Abstract Bismuth telluride (Bi 2 Te 3 ) is a leading material for flexible thermoelectric films, making it suited for low‐grade energy harvesting and sensing applications in wearable devices. However, the performance of Bi 2 Te 3 films suffers from low mobility, a consequence of their small grain size and lack of preferred crystal orientation. Here, we demonstrate that a two‐step annealing process combining in situ and post‐annealing heat treatment can significantly enhance the thermoelectric properties of n‐type Bi 2 Te 3 films prepared by magnetron sputtering. This method promotes pronounced grain growth and strengthens the preferred ( 00l ) crystal texture, increasing charge carrier mobility from 2.84 cm 2 V −1 s −1 to 132.54 cm 2 V −1 s −1 . Meanwhile, the two‐step annealing introduces Bi Te antisite defects, which optimizes the carrier concentration to 1.29 × 10 19 cm −3 . The combination of the tailored carrier concentration and exceptionally high mobility produces a room‐temperature power factor of 14.5 μW cm −1 K −2 in the fabricated Bi 2 Te 3 ‐based films, with a high power density of 545.66 μW cm −2 at a temperature difference of 30 K. A minimal electrical variation (<7%) during the bending test demonstrates the excellent bending resistance and stability of the flexible Bi 2 Te 3 films. This study demonstrates that the two‐step annealing process is an effective method to improve the mobility and performance of Bi 2 Te 3 ‐based films.

Sulfur dioxide (SO2) capture is of critical importance for environmental protection and sustainable sulfur resource cycling. This process demands sorbents that exhibit high SO2 capacity, precise molecular recognition, and robust tolerance under extreme conditions. Here, we report a sp2 carbon-conjugated covalent organic framework engineered with densely aligned and ordered pyridazine groups (DpTb-COF). This design enables efficient SO2 capture, achieving an ultrahigh capacity of 19.4 mmol/g (25 °C, 1.0 bar) and exhibiting precise selectivity gradients (SO2/H2S = 11.3, SO2/COS = 13.1, SO2/CO2 = 55.3, SO2/N2 = 730.1, 0.1/0.9=v/v). Its exceptional stability is evidenced by negligible performance loss over 50 adsorption-desorption cycles. This enhanced performance is achieved by strategically anchoring pyridazine motifs into the highly conjugated DpTb-COF framework. Unlike their non-conjugated counterparts, DpTb-COF's planar conjugated structure promotes framework electron delocalization, which synergistically enhances SO2 affinity via enriched π-electron density while weakening interaction with CO2 due to reduced basicity. Furthermore, DpTb-COF exhibits remarkable resilience against humidity and corrosive conditions, maintaining its structural integrity and performance. The captured SO2 can be efficiently transformed into cyclic sulfites over the Cu1@DpTb-COF catalyst. This work thereby establishes a rational design strategy for high-performance multifunctional materials that enable both capture and upcycling of acid gases.

The strong acidity of Brønsted acid sites in zeolites often leads to uncontrollable reactions and rapid deactivation. Therefore, strategically weakening zeolite acidity is essential for balancing reactivity with stability. The local coordination environment of framework aluminum usually governs its acidity. Hydroxylation of framework aluminum is often inevitable under high-temperature and humid "working" conditions; however, the impact of hydroxyl coordination on the relevant acidity and catalytic behavior remains unclear. Here, we demonstrate how hydroxylation of framework aluminum strategically moderates acidity and enhances catalytic stability. Density functional theory (DFT) calculations predict that an increase in the hydroxyl groups coordinated to framework aluminum leads to a progressive weakening of Brønsted acidity. We experimentally validate this prediction by precisely manipulating hydroxylation in ZSM-5 zeolite via steaming treatment and analyzing the effects using 2D NMR spectroscopy with 2-13C-acetone as a probe molecule. The hydroxylated aluminum sites exhibit reduced adsorption and activation of methanol in the dehydration reaction, consistent with their weaker acidity. Catalytic tests reveal that the hydroxylated samples significantly enhance catalyst lifespan in the MTO process, while preserving stable reactivity. These findings provide key insights into how coordination perturbations influence zeolite acidity and catalytic performance, offering valuable guidance for designing zeolites with targeted catalytic functions.

