Fast One-Step Fabrication of Highly Regular Microscrolls with Controllable Surface Morphology.

Although rolling origami technology has provided convenient access to three-dimensional (3D) microstructure systems, the high yield and scalable construction of complex rolling structures with well-defined geometry without impeding functionality has remained challenging. The straightforward, one-step fabrication that uses external mechanical stress to scroll micrometer thick, flexible planar films with centimeter lateral dimensions into tubular or spiral geometry within a few seconds is demonstrated. The method allows controlling the scrolls' diameter, number of windings and nanostructured surface morphology, and is applicable to a wide range of functional materials.

Self-supporting VO nanofiber-based electrodes for magnesium-lithium-ion hybrid batteries.

The increasing demand for high energy, sustainable and safer rechargeable electrochemical storage systems for portable devices and electric vehicles can be satisfied by the use of hybrid batteries. Hybrid batteries, such as magnesium-lithium-ion batteries (MLIBs), using a dual-salt electrolyte take advantage of both the fast Li intercalation kinetics of lithium-ion batteries (LIBs) and the dendrite-free anode reactions. Here we report the utilization of a binder-free and self-supporting VO nanofiber-based cathode for MLIBs.

Highly Porous Free-Standing rGO/SnO Pseudocapacitive Cathodes for High-Rate and Long-Cycling Al-Ion Batteries.

Establishing energy storage systems beyond conventional lithium ion batteries requires the development of novel types of electrode materials. Such materials should be capable of accommodating ion species other than Li, and ideally, these ion species should be of multivalent nature, such as Al. Along this line, we introduce a highly porous aerogel cathode composed of reduced graphene oxide, which is loaded with nanostructured SnO.

Fast-Growing Bacterial Cellulose with Outstanding Mechanical Properties via Cross-Linking by Multivalent Ions.

Bacterial cellulose is an organic product of certain bacterias' metabolism. It differs from plant cellulose by exhibiting a high strength and purity, making it especially interesting for flexible electronics, membranes for water purification, tissue engineering for humans or even as artificial skin and ligaments for robotic devices. However, bacterial cellulose's naturally slow growth rate has limited its large-scale applicability to date.

Binder-Free VO Cathode for High Energy Density Rechargeable Aluminum-Ion Batteries.

Nowadays, research on electrochemical storage systems moves into the direction of post-lithium-ion batteries, such as aluminum-ion batteries, and the exploration of suitable materials for such batteries. Vanadium pentoxide (VO) is one of the most promising host materials for the intercalation of multivalent ions. Here, we report on the fabrication of a binder-free and self-supporting VO micrometer-thick paper-like electrode material and its use as the cathode for rechargeable aluminum-ion batteries.

Bioinspired synthesis of SnO crosses as backbone in artificial sponges.

The distinct electronic properties, including p-type semiconducting and a wide optical band gap, renders SnO suitable for applications such as microelectronic devices, gas sensors and electrodes. However, the synthesis of SnO is rather challenging due to the instability of the oxide, which is usually obtained as a by-product of SnO fabrication. In this work, we developed a bioinspired synthesis, based on a hydrothermal approach, for the direct production of SnO nanoparticles.

Peptide Controlled Shaping of Biomineralized Tin(II) Oxide into Flower-Like Particles.

The size and morphology of metal oxide particles have a large impact on the physicochemical properties of these materials, e.g., the aspect ratio of particles affects their catalytic activity.

Genetically Induced In Situ-Poling for Piezo-Active Biohybrid Nanowires.

Polycrystalline piezo-active materials only exhibit a high macroscopic piezoresponse if they consist of particles with oriented crystal directions and aligned intrinsic dipole moments. For ferroelectric materials, the postsynthesis alignment of the dipoles is generally achieved by electric poling procedures. However, there are numerous technically interesting non-ferroelectric piezo-active materials like zinc oxide (ZnO).

Free-standing nanostructured vanadium pentoxide films for metal-ion batteries.

Owing to their unique layer structure, high aspect ratio and intercalation capability, vanadium pentoxide (V2O5) nanofibers are close-to-ideal building blocks for high performance electrodes for metal-ion batteries. However, thus far investigated electrodes composed of V2O5 nanofibers mostly contain binders and conductive agents, which reduce the electrodes' gravimetric capacity. Here we demonstrate self-supporting V2O5 nanofiber-based films that combine high mechanical flexibility and stability with good electrical conductivity.

Ultrahigh Damping Capacities in Lightweight Structural Materials.

The demand to outperform current technologies pushes scientists to develop novel strategies, which enable the fabrication of materials with exceptional properties. Along this line, lightweight structural materials are of great interest due to their versatile applicability as sensors, catalysts, battery electrodes, and acoustic or mechanical dampers. Here, we report a strategy to design ultralight (ρ = 3 mg/cm) and hierarchically structured ceramic scaffolds of macroscopic size.

