Structure Of Functional Materials Research Articles

Inverse Design of Ferroelectric-Order in Perovskite Crystal for Self-Powered Ultraviolet Photodetection.

It has always been a hot topic to design an orderly mesoscopic structure in functional materials to tailor the macroscopic properties or realize new functions. The existence of domains in ferroelectric materials has been proven to affect the macroscopic properties, being actively studied in nonlinear optical conversion and piezoelectric effects. However, the high-efficiency photoelectric conversion capability of ferroelectric crystals has not yet been explored. Here, the authors study the orderly arrangement of ferroelectric order in KTa1- x Nbx O3 (KTN) perovskite crystals, and design the "head-to-head" domains by tuning the Curie temperature Tc , thereby generating abundant charged domain walls and robust conductive channels for electrons and holes. An ultrahigh ultraviolet photoresponsivity is achieved in the KTN crystal under zero bias voltage, being about four orders magnitude higher than that of the well-known ferroelectric materials. The substantial improvement can be attributed to the judiciously designed ferroelectric order, as demonstrated by the conductive atomic force microscopy. In addition, KTN detector exhibits high stability and reliability after high-temperature and fatigue treatment. KTN crystal features giant photoresponsivity, high electric-optical coefficient, and large χ(2) nonlinearity concurrently, indicating its great potential for application of all-optical devices on photonic chips.

Gene-like Precise Construction of Functional DNA Materials

ConspectusDeveloping a new system of material chemistry is an important molecular foundation for the design and preparation of functional materials, which resembles the preparation of raw materials such as bricks for constructing a building that determines the quality of the building. However, precisely controlling the synthesis processes and structures of functional materials always remains a grand challenge. It is expected to propose a paradigm of “gene-like” precise construction to realize the rational synthesis of functional materials, i.e., a “structure-function-application” principle for the precise construction. As the core genetic material of life, the DNA molecule is a bioactive macromolecule that can accurately encode genetic information and also can act as the generic molecular building block for the precise construction of functional materials. In this Account, we describe our work on the design and construction of functional DNA materials, to illustrate the principle of “gene-like” construction of functional DNA materials. The DNA molecule shows the unique advantages in the “gene-like” construction of functional materials, mainly including the precise arrangement of bases (monomers), the controllable design and assembly of structure, the precise transmission of sequence information, and customization of function. First, the number and sequence of four deoxynucleotide monomers that constitute the DNA strand can be rationally designed and accurately synthesized. Second, the sequence information on DNA endows the precise and efficient assembly of DNA molecules and ensures the precise regulation on the specific biological functions of functional DNA materials. Third, the functions of DNA materials can couple with the biological environments, so as to achieve the predetermined applications. Based on the scale of the constructed DNA materials, we categorize DNA materials into three classes: molecular scale, nanoscale, and macroscale. At the molecular scale, the representative material is branched DNA-based materials; the construction strategies mainly include target-triggered polymerization, enzymatic extension, and hybrid coupling; the applications mainly include the nonenzymatic detection of base mutation, the construction of artificial cells for the study of compartmentalization and the confinement effect, and the regulation of optical and antibacterial properties of supernanoclusters. At the nanoscale, the representative material is the DNA nanocomplex; the construction strategies mainly include hybridization with polymer, small molecule, and metal ions; the applications mainly include gene drug delivery and luminescence bioimaging. At the macroscale, the representative material is the DNA hydrogel; the construction strategies mainly include double-rolling circle amplification (double-RCA), multistage-RCA, and chemical cross-linking; the applications mainly include cell isolation, cell delivery, antibacterial agents, and self-healing electric circuits. Based on the “gene-like” paradigm, we expect to develop a wider variety of functional DNA materials by the precise regulation of DNA assembly behaviors and topological structures. We further envision that our work on the design, synthesis, and applications of functional DNA materials is a typical paradigm for the “gene-like” precise construction of functional materials and hopefully will promote the development of materials genome.

Controlled tuning of atomistic structure in functional materials by acoustic standing waves and electric fields

Controlled tuning of atomistic structure in functional materials by acoustic standing waves and electric fields

Recent Advances in the Understanding of the Evolution of Surfaces and Interfaces in Solid Oxide Cells

AbstractIn solid oxide electrochemical cells the critical processes of fuel oxidation and oxygen reduction occur at surfaces, and ultimately define the performance of the devices. Understanding how these process occur and the role of defects such as dislocations and grain boundaries in these charge transfer processes, and the effect of cation segregation on surface exchange are all topics of current significance. To address these issues, a suite of advanced analytical techniques are developed to allow in situ analysis of key processes, complementing established ex‐situ techniques. In addition the application of surface sensitive techniques such as surface diffraction and ion scattering spectroscopy, offer unprecedented levels of information on the surface chemistry and structure of functional materials.