ABSTRACT Flexible thermoelectrics convert body heat into electricity, offering a promising route towards self‐powered wearable electronics while overcoming the limitations of conventional batteries. Among emerging flexible thermoelectric materials, silver selenide (Ag 2 Se) has attracted widespread attention because it combines outstanding near‐room‐temperature thermoelectric performance with low cost, excellent mechanical flexibility, and superior biocompatibility. Over the past five years, orientation engineering has emerged as an effective strategy for simultaneously enhancing carrier transport and suppressing carrier scattering, leading to remarkable improvements in both material properties and device performance. In this Perspective, we systematically review recent progress in highly oriented Ag 2 Se films, including deposited, nanowire‐based, selenized, and free‐standing architectures. We further propose film thickness together with near‐room‐temperature power factor as practical metrics for benchmarking their application potential. By correlating fabrication strategies, microstructural evolution, crystallographic orientation, and thermoelectric performance, we establish a unified framework for understanding orientation‐dependent charge transport in Ag 2 Se films. Finally, we discuss the remaining scientific and technological challenges and highlight future opportunities for developing scalable, mechanically robust, and high‐performance Ag 2 Se films for next‐generation wearable thermoelectric energy harvesters and self‐powered physiological monitoring systems.

ABSTRACT Thermoelectric performance of GeTe across broad temperature ranges is fundamentally constrained by its temperature‐dependent optimization of carrier concentration, where traditional static doping cannot satisfy. Here, we present a dynamic doping strategy that can harness temperature‐driven Cu migration to achieve temperature‐dependent carrier optimization. At low temperatures, Cu preferentially occupies interstitial sites, effectively suppressing excessive intrinsic carrier concentrations. With increasing temperature, Cu migrates to cationic substitutional sites, acting as acceptor‐like dopants. This adaptive behavior maintains the carrier concentration within the optimal range at both low and high temperatures while introducing localized lattice strains that suppress the lattice thermal conductivity approaching the amorphous limit. Consequently, a peak figure of merit ( ZT ) reaching ∼2.4 at 673 K and an average ZT of ∼1.6 across 300–773 K are achieved. A four‐legged module is constructed and achieves a power density of ∼5.9 KW m −2 with a temperature gradient of ∼360 K. This study establishes adaptive carrier regulation via dynamic doping as a key mechanism for achieving high thermoelectric performance across a wide temperature range.

With the advantages of material-saving shapable production and facile geometry design, shapable methods provide a broad prospect for the future thermoelectric material production. Herein, cold spraying followed by annealing (CSA) induces enriched defects in the bulk material, which can lead to excellent thermoelectric performance and hardness. Compared with the HP process, CSA contributes to more pores and intrinsic defects. The enriched intrinsic defects contribute to moderate electrical performance. Simultaneously, these defects strongly scatter phonons, leading to ultra-low total thermal conductivity values of similar to 0.64 W m-1 K-1 for both p-type CSA Bi0.5 Sb1.5 Te3 and n-type CSA Bi2 Te2.7 Se0.3 bulks at room temperature. Correspondingly, CSA bulks possess excellent room-temperature zT of similar to 1.1 (p-type Bi0.5 Sb1.5 Te3 ) and similar to 0.9 (n-type Bi2 Te2.7 Se0.3 ), respectively, which are comparable to those prepared by HP and other shapable methods. Furthermore, a four-leg thermoelectric device is assembled based on as-prepared ptype CSA Bi0.5 Sb1.5 Te3 and n-type CSA Bi2 Te2.7 Se0.3 bulks, achieving a rational energy conversion efficiency of similar to 4% under a small temperature difference of 100 K. This study demonstrates CSA method is promising for future shapable production of high-performance thermoelectric materials. (c) 2026 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Thermoelectric technology provides a sustainable solution for harvesting waste heat. High-efficiency waste heat recovery demands high figure of merit (ZT) materials, which are limited by intrinsic carrier and phonon coupling. Here, we introduce VSe2 nanowire precipitates to construct selective interfacial barriers for effective decoupling. Specifically, the electron transport is optimized by the synergistic effects of the minimization of the Fermi level mismatch between the VSe2 and GeTe, and a substantial reduction of interface state density via semi-coherent interfaces. Concurrently, the significant phonon frequency mismatch at interfacial barriers effectively suppresses phonon transport. This approach yields a high ZT of 2.7 at 773 K, and record-high average ZT of 1.9 across 300-773 K in the (Ge0.82Mn0.04Bi0.04Pb0.1Te)0.99(VSe2)0.01. The corresponding π-type module exhibits a conversion efficiency of 11.4% under a 440 K temperature difference. This work highlights the potential of selective interfacial barriers for advancing thermoelectrics and energy-harvesting applications.

