The 3D printing of functional aerogels, particularly those incorporating additives, represents a transformative approach in materials science, enabling the creation of highly customizable structures with advanced properties. This study introduces a 3D printing methodology for fabricating aerogel structures infused with titanium dioxide (TiO2) nanoparticles, designed to enhance photocatalytic and environmental remediation applications. A commercially available 3D printer was adapted with a custom syringe pump system, allowing precise control over the extrusion of a shear-thinning aerogel ink. The ink formulation, tailored for compatibility with the system, achieved homogeneous dispersion of TiO2 nanoparticles (55-230 nm) within the silica aerogel matrix at 50 wt % relative to silica content. Postprocessing steps, including gelation in ammonia vapor and supercritical CO2 drying, preserved the intricate geometries of printed structures, which achieved a specific surface area of 407 m2/g and a density of 0.15 g/cm3. Rheological analysis demonstrated the ink's suitability for 3D printing, with viscosity decreasing from 10,000 Pa·s to 1 Pa·s under shear, enabling smooth extrusion due to shear thinning behavior, and elastic moduli confirming strong structural integrity necessary for retaining printed shapes. This approach enabled 3D printing of aerogel structures with <1 mm precision. It provides a scalable and cost-effective pathway for producing functional aerogels with tailored properties for potential applications in catalysis, thermal insulation, and environmental remediation.

KUHYTECH: Powering the future of hydrogen technologies KUHyTech (Koç University Hydrogen Technologies Center) is an interdisciplinary research centre advancing hydrogen technologies with projects ranging from fundamental science to industrial applications, supporting Türkiye’s net-zero ambitions through innovations across the hydrogen value chain. KOÇ UNIVERSITY Hydrogen Technologies Center (KUHyTech) is an interdisciplinary centre of excellence established in January 2024 with the support of Koç Group companies and recognised as a Research Centre by the Council of Higher Education in Türkiye (YÖK). The centre contributes to Türkiye’s 2053 net-zero targets by developing technologies on hydrogen production, storage, transportation, and utilisation. Through strong industry collaborations, KUHyTech fosters industry–academia interaction while adopting a holistic research approach that bridges fundamental science and industrial-scale applications. Within the Center, approximately 15 expert faculty members from the departments of Chemical and Biological Engineering, Materials Science and Engineering, Physics, Chemistry, and Mechanical Engineering come together. This structure creates a research ecosystem spanning from fundamental sciences to applied engineering, providing a broad research capacity from molecular-level phenomena to system integration.

This study introduces a new strategy to electrocatalyst synthesis by immobilizing platinum nanoparticles (Pt-NPs) on carbon spherogels-nanoporous, monodisperse carbon hollow spheres with diameters of 170-240 nm and surface areas of up to 800 m2 g-1 with or without incorporated titanium-dioxide (TiO2) sublayers, using supercritical deposition. The resulting materials feature precisely tunable Pt-loadings (2-11 wt%), narrow Pt-NP size distributions, low interparticle distances (4.4-8.2 nm), and high Pt-NP dispersion (Pt-NP mean diameter 2.2-3.5 nm). The presence of TiO2 sublayers enhances both catalytic activity and durability in the hydrogen evolution reaction compared to a commercial Pt/C benchmark with similar Pt content. TiO2 containing electrocatalysts exhibit Pt-NPs in the inner part of spheres and outstanding stability, demonstrated by (a) minimal potential shifts (1-4 mV) after accelerated stability tests, (b) suppression of Pt-NP growth and detachment, and (c) structural integrity retention after 70 h under harsh conditions. These findings highlight the potential of spherogels as advanced catalyst supports and offer a scalable synthesis route without requirement for hazardous templating agents. Thanks to the tunable support morphology, precise Pt-NP deposition, and remarkable long-term performance, this approach emerges as a strong candidate for designing next generation electrocatalysts.

