidently, the viability and stability of the electrocatalysts are fundamental to the electrochemical water-splitting process. However, the net efficiency of this process is noticeably hindered by the kinetic drawbacks related to the OER. Hence, NiFe LDH has been widely used as a highly efficient OER and HER catalyst material due to its unique nanostructure, tunable composition, and favorable electronic structure. This review offers a systematic analysis of the latest progress in the fabrication of functional NiFe LDH catalysts and associated fabrication strategies, structure optimizations, and performance improvements. Special emphasis is given to understanding the role of nanostructure engineering in increasing active site accessibility, enhancing the effectiveness of subsequent electron transfer, and boosting the intrinsic catalytic activity for HER and OER. Moreover, we discuss the influence of doping, defects, and the formation of heterostructures with other materials on the OER and HER activities of NiFe LDHs. Additional accounts of basic structures and the OER and HER catalytic activities are provided, along with an enhanced theoretical understanding based on DFT studies on the NiFe LDH. Moreover, the limitations and potential developments of the work focus on the need for existing synthesis approaches, the stability of the NiFe LDH catalysts, and their insertion into working electrochemical processes. This review is a comprehensive analysis of the current state of research and developments in the use of NiFe LDH catalysts for the electrochemical water-splitting process to foster improved development of sustainable hydrogen sources in the future. Full article

Attention to electrochemical energy storage (EES) devices continues to grow as the demand increases for energy storage systems in the storage and transmission of renewable energy. The expanded market requirement for mobile electronics devices and flexible electronic devices also calls for efficient energy suppliers. EES devices applying pseudocapacitive materials and generated pseudocapacitive storage are gaining increasing focus because they are capable of overcoming the capacity limitations of electrical double-layer capacitors (EDLCs) and offsetting the rate performance of batteries. The pseudocapacitive storage mechanism generally occurs on the surface or near the surface of the electrode materials, which could avoid the slow ion diffusion process. Developing materials with beneficial nanostructures and optimized phases supporting pseudocapacitive storage would efficiently improve the energy density and charging rate for EES devices, such as batteries and flexible supercapacitors. This review offers a detailed assessment of pseudocapacitance, including classification, working mechanisms, analysis methods, promotion routes and advanced applications. The future challenges facing the effective utilization of pseudocapacitive mechanisms in upcoming energy storage devices are also discussed. Full article

The performance of an orthopedic procedure depends on several tandem functionalities. Such characteristics include materials’ surface properties and subsequent responses. Implant surfaces are typically roughened; this roughness can further be optimized to a specific morphology such as nanotubular roughness (ZrNTs) and the surfaces can further be used as static drug reservoirs. ZrNTs coatings are attracting interest due to their potential to improve the success rate of implant systems, by means of better physical affixation and also micro/nano physio-chemical interaction with the extracellular matrix (ECM). Effective control over the drug release properties from such coatings has been the subject of several published reports. In this study, a novel and simple approach to extending drug release time and limiting the undesirable burst release from zirconia nanotubes (ZrNTs) via structural modification was demonstrated. The latter involved fabricating a double-layered structure with a modulated diameter and was achieved by varying the voltage and time during electrochemical anodization. The structurally modified ZrNTs and their homogenous equivalents were characterized via SEM and ToF-SIMS, and their drug release properties were monitored and compared using UV–Vis spectroscopy. We report a significant reduction in the initial burst release phenomenon and enhanced overall release time. The simple structural modification of ZrNTs can successfully enhance drug release performance, allowing for flexibility in designing drug delivery coatings for specific implant challenges, and offering a new horizon for smart biomaterials based on metal oxide nanostructures. Full article

Traditionally, structural wire is characterized by a homogeneous microstructure, where the average grain size in different parts of the wire is uniform. According to the classical Hall–Petch relationship, a homogeneous polycrystalline metal can be strengthened by decreasing the average grain size since an increase in the volume fraction of grain boundaries will further impede the motion of dislocations. However, a decrease in the grain size inevitably leads to a decrease in the ductility and deformability of the material due to limited dislocation mobility. Putting a gradient microstructure into the wire has promising potential for overcoming the compromise between strength and ductility. This is proposed a new combined technology in this paper in order to obtain a gradient microstructure. This technology consists of deforming the wire in a rotating equal-channel step die and subsequent traditional drawing. Deformation of copper wire with a diameter of 6.5 mm to a diameter of 5.0 mm was carried out in three passes at room temperature. As a result of such processing, a gradient microstructure with a surface nanostructured layer (grain size ~400 nm) with a gradual increase in grain size towards the center of the wire was obtained. As a result, the microhardness in the surface zone was 1150 MPa, 770 Mpa in the neutral zone, and 685 MPa in the central zone of the wire. Such a symmetrical spread of microhardness, observed over the entire cross-section of the rod, is a direct confirmation of the presence of a gradient microstructure in deformed materials. The strength characteristics of the wire were doubled: the tensile strength increased from 335 MPa to 675 MPa, and the yield strength from 230 MPa to 445 MPa. At the same time, the relative elongation decreased from 20% to 16%, and the relative contraction from 28% to 23%. Despite the fact that the ductility of copper is decreased after cyclic deformation, its values remain at a fairly high level. The validity of all results is confirmed by numerous experiments using a complex of traditional and modern research methods, which include optical, scanning, and transmission microscopy; determination of mechanical properties under tension; and measurement of hardness and electrical resistance. These methods allow reliable interpretation of the fine microstructure of the wire and provide information on its strength, plastic, and electrical properties. Full article

