Saeed Ashtiani

Designing efficient electrocatalysts for industrial-scale seawater splitting that can mitigate anodic corrosion while effectively driving oxygen evolution remains a significant challenge. Strategic surface engineering is crucial in developing electrocatalysts, bridging the gap between fundamental research and the practical demands of industrial water-splitting applications. In this work, we present the development of a CoZnCr@MXene heterostructure, which achieves a low cell voltage of 1.55 V at a current density of 50 mA cm⁻² and outperform RuO₂ in alkaline seawater electrolyte. The remarkable performance is attributed to synergistic enhancements arising from compositional tuning, surface engineering, and the integration of conductive supports, which collectively lead to substantial reductions in overpotentials for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The CoZnCr@MXene catalyst exhibits excellent stability and selective oxidation in alkaline seawater, with MXene incorporation effectively suppresses chloride-induced corrosion while enhancing charge transfer efficiency. Furthermore, when employed in an anion exchange membrane (AEM) electrolyzer, the CoZnCr@MXene catalyst delivers a current density of 500 mA cm⁻² at an operating voltage of 1.72 V at 60 °C, corresponding to a cell efficiency of 77.8%. The calculated hydrogen production cost is $0.86 per gallon of gasoline-equivalent (GGE), significantly below the 2026 technical target of $2.00/GGE set by the U.S. Department of Energy. This work represents a significant breakthrough in the design of long-lasting, noble-metal-free electrodes for industrial-scale alkaline seawater electrolysis.

This study uses glue-assisted exfoliation to obtain 2D Nb ₄ P ₂ S ₂₁ nanoplates, showing promising low-voltage cathode performance and enhanced electrochemical activity in ether-based electrolytes, despite some shuttle effect challenges.

Gas separation matrix membranes (MMMs) benefit from a combination of a polymer matrix and heterogeneous solid or liquid (nano) additives. However, improvements in mechanical strength of membrane permeability or gas selectivity are often overbalanced by morphological deficiencies, such as aggregation or sedimentation of the nanofiller, due to poor control at the nano level. Here, the controlled orthogonal magnetic field deposition of self‐invented spinel Co_0.5Ni_0.5FeCrO₄ magnetic nanoparticles (SMNPs) into the cellulose triacetate (CTA) results in well‐defined gas transport pathways in the membrane and enhances gas separation performances by expanding the effective‐selective surface area. Contrariwise, the structural observation of the fabricated MMMs in the absence of the magnetic field shows precipitation and aggregation of the particles at the bottom of the membrane. The permeability and selectivity of the H₂/CO₂ and O₂/N₂ gas pairs surpass the 2008 and 2015 Robeson upper bounds for the controlled embedding of the SMNPs series (up to 15 wt.%) while the neat CTA or MMM with a random non‐controlled SMNPs distribution exhibits substantially lower permeability and selectivity values. This work contributes to the development of magnetic field casting as a facile technique that advances the gas transport properties of MMMs, efficient for air separation.

Mixed-matrix membranes (MMMs) possess the unique properties and inherent characteristics of their component polymer and inorganic fillers, or other possible types of additives. However, the successful fabrication of compact and defect-free MMMs with a homogeneous filler distribution poses a major challenge, due to poor filler/polymer compatibility. In this study, we use two-dimensional multi-layered Ti₃C₂T_x MXene nanofillers to improve the compatibility and CO₂/CH₄ separation performance of cellulose triacetate (CTA)-based MMMs. CTA-based MMMs with TiO₂-based 1D (nanotubes) and 0D (nanofillers) additives were also fabricated and tested for comparison. The high thermal stability, compact homogeneous structure, and stable long-term CO₂/CH₄ separation performance of the CTA-2D samples suggest the potential application of the membrane in bio/natural gas separation. The best results were obtained for the CTA-2D sample with a loading of 3 wt.%, which exhibited a 5-fold increase in CO₂ permeability and 2-fold increase in CO₂/CH₄ selectivity, compared with the pristine CTA membrane, approaching the state-of-the-art Robeson 2008 upper bound. The dimensional (shape) effect on separation performance was determined as 2D > 1D > 0D. The use of lamellar stacked MXene with abundant surface-terminating groups not only prevents the aggregation of particles but also enhances the CO₂ adsorption properties and provides additional transport channels, resulting in improved CO₂ permeability and CO₂/CH₄ selectivity.

