Hybrid helical magnetic microrobots are achieved by sequential electrodeposition of a CoNi alloy and PPy inside a photoresist template patterned by 3D laser lithography. A controlled actuation of the microrobots by a rotating magnetic field is demonstrated in a fluidic environment.

Here, we present a new concept of a core-shell type ionic liquid/metal organic framework (IL/MOF) composite. A hydrophilic IL, 1-(2-hydroxyethyl)-3-methylimidazolium dicyanamide, [HEMIM][DCA], was deposited on a hydrophobic zeolitic imidazolate framework, ZIF-8. The composite exhibited approximately 5.7 times higher CO uptake and 45 times higher CO/CH selectivity at 1 mbar and 25 °C compared to the parent MOF. Characterization showed that IL molecules deposited on the external surface of the MOF, forming a core (MOF)-shell (IL) type material, in which IL acts as a smart gate for the guest molecules.

Twenty-nine different imidazolium ionic liquids (ILs) were combined with two different metal−organic frameworks (MOFs), ZIF-8 and CuBTC, and the resulting IL/MOF composites were characterized in detail by combining X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer−Emmett−Teller (BET), and Fourier transform infrared (FTIR) spectroscopy. Characterization data illustrated that MOFs remained structurally intact upon combining them with ILs. Thermogravimetric analysis performed on IL/MOF composites showed that most of the composites have lower thermal stabilities compared to the bulk ILs and pristine MOFs, whereas composites with ILs having a functional group in their anions showed thermal stability limits higher than those of bulk ILs. The derivative onset temperatures representing the maximum tolerable temperatures of the composites were analyzed based on the structural differences in MOFs and ILs, such as the changes in the alkyl chain length, methylation on the C2 site, and functionalization of the cation and the size/electronic changes on the anion. Data illustrated that the maximum tolerable temperatures of IL/MOF composites decrease with an increase in the alkyl chain length on the IL's imidazolium ring. Substitution of the alkyl group with functionalized groups in the IL's imidazolium ring also led to a decrease in the maximum tolerable temperatures of the composites. Whereas, fluorination of the anion resulted in an increase in the thermal stability limits of the corresponding IL/MOF composites. Furthermore, ILs having a dicyanamide, acetate, and phosphate anion also showed an increase in their maximum tolerable temperatures when combined with CuBTC compared to their bulk counterparts. Moreover, simple structural descriptors for each cation and anion were defined by means of the density functional theory (DFT) calculations and used in the quantitative structure−property relationship (QSPR) analysis to correlate the maximum tolerable temperatures of IL/MOF composites to the IL's cation and anion structure. Results presented in this study will provide a guideline for the selection of proper IL−MOF pairs according to the application temperature of IL/MOF composites in various fields.

Wireless‐manipulated graphite coated nanomagnets are promising candidates for minimally invasive targeted drug delivery platforms. Iron nanowires coated with graphitic shells are synthesized by template‐assisted deposition. The use of porous aluminum oxide templates enables both the batch production of nanowires by electrodeposition and their subsequent conformal encapsulation in graphite using chemical vapor deposition (CVD). High quality graphitic shells are obtained when CVD conditions are optimized using acetylene as carbon feedstock at 740 °C. Interestingly, the iron nanowires transform into iron carbide during the CVD process leading to changes in magnetic properties. The graphite coated iron nanowires are precisely manipulated against a water flow (0.1 mm/s) using a magnetic field of 350 Oe and a gradient of 50 kOe m−1 in a 5‐DOF magnetic manipulation system. Our approach opens new avenues for the design and synthesis of functional graphite coated nanowires that are promising for nanorobotics applications.

We show that a significant enhancement of solar cell efficiency can be achieved in cells fabricated on black Si made using inductively coupled plasma-reactive ion etching (ICP-RIE). The ICP-RIE-fabricated black Si results in an array of vertically oriented defect-free Si nanocones (average height ∼150 nm; apex diameter ∼25 nm) exhibiting an average reflectance ≤2% over most of the relevant solar spectral range. The enabling role of the ultralow reflectance of the nanostructured black Si has been demonstrated using a heterojunction solar cell fabricated by depositing a n-type CdS film on p-Si nanocones followed by a transparent conducting coating of Al-doped ZnO (AZO). The fabricated n-CdS/p-Si heterojunction exhibits promising power conversion efficiency close to 3%, up from a mere efficient 0.15% for a similar cell fabricated on a planar Si. The effect of the fabrication process for the black Si on solar cell performance has been investigated through the measurements of carrier lifetime and surface recombination velocity. The accompanying model and simulation analysis shows that the conical structure leads to the effective dielectric constant varying smoothly from the value of the air at the top to the value of Si at the base over the length of the nanocone, leading to a substantial reduction of its reflectance.

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The surface properties of electrodeposited poly(pyrrole) (Ppy) doped with sodium dodecylbenzenesulphonate (NaDBS) are modified by two methods: addition of poly(ethylene glycol) (PEG) during the electrodeposition and through redox cycling post electrodeposition. X-ray photoelectron spectroscopy (XPS) was used to ascertain PEG incorporation and to analyze the change in the oxidation state of the polymer. Anodic cycling resulted in the formation of micrometer-sized surface cracks which increased the amount of Rhodamine-B dye adsorbed onto the surface, and played a role in decreasing the wettability of the surface. The change in surface wettability caused by these cracks was mitigated by the presence of PEG in the Ppy matrix. Compared to the incorporation of PEG, redox cycling was more effective in passively modulating the adhesion of NIH 3T3 fibroblast cells on the Ppy surface. Based on the attenuation of surface polarity of the Ppy surfaces by the incorporated PEG, a mechanism is proposed to explain the observed cell adhesion behavior.

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