Fuel-Free Light-Powered TiO₂/Pt Janus Micromotors for Enhanced Nitroaromatic Explosives Degradation

Nitroaromatic explosives such as 2,4,6-trinitrotoluene (2,4,6-TNT) and 2,4-dinitrotoluene (2,4-DNT) are two common nitroaromatic compounds in ammunition. Their leakage leads to serious environmental pollution and threatens human health. It is important to remove or decompose them rapidly and efficiently. In this work, we present that light-powered TiO₂/Pt Janus micromotors have high efficiency for the “on-the-fly” photocatalytic degradation of 2,4-DNT and 2,4,6-TNT in pure water under UV irradiation. The redox reactions, induced by photogenerated holes and electrons on the TiO₂/Pt Janus micromotor surfaces, produce a local electric field that propels the micromotors as well as oxidative species that are able to photodegrade 2,4-DNT and 2,4,6-TNT. Furthermore, the moving TiO₂/Pt Janus micromotors show an efficient degradation of nitroaromatic compounds as compared to the stationary ones thanks to the enhanced mixing and mass transfer in the solution by movement of these micromotors. Such fuel-free light-powered micromotors for explosive degradation are expected to find a way to environmental remediation and security applications

Fuel-Free Light-Powered TiO₂/Pt Janus Micromotors for Enhanced Nitroaromatic Explosives Degradation

Nitroaromatic explosives such as 2,4,6-trinitrotoluene (2,4,6-TNT) and 2,4-dinitrotoluene (2,4-DNT) are two common nitroaromatic compounds in ammunition. Their leakage leads to serious environmental pollution and threatens human health. It is important to remove or decompose them rapidly and efficiently. In this work, we present that light-powered TiO₂/Pt Janus micromotors have high efficiency for the “on-the-fly” photocatalytic degradation of 2,4-DNT and 2,4,6-TNT in pure water under UV irradiation. The redox reactions, induced by photogenerated holes and electrons on the TiO₂/Pt Janus micromotor surfaces, produce a local electric field that propels the micromotors as well as oxidative species that are able to photodegrade 2,4-DNT and 2,4,6-TNT. Furthermore, the moving TiO₂/Pt Janus micromotors show an efficient degradation of nitroaromatic compounds as compared to the stationary ones thanks to the enhanced mixing and mass transfer in the solution by movement of these micromotors. Such fuel-free light-powered micromotors for explosive degradation are expected to find a way to environmental remediation and security applications

Fuel-Free Light-Powered TiO₂/Pt Janus Micromotors for Enhanced Nitroaromatic Explosives Degradation

Nitroaromatic explosives such as 2,4,6-trinitrotoluene (2,4,6-TNT) and 2,4-dinitrotoluene (2,4-DNT) are two common nitroaromatic compounds in ammunition. Their leakage leads to serious environmental pollution and threatens human health. It is important to remove or decompose them rapidly and efficiently. In this work, we present that light-powered TiO₂/Pt Janus micromotors have high efficiency for the “on-the-fly” photocatalytic degradation of 2,4-DNT and 2,4,6-TNT in pure water under UV irradiation. The redox reactions, induced by photogenerated holes and electrons on the TiO₂/Pt Janus micromotor surfaces, produce a local electric field that propels the micromotors as well as oxidative species that are able to photodegrade 2,4-DNT and 2,4,6-TNT. Furthermore, the moving TiO₂/Pt Janus micromotors show an efficient degradation of nitroaromatic compounds as compared to the stationary ones thanks to the enhanced mixing and mass transfer in the solution by movement of these micromotors. Such fuel-free light-powered micromotors for explosive degradation are expected to find a way to environmental remediation and security applications

Fuel-Free Light-Powered TiO₂/Pt Janus Micromotors for Enhanced Nitroaromatic Explosives Degradation

