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High piezoelectricity of (K,Na)NbO3 (KNN) lead-free materials benefits from a polymorphic phase transition (PPT) around room temperature, but its temperature sensitivity has been a bottleneck impeding their applications. We find that good thermal stability can be achieved in CaZrO3-modified KNN lead-free piezoceramics, in which the normalized strain d33* almost keeps constant from room temperature up to 140 oC. In situ synchrotron X-ray diffraction experiments combined with permitivity measurements disclose the occurrence of a new phase transformation under an electrical field, which extends the transition range between tetragonal and orthorhombic phases. It is revealed that such an electrically-enhanced diffused polymorphic phase transition (EED-PPT) contributed to the boosted thermal stability of KNN based lead-free piezoceramics with high piezoelectricity. The present approach based on phase engineering should also be effective in endowing other lead-free piezoelectrics with high piezoelectricity and good temperature stability.

High-performance photocatalysts should have highly crystallized nanocrystals (NCs) with small sizes, high separation efficiency of photogenerated electron–hole pairs, fast transport and consumption of photon-excited electrons from the surface of catalyst, high adsorption of organic pollutant, and suitable band gap for maximally utilizing sunlight energy. However, the design and synthesis of these versatile structures still remain a big challenge. Here, we report a novel strategy for the synthesis of ultrasmall and highly crystallized graphene–ZnFe2O4 photocatalyst through interface engineering by using interconnected graphene network as barrier for spatially confined growth of ZnFe2O4, as transport channels for photon-excited electron from the surface of catalyst, as well as the electron reservoir for suppressing the recombination of photogenerated electron–hole pairs. As a result, about 20 nm ZnFe2O4 NCs with highly crystallized (311) plane confined in the graphene network exhibit an excellent visible-light-driven photocatalytic activity with an ultrafast degradation rate of 1.924 × 10−7 mol g−1 s−1 for methylene blue, much higher than those of previously reported photocatalysts such as spinel-based photocatalysts (20 times), TiO2-based photocatalysts (4 times), and other photocatalysts (4 times). Our strategy can be further extended to fabricate other catalysts and electrode materials for supercapacitors and Li-ion batteries.

A series of lanthanide metal-organic frameworks (Ln-MOFs) are synthesized through solvothermal conditions with 1,3-bis(4-carboxyphenyl) imidazolium (H2L). Owing to the lanthanide contraction effect, two different types of Ln-MOFs, namely, {[Ln(L)(2)(OH)]center dot 3H(2)O}(n) (Ln:Pr, Nd, Sm) and {[Ln(L)(2)(COO) (H2O)(2)]center dot H2O}(n) (Ln:Eu, Gd, Tb, Dy, Tm, Yb, Y), and their corresponding codoped Ln-MOFs EuxTb1-xL are obtained. With careful adjustment of the relative concentration of the lanthanide ions and the excitation wavelength, the color of the luminescence can be systematically modulated and white light emission can be further successfully achieved. Furthermore, by virtue of the temperature-dependent luminescent behavior, Eu0.2Tb0.8L allows for the design of a thermometer with an excellent linear response to temperature over a wide range, from 40 to 300 K. This work highlights the practical applications of Ln-MOFs for tailoring fluorescent color and even obtaining practical white light emission, and especially for sensing temperature as luminescent thermometers in a single framework by controlling in different ways.

Reported here is a bioinspired fabrication of superhydrophobic graphene surfaces by means of two-beam laser interference (TBLI) treatment of graphene oxide (GO) films. Microscale grating-like structures with tunable periods and additional nanoscale roughness are readily created on graphene films due to laser induced ablation effect. Synchronously, abundant hydrophilic oxygen-containing groups (OCGs) on GO sheets can be drastically removed after TBLI treatment, which lower its surface energy significantly. The synergistic effect of micro-nanostructuring and the OCGs removal endows the resultant graphene films with unique superhydrophobicity. Additionally, dual TBLI treatment with 90° rotation is implemented to fabricate superhydrophobic graphene films with two-dimensional grating-like structures that can effectively avoid the anisotropic hydrophobicity originated from the grooved structures. Moreover, the superhydrophobic graphene films become conductive due to the laser reduction effect. Unique optical characteristics including transmission diffraction and brilliant structural color are also observed due to the presence of periodic microstructures. As a mask-free, chemical-free, and cost-effective method, the TBLI processing of GO may open up a new way to biomimetic graphene surfaces, and thus hold great promise for the development of novel graphene-based microdevices.

Thermoelectric materials have potential applications in energy harvesting and electronic cooling devices, and bismuth antimony telluride (BiSbTe) alloys are the state-of-the-art thermoelectric materials that have been widely used for several decades. It is demonstrated that mixing SiC nanoparticles into the BiSbTe matrix effectively enhances its thermoelectric properties; a high dimensionless figure of merit (ZT) value of up to 1.33 at 373 K is obtained in Bi0.3Sb1.7Te3 incorporated with only 0.4 vol% SiC nanoparticles. SiC nanoinclusions possessing coherent interfaces with the Bi0.3Sb1.7Te3 matrix can increase the Seebeck coefficient while increasing the electrical conductivity, in addition to its effect of reducing lattice thermal conductivity by enhancing phonon scattering. Nano-SiC dispersion further endows the BiSbTe alloys with better mechanical properties, which are favorable for practical applications and device fabrication.

