Hot Fingers: Individually Addressable Graphene-Heater Actuated Liquid Crystal Grippers.

Liquid crystal-based actuators are receiving increased attention for their applications in wearables and biomedical or surgical devices, with selective actuation of individual parts/fingers still being in its infancy. This work presents the design and realization of two gripper devices with four individually addressable liquid-crystal network (LCN) actuators thermally driven via printed graphene-based heating elements. The resistive heat causes the all-organic actuator to bend due to anisotropic volume expansions of the splay-aligned sample.

Urchin-Like Structured MoO /Mo P/Mo C Triple-Interface Heterojunction Encapsulated within Nitrogen-Doped Carbon for Enhanced Hydrogen Evolution Reaction.

The development of highly efficient and cost-effective hydrogen evolution reaction (HER) catalysts is highly desirable to efficiently promote the HER process, especially under alkaline condition. Herein, a polyoxometalates-organic-complex-induced carbonization method is developed to construct MoO /Mo P/Mo C triple-interface heterojunction encapsulated into nitrogen-doped carbon with urchin-like structure using ammonium phosphomolybdate and dopamine. Furthermore, the mass ratio of dopamine and ammonium phosphomolybdate is found critical for the successful formation of such triple-interface heterojunction.

Waste-Derived Copper-Lead Electrocatalysts for CO Reduction.

It remains a real challenge to control the selectivity of the electrocatalytic CO reduction (eCOR) reaction to valuable chemicals and fuels. Most of the electrocatalysts are made of non-renewable metal resources, which hampers their large-scale implementation. Here, we report the preparation of bimetallic copper-lead (CuPb) electrocatalysts from industrial metallurgical waste.

Ceria-Supported Cobalt Catalyst for Low-Temperature Methanation at Low Partial Pressures of CO.

The direct catalytic conversion of atmospheric CO to valuable chemicals is a promising solution to avert negative consequences of rising CO concentration. However, heterogeneous catalysts efficient at low partial pressures of CO still need to be developed. Here, we explore Co/CeO as a catalyst for the methanation of diluted CO streams.

Mapping and Controlling Liquid Layer Thickness in Liquid-Phase (Scanning) Transmission Electron Microscopy.

Liquid-Phase (Scanning) Transmission Electron Microscopy (LP-(S)TEM) has become an essential technique to monitor nanoscale materials processes in liquids in real-time. Due to the pressure difference between the liquid and the microscope vacuum, bending of the silicon nitride (SiN ) membrane windows generally occurs. This causes a spatially varying liquid layer thickness that makes interpretation of LP-(S)TEM results difficult due to a locally varying achievable resolution and diffusion limitations.

Elucidating dynamic behavior of synthetic supramolecular polymers in water by hydrogen/deuterium exchange mass spectrometry.

A comprehensive understanding of the structure, self-assembly mechanism, and dynamics of one-dimensional supramolecular polymers in water is essential for their application as biomaterials. Although a plethora of techniques are available to study the first two properties, there is a paucity in possibilities to study dynamic exchange of monomers between supramolecular polymers in solution. We recently introduced hydrogen/deuterium exchange mass spectrometry (HDX-MS) to characterize the dynamic nature of synthetic supramolecular polymers with only a minimal perturbation of the chemical structure.

Translating 2D Director Profile to 3D Topography in a Liquid Crystal Polymer.

Morphological properties of surfaces play a key role in natural and man-made objects. The development of robust methods to fabricate micro/nano surface structures has been a long pursuit. Herein, an approach based on molecular self-assembling of liquid crystal polymers (LCPs) is presented to directly translate 2D molecular director profiles obtained by a photoalignment procedure into 3D topographies, without involving further multi-step lithographic processes.

Photoswitching between Water-Tolerant Adhesion and Swift Release by Inverting Liquid Crystal Fingerprint Topography.

Although switchable adhesive surfaces are important and desirable for soft robotics, it is still challenging to replicate nature's switchable adhesion capability on artificial surfaces, especially for underwater applications. Here polymeric coatings with fingerprint topographies that are capable of switching the surface adhesion upon light illumination are reported. This is achieved via a synergistic combination of surface topographical inversion and spatially selective distribution of adhesive polymers.

A Soft Transporter Robot Fueled by Light.

Mobile organisms with ability for locomotion and transportation, such as humans and other animals, utilize orchestrated actuation to perform actions. Mimicking these functionalities in synthetic, light-responsive untethered soft-bodied devices remains a challenge. Inspired by multitasking and mobile biological systems, an untethered soft transporter robot with controlled multidirectional locomotion with the ability of picking up, transporting, and delivering cargo driven entirely by blue light is created.

Assessment of the Location of Pt Nanoparticles in Pt/zeolite Y/γ-AlO Composite Catalysts.

The location of Pt nanoparticles was studied in Pt/zeolite Y/γ-AlO composite catalysts prepared by HPtCl ⋅ 6HO (CPA) or Pt(NH)(NO) (PTA) as Pt precursors. The aim of this study is to validate findings from Transmission Electron Microscopy (TEM) by using characterization techniques that sample larger amounts of catalyst per measurement. Quantitative X-ray Photoelectron Spectroscopy (XPS) showed that the catalyst prepared with CPA led to a significantly higher Pt/Al atomic ratio than the catalyst prepared with PTA confirming that the 1-2 nm sized Pt nanoparticles in the former catalyst were located on the open and mesoporous γ-AlO component, whereas they were located in the micropores of zeolite Y in the latter.