A novel method was developed to synthesize composites of Cu-BTC with alginate. The gelation was triggered by the open Cu metal centers which are coordinated to the BTC ligands. The resulting gel was dried supercritically to obtain the aerogel composite. Cu-BTC content in the composite was tuned in to the mass ratio of 1:2 to 2:1 and the resulting materials' BET surface areas ranged between 450 and 1162 m2/g. The equilibrium uptake of CO2 for AlgA/Cu-BTC (2:1), AlgA/Cu-BTC (1:1), and AlgA/Cu-BTC (1:2) at 1 bar and 298 K was determined as 0.132, 0.325, and 0.434 mmol g-1, respectively for a binary mixture of 15% CO2/85% N2. Uptake values determined by dynamic adsorption experiments were slightly lower than those obtained for single-component CO2 conditions, which was attributed to competitive adsorption between CO2 and N2. The simulated CO2 adsorption isotherms slightly overestimated the experimental uptake values, which is consistent with the involvement of open Cu metal centers in the gelation of sodium alginate. This is the first time that a MOF is utilized as a gelation triggering agent and is likely to lead to the development of novel nanostructured alginate aerogel/gel composites of MOFs with divalent cation centers.

Kraft lignin exhibits significant potential for adhesive applications; however, its valorization in water-based systems remains challenging due to poor dispersion and hydrophobicity. Herein, we report a facile and effective approach for preparing a kraft lignin suspension using cellulose nanocrystals (CNCs). The interactions and structures were investigated using surface analysis, rheology, and optical observations. Oscillation tests reveal that hydrogen-bond-driven gelation of the percolated CNC network is critical for physically stabilizing lignin without chemical modification. Building on this mechanistic understanding, we evaluated the influence of CNC-lignin structures on the curing behavior, thermal stability, and adhesive performance of urea-formaldehyde (UF), the most widely used wood adhesive. The resulting composite exhibited lap-shear strengths of up to 5.2 MPa, demonstrating the potential of CNC-mediated lignin stabilization as a high-performance and sustainable strategy for water-based adhesive formulations.

Green hydrogen production via water electrolysis is a key technology for reaching net-zero CO2 emission targets due to its ability to generate high-purity hydrogen with minimal environmental impact. This study investigates the effect of Co on Pt-based electrocatalysts supported on cellulose-based carbon aerogels (cellulose-CA) using supercritical deposition (SCD) on hydrogen evolution reaction (HER) activity and stability. Pt and Co precursors were deposited onto cellulose-CA via SCD and converted via two routes (ex-situ thermal and chemical) under N-2 and H-2 flow at 1 bar and 200 degrees C. Characterizations (ICP-MS, STEM, XPS, SEM, Raman, and XRD) confirmed successful Pt and Co incorporation and preservation of the cellulose-CA microstructure (overall accessible surface area similar to 2100 - 2700 m(2) g(-1)). The Co-modified electrocatalysts exhibited similar overpotentials at 20 mA/cm(2) despite half the Pt loading, with thermally converted Pt-Co-cellulose-CA showing the lowest overpotential (64 mV) and potential shift (4 mV). Our results demonstrate that Co-modification via SCD enhances the activity and stability of biobased CA electrocatalysts with low Pt content around 2.8 wt%.

Hydrogen internal combustion engines (H2-ICEs) are gaining interest as a route to meet Euro 7 emission standards and carbon neutrality goals. However, their exhaust-rich in water vapor, oxygen, and hydrogen-poses challenges for NOx control. This study evaluates the NH3-SCR performance over a Cu/CHA catalyst under H2-ICE-relevant conditions (H2O:1-20 vol%, O2:1-14 vol%, and H2 0/500 ppm, 150-490 degrees C). NH3-TPD revealed reduced NH3 uptake with increasing water. NH3 oxidation and low-temperature SCR activity declined with higher H2O while high-temperature conversion improved. Above 250 degrees C, NOx conversion exceeded 99% regardless of water concentration at 60,000 h-1 GHSV. Increasing water concentration from 1 to 20 vol% resulted in lower NO conversion but with less transient NH3 inhibition behavior. H2 co-feed affected high-temperature deNOx efficiency but had minimal impact between 150 and 400 degrees C. A kinetic model was developed which captured Standard, Fast SCR and NH3 inhibition behavior under a wide range of water concentrations.