Bayesian inference of atomistic structure in functional materials

Tailoring the functional properties of advanced organic/inorganic heterogeneous devices to their intended technological applications requires knowledge and control of the microscopic structure inside the device. Atomistic quantum mechanical simulation methods deliver accurate energies and properties for individual configurations, however, finding the most favourable configurations remains computationally prohibitive. We propose a ‘building block’-based Bayesian Optimisation Structure Search (BOSS) approach for addressing extended organic/inorganic interface problems and demonstrate its feasibility in a molecular surface adsorption study. In BOSS, a Bayesian model identifies material energy landscapes in an accelerated fashion from atomistic configurations sampled during active learning. This allowed us to identify several most favourable molecular adsorption configurations for C60 on the (101) surface of TiO2 anatase and clarify the key molecule-surface interactions governing structural assembly. Inferred structures were in good agreement with detailed experimental images of this surface adsorbate, demonstrating good predictive power of BOSS and opening the route towards large-scale surface adsorption studies of molecular aggregates and films.

Graphene and its derivatives as versatile templates for materials synthesis and functional applications.

The obvious incongruity between the increasing depletion of fossil fuel and the finite amount of resources has motivated us to seek means to maintain sustainability in our society. Developing renewable and highly efficient energy conversion and storage systems represents one of the most promising and viable methods. Although the efficiency of energy conversion and storage devices depends on various factors, their overall performances strongly rely on the structure and functional properties of materials. Graphene and its derivatives as versatile templates for materials synthesis have garnered widespread interest because of their flexible capability to tune the morphology and structure of functional materials. Herein, we have demonstrated recent progress on graphene and its derivatives as versatile templates for materials synthesis, particularly highlighting the basic fundamental roles of graphene in the materials preparation process. Then, a concise overview of the functional applications of materials obtained from graphene-templated approaches has been presented with a few selected examples to show the wide scope of potential in energy storage and conversion. Finally, a brief perspective and potential future challenges in this burgeoning research area have been discussed.

Near Surface Phase Transition of Solute Derived Pt Monolayers

As the loadings of precious metals in surface-chemical systems continue to decrease for photo-and electro-catalysts for energy and environmental applications, the study of near-surface electronic and atomic structure in functional materials becomes critically important. Extremely small quantities of active elements, whether grown as clusters or ultrathin films, exhibit changes in catalytic activity that arise from both size effects and electron-transfer effects. These size and transfer effects can be related to increased propensity for oxidation of the metallic deposit, as well as to various changes in electrochemical performance such as durability or required overpotential for a given reaction. This work establishes a minimum threshold for Pt loading beyond which bulk-type electronic behavior may be expected. By iteratively growing atomic monolayers and multilayers using self-limited electrodeposition and studying these films using core-electron spectroscopy (X-ray absorption and X-ray photoelectron spectroscopy), electrochemical methods and DFT-based computations the fundamental interactions that govern oxidation state and electron transfer near the surface of a Pt–Au bimetallic system have been explored. It has been shown that the Pt–Au system exhibits increased tendency for the Pt layer to remain cationic below a minimum threshold film thickness of two monolayers. At monodispersed levels of submonolayer coverage Pt exhibits deviated electronic structure, reactivity, and metal stability compared to films in excess of this minimum threshold thickness. At three monolayers Pt is thick enough to avoid the preference for cationicity and the resulting higher rates of metal dissolution, but thin enough to benefit from electron transfers from Au that assist in lowering the overpotentials for CO oxidation. This study shows the efficacy of a concerted method for the investigation of near-surface phenomena in multicomponent systems. By combining electrochemical and vacuum studies of solute-derived samples with advanced computational techniques, a multifaceted understanding of these architectures has been achieved.

Hemoglobin‐CdTe‐CaCO3@Polyelectrolytes 3D Architecture: Fabrication, Characterization, and Application in Biosensing

AbstractA Hemoglobin‐CdTe‐CaCO3@polyelectrolyte 3D architecture is synthesized by a stepwise layer‐by‐layer method and is further used to fabricate an electrochemistry biosensor. While the calcium carbonate (CaCO3) microsphere acts as an effective host for the loading of cadmium telluride (CdTe) quantum dots due to its channel‐like structure, the polyelectrolyte layers further increase the loading amount and help in the formation of a thick and uniform quantum‐dot “shell”, which not only improves the stability of the spheres in water, but also contributes to the fast and effective direct electron transfer between the protein redox center and the macroscopic electrode. The materials are characterized and compared, and the possible mechanism for the direct electrochemistry phenomenon is hypothesized. Our work not only provides a facile and effective route for the preparation of quantum‐dot‐loaded spheres, but also sets an example of how the structure of functional materials can be tuned and related to their applications. In addition, it is one of the few examples of using CaCO3 microspheres in quantum‐dot loading and biosensing.

SYNTHESIS OF DESIGNED TEMPLATES FOR NOVEL SEMICONDUCTOR MATERIALS WITH HOLLOW STRUCTURES

We develop several strategies for the synthesis of novel templates based on a solution method aimed at the synthesis of hollow structures for functional materials. Hollow ZnO microrings are successfully established using a new sacrificial template route by employing insoluble salts as the template. We also develop an in situ template strategy to synthesize ZnO tubes on zinc foil in an acid medium to avoid the multiple steps that are currently used in the preparation of other hollow structures. Finally, a bubble template method is discovered for the preparation of a new type of complex ZnO hollow structures constructed by polyhedral particles. The unique methods presented herein provide a new template technique for chemically designing and synthesizing functional materials with hollow structures.

機能材料の内部構造分析法

機能材料の内部構造分析法