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Metal nanoparticle exsolution from metal oxide hosts has recently garnered great attention to improve the performance of energy conversion and storage devices. In this study, the nickel exsolution mechanisms in a vertically aligned nanostructure (VAN) thin film of heteroepitaxial (Sr 0.9 Pr 0.1 ) 0.9 Ti 0.9 Ni 0.1 O 3−δ -Ce 0.9 Gd 0.1 O 1.95 with a columnar architecture was investigated for the first time. Experimental results and Density Functional Theory (DFT) calculations reveal that the multiple vertical interphases in a VAN with a hierarchical arrangement provide faster and more selective Ni diffusion pathways to the surface than traditional bulk diffusion in epitaxial films. Kinetic studies conducted at different temperatures and times indicate that the nucleation process of the exsolved metal nanoparticles primarily takes place at the surface through the phase boundaries of the columns. The vertical strain is crucial in preserving the film’s microstructure, yielding a robust heteroepitaxial architecture after reduction. This innovative heteromaterial opens up new possibilities for designing efficient devices through advanced structural engineering to achieve controlled nanoparticle formation. Exsolved Nickel nanoparticles enhance the performance in energy conversion devices. Here, we report a nanoengineered vertically aligned nanostructure (VAN) that provides faster and more selective paths for Ni diffusion compared to traditional films.

The development of materials with improved performance and stability relies on the analysis of local compositional inhomogeneities, which may occur at various stages from synthesis to application. This type of analysis benefits from rapid methods that provide high lateral and depth resolution, alongside broad elemental sensitivity. The latter is of paramount importance when considering devices such as lithium‐ion batteries and solid oxide cells, whose operating principle depends on the transfer and accumulation of light elements. In this work, we validate glow discharge optical emission spectroscopy (GDOES) as an alternative to state‐of‐the‐art techniques for the chemical analysis of complex oxides. We consider several systems of technological interest for materials used in energy storage and conversion‐related applications, namely highly complex perovskite oxide thin films with formula ABO3 (A = La, Sr, and B = Fe, Co, Mn) and single‐phase SrFeO3‐δ (SFO). Quantitative, depth‐resolved elemental maps of B‐site cations in combinatorial films are generated and benchmarked against state‐of‐the‐art methods. Additionally, an oxygen quantification was achieved on films subjected to different post‐annealing treatments. This work demonstrates the potential of GDOES for fast analysis of complex oxide films and heterostructures, enabling both laterally and nanoscale depth‐resolved elemental analysis, including difficult‐to‐quantify light elements. This work demonstrates how glow discharge optical emission spectroscopy enables rapid, depth‐resolved chemical analysis of complex oxide thin films and interfaces. The study validates its quantitative capability for perovskites and oxygen non‐stoichiometry, benchmarking against state‐of‐the‐art techniques. The results highlight GDOES as a fast, high‐resolution tool for compositional mapping and nanoscale characterization in energy‐relevant materials.

While grain boundary engineering is attracting great interest as a potential strategy to fabricate highly electrochemically active materials, open questions remain in relation to the fundamental mechanisms of local property enhancement as well as to the potential technological impact of such nanostructuring strategies. In this paper, the ability to turn a predominantly electronic conductor into an excellent mixed‐ionic electronic conductor by grain boundary doping is demonstrated for nanocrystalline films of lanthanum chromite. A four‐orders‐of‐magnitude increase in the oxygen diffusion coefficient at grain boundaries is observed, and related  to local chemical changes. It is shown that grain boundary effects can be effectively exploited for technological purposes by fabricating a proof‐of‐concept symmetric solid oxide cell based on lanthanum chromite film electrodes. The cell is operated under reversible gas feeding conditions, exhibiting electrode self‐healing characteristics. The results provide new insights on the fundamental aspects of fast grain boundary oxygen diffusion and validate grain boundary engineering as a technologically relevant strategy for the realization of solid oxide cells with enhanced performance. Nanocrystalline thin‐films of lanthanum chromite exhibit extraordinary properties of fast oxygen kinetics. These properties are due to the peculiar chemistry of grain boundaries and can be harnessed for fabricating symmetric electrochemical devices with self‐healing properties.

