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ABX3 (X = O) perovskite oxides are an uprising class of alternative electrocatalysts in eminent technologies like electrocatalysis, photocatalysis, thermocatalysis, and energy storage. The perquisites of perovskite oxide catalysts encompass ordered atomic structure, structural/compositional extensibility, flexible electronic structure, lucrativeness, and so on. The ingenuity to precisely control and tune the inherent properties by reconstructing their crystal structure is particularly advantageous in electrocatalysis reactions like oxygen reduction and evolution reactions (ORR and OER). Incorporating multidimensional imperfections in the presumably perfect crystal structure of the perovskite catalysts is garnering booming attention among researchers. This concept can expertly influence the electronic structure and boost the reaction kinetics during electrocatalysis. Defects or imperfections are achieved by substituting A‐ and/or B‐sites with heteroatoms or by oxygen vacancies. Defect engineering points to a promising new direction in the development of perovskite oxide catalysts. This work surveys the recent progress in defect engineering and how it plays a vital role in their design, and application in electrocatalysis, mainly ORR/OER. The architecture, dimensionality, and the types of perovskite oxides based on their cations, crystal structures, and stoichiometries are surveyed for a comprehensive understanding. This review aims to provide an extensive outlook on oxide perovskite catalysts concerning structural defects. [ABSTRACT FROM AUTHOR]

Anode‐free all‐solid‐state batteries (AF‐ASSBs) have received significant attention as a next‐generation battery system due to their high energy density and safety. However, this system still faces challenges, such as poor Coulombic efficiency and short‐circuiting caused by Li dendrite growth. In this study, the AF‐ASSBs are demonstrated with reliable and robust electrochemical properties by employing Cu–Sn nanotube (NT) thin layer (~1 µm) on the Cu current collector for regulating Li electrodeposition. LixSn phases with high Li‐ion diffusivity in the lithiated Cu–Sn NT layer enable facile Li diffusion along with its one‐dimensional hollow geometry. The unique structure, in which Li electrodeposition takes place between the Cu–Sn NT layer and the current collector by the Coble creep mechanism, improves cell durability by preventing solid electrolyte (SE) decomposition and Li dendrite growth. Furthermore, the large surface area of the Cu–Sn NT layer ensures close contact with the SE layer, leading to a reduced lithiation overpotential compared to that of a flat Cu–Sn layer. The Cu–Sn NT layer also maintains its structural integrity owing to its high mechanical properties and porous nature, which could further alleviate the mechanical stress. The LiNi0.8Co0.1Mn0.1O2 (NCM)|SE|Cu–Sn NT@Cu cell with a practical capacity of 2.9 mAh cm−2 exhibits 83.8% cycle retention after 150 cycles and an average Coulombic efficiency of 99.85% at room temperature. It also demonstrates a critical current density 4.5 times higher compared to the NCM|SE|Cu cell. [ABSTRACT FROM AUTHOR]

Emerging classes of concentrator photovoltaic (CPV) modules reach efficiencies that are far greater than those of even the highest performance flat-plate PV technologies, with architectures that have the potential to provide the lowest cost of energy in locations with high direct normal irradiance (DNI). A disadvantage is their inability to effectively use diffuse sunlight, thereby constraining widespread geographic deployment and limiting performance even under the most favorable DNI conditions. This study introduces a module design that integrates capabilities in flat-plate PV directly with the most sophisticated CPV technologies, for capture of both direct and diffuse sunlight, thereby achieving efficiency in PV conversion of the global solar radiation. Specific examples of this scheme exploit commodity silicon (Si) cells integrated with two different CPV module designs, where they capture light that is not efficiently directed by the concentrator optics onto large-scale arrays of miniature multijunction (MJ) solar cells that use advanced III-V semiconductor technologies. In this CPV+ scheme ("+" denotes the addition of diffuse collector), the Si and MJ cells operate independently on indirect and direct solar radiation, respectively. On-sun experimental studies of CPV+ modules at latitudes of 35.9886° N (Durham, NC), 40.1125° N (Bondville, IL), and 38.9072° N (Washington, DC) show improvements in absolute module efficiencies of between 1.02% and 8.45% over values obtained using otherwise similar CPV modules, depending on weather conditions. These concepts have the potential to expand the geographic reach and improve the cost-effectiveness of the highest efficiency forms of PV power generation.

This paper introduces a class of ferromagnetic, folded, soft composite material for skin-interfaced electrodes with releasable interfaces to stretchable, wireless electronic measurement systems. These electrodes establish intimate, adhesive contacts to the skin, in dimensionally stable formats compatible with multiple days of continuous operation, with several key advantages over conventional hydrogel based alternatives. The reported studies focus on aspects ranging from ferromagnetic and mechanical behavior of the materials systems, to electrical properties associated with their skin interface, to system-level integration for advanced electrophysiological monitoring applications. The work combines experimental measurement and theoretical modeling to establish the key design considerations. These concepts have potential uses across a diverse set of skin-integrated electronic technologies.

