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Thermoelectrics has played a fascinating role in the developments of direct energy conversion technologies. Over the past decade, sulfur-based thermoelectric materials have been significantly advanced in optimizing electrical and thermal transport due to their similarities in chemical and structural properties with tellurides and selenides. This review provides research progress on metal sulfides, particularly focuses on materials exhibiting high thermoelectric figure of merit (ZT > 1.0). It highlights the potential compounds, e.g.CuS, SnS, PbS based, and polysulfides. Great strategies of superionic conducting, band configuration tuning, high-entropy alloying, and anomalous harmonic scattering are try to demonstrate the performance-improved mechanisms for thermoelectric sulfides. In addition, some common synthesis recipes are briefly introduced, and thereby making potential candidates as excellent alternatives for producing thermoelectric power generators in the mid temperature. Key outcomes along with how to further improve the thermoelectric performance and promote its scale-up applications are also outlined at the end.

Objective: This study aimed to observe the drug distribution ex-vivo after transdermal drug delivery (TDD) by Shock Wave (SW) and to explore the different effects of the two types of shock waves. Materials and Methods: Nine female Sprague-Dawley (SD) rats were randomly divided into 3 groups: (i) control group; (ii) RESW group (0.35mJ/mm2, 2 Hz, 400 pulse); (iii) FESW group (0.16mJ/mm2, 2 Hz, 400 pulse). Micro positron emission tomography/computed tomography (PET/CT) was used to observe the distribution of [18]F-NaF. Furthermore, 12 SD rats were randomly divided into 4 groups: (i) control group; (ii) FESW group 1 (0.03mJ/mm2, 2 Hz, 400 pulse); (iii) FESW group 2 (0.16mJ/mm2, 2 Hz, 400 pulse); (iv) FESW group 3 (0.35mJ/mm2, 2 Hz, 400 pulse). High-performance liquid chromatography (HPLC) tested diclofenac sodium and glucose percutaneously TDD by FESW. Statistical significance was conducted by analysis of variance of repeated measurement. Results: The micro PET/CT observed FESW could penetrate [18]F-NaF through the skin, while RESW could not. The second study found the higher the energy of the FESW, the more diclofenac sodium and glucose penetration. Repeated measures analysis of variance found a within-subject effect (diclofenac sodium, F = 4.77, p = 0.03), (glucose, F = 8.95, p = 0.006), significant differences between the control group, FESW group 1, and FESW group 2 (p < 0.05). Conclusion: The study found that FESW can penetrate [18]F-NaF, sugar and diclofenac sodium into the rat body. FESW has a good indication of drug penetration, which provides new biological evidence for route administration.

Higher manganese silicide (HMS) is a naturally abundant, eco-friendly, and low-cost p-type thermoelectric semiconductor with high power factor (PF); however, its figure of merit (ZT) is very low due to an intrinsically high thermal conductivity (κ). It is also difficult to synthesize a HMS single phase without MnSi or Si second phase, which generally leads to a significant decrease of the PFand/or increased κ. In this study, pure HMS was obtained via wet ball milling in combination with spark plasma sintering. A further p-type MnTe, with high Seebeck coefficient (S) and low κ, was incorporated into the HMS matrix to form MnTe/HMS composites. To effectively decrease κ, while simultaneously enhancing the electrical conductivity, Te nanowires of ∼35 nm in diameter were synthesized with a solution phase method and subsequently embedded to HMS to form MnTe/HMS nano/bulk structures. The incorporation of Te nanowires led to a 38% reduction of κ in addition to a slight increase of S. Finally, the ZTmaxof MnTe/HMS nano/bulk composites increased by ∼71% from 0.41 to 0.70. This study demonstrates a unique and facile method to boost the ZTof HMS to a high level, which is also applicable to other thermoelectric materials.

Nanostructuring and defect engineering are increasingly employed as processing strategies for thermoelectric performance enhancement, and special attention has been paid to nanostructured interfaces and dislocations that can effectively scatter low- and mid-frequency phonons. This work demonstrated that their combination was realized in Fe2O3-dispersed tetrahedrite (Cu12Sb4S13) nanocomposites, leading to significantly reduced thermal conductivities around 0.9 W m–1K–1at all temperatures and hence a high ZTvalue of ∼1.0, which increases by ∼33% compared with that of the matrix. The plausible enhancement mechanisms have been analyzed with an emphasis on the incorporation of magnetic γ-Fe2O3nanoparticles (NPs) into Cu11.5Ni0.5Sb4S13, leading to various nanostructures (NPs, nanoprecipitates, and nanotwins) and dislocations. A calculated efficiency of ∼9.3% and an average ZTof 0.63 also reveal the potential application of tetrahedrite at medium temperatures. Additionally, the mechanical properties are improved because of a second phase strengthening and nanotwin structures.