The aim of this study is to investigate the activity and stability of carbon aerogel‐supported platinum electrocatalysts in the hydrogen evolution reaction, compared to current solutions based on carbon black. Self‐synthesized carbon aerogels (pyrolyzed cellulose, and chitosan‐based aerogels) with multiscale porosity and high overall specific surface area (up to ≈2500 m2 g−1), as well as Vulcan XC‐72R supports were loaded via supercritical deposition (SCD) with platinum nanoparticles (mean particle diameter ≈1.3–2.0 nm, 2.8–3.8 wt% Pt loading). Overpotentials ranged from 46.5 to 50.0 mV at 10 mA cm−2, whereas self‐synthesized electrocatalysts had similar overpotentials as compared to a commercial catalyst with ≈8–10 times higher Pt loading. In addition, Pt‐carbon aerogel electrocatalysts had higher stability and durability as compared to Pt‐Vulcan, most probably due to the high micro‐ to mesoporosity of carbon aerogels, which promotes nanoparticle stability. The current density at 40 mV for Pt‐Vulcan decreased by 80% after 20 h, whereas an insignificant drop was observed for Pt‐carbon aerogels. These results show that the applied combination of materials (biopolymer‐based carbon aerogels) and loading method (SCD) are a promising approach for synthesizing stable electrocatalysts with reduced platinum content for green hydrogen production.

Cellulose chains self-assemble at the nanoscale, forming cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs), and cellulose microfibrils (MFCs), which have been widely incorporated into petroleum-derived adhesive formulations to mitigate environmental and health impacts. However, the microstructure-rheology-performance relations of different morphologies need to be elucidated. This study investigated the dispersion, stability, phase behavior, rheology, and curing behavior of urea-formaldehyde (UF) adhesives modified with wood-derived cellulose nanoparticles, including CNCs, CNFs, and MFCs. Our results show that CNC and CNF were homogeneously distributed in the UF solution, whereas MFCs agglomerated due to a higher degree of entanglement. The addition of CNCs to UF resin allowed precise tuning of the flow properties of the composites with filler content, affecting the properties over several orders of magnitude at concentrations as low as a few percent. Composites with low CNC concentrations (1-3 wt%) were homogeneously dispersed in the UF solution, forming a network between negatively charged CNCs and the UF matrix. However, adhesives with higher CNC concentrations (4 and 5 wt%) disrupted the long-range particle network, causing clustering in the UF-CNC mixture and promoting gel formation- an undesirable form for practical applications. These physicochemical characteristics are well reflected in the adhesion behavior characterized by lap-shear tests.

The widespread use of environmentally friendly medium-density fiberboard (MDF) panels as a wood composites is driven by their versatility, affordability, and durability. However, reliance on traditional wood preservatives and modifications raises significant environmental, health, and cost concerns due to harmful chemicals. To address this, we present a one-step nitric acid steam oxidative modification on wood fibers to directly introduce carboxylic acid groups on the surface and eliminate the need for catalysts, organic solvents, or complex multistep procedures often used in traditional methods, such as TEMPO-mediated oxidation. Our multiscale characterization techniques revealed significant changes in the morphology, crystallinity, and surface features of the treated wood fibers, which directly translated to enhanced bulk mechanical properties of the wood composites. Remarkably, the internal bond strength (IBS) of the wood panels increased from 0.27 MPa in untreated panels to 0.89 MPa in panels treated with 5% carboxylated (CA) fibers, suggesting a 3.3-fold enhancement. Additionally, the water uptake of the modified panels was dramatically reduced, with 5% CA-treated panels absorbing only 3.46% compared with 30.38% in unmodified panels, signifying dimensional stability. Furthermore, the curing temperature of the adhesive with CA-treated fibers was lowered by 50 degrees C without reducing composite strength, highlighting significant energy savings. Also, formaldehyde emissions from the 10% CA-modified panels were reduced by 14.82% compared with unmodified panels, aligning with regulatory standards. These findings demonstrate that catalyst-free oxidation enhances adhesive bonding and mechanical performance in wood composites while providing an eco-friendly method for lignocellulosic fiber modification.