Osteoporotic Bone Recovery by a Highly Bone-Inductive Calcium Phosphate Polymer-Induced Liquid-Precursor.

Osteoporosis is an incurable chronic disease characterized by a lack of mineral mass in the bones. Here, the full recovery of osteoporotic bone is achieved by using a calcium phosphate polymer-induced liquid-precursor (CaP-PILP). This free-flowing CaP-PILP material displays excellent bone inductivity and is able to readily penetrate into collagen fibrils and form intrafibrillar hydroxyapatite crystals oriented along the -axis.

Water-Based Synthesis of Hydrophobic Ionic Liquids [N][oleate] and [P][oleate] and their Bioprocess Compatibility.

The conversion of organic waste streams into carboxylic acids as renewable feedstocks results in relatively dilute aqueous streams. Carboxylic acids can be recovered from such streams by using liquid-liquid extraction. Hydrophobic ionic liquids (ILs) are novel extractants that can be used for carboxylic acid recovery.

Stability of CoP Electrocatalysts in Continuous and Interrupted Acidic Electrolysis of Water.

Cobalt phosphides are an emerging earth-abundant alternative to platinum-group-metal-based electrocatalysts for the hydrogen evolution reaction (HER). Yet, their stability is inferior to platinum and compromises the large-scale applicability of CoP in water electrolyzers. In the present study, we employed flat, thin CoP electrodes prepared through the thermal phosphidation (PH) of CoO films made by plasma-enhanced atomic layer deposition to evaluate their stability in acidic water electrolysis by using a multi-technique approach.

Mechanism of Carbon Monoxide Dissociation on a Cobalt Fischer-Tropsch Catalyst.

The way in which the triple bond in CO dissociates, a key reaction step in the Fischer-Tropsch (FT) reaction, is a subject of intense debate. Direct CO dissociation on a Co catalyst was probed by CO/CO scrambling in the absence and presence of H. The initial scrambling rate without H was significantly higher than the rate of CO consumption under CO hydrogenation conditions, which indicated that the surface contained sites sufficiently reactive to dissociate CO without the assistance of H atoms.

On the Role of Acidity in Bulk and Nanosheet [T]MFI (T=Al Ga, Fe, B) Zeolites in the Methanol-to-Hydrocarbons Reaction.

The influence of framework substituents (Al, Ga, Fe and B) and morphology (bulk vs. nanometer-sized sheets) of MFI zeolites on the acidity and catalytic performance in the methanol-to-hydrocarbons (MTH) reaction was investigated. The Brønsted acid density and strength decreased in the order Al(OH)Si>Ga(OH)Si>Fe(OH)Si≫B(OH)Si.

Silica Mineralization of DNA-Inspired 1D and 2D Supramolecular Polymers.

The preparation of hybrid materials from supramolecular polymers through the sol-gel process is presented. Supramolecular polymers are assembled from phosphodiester-linked pyrene oligomers and act as water-soluble one- or two-dimensional templates for silicification. The fibrillary and planar morphologies of the assemblies, as well as the excitonic interactions between the chromophores, remain unaffected by the silicification process.

Effects of the Functionalization of the Ordered Mesoporous Carbon Support Surface on Iron Catalysts for the Fischer-Tropsch Synthesis of Lower Olefins.

Ordered mesoporous carbon (CMK-3) with different surface modifications is applied as a support for Fe-based catalysts in the Fischer-Tropsch to olefins synthesis (FTO) with and without sodium and sulfur promoters. Different concentrations of functional groups do not affect the size (3-5 nm) of Fe particles in the fresh catalysts but iron (carbide) supported on N-enriched CMK-3 and a support with a lower concentration of functional groups show higher catalytic activity under industrially relevant FTO conditions (340 °C, 10 bar, H/CO=2) compared to a support with an O-enriched surface. The addition of promoters leads to more noticeable enhancements of the catalytic activity (3-5 times higher) and the selectivity to C-C olefins (≈2 times higher) than surface functionalization of the support.

A DFT Study of CO Hydrogenation on Faujasite-Supported Ir Clusters: on the Role of Water for Selectivity Control.

Reaction mechanisms for the catalytic hydrogenation of CO by faujasite-supported Ir clusters were studied by periodic DFT calculations. The reaction can proceed through two alternative paths. The thermodynamically favoured path results in the reduction of CO to CO, whereas the other, kinetically preferred channel involves CO hydrogenation to formic acid under water-free conditions.

X-ray Excited Optical Fluorescence and Diffraction Imaging of Reactivity and Crystallinity in a Zeolite Crystal: Crystallography and Molecular Spectroscopy in One.

Structure-activity relationships in heterogeneous catalysis are challenging to be measured on a single-particle level. For the first time, one X-ray beam is used to determine the crystallographic structure and reactivity of a single zeolite crystal. The method generates μm-resolved X-ray diffraction (μ-XRD) and X-ray excited optical fluorescence (μ-XEOF) maps of the crystallinity and Brønsted reactivity of a zeolite crystal previously reacted with a styrene probe molecule.