Lower-cost thermoelectrics: Thermoelectric materials convert heat to electricity, making them attractive for heat harvesting or cooling applications. However, many high-performance thermoelectrics are made of expensive or toxic materials. He et al. found that a material composed of primarily tin and sulfur could be optimized to have relatively good thermoelectric properties. Introducing about 10% selenium to tin sulfide helped tune these properties by electronic band manipulation. This material is a step toward more earth-abundant, less toxic, and lower-cost thermoelectrics than the telluride-based materials currently in use. Science , this issue p. 1418

A cooler tin selenide: Thermoelectric materials can convert heat into electricity or be used as the basis of cooling devices. Qin et al . found that doping a tin selenide thermoelectric material with lead and sodium improved the room temperature thermoelectric properties, an effect created by manipulation of the electronic bands. The authors showed that the material could be used not only for power generation but also cooling. If optimal contact materials are identified, then this approach may be attractive for future applications. —BG

Evaporation, a ubiquitous process driving Earth's water-energy cycle, has been largely untapped for energy harvesting. Here, we introduce "evapolectrics," a scalable strategy that directly converts evaporation enthalpy into electricity via thermoelectric generators (TEGs). By leveraging porous graphite coatings and optimizing wind speeds (2.8 m/s) and wet-bulb depression, a robust temperature gradient (ΔT) over 6 °C can be maintained across TEGs. This translates to a power density of 4.2 W/m², which exceeds other ambient energy harvesting technologies, such as triboelectric and hydrovoltaics. We also demonstrate the evapolectrics' ability to sustain a continuous power output of 2.72 mW over 30 min and scalability via a 7 × 7 device array. Unlike intermittent sources like solar or wind, evaporation's perennial nature offers reliable ambient energy harvesting. With global evaporation rates suggesting harvestable energy of ∼10⁵ TJ/year, evapotetics present a transformative approach to power self-sustaining devices, augmented by advances in thermoelectric materials.

Recently, several creative processing techniques yielded thermoelectrics with reduced thermal conductivity and, thereby, an enhanced figure or merit. These were based on engineered complex microstructures with attendant dislocation structures. In this study, we implement highly controlled mesoscopic dislocation structures into the model thermoelectric SrTiO₃ in order to quantify phonon scattering at dislocations. Both single crystals and polycrystalline material have been furnished with enhanced dislocation densities increased by a factor of 150–300 by plastic deformation. Thermal conductivity was measured using laser flash analysis between room temperature and 325 °C. Etch pit techniques and ultra-high voltage electron microscopy afford quantification of dislocation density. Experimental results were compared to predictions by the Debye-Callaway model. The latter revealed that dislocation densities of 10¹⁵ m⁻² would be necessary for the reduction of thermal conductivity of SrTiO₃ in the investigated temperature range, which could not be realized using the plastic deformation mechanism applied.

FeM (M = Se, Te) chalcogenides have been well studied as promising magnets and superconductors, yet their potential as electrocatalysts is often considered limited due to anion dissolution and oxidation during electrochemical reactions. Here, we show that by using two-dimensional (2D) FeTeSe nanosheets, these conventionally perceived limitations can be leveraged to enable the reaction-driven in-situ generation of anisotropic in-plane tensile and out-of-plane compressive strains during the alkaline low-concentration nitrate reduction reaction (NO₃⁻RR). The reconstructed catalyst demonstrates enhanced performance, yielding ammonia with a near-unity Faradaic efficiency and a high yield rate of 42.14 ± 2.06 mg h⁻¹ mg_cat⁻¹. A series of operando synchrotron-based X-ray measurements and ex-situ characterizations, alongside theoretical calculations, reveal that strain formation is ascribed to chalcogen vacancies created by partial Se/Te leaching, which facilitate the adsorption and dissociation of OH⁻/NO₃⁻ from the electrolyte, resulting in an O(H)-doped strained lattice. Combined electrochemical and computational investigations suggest that the superior catalytic performance arises from the synergistic contributions from the exposed strained Fe sites and surface hydroxyl groups. These findings highlight the potential of 2D transition metal chalcogenides for in-situ structural engineering during electrochemical reactions to enhance catalytic activity for NO₃⁻RR and beyond.