Mesocrystalline calcium silicate hydrate: A bioinspired route toward elastic concrete materials.

Calcium silicate hydrate (C-S-H) is the binder in concrete, the most used synthetic material in the world. The main weakness of concrete is the lack of elasticity and poor flexural strength considerably limiting its potential, making reinforcing steel constructions necessary. Although the properties of C-S-H could be significantly improved in organic hybrids, the full potential of this approach could not be reached because of the random C-S-H nanoplatelet structure.

Template-controlled piezoactivity of ZnO thin films grown via a bioinspired approach.

Biomaterials are used as model systems for the deposition of functional inorganic materials under mild reaction conditions where organic templates direct the deposition process. In this study, this principle was adapted for the formation of piezoelectric ZnO thin films. The influence of two different organic templates (namely, a carboxylate-terminated self-assembled monolayer and a sulfonate-terminated polyelectrolyte multilayer) on the deposition and therefore on the piezoelectric performance was investigated.

Cuttlebone-like VO Nanofibre Scaffolds - Advances in Structuring Cellular Solids.

The synthesis of ceramic materials combining high porosity and permeability with good mechanical stability is challenging, as optimising the latter requires compromises regarding the first two properties. Nonetheless, significant progress can be made in this direction by taking advantage of the structural design principles evolved by nature. Natural cellular solids achieve good mechanical stability via a defined hierarchical organisation of the building blocks they are composed of.

Strengthening of Ceramic-based Artificial Nacre via Synergistic Interactions of 1D Vanadium Pentoxide and 2D Graphene Oxide Building Blocks.

Nature has evolved hierarchical structures of hybrid materials with excellent mechanical properties. Inspired by nacre's architecture, a ternary nanostructured composite has been developed, wherein stacked lamellas of 1D vanadium pentoxide nanofibres, intercalated with water molecules, are complemented by 2D graphene oxide (GO) nanosheets. The components self-assemble at low temperature into hierarchically arranged, highly flexible ceramic-based papers.

Piezoelectric Templates - New Views on Biomineralization and Biomimetics.

Biomineralization in general is based on electrostatic interactions and molecular recognition of organic and inorganic phases. These principles of biomineralization have also been utilized and transferred to bio-inspired synthesis of functional materials during the past decades. Proteins involved in both, biomineralization and bio-inspired processes, are often piezoelectric due to their dipolar character hinting to the impact of a template's piezoelectricity on mineralization processes.

Silicateins--a novel paradigm in bioinorganic chemistry: enzymatic synthesis of inorganic polymeric silica.

The inorganic matrix of the siliceous skeletal elements of sponges, that is, spicules, is formed of amorphous biosilica. Until a decade ago, it remained unclear how the hard biosilica monoliths of the spicules are formed in sponges that live in a silica-poor (<50 μM) aquatic environment. The following two discoveries caused a paradigm shift and allowed an elucidation of the processes underlying spicule formation; first the discovery that in the spicules only one major protein, silicatein, exists and second, that this protein displays a bio-catalytical, enzymatic function.

Hydrogen-bond reinforced vanadia nanofiber paper of high stiffness.

Low-temperature, solution-based self-assembly of vanadia nanofibers yields a free-standing, ceramic paper with an outstanding combination of high strength, stiffness, and macroscopic flexibility. Its excellent mechanical performance results from a brick-and-mortar like architecture, which combines strong covalent bonding within the single-crystalline nanofibers with an intricate hydrogen bonding network between them.

Fabrication and characterization of biocompatible nacre-like structures from α-zirconium hydrogen phosphate hydrate and chitosan.

Composite materials with an ordered layered structure resembling that of nacre were fabricated by layer-by-layer assembly making use of presynthesized α-zirconium hydrogenphosphate hydrate (ZrP) platelets and chitosan. These two biocompatible materials were chosen in view of possible applications in the biomedical field, e.g.

Toughening through nature-adapted nanoscale design.

The extraordinary combination of strength and toughness attained by nature's highly sophisticated structural design in nacre has inspired the synthesis of novel nanocomposites. In this context, the organic-inorganic hierarchical design of nacre has been mimicked. However, two key features of nacre, namely the scaling of the structural components and the low content of the organic phase, have not been replicated yet.

Bio-sintering processes in hexactinellid sponges: fusion of bio-silica in giant basal spicules from Monorhaphis chuni.

The two sponge classes, Hexactinellida and Demospongiae, comprise a skeleton that is composed of siliceous skeletal elements (spicules). Spicule growth proceeds by appositional layering of lamellae that consist of silica nanoparticles, which are synthesized via the sponge-specific enzyme silicatein. While in demosponges during maturation the lamellae consolidate to a solid rod, the lamellar organization of hexactinellid spicules largely persists.