Nitrogen oxides are one of the main atmospheric pollutants and pose a threat to the ecological environment and human health. Selective catalytic reduction (NH₃-SCR) is an effective way of removing nitrogen oxides, with the catalyst being the key to this technology. Two-dimensional nanostructured layered double oxide (LDO) has attracted increasing attention due to the controllability of cations in the layers and the exchangeability of anions between layers. As a derivative of layered double hydroxide (LDH), LDO not only inherits the controllability and diversity inherent in the LDH structure but also exhibits excellent performance in the catalytic field. This article contains three main sections. It begins with a brief discussion of the development of LDO catalysts and analyzes the advantages of the LDO structure. The later section introduces the synthesis methods of LDH, clarifies the conversion relationship between LDH and LDO, and summarizes the modification impacts of the properties of LDO catalysts. The application of LDO catalysts used in NH₃-SCR under wild temperature conditions is discussed, and the different types, reaction processes, and mechanisms of LDO catalysts are described in the third section. Finally, future research directions and outlooks are also offered to assist the development of LDO catalysts and overcome the difficult points related to NH₃-SCR. Full article

Water splitting is an important approach to hydrogen production. But the efficiency of the process is always controlled by the oxygen evolution reaction process. In this study, a three-dimensional nickel–molybdenum binary nanoarray microstructure electrocatalyst is successfully synthesized. It is grown uniformly on Ni foam using a hydrothermal method. Attributed to their unique nanostructure and controllable nature, the Ni-Mo-based nanoarray samples show superior reactivity and durability in oxygen evolution reactions. The series of Ni-Mo-based electrocatalysts presents a competitive overpotential of 296 mV at 10 mA·cm⁻² for an OER in 1.0 M KOH, corresponding with a low Tafel slope of 121 mV dec⁻¹. The three-dimensional nanostructure has a large double-layer capacitance and plenty of channels for ion transfer, which demonstrates more active sites and improved charge transmission. This study provides a valuable reference for the development of non-precious catalysts for water splitting. Full article

Ni-based catalysts have been widely used for the CO₂ reforming of methane (CRM) process, but deactivation is their main problem. This study created an alternative electronic Ni-NiO-CeO₂ interaction on the surface of 5 wt% Ni-5 wt% CeO₂/Al₂O₃-MgO (5Ni5Ce(xh)/MA) catalysts to enhance catalytic potential simultaneously with coke resistance for the CRM process. The Ni-NiO-CeO₂ network was developed on Al₂O₃-MgO through layered double hydroxide synthesis via our ammonia vapor diffusion impregnation method. The physical properties of the fresh catalysts were analyzed employing FESEM, N₂ physisorption, and XRD. The chemical properties on the catalyst surface were analyzed employing H₂-TPR, XPS, H₂-TPD, CO₂-TPD, and O₂-TPD. The CRM performances of reduced catalysts were evaluated at 600 °C under ambient pressure. Carbon deposits on spent catalysts were determined quantitatively and qualitatively by TPO, FESEM, and XRD. Compared to 5 wt% Ni-5 wt% CeO₂/Al₂O₃-MgO prepared by the traditional impregnation method, the electronic interaction of the Ni-NiO-CeO₂ network with the Al₂O₃-MgO support was constructed along the time of ammonia diffusion treatment. The electronic interaction in the Ni-NiO-CeO₂ nanostructure of the treated catalyst develops surface hydroxyl sites with an efficient pathway of OH* and O* transfer that improves catalytic activities and coke oxidation. Full article

The organization of modifiable and functional building components into various superstructures is of great interest due to their broad applications. Supramolecular self-assembly, based on rationally designed building blocks and appropriately utilized driving forces, is a promising and widely used strategy for constructing superstructures with well-defined nanostructures and diverse morphologies across multiple length scales. In this study, two homogeneous organohydrogels with distinct appearances were constructed by simply mixing polyoxometalate (phosphomolybdic acid, HPMo) and a double-tailed zwitterionic quaternary ammonium amphiphile in a binary solvent of water and dimethyl sulfoxide (DMSO). The delicate balance between electrostatic attraction and repulsion of anionic HPMo clusters and zwitterionic structures drove them to co-assemble into homogeneous organohydrogels with diverse microstructures. Notably, the morphologies of the organohydrogels, including unilamellar vesicles, onion-like vesicles, and spherical aggregates, can be controlled by adjusting the ionic interactions between the zwitterionic amphiphiles and phosphomolybdic acid clusters. Furthermore, we observed an organohydrogel fabricated with densely stacked onion-like structures (multilamellar vesicles) consisting of more than a dozen layers at certain proportions. Additionally, the relationships between the self-assembled architectures and the intermolecular interactions among the polyoxometalate, zwitterionic amphiphile, and solvent molecules were elucidated. This study offers valuable insights into the mechanisms of polyoxometalate-zwitterionic amphiphile co-assembly, which are essential for the development of materials with specific structures and emerging functionalities. Full article

