A composite foam consisting of foamed cross-linking polystyrene (c-PS) and boron nitride nanosheets (BNNSs) was synthesized, which shows a higher thermal conductivity (TC) than the corresponding solid counterparts. The BNNSs fillers are found to be aligned along the cell wall as a result of the biaxial stress field from cell expansion during the formation of 3-dimensional interconnectivity in the foams, resulting in an enhanced TC of 1.28 W/m K, near 2 and 4 times those of its solid counterpart and pure c-PS, respectively. It is found that the foaming-assisted formation of the filler network is an efficient strategy to improve the TC at low filler loadings in the composites. Furthermore, the composite foams exhibit low-density, rather low dielectric constants and dissipation factors at wide frequency and temperature ranges. The present work provides a novel approach to designing and preparing lightweight heat conductive polymers with low filler loadings as low-density heat management materials for potential applications in aeronautics and aerospace components.

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The elastic composite-based piezoelectric energy-harvesting technology is highly desired to enable a wide range of device applications, including self-powered wearable electronics, robotic skins, and biomedical devices. Recently developed piezoelectric composites are based on inorganic piezoelectric fillers and polymeric soft matrix to take advantages of both components. However, there are still limitations such as weak stress transfer to piezoelectric elements and poor dispersion of fillers in matrix. In this report, a highly enhanced piezocomposite energy harvester (PCEH) is developed using a three-dimensional electroceramic skeleton by mimicking and reproducing the sea porifera architecture. This new mechanically reinforced PCEH is demonstrated to resolve the problems of previous reported conventional piezocomposites and in turn induces stronger piezoelectric energy-harvesting responses. The generated voltage, current density, and instantaneous power density of the biomimetic PCEH device reach up to ∼16 times higher power output than that of conventional randomly dispersed particle-based PCEH. This work broadens further developments of the high-output elastic piezocomposite energy harvesting and sensor application with biomimetic architecture.

The sol−gel method exhibits the advantages of simple preparation, low cost, and easy control of stoichiometry, which is widely used for the fabrication of BiFeO 3 -based perovskite ferroelectric films. However, because of the volatilization of organic solvents during the annealing process, voids will inevitably be formed. In this article, high-quality BiFeO 3 -based thin films (with or without La doping) were prepared by physical vapor deposition methods, namely as magnetron sputtering and pulsed laser deposition, respectively. The deposition procedure of gas particles and the annealing process of thin films could be performed simultaneously by pulsed laser deposition, while is impossible by magnetron sputtering. As a result, pulsed laser deposition is considered as a more suitable approach for ferroelectric thin films fabrication. Besides the adoption of the pulsed laser deposition approach for the fabrication of highly dense thin films, the integration of electron transport layers (SnO 2 , TiO 2 , and ZnO) and La 3+ doping is demonstrated to help to alleviate the problem of high electron−hole recombination rate, which then increases the photovoltaic conversion efficiency. In this contribution, planar solar cells, which were fabricated by the pulsed laser deposition approach with TiO 2 as the electron transport layer, exhibited the best efficiency of 5.62% with a reduced leakage current density. This work provides a promising paradigm for the further development of high-performance BiFeO 3 -based perovskite solar cells through the modulation of fabrication process and introduction of electron transport layers.

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