Micro-supercapacitor applications of flexible devices with screen printable MXene sediment inks.

This study explored the underlying synergy between titanium dioxide nanotube (TNT) and carbon nanotube (CNT) hybrid fillers in cellulose triacetate (CTA)-based mixed matrix membranes (MMMs) for natural gas purification. The CNT@TNT hybrid nanofillers were blended with CTA polymer and cast as a thin film by a facile casting technique, after which they were used for single gas separation. The hybrid filler-based membrane depicted a higher CO₂ uptake affinity than the single filler (CNT/TNT)-based membrane. The gas separation results indicate that the hybrid fillers (TNT@CNT) are strongly selective for CO₂ over CH₄ and H₂ over CH₄. The increment in the CO₂/CH₄ and H₂/CH₄ selectivities compared to the pristine CTA membrane was 42.98 from 25.08 and 48.43 from 36.58, respectively. Similarly, the CO₂ and H₂ permeability of the CTA-TNT@CNT membrane increased by six- and five-fold, respectively, compared to the pristine CTA membrane. Such significant improvements in CO₂/CH₄ and H₂/CH₄ separation performance and thermal and mechanical properties suggest a feasible and practical approach for potential biogas upgrading and natural gas purification.

The study of the effects associated with the compatibility of the components of the hybrid filler with polymer matrix, which ultimately decide on achieving mixed matrix membranes (MMMs) with better gas separation properties, is essential. Herein, a facile solution casting process of simple incorporating CeO₂@GO hybrid inorganic filler material is implemented. Significant improvements in material and physico-chemical properties of the synthesized membranes were observed by SEM, XRD, TGA, and stress-strain measurements. Usage of graphene oxide (GO) with polar groups on the surface enabled forming bonds with ceria (CeO₂) nanoparticles and CTA polymer and provided the homogeneous dispersion of the nanofillers in the hybrid MMMs. Moreover, increasing GO loading concentration enhanced both gas permeation in MMMs and CO₂ gas uptakes. The best performance was achieved by the membrane containing 7 wt.% of GO with CO₂ permeability of 10.14 Barrer and CO₂/CH₄ selectivity 50.7. This increase in selectivity is almost fifteen folds higher than the CTA-CeO₂ membrane sample, suggesting the detrimental effect of GO for enhancing the selectivity property of the MMMs. Hence, a favorable synergistic effect of CeO₂@GO hybrid fillers on gas separation performance is observed, propounding the efficient and feasible strategy of using hybrid fillers in the membrane for the potential biogas upgrading process.

Due to the high affinity of ceria (CeO₂) towards carbon dioxide (CO₂) and the high thermal and mechanical properties of cellulose triacetate (CTA) polymer, mixed-matrix CTA-CeO₂ membranes were fabricated. A facile solution-casting method was used for the fabrication process. CeO₂ nanoparticles at concentrations of 0.32, 0.64 and 0.9 wt.% were incorporated into the CTA matrix. The physico-chemical properties of the membranes were evaluated by SEM-EDS, XRD, FTIR, TGA, DSC and strain-stress analysis. Gas sorption and permeation affinity were evaluated using different single gases. The CTA-CeO₂ (0.64) membrane matrix showed a high affinity towards CO₂ sorption. Almost complete saturation of CeO₂ nanoparticles with CO₂ was observed, even at low pressure. Embedding CeO₂ nanoparticles led to increased gas permeability compared to pristine CTA. The highest gas permeabilities were achieved with 0.64 wt.%, with a threefold increase in CO₂ permeability as compared to pristine CTA membranes. Unwanted aggregation of the filler nanoparticles was observed at a 0.9 wt.% concentration of CeO₂ and was reflected in decreased gas permeability compared to lower filler loadings with homogenous filler distributions. The determined gas selectivity was in the order CO₂/CH₄ > CO₂/N₂ > O₂/N₂ > H₂/CO₂ and suggests the potential of CTA-CeO₂ membranes for CO₂ separation in flue/biogas applications.