Nitroaromatic explosives such as 2,4,6-trinitrotoluene (2,4,6-TNT) and 2,4-dinitrotoluene (2,4-DNT) are two common nitroaromatic compounds in ammunition. Their leakage leads to serious environmental pollution and threatens human health. It is important to remove or decompose them rapidly and efficiently. In this work, we present that light-powered TiO₂/Pt Janus micromotors have high efficiency for the “on-the-fly” photocatalytic degradation of 2,4-DNT and 2,4,6-TNT in pure water under UV irradiation. The redox reactions, induced by photogenerated holes and electrons on the TiO₂/Pt Janus micromotor surfaces, produce a local electric field that propels the micromotors as well as oxidative species that are able to photodegrade 2,4-DNT and 2,4,6-TNT. Furthermore, the moving TiO₂/Pt Janus micromotors show an efficient degradation of nitroaromatic compounds as compared to the stationary ones thanks to the enhanced mixing and mass transfer in the solution by movement of these micromotors. Such fuel-free light-powered micromotors for explosive degradation are expected to find a way to environmental remediation and security applications

Autonomous Motion and Temperature-Controlled Drug Delivery of Mg/Pt-Poly(<i>N</i>‑isopropylacrylamide) Janus Micromotors Driven by Simulated Body Fluid and Blood Plasma

In this work, we have demonstrated the autonomous motion of biologically-friendly Mg/Pt-Poly­(<i>N</i>-isopropylacrylamide) (PNIPAM) Janus micromotors in simulated body fluids (SBF) or blood plasma without any other additives. The pit corrosion of chloride anions and the buffering effect of SBF or blood plasma in removing the Mg­(OH)₂ passivation layer play major roles for accelerating Mg–H₂O reaction to produce hydrogen propulsion for the micromotors. Furthermore, the Mg/Pt-PNIPAM Janus micromotors can effectively uptake, transport, and temperature-control-release drug molecules by taking advantage of the partial surface-attached thermoresponsive PNIPAM hydrogel layers. The PNIPAM hydrogel layers on the micromotors can be easily replaced with other responsive polymers or antibodies by the surface modification strategy, suggesting that the as-proposed micromotors also hold a promising potential for separation and detection of heavy metal ions, toxicants, or proteins

Responsive Hydrogel-based Photonic Nanochains for Microenvironment Sensing and Imaging in Real Time and High Resolution

Microenvironment sensing and imaging are of importance in microscale zones like microreactors, microfluidic systems, and biological cells. But they are so far implemented only based on chemical colors from dyes or quantum dots, which suffered either from photobleaching, quenching, or photoblinking behaviors, or from limited color gamut. In contrast, structural colors from hydrogel-based photonic crystals (PCs) may be stable and tunable in the whole visible spectrum by diffraction peak shift, facilitating the visual detection with high accuracy. However, the current hydrogel-based PCs are all inappropriate for microscale detection due to the bulk size. Here we demonstrate the smallest hydrogel-based PCs, responsive hydrogel-based photonic nanochains with high-resolution and real-time response, by developing a general hydrogen bond-guided template polymerization method. A variety of mechanically separated stimuli-responsive hydrogel-based photonic nanochains have been obtained in a large scale including those responding to pH, solvent, and temperature. Each of them has a submicrometer diameter and is composed of individual one-dimensional periodic structure of magnetic particles locked by a tens-of-nanometer-thick peapod-like responsive hydrogel shell. Taking the pH-responsive hydrogel-based photonic nanochains, for example, pH-induced hydrogel volume change notably alters the nanochain length, resulting in a significant variation of the structural color. The submicrometer size endows the nanochains with improved resolution and response time by 2–3 orders of magnitude than the previous counterparts. Our results for the first time validate the feasibility of using structural colors for microenvironment sensing and imaging and may further promote the applications of responsive PCs, such as in displays and printing

Complex-Mediated Synthesis of Tantalum Oxyfluoride Hierarchical Nanostructures for Highly Efficient Photocatalytic Hydrogen Evolution

