Abstract Fe-based perovskite La0.5Sr0.5FeO3–δ (LSF) is a potential oxygen electrode material for reversible solid oxide cells (R-SOCs) due to low cost and good thermal matching with common electrolytes. However, its catalytic activities for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are insufficient compared with traditional Co-based perovskite. Herein, we propose incorporating chlorine-anions (Cl–) into LSF as the oxygen electrode for R-SOCs, synergistic optimization of lattice defects, electronic structure, and surface chemical properties of Fe-based perovskite, thereby significantly enhancing their ORR and OER catalytic activity. Experimental results combined with density functional theory (DFT) calculations showed that appropriate Cl– doping can increase the LSF unit cell volume and induce local lattice distortion and then significantly reduce oxygen vacancy formation energy (EVo··) and increase oxygen vacancy (Vo··) concentration. DFT calculations confirmed that Cl– doping can reduce the hybridization between Fe 3d and O 2p and weaken the covalency of metal–oxygen bonds (Fe–O), thereby facilitating the formation and redistribution of Vo··. The oxygen surface exchange coefficient (kchem) and bulk diffusion coefficient (Dchem) of La0.5Sr0.5FeO2.95–δCl0.05 (LSFCl0.05) at 750 °C were increased by 3 times and 4 times, respectively. Distribution of relaxation time (DRT) showed that Cl– doping significantly enhances the adsorption and dissociation steps in the ORR process of the LSF oxygen electrode, thereby reducing the polarization impedance. A single cell with a LSFCl0.05 oxygen electrode achieved a maximum power density of 1.493 W·cm–2 in solid oxide fuel cell (SOFC) mode and a high electrolysis current density of 2.306 A·cm–2 in solid oxide electrolysis cell (SOEC) mode at 750 °C, and the performances were improved by 50% and 53%, respectively. Additionally, it demonstrated excellent long-term stability in both two modes and cycle stability between SOFC and SOEC modes. This work significantly enhances the catalytic activities of Fe-based perovskites for ORR/OER, providing a practically feasible avenue for developing high performance oxygen electrode materials for R-SOCs.
Abstract Rare earth elements (REEs) are essential to clean energy and many other technologies, but REE mines are concentrated in a few geographical locations in the world and their broad accessibility is susceptible to trade bottlenecks. Waste streams from mining and other industrial processes containing trace REEs are attractive REE sources for enhancing the supply chain, but their separation from the waste stream remains a key challenge. Metal–organic frameworks (MOFs) offer well-defined, nanoscale pore structures highly conducive to chemical functionalization, allowing the design of organic ligand-modified MOFs with favorable 3D coordination geometries to achieve preferential binding to REEs. In this study, we modified MIL-101 with different loadings of the organophosphonate ligand, phosphonomethyliminodiacetic acid (PMIDA), and investigated their efficacy to recover three trivalent REE cations (Nd3+, Gd3+, and Dy3+) in the absence and presence of a common competing cation, Fe(III). PMIDA-modified MIL-101 maintained the crystalline structure and high specific surface area of MIL-101 and exhibited high-capacity adsorption of all three REEs, up to 195 mg g–1, with a small reduction in capacity in the presence of Fe(III). The REE adsorption exhibited a nonlinear relationship with the PMIDA loading: a higher PMIDA loading led to only a moderate increase in REE adsorption capacity but a notably higher number of available coordination sites per adsorbed REE and hence stronger REE-PMIDA complexes. Molecular dynamics simulations confirmed the formation of polyhedral PMIDA-REE complexes within MIL-101 nanopores, with a higher coordination number and binding energy at a higher PMIDA loading. These results suggest that the PMIDA-modified MIL-101 can provide a coordination environment similar to that found in the solvent extraction process, and careful selection of ligands and the MOF pore structure could enable highly precise separation of target REEs. The adsorbed REE could be eluted using 0.01 mol L–1 HCl, albeit with a nonnegligible loss in adsorption capacity over repeated use.