Ag2S-based thermoelectric materials hold significant promise for wearable energy harvesting owing to their high Seebeck coefficient near room temperature and excellent mechanical flexibility. However, their intrinsically low carrier concentration results in poor baseline electrical performance. Therefore, enhancing the electrical and, consequently, thermoelectric properties of Ag2S while preserving its superior plasticity is particularly crucial. In this work, the electrical properties of Ag2S were tuned through Te doping and further optimized by introducing Al at the cationic sites. First-principles calculations reveal that Al doping narrows the bandgap and induces a transition from an indirect to a direct bandgap, thereby increasing carrier concentration and electrical conductivity and leading to a higher power factor. Additionally, Al doping introduces point defects, and precise control over the Al content results in the formation of moderately intensive segregated secondary phases in Ag1.995-xAlxTe0.5S0.5, which effectively suppresses thermal conductivity. As a result, when x = 0.005, a room-temperature ZT of approximately 0.34 is achieved, with a peak ZT of about 0.83 at 671 K. Furthermore, at x = 0.003, the bending strain exceeds 25 %, highlighting the excellent flexibility of the material. A flexible device fabricated using Ag1.99Al0.005Te0.5S0.5 delivers an output power of approximately 1.4 mu W at a temperature difference of 15 K, underscoring its strong potential for next-generation wearable thermoelectric applications.

Bismuth telluride (Bi2Te3) is a leading material for flexible thermoelectric films, making it suited for low-grade energy harvesting and sensing applications in wearable devices. However, the performance of Bi2Te3 films suffers from low mobility, a consequence of their small grain size and lack of preferred crystal orientation. Here, we demonstrate that a two-step annealing process combining in situ and post-annealing heat treatment can significantly enhance the thermoelectric properties of n-type Bi2Te3 films prepared by magnetron sputtering. This method promotes pronounced grain growth and strengthens the preferred (00l) crystal texture, increasing charge carrier mobility from 2.84 cm(2) V-1 s(-1) to 132.54 cm(2) V-1 s(-1). Meanwhile, the two-step annealing introduces Bi-Te antisite defects, which optimizes the carrier concentration to 1.29 & times; 10(19) cm(-3). The combination of the tailored carrier concentration and exceptionally high mobility produces a room-temperature power factor of 14.5 mu W cm(-1) K-2 in the fabricated Bi2Te3-based films, with a high power density of 545.66 mu W cm(-2) at a temperature difference of 30 K. A minimal electrical variation (<7%) during the bending test demonstrates the excellent bending resistance and stability of the flexible Bi2Te3 films. This study demonstrates that the two-step annealing process is an effective method to improve the mobility and performance of Bi2Te3-based films.