Internet-of-thing (IoT) is an assembly of devices that collect and share data with other devices and communicate via the internet. This massive network of devices, generates and communicates data and is the key to the value in IoT, allowing access to raw information, gaining insight, and making an intelligent decisions. Today, there are billions of IoT devices such as sensors and actuators deployed. Many of these applications are easy to connect, but those tucked away in hard-to-access spots will need to harvest ambient energy. Therefore, the aim is to create devices that are self-report in real-time. Efforts are underway to install a self-powered unit in IoT devices that can generate sufficient power from environmental conditions such as light, vibration , and heat . In this review paper, we discuss the recent progress made in materials and device development in power- and, storage units, and power management relevant for IoT applications. This review paper will give a comprehensive overview for new researchers entering the field of IoT and a collection of challenges as well as perspectives for people already working in this field.

Oxygen mass transport in perovskite oxides is relevant for a variety of energy and information technologies. In oxide thin films, cation nonstoichiometry is often found but its impact on the oxygen transport properties is not well understood. Here, we used oxygen isotope exchange depth profile technique coupled with secondary ion mass spectrometry to study oxygen mass transport and the defect compensation mechanism of Mn-deficient La0.8Sr0.2MnyO3±δ epitaxial thin films. Oxygen diffusivity and surface exchange coefficients were observed to be consistent with literature measurements and to be independent on the degree of Mn deficiency in the layers. Defect chemistry modeling, together with a collection of different experimental techniques, suggests that the Mn-deficiency is mainly compensated by the formation of LaMn× antisite defects. The results highlight the importance of antisite defects in perovskite thin films for mitigating cationic nonstoichiometry effects on oxygen mass transport properties.

Oxygen mass transport in perovskite oxides is relevant for a variety of energy and information technologies. In oxide thin films, cation nonstoichiometry is often found but its impact on the oxygen transport properties is not well understood. Here, we used oxygen isotope exchange depth profile technique coupled with secondary ion mass spectrometry to study oxygen mass transport and the defect compensation mechanism of Mn-deficient La 0.8 Sr 0.2 Mn y O 3± δ epitaxial thin films. Oxygen diffusivity and surface exchange coefficients were observed to be consistent with literature measurements and to be independent on the degree of Mn deficiency in the layers. Defect chemistry modeling, together with a collection of different experimental techniques, suggests that the Mn-deficiency is mainly compensated by the formation of La Mn × antisite defects. The results highlight the importance of antisite defects in perovskite thin films for mitigating cationic nonstoichiometry effects on oxygen mass transport properties.

The exploitation of advanced materials for novel energy, health and computing applications requires fundamental understanding of enabling physicochemical mechanisms, including ionic and electronic conductivity, defect formation processes and reaction kinetics. Therefore, access to underlying constants of functional materials via advanced but straightforward experimental techniques is key. We present a novel, cheap and widely applicable approach to analyze oxygen-tracer-diffusion in thin films with unprecedented time resolution based on the novel in situ isotope-exchange Raman spectroscopy (IERS) methodology. Raman spectroscopy is sensitive to changes in the local isotopic composition, manifested by a frequency shift of the oxygen Raman modes. Employing a Raman transparent capping layer allows to establish an in-plane tracer gradient and follow the isotope exchange and diffusion processes via consecutive spatial and time resolved in situ Raman line scans. Mass-transport coefficients are calculated from these isotopic gradients, similar to conventional techniques, but with an additional time-component, not accessible by other techniques. Here, we study gadolinium doped ceria (CGO) thin films, capped with Si3N4 or Al2O3. We report diffusion coefficients within the temperature range of interest for intermediate temperature emerging applications (300-500{\\deg}C) and confirm the validity of the measurement procedure and extracted parameters by comparison with FEM simulations and literature results.

Functional properties of mixed ionic electronic conductors (MIECs) can be radically modified by (de)insertion of mobile charged defects. A complete control of this dynamic behaviour has multiple applications in a myriad of fields including advanced computing, data processing, sensing or energy conversion. However, the effect of different MIECs state-of-charge is not fully understood yet and there is a lack of strategies for fully controlling the defect content in a material. In this work we present a model-less technique to characterize ionic defect concentration and ionic insertion kinetics in MIEC materials: Optoionic Impedance Spectroscopy (OIS). The proof of concept and advantages of OIS are demonstrated by studying the oxygen (de)insertion in thin films of hole-doped perovskite oxides. Ion migration into/out of the studied materials is achieved by the application of an electrochemical potential, achieving stable and reversible modification of its optical properties. By tracking the dynamic variation of optical properties depending on the gating conditions, OIS enables to extract electrochemical parameters involved in the electrochromic process. The results demonstrate the capability of the technique to effectively characterize the kinetics of single- and even multi- layer systems. The technique can be employed for studying underlying mechanisms of the response characteristics of MIEC-based devices.