Supercritical ion exchange (SCIE) was utilized for site-selective synthesis of copper species on SSZ-13 for selective catalytic reduction (SCR) of NOx with NH3. Changes in SCR rates due to the variation of copper speciation were investigated for Cu-exchanged SSZ-13 (Si/Al=7.5) with different Cu loadings (0.2-1.2 wt.%) by altering synthesis conditions including SCIE temperature (40-80 degrees C) and fluid phase concentration of Cu(tfa)2 precursor. Relative coverages of two different Cu species on 8MR and 6MR of SSZ-13 varied with SCIE conditions. UV-Vis data suggested that the ZCuOH species dominated the Cu speciation as the synthesis temperature increased from 40 degrees C to 80 degrees C whereas Z2Cu species became dominant with increasing fluid phase concentrations of Cu precursor. ATR-FTIR profiles supported the UV-Vis findings. A mechanism for SCIE was proposed considering the temperature dependence of the fractional coverages of ZCuOH and Z2Cu. Catalytic activity assessments in the differential conversion regime showed that SCR rate increased with increasing SCIE temperature from 40 to 80 degrees C at similar Cu loadings. Kinetic data were complemented by NO2-TPD measurements allowing the determination of fractional coverages of ZCuOH and Z2Cu and validated the observations from UV-Vis and FTIR, and was in agreement with H2-TPR, NH3-TPD and FTIR of the NH3 saturated samples. The findings underscore the impact for controlling the nature of active sites via SCIE method for Cu/SSZ-13 synthesis, paving the way for efficient catalyst development in NOx abatement.

Using MOFs in powder form leads to mass transfer limitations and large pressure drops in packed bed adsorbers. Use of MOF/aerogel composites (called MOFACs) in bead form could overcome these challenges without compromising the MOF's adsorption performance, as observed with other shaping methods, such as the use of polymeric binders. In this study, Ca-alginate-aerogel-MIL-160(Al) MOFACs (AlgMIL160) were prepared via sol/gel-assisted direct mixing methods, followed by supercritical drying. The gas sorption, powder X-ray diffraction, FTIR, and scanning electron microscopy characterization results showed that the MOF was successfully incorporated into the aerogel, while the MOF structure was preserved. Adsorption measurements were carried out in both static single-component and dynamic binary gas mixture modes. Obtained isotherms were successfully fitted to the Langmuir model followed by ideal adsorbed solution theory (IAST). The single-component gas adsorption isotherms of CO2 on MOFACs with MIL-160(Al) loadings of 25, 50, and 75 wt % revealed a CO2 uptake of 0.43, 0.70, and 0.98 mmol/g at 150 mbar and 25 °C which were higher than that of pure MOF (1.23 mmol/g) based on the MOF loading in the composites, showing the synergistic effect of aerogel and MOF composites. Incorporation of MIL-160(Al) into the aerogel network which is comprised of 75% MIL-160(Al) and 25% Ca-alginate aerogel enhanced MIL-160(Al)'s CO2/N2 IAST selectivity from 53 to 70 at 25 °C and 1000 mbar. Both experimental and simulated CO2 adsorption isotherms showed good agreement. The dynamic adsorption performance of the MOFACs studied by using a binary mixture of 15% CO2/85% N2 was close to the single-component CO2 adsorption with slightly decreased uptake showing the competitive adsorptions between CO2 and N2 molecules. This novel nanocomposite with remarkable CO2 capture performance can be used in gas adsorbers without causing large pressure drops.