Carbon-based microwave absorption (MA) materials remain constrained by complex synthesis, toxic precursors and narrow absorption bandwidth. Inspired by the decomposition behavior of carbonates, we report a simple and green in situ gas-foaming strategy to fabricate lychee-like nitrogen-doped hollow carbon spheres (NHCS). MnCO3 is employed as an in situ foaming agent, releasing CO2 during carbonization to generate hierarchical porosity without secondary chemical etching. The resulting hollow architectures can optimize impedance matching, intensify interfacial polarization at the wrinkled surfaces, and thus promote multiple electromagnetic scattering within the internal cavities. Consequently, these NHCS exhibit a strong reflection loss of -51.07 dB and an effective absorption bandwidth (EAB) of 5.92 GHz at a low filler loading of 8 wt%. To overcome the intrinsic bandwidth limits of particulate absorbers, a honeycomb structure was further developed, realizing an ultra-wide EAB of 14.83 GHz. This work establishes a green, template-engineering pathway for microstructure design and offers a viable route toward high-performance MA materials.

ABSTRACT Ag 2 Se‐based thermoelectric thin films are attractive for near‐room‐temperature energy harvesting, yet suffer from severe non‐stoichiometry (Ag/Se > 2:1) due to Se vacancies, which induce excessive carrier concentration and degrade thermoelectric performance. Here we overcome this limitation through stoichiometry engineering by using a combined liquid‐phase etching, physical exfoliation, and Se vapour annealing strategy. Such an approach suppresses vacancy formation while preserving high crystallinity, enabling optimized carrier concentration and reduced thermal transport. The resulting films exhibit a high power factor of ∼32.2 µW cm −1 K −2 at 398 K and a competitive thermoelectric figure of merit ( ZT ) of ∼1.1 at 300 K. A five‐leg flexible device delivers a normalized power density of ∼4.2 µW cm −2 K −2 and maintains > 97% performance after 1000 bending cycles (4 mm radius). These results highlight stoichiometry control as an effective strategy for enhancing the performance and durability of flexible thermoelectric devices.

Thermoelectric performance is constrained by the coupling of phonon and carrier transport, which imposes a compromise between carrier mobility and lattice thermal conductivity. Here, we introduce a universal strategy of alkali-metal (Na, K, Cs) doping for decoupling phonon and carrier transport in multiple IV-VI compounds (including both n-type PbTe and p-type GeTe, SnTe, and TAGS), achieving highly competitive thermoelectric performance. For instance, Cs doping enables TAGS to attain a record-high peak ZT of similar to 2.1 at 723 K and an average ZT ave of similar to 1.53 from 300 to 723 K. Thermally, the larger alkali-metal atoms induce more intense strain fields to enhance phonon scattering, while their heavy atomic mass softens phonon modes to reduce phonon group velocity. Electrically, the isovalent nature of alkali-metal atoms minimizes ionized impurity scattering, thus preserving carrier transport. A thermoelectric module composed of optimized p-type GeTe and n-type PbTe achieves a conversion efficiency of similar to 9.0% and a power density of 0.86 W cm-2 under a temperature difference of similar to 370 K. This work establishes a general design principle for decoupling phonon and carrier transport in mid-temperature thermoelectric systems.

Nanoprecipitate engineering is an effective strategy to enhance the thermoelectric performance of Bi2-xSbxTe3-based materials by increasing phonon scattering and decreasing lattice thermal conductivity. However, dense incoherent interfaces also intensify carrier scattering that limits overall performance improvement. In this study, we demonstrate that Pb doping induces semi-coherent interfaces to significantly enhance the thermoelectric performance of Bi0.4Sb1.6Te3 through synergistic transport optimization. Pb doping lowers the formation energy of Sb vacancies, thereby promoting the formation of Sb nanoprecipitates with semi-coherent interfaces. These interfaces suppress carrier scattering, resulting in a high weighted mobility of 544 cm2 V-1 s-1 and a power factor of 48 μW cm-1 K-2 at room temperature. Meanwhile, Sb nanoprecipitates effectively scatter phonons, leading to a low lattice thermal conductivity of 0.51 W m-1 K-1 at 460 K. Owing to these combined effects, the maximum figure-of-merit (ZT) increases from 0.81 for pristine Bi0.4Sb1.6Te3 to 1.06 for Bi0.4Sb1.594Pb0.006Te3 at 460 K, with a peak conversion efficiency of ∼5.5% at a temperature difference of 200 K. This work demonstrates that introducing semi-coherent interfaces is an effective method to enhance the performance of Bi2-xSbxTe3-based materials.

