Bimetallic MOF‐derived magnetic/carbon composites have shown great potential as lightweight microwave absorbers, while direct pyrolysis products still suffer from severe particle agglomeration and limited electromagnetic loss. Here, star‐shaped Co/Co 3 O 4 @carbon/graphene composites were fabricated via room‐temperature Co–Zn MOF synthesis followed by high‐temperature pyrolysis with incorporated graphene oxide. Structural characterization confirms that Co/Co 3 O 4 nanoparticles are uniformly anchored on crumpled reduced graphene sheets, fully inheriting the star‐shaped morphology of the parent MOF. Benefiting from the synergistic contribution of magnetic loss, dielectric loss, and conductive loss, the optimal S2 sample delivers a minimum reflection loss of −49.76 dB at a matching thickness of 1.88 mm, with an ultralow filler loading of only 17.5 wt.%. The corresponding effective absorption bandwidth reaches 5.44 GHz (12.56–18.00 GHz) at a matching thickness of 1.77 mm. The performance enhancement introduced by graphene can be attributed to the combined effect of multi‐interface polarization, continuous conductive loss, and optimized impedance matching.
Defect‐engineered TiO 2 photocatalysts are extensively investigated for photocatalytic hydrogen evolution; however, the highly heterogeneous nature of the literature, including inconsistent descriptors, diverse synthesis protocols, nonuniform activity metrics, and incomplete mechanistic reporting, limits the applicability of conventional machine‐learning approaches based solely on statistical regression. Here, we present a literature‐grounded large language model (LLM)‐assisted scientific reasoning framework for defect‐engineered TiO 2 photocatalysts integrating curated literature data, mechanistic rule extraction, and retrieval‐augmented reasoning. A harmonized database was constructed from experimentally relevant publications specifically selected for hydrogen‐evolution‐related defect engineering in TiO 2 , covering polymorph‐dependent behavior, hydrogenation conditions, Ti 3+ defect states, oxygen vacancies, illumination conditions, and photocatalytic activity descriptors. In parallel, mechanistic evidence sentences and literature‐derived, expert‐defined mechanistic rules were encoded into a structured reasoning layer enabling explainable inference beyond black‐box prediction. The resulting framework combines structured experimental descriptors, semantic literature retrieval, and mechanistic interpretation to generate confidence‐aware recommendations for optimal defect‐engineering conditions. For example, the AI agent identified a literature‐supported anatase hydrogenation activity window centered near ~500 °C under H 2 ‐containing atmospheres for approximately 1 h, supported by mechanistic evidence linking balanced Ti 3+ /oxygen‐vacancy populations with enhanced photocatalytic hydrogen evolution.
Integrating perovskite solar cells (PSCs) with supercapacitors (SCs) offers a promising solution for energy conversion and storage in low‐power systems, such as internet of things (IoT) devices. However, these integrated systems can experience SC self‐discharge through the PSC under dark conditions and in absence of external load, thereby reducing the storage capacity. To investigate this self‐discharge mechanism, we use impedance spectroscopy (IS) at different DC bias voltages to evaluate the passive elements of the equivalent electric circuit of (FAPbI 3 ) 0.7 (MAPbBr 3 ) 0.3 PSCs, and carbon‐based SCs, which show a power conversion efficiency of 10.5%, and a capacitance of 0.31 F, respectively. Based on the IS characterization, we propose a model that accounts for the voltage‐dependance of the passive elements in the PSC as the SC discharges. Finally, we conduct a Simulink–Simscape simulation using the experimentally determined parameters to demonstrate the charge loss of the SC during the initial hundred seconds, when its voltage exceeds the PSC’s threshold where the transition from shunt resistance to diode dominated behavior occurs (approximately 0.5 V). Once the SC reaches this voltage, its stored charge is maintained for several hours. These findings provide a predictive framework for optimizing the energy autonomy of next‐generation self‐powered IoT devices.
The structural, electronic, magnetic, elastic, thermodynamic, optical, and thermoelectric properties of Heusler alloy were studied in the XA and ordered phases within the framework of density functional theory. The calculated total energies reveal that the ordered phase is the most stable configuration in the ferromagnetic state under the GGA + U approximation. The total magnetic moments of in both the XA and structures are consistent with the Slater-Pauling relation . Analysis of the density of states and band structure reveals that the phase of the compound exhibits metallic nature in spin-up and spin-down orientations, whereas the XA phase is half-metallic. The results of the elastic-property analysis indicate that both studied phases exhibit elastic anisotropy and satisfy Born's mechanical stability criteria. Furthermore, the thermodynamic properties were evaluated using the quasi-harmonic Debye model implemented in the Gibbs code. The optical properties were investigated in detail through a systematic calculation of the relevant optical parameters. Regarding the thermoelectric behavior of the two phases, the transport coefficients were analyzed over the temperature range of 50-800 K.
The current work emphasizes the importance of a saturated polarization–electric (P–E) field hysteresis loop response for ensuring ferroelectricity in a system. Even the “so called” strong evidences of a phase‐pure tetragonal, high density (>98%), low loss (tan δ < 0.03) BaTiO 3 ceramics with sharp dielectric anomaly versus temperature plots could not show saturated P–E loops. Starting from an industrial grade commercial BaTiO 3 precursor, a single‐step conventional sintering profile yielded worst ferroelectric response, while the two‐step sintered ceramics assured ferroelectricity. This is in sharp contrast to many oxide ceramics where a single‐step sintering profile is generally considered to be good enough for the chosen property/application. Along with different microstructural development, the formation of oxygen vacancy‐related defect complexes (for the single‐step sintered ceramic) was assigned to be the possible reason for promoting extrinsic dielectric contributions which eventually prevented the domain wall mobilities in BaTiO 3 ceramic.
