Si nanocrystals ͑nc-Si͒ with different sizes embedded in SiO 2 matrix have been synthesized with various recipes of Si ion implantation. The influence of nanocrystal size on optical properties, including dielectric functions and optical constants, of the nc-Si has been investigated with spectroscopic ellipsometry. The optical properties of the nc-Si are found to be well described by the four-term Forouhi-Bloomer model. A strong dependence of the dielectric functions and optical constants on the nc-Si size is observed. For the imaginary part of the dielectric functions, the magnitude of the main peaks at the transition energies E 1 and E 2 exhibits a large reduction and a significant redshift in E 2 depending on the nc-Si size. A band gap expansion is observed when the nc-Si size is reduced. The band gap expansion with the reduction of nc-Si size is in good agreement with the prediction of first-principles calculations based on quantum confinement.
A novel near-infrared-responsive (NIR-responsive) photothermal therapy (PTT) agent based on perylenediimide-encapsulated (PDI-encapsulated) PEGylated silica nanocapsules (SNCs) is developed. Dicyclohexylamino-PDI (DCAPDI) with electron-donating cyclohexylamino substitutes at bay positions aggregates into J-aggregation in the core of SNCs, and their electronic coupling interactions are strengthened because of the spatial confinement of SNCs, resulting in strong NIR absorption but negligible fluorescence emission which is crucial for NIR-responsive PTT. Based on our knowledge, this is the first example of generating NIR photothermal conversion by means of molecular aggregation derived from spatial confinement. Unprecedented photostability is achieved with the DCAPDI-encapsulated SNCs in response to more than 60 runs of cyclic NIR exposure with each run exposed to the 808 nm, 1 W cm −2 laser for 10 min. It overcomes the common photodegradation problem of small organic NIR dyes under continuous high-power laser irradiation thanks to the robust molecular skeleton of PDIs and their formation of structurally stable J-aggregates in SNCs. The DCAPDI-encapsulated SNCs demonstrate low cellular cytotoxicity and excellent in vivo photothermal efficacy in tumor ablation in a tumor-bearing zebrafish model, and thus allow the practical employment of a stable photothermal agent in clinical applications.
Hollow structuring of active components is an effective strategy to improve the kinetics of oxygen electrode catalysts, arising from the increased the active surface area, the defects on the exposed surface, and the accessible active sites.
HIGHLIGHTS • Cost-effective and time-efficient process for hybrid reduced graphene oxide (rGO) nanosheets with special magnetoresistance properties was fabricated. • The prepared hybrid rGO nanosheets have large magnetoresistance at low magnetic field at room temperature and used in wireless magnetic field sensors for quick detection of low electromagnetic radiation. ABSTRACT Very few materials show large magnetoresistance (MR) under a low magnetic field at room temperature, which causes the barrier to the development of magnetic field sensors for detecting low-level electromagnetic radiation in realtime. Here, a hybrid reduced graphene oxide (rGO)-based magnetic field sensor is produced by in situ deposition of FeCo nanoparticles (NPs) on reduced graphene oxide (rGO). Special quantum magnetoresistance (MR) of the hybrid rGO is observed, which unveils that Abrikosov's quantum model for layered materials can occur in hybrid rGO; meanwhile, the MR value can be tunable by adjusting the particle density of FeCo NPs on rGO nanosheets. Very high MR value up to 21.02 ± 5.74% at 10 kOe at room temperature is achieved, and the average increasing rate of resistance per kOe is up to 0.9282 Ω kOe −1. In this paper, we demonstrate that the hybrid rGO-based magnetic field sensor can be embedded in a wireless system for real-time detection of low-level electromagnetic radiation caused by a working mobile phone. We believe that the two-dimensional nanomaterials with controllable MR can be integrated with a wireless system for the future connected society.
The increasing emergence of infectious diseases like COVID-19 has created an urgent need for filtration/purification materials coupled with multifunctional features such as mechanical integrity, excellent airflow/filtration, and antibacterial/antimicrobial properties. Polymer membranes and metal−organic frameworks (MOFs) have demonstrated high effectiveness in air filtration and purification. MOF nanoparticles have been introduced into electrospun polymer nanofibrous membranes through embedding or postsolution growth. However, the derived hybrids are still facing the issue of (1) limited MOF exposure, which leads to low efficacy; and (2) uncontrollable growth, which leads to pore blocking and low breathability. In this work, we customized an electrospray-on-electrospinning in situ process to dynamically integrate MOF nanoparticles into a robust and elastic continuous nanofibrous membrane for advanced properties including high mechanical strength and flexibility, excellent breathability, particle filtration, and good antimicrobial performance. Biodegradable polylactic acid was reinforced by the poly(hydroxybutyrate)-di-poly(DLA-CL) x copolymer (PHBR) and used as an electrospinning matrix, while MOF nanoparticles were simultaneously electrically sprayed onto the nanofibers with easily controllable MOF loading. The MOF nanoparticles were homogeneously deposited onto nanofibers without clogging the pores in the membrane. The collision of PLA and MOF under the wet status during electrospinning and the hydrogen bonding through C� O and N−H bonds strengthen the affinity between PLA nanofibers and MOF nanoparticles. Because of these factors, the MOFincorporated PLA/PHBR nanofibrous membrane achieved over 95% particle filtration efficiency with enhanced mechanical properties while maintaining high breathability. Meanwhile, it exhibits excellent photocatalytic antibacterial performance, which is necessary to kill microbes. The electrospray-on-electrospinning in situ process provides an efficient and straightforward way to hybridize one-dimensional (1D) or two-dimensional (2D) nanomaterials into a continuous nanofibrous membrane with strong interaction and controllable loading. Upon integrating proper functionalities from the materials, the obtained hybrids are able to achieve multifunctionalities for various applications.
The authors report the photon-induced conduction modulation in SiO 2 thin films embedded with germanium nanocrystals ͑nc-Ge͒. The conduction of the oxide could be switched to a higher-or lower-conductance state by a ultraviolet ͑UV͒ illumination. The conduction modulation is caused by charging and discharging in the nc-Ge due to the UV illumination. If the charging process is dominant, the oxide conductance is reduced; however, if the discharging process is dominant, the oxide conductance is increased. As the conduction can be modulated by UV illumination, it could have potential applications in silicon-based optical memory devices.
Lithium-ion batteries (LiB) play an important role for energy storage in our increasingly-electrified modern world, with polymer electrolyte (PE) materials poised to revolutionise battery design by eliminating the most critical...
The structural battery is a multifunctional energy storage device that aims to address the weight and volume efficiency issues that conventional batteries face, especially in electric transportation. By combining the functions of mechanical load bearing and energy storage, structural batteries can reduce the reliance on, or even eventually replace the main power source in an electric vehicle or a drone. However, one of the key challenges to be addressed before achieving multifunctionality in structural batteries would be the design of a suitable multifunctional structural battery electrolyte. The structural battery electrolyte is the constituent that provides mechanical integrity under flexural loads or impact and hence determines the electrochemical and much of the mechanical performance of a structural battery device. This concept paper aims to cover the key considerations and challenges facing the design of structural battery electrolytes. In addition, the main approaches to surmount these challenges are highlighted, keeping design aspects like sustainability and recyclability in view.[a] M.
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