Flexible thermoelectrics convert body heat into electricity, offering a promising route towards self-powered wearable electronics while overcoming the limitations of conventional batteries. Among emerging flexible thermoelectric materials, silver selenide (Ag2Se) has attracted widespread attention because it combines outstanding near-room-temperature thermoelectric performance with low cost, excellent mechanical flexibility, and superior biocompatibility. Over the past five years, orientation engineering has emerged as an effective strategy for simultaneously enhancing carrier transport and suppressing carrier scattering, leading to remarkable improvements in both material properties and device performance. In this Perspective, we systematically review recent progress in highly oriented Ag2Se films, including deposited, nanowire-based, selenized, and free-standing architectures. We further propose film thickness together with near-room-temperature power factor as practical metrics for benchmarking their application potential. By correlating fabrication strategies, microstructural evolution, crystallographic orientation, and thermoelectric performance, we establish a unified framework for understanding orientation-dependent charge transport in Ag2Se films. Finally, we discuss the remaining scientific and technological challenges and highlight future opportunities for developing scalable, mechanically robust, and high-performance Ag2Se films for next-generation wearable thermoelectric energy harvesters and self-powered physiological monitoring systems.

Catalytic conversion of acid waste gases into value-added chemicals is crucial for sustainable carbon and sulfur utilization, and designing efficient and stable catalysts shows great significance in achieving this goal. Herein, we report an olefin-linked, bipyridine-functionalized COF with atomically dispersed Cu active sites (xCu@COF-PzBpy) that combines high specific surface area, robust stability, and an asymmetric Cu-N4 coordination geometry induced by the interlayer stress effect. The newly engineered Cu-N4 active centers demonstrate enhanced activation capability for both acid gases and epoxides, endowing xCu@COF-PzBpy with an exceptional catalytic performance for their upcycling under ambient conditions. This performance outperforms nearly all previously reported catalysts. Similarly, the high catalytic activities of xCu@COF-PzBpy can be extended to the COS and SO2 cycloaddition. No activity loss, Cu leaching, and/or aggregation were observed over 10 cycles. This work provides a new strategy for developing efficient and reusable catalysts for acid waste gas upcycling, addressing environmental challenges while enabling green and sustainable cycles.

Translation and rotation are the two most fundamental forms of diffusion, yet their coupling mechanism is not clear, especially under confinement. Here, we provided evidence of the coupling between rotation and translation using a substituted benzene molecule as an example. A counterintuitive behavior was observed where the movement of the smaller molecule with an asymmetric shape was unexpectedly slower than the larger one with a symmetric shape in confined channels of zeolite. We showed that this diffusion behavior was caused by the presence of the specific and selective interaction of the asymmetric guest with the pores, which increased the local restricted residence time, thus inhibiting the translation under confinement, as further confirmed by dynamic breakthrough curves, uptake measurements, quasi-elastic neutron scattering, and 2H solid-state NMR techniques. Our work correlated asymmetric rotation and diffusion under a confined environment, which enriched our understanding of the coupling between rotation and translation and could shed light on a fundamental understanding of the diffusion process.

Compared to methanol, dimethyl ether (DME) is a more ideal and attractive raw material for industrial applications. Typically, the industrially zeolite-catalyzed methanol dehydration to DME occurs at temperatures above 423 kelvin. Improving catalytic reactivity and reducing energy consumption are urgently needed but remain challenging. Here, we report an unexplored associative strategy to realize DME formation at room temperature and the generation of olefins even at 413 kelvin, which is achieved by coinjecting basic acetone to manipulate the local chemical microenvironment of the methanol reactant inside the H-ZSM-5 zeolite. The crucial role of acetone in accelerating methanol direct dehydration to DME is highlighted as the obvious destabilization effect for the adsorbed methanol cluster with strong hydrogen bonds and the subsequent traction of water during DME formation. These findings offer more insights into the rational design of reaction systems by manipulating the local surroundings to regulate catalytic performances and should represent a large step forward in methanol conversion technology.