Abstract It is well-known that when a thin layer of metal is thermally deposited on top of a polymer thin film (particularly a cross-linked elastomer thin film), self-organized wrinkles form due to the thermal stresses generated at the metal polymer interface due to mismatch between the coefficients of thermal expansion of the two individual layers. It has been extensively reported that the wavelength of the wrinkles (λS) varies linearly with the metal film thickness (hM), which is consistent with the linear elastic buckling theory. However, in this paper, we show that in addition to hM, the polymer (bottom) layer thickness (hFP) and the elasticity of the polymer film (vis-à-vis the amount of cross-linker percentage, CL) in the Sylgard 184 film also influence both the wavelength (λS) and amplitude (aS) of the wrinkles, when a thin aluminum (Al) layer is thermally deposited over a spin-coated, fully cross-linked polydimethylsiloxane (PDMS) Sylgard 184 thin film. We show that both λS and aS show nonlinear and nonmonotonic dependence on hFP as well as CL. The work sheds new insight into how the thermal stress-mediated deformation and growth of the instability patterns at the metal–polymer interface are influenced by the presence of a rigid substrate underneath the bottom polymer layer. Based on careful atomic force microscopy, we also capture stress relaxation-mediated partial flattening of the wrinkles in the films with high CL due to stress relaxation. The work unleashes the potential of creating patterns on demand by modulating different parameters of the metal polymer thin bilayer system with possible modulation of wettability and optical properties.
Abstract The therapeutic efficacy of glioma immunotherapy is severely hampered by immunosuppression in the tumor microenvironment. Here, we develop an oxygen‑amplified carrier‑free nanomedicine (IHC NPs) through hydrophobic self‑assembly of IR-820, hemin, and celecoxib. IHC NPs exhibit excellent stability, biological safety, and preferential tumor accumulation. In the subcutaneous glioma model, the combination of IHC NPs and αPD-L1 significantly inhibited subcutaneous tumor growth and effectively prevented distant tumor metastasis. Mechanistically, hemin catalyzes endogenous H2O2 to generate oxygen, thereby alleviating tumor hypoxia. This oxygen boost potentiates IR-820‑mediated photodynamic therapy and hemin-based ferroptosis, enhancing direct tumor cell killing. Concurrently, celecoxib blocks the COX‑2/PGE2 pathway, reversing immunosuppression within the tumor microenvironment. Through the synergistic strategy combining oxygen-sensitized photodynamic therapy, ferroptosis, COX-2/PGE2 suppression, and PD-1/PD-L1 blockade, this therapeutic regimen effectively induces tumor immunogenic cell death, promotes dendritic cell maturation, enhances intratumoral infiltration of cytotoxic T lymphocytes, reduces the abundance of regulatory T cells, and triggers the generation of effector memory T cells, thereby potently activating the host immune system. Collectively, our work provides a promising oxygen‑amplified carrier‑free nanomedicine for robust glioma immunotherapy.
Abstract Highly porous hydrogel scaffolds are critical for advancing three-dimensional printing in tissue engineering. Interconnected porous networks facilitate nutrient diffusion, waste removal, and cell infiltration, necessary processes for tissue regeneration. Emulgel-based inks are developed using oil-in-water Pickering emulsions, in which mineral oil serves as a sacrificial porogen within a carboxymethyl cellulose (CMC)/Laponite matrix, with Laponite providing stabilization of the emulsion. Nine formulations are prepared by varying CMC (0.5-1.0 wt %) and mineral oil (10-20 wt %) concentrations at fixed Laponite (2 wt %). Rheological characterization confirms pronounced shear thinning, appropriate viscoelasticity, and rapid thixotropic recovery, establishing suitability for extrusion-based printing. Post-printing lyophilization and oil removal produce interconnected, homogeneous pore networks, as revealed by scanning electron microscopy (SEM) and micro-computed tomography (micro-CT). Hydrated scaffolds exhibit compressive moduli of 20-30 kPa, overlapping with native soft tissue stiffness. Swelling and degradation analyses confirm structural stability under physiological conditions. Biological assessment using human dental pulp mesenchymal stromal cells (DPMSCs) identifies the 1.0 wt % CMC, Laponite, and 10 wt % oil formulation as optimal, supporting sustained cell proliferation over 28 days following lyophilization and pre-conditioning. This platform provides fabrication advances in 3D-printed hydrogel scaffolds, enhanced porosity, and mechanical properties for soft-tissue engineering and drug delivery applications.