A nanoparticle-anchored three-dimensional microsphere flower-structured layered double hydroxide (LDH) material with Fe₃O₄ particles was successfully prepared using simple hydrothermal and hot solvent methods. Micro-nanostructured Fe₃O₄@LDHs (SLF) composites balance microwave absorption, corrosion protection, and UV aging resistance. The minimum reflection loss value of SLF is −35.75 dB at 14.16 GHz, when the absorber thickness is 8 mm, and the absorption bandwidth at this frequency is up to 2.56 GHz for RL values less than −10 dB, while the LL is only 1 GHz. The SLF /EP coating has not only excellent microwave absorption performance but also excellent corrosion and UV aging resistance performance. The coating still has some anti-corrosion effect after 10 d of immersion. This work is intended as a reference for the development of new coatings with excellent microwave absorption properties as well as corrosion and UV aging resistance for wind turbine tower barrels (seaside wind power generation equipment) surfaces. Full article

The technology of obtaining porous nanostructures is based on ecological organosilicon materials and their uses in some spheres of human life, for example, for medical preparations, for thermal insulation of building structures and industrial equipment, and for cleaning. The purpose of this study was to establish correlations between various experimental parameters (shear stress, speed pulsations, temperature, viscosity, and processing time) and the rheological characteristics of suspensions obtained by the method of liquid-phase dispersion; it was a study of hydrodynamic effects and the processes of heat and mass exchange in liquid systems during the liquid-phase dispersion of hydrogel monoliths by means of discrete-pulse activation in a special rotary apparatus. The dehydration of hydrogels was carried out by two methods: convective drying in a layer and spraying in the coolant flow. Experiments have shown that the key parameters for obtaining stable homogeneous suspensions are a synergistic combination of concentration factors and processing time. To obtain adsorbents in the form of pastes with specified adsorption properties and a monolith size of up to 300 μm, the optimal parameters were a hydrogel concentration of 70% and a processing time in the double-recirculation mode. Xerogels obtained by convective drying are a polydisperse mixture of strong monoliths and fragile aggregates. In contrast, xerogel monoliths obtained by spray drying show great homogeneity in terms of dispersion and strength characteristics. The rheological parameters of the hydrogel dispersions, which depend on the concentration and hydrodynamic treatment modes, are the dominant factors affecting the moisture extraction during drying. This study marks the first investigation into the resilience of porous organosilicon structures against the influence of intense turbulence fields and mechanical stresses experienced within the rotor apparatus during suspension production. Full article

Boosting the harmonic generation of light in nanostructures through efficiently enhancing the light–matter interaction has received enormous attention and applications. Low-index dielectric nanoparticles, as one of the crucial members of nanophotonics, have not been successful in nonlinear enhancement due to weak Mie resonance and poor light confinement. Here, we designed efficient third harmonic generation (THG) in low-index dielectric nanopillars sandwiched by double layers of metal dressing (Au/polymer/Au), where the polymer offers essential nonlinear susceptibility. The resonance of the low-index nanopillars significantly enhanced the scattering and had a strong magnetic response that could boost the THG effect. We predict that the THG efficiency reaches up to 3 × 10⁻⁶ (six orders of enhancement) at a third harmonic wavelength of 300 nm. The efficient THG in low-index dielectric nanopillars may open the possibility for the development of a new type of efficient nonlinear coherent source. Full article

Two-dimensional (2D) nanolayered and nanohybrid structures, which are composed of different species of organic anions and multi-valence inorganic cations, are considered favorable in the field of energy storage for use as supercapacitors. In this study, host–guest interactions were used to build a series of these nanohybrids. The host was the layered double hydroxides of vanadium–cobalt (V/Co) nanolayers with different molar ratios. Cyanate was used as a guest to design a V/Co supercapacitor with a 2D-nanolayered structure. In addition, oxalate was used as a new additive to improve the performance of the V/Co supercapacitor. X-ray diffraction, infrared spectroscopy, thermal analyses, and scanning electron microscopy confirmed the formation of the nanolayered structures of cyanate-V/Co. In the case of the oxalate-V/Co nanostructures, a new phase of cobalt oxalate was produced and combined with the nanolayered structure to build a 3D porous structure. A three-assembly electrode system was used to study the electrochemical supercapacitive behavior of the cyanate-V/Co and oxalate-V/Co nanolayered structures. The results indicated that the OXVC-20 electrode possessed the highest specific capacitance as compared to that of the OXVC-16 and CNOVC electrodes. An excellent stability performance of up to 91% after various charge–discharge cycles was detected for the optimum case. Because of the positive effect of oxalate on the supercapacitance performance of the V/Co supercapacitor, it is suggested as a new track for building active electrodes for high-performance supercapacitor applications. Full article