The debate over the optimal orientation of Ag2Se thin films and its influence on thermoelectric performance remains ongoing. Here, we report a wet-chemical selenization-based anisotropy optimization technique to control the in-plane orientation of the Ag2Se thin film, steering it away from (002) nearly parallel planes that hinder charge carrier mobility. This approach enables us to achieve an impressive power factor of 30.8 μW cm−1 K−2 at 343 K. The as-fabricated Ag2Se thin film demonstrates remarkable durability, retaining over 90% of its power factor after six months of air exposure, and outstanding flexibility, with performance variation staying within 5% after 2000 bending cycles at a 5 mm radius. These attributes are attributed to the controlled film thickness, crystallinity, and strong adhesion to the polyimide substrate. Additionally, the as-assembled slotted thermoelectric device delivers an output power of 0.58 μW and a competitive power density of 807 μW cm−2 at a temperature difference of 20 K, alongside a high normalized power density of 1.8 μW cm−2 K−2, highlighting its potential for practical application. This study provides valuable insights into the design of high-performance, highly flexible thermoelectric thin films for real-world applications. The authors report a wet-chemical selenization-based anisotropy optimization to control the orientation of the Ag2Se thin film, achieving a power factor of 30.8 μW cm−1 K−2 in the thin film and a normalized power density of 1.8 μW cm−2 K−2 in the device.

Conductive polymers, particularly poly(3,4-ethylenedioxythiophene):(styrene sulfonate) (PEDOT:PSS), are gaining significant attention in flexible thermoelectrics due to their excellent flexibility, low thermal conductivity, and structural stability. However, the electrical conductivity of pristine PEDOT:PSS (below 1 S cm(-1)) limits its power factor. Although polar solvent doping can enhance electrical conductivity, such methods often require complex acid-based post-treatments, compromising material stability and safety. Here, we report highly conductive graphene quantum dot (GQDs)-incorporated PEDOT:PSS films, fabricated via a solvent-free process. The incorporation of trace amounts of GQDs into the PSS and PEDOT matrix enhances the pi-pi conjugation within the PEDOT matrix, achieving a electrical conductivity of 3027 S cm(-1) and a power factor of up to 207.8 mu W m(-1) K-2 at room temperature. The solvent-free process preserves film flexibility, making them ideal for flexible thermoelectric devices. These findings present a scalable strategy to enhance the performance of organic thermoelectric materials.

Ag 2 Se‐based films are promising candidates for flexible thermoelectric devices (F‐TEDs) owing to their excellent electrical transport properties near room temperature. Through compositional engineering and orientation control, Ag 2 Se flexible films have achieved thermoelectric performance comparable to high‐cost Bi 2 Te 3 materials. However, current fabrication methods often rely on complex processes and expensive equipments, hindering large‐scale commercialization. Here, we report a facile, low‐cost, and environmentally robust approach to fabricate highly oriented Ag 2 Se films. Through rational post‐treatments, the crystalline structure and chemical composition are finely tuned to achieve an optimal balance between carrier concentration and mobility. As a result, the Ag 2 Se films exhibit a competitive average power factor of ∼27 µW cm −1 K −2 (298–393 K) together with excellent mechanical flexibility. Furthermore, an in‐plane device delivers an outstanding normalized power density of 3.4 µW cm −2 K −2 at a temperature difference of 10 K, outperforming most reported F‐TEDs. Importantly, this simple yet effective fabrication strategy offers a scalable pathway toward the commercialization of high‐performance and flexible thermoelectric technologies.