In this study, two different green microalgae, Chlamydomonas nivalis (C. nivalis) and Nannochloropsis gaditana (N. gaditana), were cultivated in open ponds and the harvested wet biomass was converted to bio-crude by hydrothermal liquefaction (HTL) with/without catalyst. Catalytic HTL experiments were performed by using copper -exchanged zeolites including Cu-MOR, Cu-ZSM-5, and Cu-SSZ13, synthesized by recently developed supercritical ion exchange method using scCO2. The composition of all bio-crudes was analyzed by elemental analysis and GC/MS. First, the effects of different operating conditions on the yields of the products and the biocrude composition were determined for non -catalytic process. Temperature, duration, and water/algae biomass ratio in the feed were the process parameters investigated in the ranges of 250-350 degrees C, 10-60 min, and 5-20 wt %, respectively. For C. nivalis, 300 degrees C, 60 min, and water/algae ratio of 4 were the optimum conditions which led to maximum bio-crude yield of 18.8 wt%, while 300 degrees C, 30 min, and water/algae ratio of 9 were the optimum ones for N. gaditana at which the maximum bio-crude yield of 34.0 wt% was observed. Bio-crude yield of N. gaditana was improved using Cu-MOR, while using catalysts for the case of C. nivalis resulted in more gasification with no positive effect on bio-crude yield. Moreover, elemental analysis showed that the fraction of nitrogen and oxygen in biocrude decreased in catalytic HTL runs, in line with the GC/MS results showing that the concentration of hydrocarbons and cyclic compounds increased in the presence of catalysts accompanied by a decrease in concentration of nitrogenous compounds.

In this study, the effect of zeolite type, copper loading, and synthesis method/conditions on the performance of a range of Cu/Zeolites in the Standard Selective Catalytic Reduction (SCR) reaction was investigated via utilizing synthesis methods of Supercritical and Aqueous Ion Exchange (SCIE and AIE). Cu/MORS synthesized via SCIE outperformed the conventionally prepared catalyst, Cu-MORA. Cu/MORS and Cu/ZSM-5 exhibited higher NO conversion than Cu/SSZ-13 at low temperatures due to higher Cu loading. However, Cu/SSZ-13 ones surpassed the other catalysts in terms of NO conversion at temperatures above 450 °C. Selective nature of SCIE under different conditions resulted in an obvious difference between the catalyst’s performance while the SCIE temperature varied from 40 to 80 °C. The results of this study showed that synthesis method/condition affects directly the Cu speciation and catalyst performance in NH3-SCR, calling for developing new synthesis methods of Cu/Zeolites to modify the catalysts performance in after-treatment systems.

Integrated optical devices can provide sophisticated, innovative solutions for handling light in a number of scientific and technological applications ranging from detection and chemical and biological analysis, through imaging to activation of photochemical reactions. Aerogels – with their unusually low refractive index, spectrally tunable optical transparency, possibility of doping the bulk material with chemically active atoms, molecules, and nanoparticles, and relatively low production cost – represent an attractive platform for fabricating integrated photonic circuits. This chapter provides a comprehensive review of the literature on the use of aerogels for a wide range of optical applications. First, we present an overview of the material properties of aerogels that are essential for their optical applications, concentrating, in particular, on the use of aerogels for controlled light guiding. Subsequently, we discuss possible techniques for fabricating channel waveguides in aerogel monoliths and describe in detail methods for making the channel surfaces hydrophobic. We summarize the studies in the literature on the characterization of light propagation in liquid-filled channels formed within aerogel monoliths, as well as on the quantification of light-guiding characteristics of aerogel-based waveguides. We then describe the current and possible future applications of aerogel-based optofluidic waveguides and briefly address the subject of using aerogels for fabricating lightweight optical reflectors. We conclude by a perspective on the emerging directions in the development of aerogel-based optical and photonic components and devices.

