Thin-film electrocaloric and pyroelectric sources for electrothermal energy interconversion have recently emerged as viable means for primary and auxiliary solid-state cooling and power generation. Two significant advances have facilitated this development: (1) the formation of high-quality polymeric and ceramic thin films with figures of merit that project system-level performance as a large percentage of Carnot efficiency and (2) the ability of these newer materials to support larger electric fields, thereby permitting operation at higher voltages. This makes the power electronic architectures more favorable for thermal to electric energy interconversion. Current research targets to adequately address commercial device needs including reduction of parasitic losses, increases in mechanical robustness, and the ability to form nearly freestanding elements with thicknesses in the range of 1–10 μm. This article describes the current state-of-the-art materials, thermodynamic cycles, and device losses and points toward potential lines of research that would lead to substantially better figures of merit for electrothermal energy interconversion.

The field of nuclear materials encompasses numerous opportunities to address and ultimately solve longstanding industrial problems by improving the fundamental understanding of materials through the integration of experiments with multiscale modeling and high-performance simulation. A particularly noteworthy example is an ongoing study of axial power distortions in a nuclear reactor induced by corrosion deposits, known as CRUD (Chalk River unidentified deposits). We describe how progress is being made toward achieving scientific advances and technological solutions on two fronts. Specifically, the study of thermal conductivity of CRUD phases has augmented missing data as well as revealed new mechanisms. Additionally, the development of a multiscale simulation framework shows potential for the validation of a new capability to predict the power distribution of a reactor, in effect direct evidence of technological impact. The material- and system-level challenges identified in the study of CRUD are similar to other well-known vexing problems in nuclear materials, such as irradiation accelerated corrosion, stress corrosion cracking, and void swelling; they all involve connecting materials science fundamentals at the atomistic- and meso-scales to technology challenges at the macroscale.

The high specific capacity, reactivity, and abundance of magnesium in the earth’s crust and the relatively good safety features of Mg metal, despite its being a reactive metal, drive intensive efforts to develop rechargeable Mg batteries as a follow-up to the success of Li-ion battery technology. However, Mg anodes cannot function in usual non-aqueous electrolyte solutions. Consequently, it is important to develop unique, complex solutions for reversible Mg metal anodes. Also, finding relevant cathode materials that can reversibly insert bivalent Mg ions is a great challenge. In this article, we review the efforts and success in the development of several families of electrolyte solutions for secondary Mg batteries, in which Mg anodes behave fully reversibly, but also exhibit the necessary wide electrochemical window. We also review attempts to develop positive electrodes for rechargeable Mg batteries. The first generation of secondary Mg batteries has already been demonstrated, but their specific energy density remains relatively low. The challenge now is to develop novel Mg battery prototypes that possess high energy density.

Single-wall carbon nanotubes (CNTs) were discovered in 1993 and have been an area of intense research since then. They offer the right dimensions to explore material science and physical chemistry at the nanoscale and are the perfect system to study low-dimensional physics and transport. In the past decade, more attention has been shifted toward making use of this unique nanomaterial in real-world applications. In this article, we focus on potential applications of CNTs in the high-performance logic computing area—the main component of the semiconductor industry. We discuss the key challenges for nanotubes to replace silicon in integrated circuits and review progress made in recent years on the material, device, and circuit integration development of CNT technology.

Hydrogen termination of diamond lowers its ionization energy, driving electron transfer from the valence band into an adsorbed water layer or to a strong molecular acceptor. This gives rise to p-type surface conductivity with holes confined to a subsurface layer of a few nanometers thickness. The transfer doping mechanism, the electronic behavior of the resulting hole accumulation layer, and the development of robust field-effect transistor (FET) devices using this platform are reviewed. An alternative method of modulating the hole carrier density has been developed based upon an electrolyte-gate architecture. The operation of the resulting “solution-gated” FET architecture in two contemporary applications will be described: the charge state control of nitrogen-vacancy centers in diamond and biosensing. Despite 25 years of work in this area, our knowledge of surface conductivity of diamond continues to develop.

This article reviews silicene, a relatively new allotrope of silicon, which can also be viewed as the silicon version of graphene. Graphene is a two-dimensional material with unique electronic properties qualitatively different from those of standard semiconductors such as silicon. While many other two-dimensional materials are now being studied, our focus here is solely on silicene. We first discuss its synthesis and the challenges presented. Next, a survey of some of its physical properties is provided. Silicene shares many of the fascinating properties of graphene, such as the so-called Dirac electronic dispersion. The slightly different structure, however, leads to a few major differences compared to graphene, such as the ability to open a bandgap in the presence of an electric field or on a substrate, a key property for digital electronics applications. We conclude with a brief survey of some of the potential applications of silicene.

New methods for the synthesis and deterministic assembly of advanced classes of nanomaterials enable integration of high-performence semiconductors with elastomeric substrates. These capabilities provide the foundations for a high-performance electronic and optoelectronic technology that can offer linear elastic mechanical responses to large strain deformations. The results create new opportunities in materials and device engineering, with important consequences in fields ranging from biomedicine to machine vision. This article summarizes the key materials science concepts and presents illustrative examples of their recent use in injectable, cellular-scale optoelectronic devices and in hemispherical compound eye cameras.

The implication of shape control in nanocrystal synthesis goes far beyond aesthetic appeal. For metal nanocrystals, the shape not only determines their physicochemical properties but also their technological relevance for catalytic, plasmonic, photonic, and electronic applications. In particular, heterogeneous catalysis is a field that can benefit tremendously from the availability of metal nanocrystals with well-controlled shapes, which may serve to significantly increase reaction efficiency while decreasing material cost. This article provides a brief overview of our recent progress in generating shape-controlled nanocrystals with enhanced catalytic activity toward oxygen reduction and formic acid oxidation, two reactions that are crucial for the successful commercialization of fuel cell technology. The impact on other industrially important reactions will be discussed as well. We hope that this article provides a roadmap for further development of metal nanocrystal-based catalysts with enhanced performance through shape-controlled synthesis.

In recent years, the emerging areas of nanophotonics and, in particular, plasmonics and metamaterials, have seen an explosion of novel ideas. However, transforming revolutionary designs into practical devices requires a significant amount of effort. The constituent materials in plasmonic structures and metamaterials play a crucial role in realizing useful and efficient devices. Similar to the way silicon shaped the nanoelectronics field, finding the best set of materials for plasmonic and metamaterial devices could revolutionize the field of nanophotonics. As a potential solution, alternative plasmonic materials have recently gained significant attention. Metals, despite being essential components of plasmonic and metamaterial devices, pose many technological challenges toward the realization of practical devices—primarily due to their high optical loss, integration, and fabrication limitations. Hence, searching for an alternative is vital to the success of future nanophotonic devices. Several classes of materials, including doped semiconductor oxides and ceramics, are discussed as potential alternatives to metals that could lead to devices with drastically improved performance and new functionalities by providing low intrinsic loss, tunability, and compatibility with standard semiconductor fabrication processes.