Recent advances in materials, mechanics, and electronic device design are rapidly establishing the foundations for health monitoring technologies that have "skin-like" properties, with options in chronic (weeks) integration with the epidermis. The resulting capabilities in physiological sensing greatly exceed those possible with conventional hard electronic systems, such as those found in wrist-mounted wearables, because of the intimate skin interface. However, most examples of such emerging classes of devices require batteries and/or hard-wired connections to enable operation. The work reported here introduces active optoelectronic systems that function without batteries and in an entirely wireless mode, with examples in thin, stretchable platforms designed for multiwavelength optical characterization of the skin. Magnetic inductive coupling and near-field communication (NFC) schemes deliver power to multicolored light-emitting diodes and extract digital data from integrated photodetectors in ways that are compatible with standard NFC-enabled platforms, such as smartphones and tablet computers. Examples in the monitoring of heart rate and temporal dynamics of arterial blood flow, in quantifying tissue oxygenation and ultraviolet dosimetry, and in performing four-color spectroscopic evaluation of the skin demonstrate the versatility of these concepts. The results have potential relevance in both hospital care and at-home diagnostics.

Power supply represents a critical challenge in the development of body-integrated electronic technologies. Although recent research establishes an impressive variety of options in energy storage (batteries and supercapacitors) and generation (triboelectric, piezoelectric, thermoelectric, and photovoltaic devices), the modest electrical performance and/or the absence of soft, biocompatible mechanical properties limit their practical use. The results presented here form the basis of soft, skin-compatible means for efficient photovoltaic generation and high-capacity storage of electrical power using dual-junction, compound semiconductor solar cells and chip-scale, rechargeable lithium-ion batteries, respectively. Miniaturized components, deformable interconnects, optimized array layouts, and dual-composition elastomer substrates, superstrates, and encapsulation layers represent key features. Systematic studies of the materials and mechanics identify optimized designs, including unusual configurations that exploit a folded, multilayer construct to improve the functional density without adversely affecting the soft, stretchable characteristics. System-level examples exploit such technologies in fully wireless sensors for precision skin thermography, with capabilities in continuous data logging and local processing, validated through demonstrations on volunteer subjects in various realistic scenarios.

Hard and soft structural composites found in biology provide inspiration for the design of advanced synthetic materials. Many examples of bio-inspired hard materials can be found in the literature; far less attention has been devoted to soft systems. Here we introduce deterministic routes to low-modulus thin film materials with stress/strain responses that can be tailored precisely to match the non-linear properties of biological tissues, with application opportunities that range from soft biomedical devices to constructs for tissue engineering. The approach combines a low-modulus matrix with an open, stretchable network as a structural reinforcement that can yield classes of composites with a wide range of desired mechanical responses, including anisotropic, spatially heterogeneous, hierarchical and self-similar designs. Demonstrative application examples in thin, skin-mounted electrophysiological sensors with mechanics precisely matched to the human epidermis and in soft, hydrogel-based vehicles for triggered drug release suggest their broad potential uses in biomedical devices.

Roll‐to‐roll dry processing enables the manufacture of high energy density and low cost Li‐ion batteries (LIBs). However, as the thickness of the electrode fabricated by dry processing becomes greater (≥10 mAh cm−2), Li‐ion migration resistance (Rion) and charge‐transfer resistance (Rct) in the electrode dramatically increase due to long diffusion lengths for Li‐ion and electron. Therefore, it is important to reduce diffusion lengths in the electrode to achieve high energy density LIBs. The dry electrode with a high areal capacity of 10 mAh cm−2 and low resistance can be achieved by following three characteristics. First, the fibrillization behavior of polytetrafluoroethylene (PTFE) binder is controlled by adjusting the processing temperature during the fibrillization process, which enables uniform distribution of PTFE binder and carbon black (CB). Second, pore size/distribution and conducting network are engineered by multi‐dimensional conducting agents, enhancing Li‐ions and electrons transport in the electrode. Finally, the structural integrity of LiNi0.80Co0.15Al0.05O2 (NCA) particles is improved without fractures, which enables uniform pore distribution in the electrode by controlling the calendering step. The prepared 10 mAh cm−2 dry electrode with homogeneous microstructure shows reduced Rion and Rct due to short diffusion lengths, which improves electrochemical performances in LIBs with a high volumetric energy density of ≈710 Wh L−1. [ABSTRACT FROM AUTHOR]