Ibuprofen loaded and unloaded alginate aerogel particles were successfully coated with methacrylic acid-ethyl acrylate copolymer in a Wurster fluidized bed. Pores of both aerogels were well-preserved during the coating process. Effects of drug loading, polymer rheology, and atomizing pressure on coating thickness and coating layer surface morphology were investigated. Coatings were conducted at circulatory particle motion regime. Due to low weight of unloaded aerogels, this regime was achieved at lower air flow rates than ibuprofen loaded aer-ogels. Coatings of ibuprofen loaded aerogels were conducted between 1.3 and 1.5 bar atomizing pressures and at 60 degrees C. Unloaded aerogels were coated at a constant and high atomizing pressure of 1.7 bar and at 60 degrees C. At this condition, coating thickness of unloaded aerogels increased linearly from 25.6 mu m to 53.4 mu m with increasing coating time from 10 to 50 min. For ibuprofen loaded aerogels, coating thickness increased non-linearly from 15.9 mu m to 84.1 mu m with increasing coating time from 10 to 180 min. Ibuprofen release from aerogels in acidic medium was prevented via coating. In the basic medium, the fastest release was obtained from uncoated aerogels and 57% of ibuprofen was released in 30 min while 44% of crystalline ibuprofen dissolved at the same time. The slowest release rate was achieved via coating and 13% of the drug was released from coated aerogels in 30 min.

Chemical modifications are widely used to enhance the properties of wood composites and create a strong bonding mechanism for enhancing the dimensional stability, water resistance as well as decreasing carcinogenic formaldehyde emission. Esterification is the most-known modification way to enhance the durability of wood composites, but it does not improve mechanical performance. In this work, we demonstrated a two-step, easy and quick wood surface modification strategy based on microwave heating and UV crosslinking. Firstly, the fiber surface was reacted with methacrylic anhydride, then using methacrylated groups on wood, the fibers are covalently linked. As a proof-of-concept the fibers cross-linked within five minutes under UV radiation using benzophenone solution. Then, the effect of crosslinked wood fiber on the properties of mechanical and swelling of fiberboard were studied. Using SEM, FTIR-ATR, and swelling tests, we investigated the wood-based products' reaction mechanism, morphology, and internal bonding strength. The chemical cross-linking gives stronger bonding, compared to hydrogen bonding, between fibers even in wet conditions, resulting in a cross-linked foam-like structure. Also, wood panels were fabricated, compared to unmodified fibers, the internal bond strength and dimensional stability of fiberboards increased slightly. Overall, these results show that chemical cross-linking of wood fibers can be a fast and promising way to produce multi-functional wood composites.

Transient kinetic models were used to compare different commercial NH3-SCR catalytic monoliths under World Harmonized Transient Cycle (WHTC) conditions for NOx abatement performance, N2O formation and NH3 slip. Towards this goal, kinetic models for four Cu-zeolite, two Vanadia and one Fe-zeolite formulation were developed using experimental data of NH3 adsorption, desorption, NH3 oxidation, NO oxidation, Standard SCR and Fast SCR reactions. Models were in very good agreement with experimental data. Cu and Fe-zeolite formulations showed high deNOx activity with cycle efficiencies > 90% and > 95% respectively, for cold and warm WHTC runs, whereas Vanadia formulations outshined with negligible N2O formation. Simulations were performed to assess the variation of tailpipe NOx as a function of reactor volume. A plateau in deNOx performance was observed for all formulations as a function of the reactor volume which was around 30 and 50 L for cold and warm WTHC runs, respectively. This was found to be due to the decreasing temperature and fractional coverage of adsorbed NH3 along the axial distance of the reactors. Models were also used to develop hybrid reactor in series designs. Successive SCR reactors consisting of different formulations were simulated. The most successful design in terms of high deNOx performance and low N2O formation was with a reactor using a Vanadia catalyst followed by a reactor with Cu-zeolite catalyst. This resulted in a very similar deNOx performance but with a significantly lower N2O emissions as compared to a reactor with the same total volume consisting of Cu-zeolite.