Organic crystals have great potential for the applications in laser devices. This article presents an effective approach for fabrication of distributed feedback single crystal lasers. With the laser interference ablation method, high quality grating structures have been fabricated on the organic single-crystalline thin film materials. The relationship between the depth, periodicity, and laser fluence is discussed. The optical properties, such as photoluminescence, and diffractive properties are studied in detail. With the appropriate period, strong laser emission has been observed from these devices. Distributed feedback lasing is demonstrated from the laser interference ablated organic single crystals for the first time.

Aging and re-poling induced enhancement of piezoelectricity are found in (K,Na)NbO3 (KNN)-based lead-free piezoelectric ceramics. For a compositionally optimized Li-doped composition, its piezoelectric coefficient d33 can be increased up to 324 pC N−1 even from a considerably high value (190 pC N−1) by means of a re-poling treatment after room-temperature aging. Such a high d33 value is only reachable in KNN ceramics with complicated modifications using Ta and Sb dopants. High-angle X-ray diffraction analysis reveals apparent changes in the crystallographic orientations related to a 90° domain switching before and after the aging and re-poling process. A possible mechanism considering both defect migration and rotation of spontaneous polarization explains the experimental results. The present study provides a general approach towards piezoelectric response enhancement in KNN-based piezoelectric ceramics.

Rectangular AgIn(WO4)(2) nanotubes with a diameter range of 80 to 120 nm and length up to 2 mu m have been synthesized by a hydrothermal method. These nanotubes exhibit interesting white light emissions when using 320 nm as the excitation wavelength. A photocatalytic reaction for water decomposition to evolve K, was performed under UV irradiation, and the rate of H, evolution is nearly seven times that of the sample prepared by a solid-state reaction, which shows much higher photocatalytic activities compared with their bulk counterparts.

Organic single crystals have attracted great attention because of their advantages of high charge-carrier mobility, high chemical purity, and potential for flexible optoelectronic devices. However, their intrinsic properties of sensitive to organic solvent and fragile result in a difficulty in the fabrication of the organic crystal-based devices. In this work, a simple and non-destructive technique of template stripping is employed to fabricate single-crystal-based organic light-emitting devices (OLEDs). Efficient and uniform carrier injection induced by an improved contact between crystals and both top and bottom electrodes is realized, so that a homogeneous and bright electroluminescence (EL) are obtained. Highly polarized EL and even white emission is also observed. Moreover, the crystal-based OLEDs exhibit good flexibility, and keep stable EL under a small bending radius and after repeated bending. It is expectable that this technique would support broad applications of the organic single crystals in the crystal-based optoelectronic devices.

To elaborately fabricate real-time monitoring and therapeutic function into a biocompatible nanoplatform is a promising route in the cancer therapy field. However, the package of diagnosis and treatment into a single-“element” nanoparticle remains challenge. Herein, ultrasmall poly(vinylpyrrolidone)-protected bismuth nanodots (PVP-Bi nanodots) are successfully synthesized through an ultrafacile strategy (1 min only under ambient conditions). The nanodots are easy to synthesize in both laboratory and large scale using low-cost bismuth ingredients. PVP-Bi nanodots with ultrasmall size show good biocompatibility. Due to the high X-ray attenuation ability of Bi element, PVP-Bi nanodots have prominent performance on X-ray computed tomography (CT) imaging. Moreover, PVP-Bi nanodots exhibit a high photothermal conversion efficiency (η = 30%) because of the strong near-infrared absorbance, which can serve as nanotheranostic agent for photothermal imaging and cancer therapy. The subsequent PVP-Bi-nanodot-mediated photothermal therapy (PTT) result shows highly efficient ablation of cancer cells both in vitro and in vivo. PVP-Bi nanodots can be almost completely excreted from mice after 7 d. Blood biochemistry and histology analysis suggests that PVP-Bi nanodots have negligible toxicity. All the positive results reveal that PVP-Bi nanodots produced through the ultrafacile method are promising single-“element” nanotheranostic platform for dual-modal CT/photothermal-imaging-guided PTT.

Organic single crystals have a great potential in the field of organic optoelectronics because of their advantages of high carrier mobility and high thermal stability. However, the application of the organic single crystals in light-emitting devices (OLEDs) has been limited by single-layered structure with unbalanced carrier injection and transport. Here, fabrication of a multilayered-structure crystal-based OLED constitutes a major step toward balanced carrier injection and transport by introducing an anodic buffer layer and electron transport layer into the device structure. Three primary color single-crystal-based OLEDs based on the multilayered structure and molecular doping exhibit a maximum luminance and current efficiency of 820 cd cm−2 and 0.9 cd A−1, respectively, which are the highest performance to date for organic single-crystal-based OLEDs. This work paves the way toward high-performance organic optoelectronic devices based on the organic single crystals.