In this work, we have, for the first time, developed a facile wet-chemical route to obtain a novel photocatalytic material of tantalum oxyfluoride hierarchical nanostructures composed of amorphous cores and single crystalline TaO₂F nanorod shells (ACHNs) by regulating the one-step hydrothermal process of TaF₅ in a mixed solution of isopropanol (i-PrOH) and H₂O. In this approach, elaborately controlling the reaction temperature and volume ratio of i-PrOH and H₂O enabled TaF₅ to transform into intermediate coordination complex ions of [TaOF₃·2F]^2– and [TaF₇]^2–, which subsequently produced tantalum oxyfluoride ACHNs via a secondary nucleation and growth due to a stepwise change in hydrolysis rates of the two complex ions. Because of the unique chemical composition, crystal structure and micromorphology, the as-prepared tantalum oxyfluoride ACHNs show a more negative flat band potential, an accelerated charge transfer, and a remarkable surface area of 152.4 m² g^–1 contributing to increased surface reaction sites. As a result, they exhibit a photocatalytic activity for hydrogen production up to 1.95 mmol h^–1 g^–1 under the illumination of a simulated solar light without any assistance of co-catalysts, indicating that the as-prepared tantalum oxyfluoride ACHNs are a novel promising photocatalytic material for hydrogen production

Low-Cost Carbothermal Reduction Preparation of Monodisperse Fe₃O₄/C Core–Shell Nanosheets for Improved Microwave Absorption

This paper demonstrates a facile and low-cost carbothermal reduction preparation of monodisperse Fe₃O₄/C core–shell nanosheets (NSs) for greatly improved microwave absorption. In this protocol, the redox reaction between sheet-like hematite (α-Fe₂O₃) precursors and acetone under inert atmosphere and elevated temperature generates Fe₃O₄/C core–shell NSs with the morphology inheriting from α-Fe₂O₃. Thus, Fe₃O₄/C core–shell NSs of different sizes (<i>a</i>) and Fe₃O₄/C core–shell nanopolyhedrons are obtained by using different precursors. Benefited from the high crystallinity of the Fe₃O₄ core and the thin carbon layer, the resultant NSs exhibit high specific saturation magnetization larger than 82.51 emu·g^–1. Simultaneously, the coercivity enhances with the increase of <i>a</i>, suggesting a strong shape anisotropy effect. Furthermore, because of the anisotropy structure and the complementary behavior between Fe₃O₄ and C, the as-obtained Fe₃O₄/C core–shell NSs exhibit strong natural magnetic resonance at a high frequency, enhanced interfacial polarization, and improved impedance matching, ensuring the enhancement of the microwave absorption. The 250 nm NSs–paraffin composites exhibit reflection loss (RL) lower than −20 dB (corresponding to 99% absorption) in a large frequency (<i>f</i>) range of 2.08–16.40 GHz with a minimum RL of −43.95 dB at <i>f</i> = 3.92 GHz when the thickness is tuned from 7.0 to 1.4 mm, indicating that the Fe₃O₄/C core–shell NSs are a good candidate to manufacture high-performance microwave absorbers. Moreover, the as-developed carbothermal reduction method could be applied for the fabrication of other composites based on ferrites and carbon

Legislative Documents

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Flexible Guidance of Microengines by Dynamic Topographical Pathways in Ferrofluids

In this work, we demonstrate a simple, versatile, and real-time motion guidance strategy for artificial microengines and motile microorganisms in a ferrofluid by dynamic topographical pathways (DTPs), which are assembled from superparamagnetic nanoparticles in response to external magnetic field (<i>H</i>). In this general strategy, the DTPs can exert anisotropic resistance forces on autonomously moving microengines and thus regulate their orientation. As the DTPs with different directions and lengths can be reversibly and swiftly assembled in response to the applied <i>H</i>, the microengines in the ferrofluid can be guided on demand with controlled motion directions and trajectories, including circular, elliptical, straight-line, semi-sine, and sinusoidal trajectories. The as-demonstrated control strategy obviates reliance on the customized responses of micromotors and applies to autonomously propelling agents swimming both in bulk and near substrate walls. Furthermore, the microengines (or motile microorganisms) in a ferrofluid can be considered as an integrated system, and it may inspire the development of intelligent systems with cooperative functions for biomedical and environmental applications