Transformation texture is normally different to deformation and recrystallization textures, thus influencing materials properties differently. As deformation and recrystallization are often inseparable to transformation in materials which shows a variety in types such as diffusional or non-diffusional transformations, different phenomena or rules of strengthening transformation textures occur. This paper summarizes the complicated phenomena and rules by comparison of a lot of authors’ published and unpublished data collected from mainly electrical steels, high manganese steels and pure titanium sheets. Three kinds of influencing deformation are identified, namely the dynamic transformation with concurrent deformation and transformation, the transformation preceded by deformation and recrystallization and the surface effect induced transformation, and the textures related with them develop in different mechanisms. It is stressed that surface effect induced transformation is particularly effective to enhance transformation texture. It is also shown that the materials properties are also improved by controlled transformation textures, in particular in electrical steels. It is hoped that these phenomena and processing techniques are beneficial to the establishment of transformation texture theory and property improvement in practice.
A sea-urchin-like CuO/ZnO porous nanostructure is obtained via a simple solution method followed by a calcination process. There are abundant pores among the resulting nanowires due to the thermal decomposition of copper–zinc hydroxide carbonate. The specific surface area of the as-prepared CuO/ZnO sample is determined as 31.3 m2·g−1. The gas-sensing performance of the sea-urchin-like CuO/ZnO sensor is studied by exposure to volatile organic compound (VOC) vapors. With contrast to a pure porous sea-urchin-like ZnO sensor, the sea-urchin-like CuO/ZnO sensor shows superior gas-sensing behavior for acetone, formaldehyde, methanol, toluene, isopropanol and ethanol. It exhibits a high response of 52.6–100 ppm acetone vapor, with short response/recovery time. This superior sensing behavior is mainly ascribed to the porous nanowire-assembled structure with abundant p–n heterojunctions.
Considering its rapid lithiation/delithiation process and robust capacitive energy storage, hierarchical porous carbon is regarded as a promising candidate for lithium-ion batteries (LIBs). However, it remains a great challenge to construct a porous structure and prevent structure stacking for carbon-based materials. Herein, a template-mediated approach is developed to synthesize hierarchical nitrogen–sulfur co-doped porous carbon (NSPC) using low-cost asphalt precursors. The strategy for synthesis uses g-C3N4 and NaHCO3 as gaseous templates and NaCl as a solid template, which causes the formation of hierarchical porous carbon with a high specific surface area. The resultant porous structure and nitrogen-doping process can prevent the aggregation of nanosheets, maintain the structural stability upon cycling, and achieve rate-capable lithium storage. Serving as a LIBs anode, reversible specific capacities of the NSPC24 electrode reach 788 and 280 mAh·g–1 at 0.1 and 1 A·g–1, respectively. Furthermore, its specific capacity remains at 830 mAh·g–1 after 115 cycles at 0.1 A·g–1. Even after 500 cycles, high specific capacities of 727 mAh·g–1 at 0.5 A·g–1 and 624 mAh·g–1 at 1 A·g–1 are achieved, demonstrating excellent cycling performance. The gas–solid bifunctional template-mediated approach can guide the design of porous materials very well, meanwhile realizing the high value-added utilization of asphalt.
In this work, pure SnO2 and Ni-doped SnO2 nanorods were synthesized through a one-step template-free hydrothermal method and then used to detect isopropanol. Sensors fabricated with the Ni-doped SnO2 nanocomposites showed the best gas sensing performance when the Ni doping amount was 1.5 mol.%. The response reached 250 at 225 °C, which was approximately 8.3 times higher than that of the pure SnO2 nanorods. The limit of detection for isopropanol was as low as 10 ppb at the optimum working temperature. In addition, it also displayed good selectivity and excellent reproducibility. It is believed that the enhanced isopropanol sensing behavior benefit from the increased oxygen defects and larger specific surface area by Ni doping.
In this work, a high-performance fiber strain sensor is fabricated by constructing a double percolated structure, consisting of carbon nanotube (CNT)/thermoplastic polyurethane (TPU) continuous phase and styrene butadiene styrene (SBS) phase, incompatible with TPU (CNT/TPU@SBS). Compared with other similar fiber strain sensor systems without double percolated structure, the CNT/TPU@SBS sensor achieves a lower percolation threshold (0.38 wt.%) and higher electrical conductivity. The conductivity of 1%-CNT/TPU@SBS (4.12×10−3 S·m−1) is two orders of magnitude higher than that of 1%-CNT/TPU (3.17×10−5 S·m−1) at the same CNT loading of 1 wt.%. Due to double percolated structure, the 1%-CNT/TPU@SBS sensor exhibits a wide strain detection range (0.2%–100%) and an ultra-high sensitivity (maximum gauge factor (GF) is 32411 at 100% strain). Besides, the 1%-CNT/TPU@SBS sensor shows a high linearity (R2 = 0.97) at 0%–20% strain, relatively fast response time (214 ms), and stability (500 loading/unloading cycles). The designed sensor can efficiently monitor physiological signals and movements and identify load distribution after being woven into a sensor array, showing broad application prospects in wearable electronics.
Due to their excellent physical and chemical properties, boron nitride nanosheets (BNNSs) have shown great application potential in many fields. However, the difficulty in scalable preparation of large-size BNNSs is still the current factor that limits this. Herein, a simple yet efficient microwave-assisted chemical exfoliation strategy is proposed to realize scalable preparation of BNNSs by using perchloric acid as the edge modifier and intercalation agent of h-BN. The as-obtained BNNSs behave a thin-layered structure (average thickness of 3.9 nm) with a high yield of ~16%. Noteworthy, the size of BNNSs is maintained to the greatest extent so as to realize the preparation of BNNSs with ultra-large size (up to 7.1 μm), which is the largest so far obtained for the top-down exfoliated BNNSs. Benefiting from the large size, it can significantly improve the thermal diffusion coefficient and the thermal conductivity of polyvinyl alcohol by 51 and 62 times respectively, both showing a higher value than the one previously reported. This demonstrates that the prepared BNNSs have great promise in enhancing the thermal conductivity of polymer materials.
In this work, transition metal phosphides (TMPs) were reinforced by a solvothermal synthesis method and in situ polymerization in dopamine with one-step phosphating and carbonizing process to form chestnut shell-like N-doped carbon coated NiCoP (NiCoP@N-C) hollow microspheres. Excellent morphologic structure is still reflected in NiCoP@N-C, which is suitable for rapid electron and electrolyte transfer. Benefiting from the excellent structure, the coating of N-doped carbon, and the synergistic effect of Ni and Co, NiCoP@N-C reveals excellent electrochemical properties (high specific capacitance of 1660 F·g−1 (830 C·g−1) at 1 A·g−1). In addition, a NiCoP@N-C//carbonization HKUST-1 (HC) achieves high specific energy of 51.8 Wh·kg−1, ultrahigh specific power of 21.63 kW·kg−1, and excellent cycling stability up to 10000 cycles (a capacitance retention of 96.7%). The results show that the NiCoP@N-C electrode material has a wide application in supercapacitors and other energy storage devices.
Human body temperature not only reflects vital signs, but also affects the state of various organs through blood circulation, and even affects lifespan. Here a wireless body temperature detection scheme was presented that the temperature was extracted by investigating the out-of-plane (OP) ferromagnetic resonance (FMR) field of 10.2 nm thick La0.7Sr0.3MnO3 (LSMO) film using electron paramagnetic resonance (EPR) technique. Within the range of 34–42 °C, the OP FMR field changes linearly with the increasing or decreasing temperature, and this variation comes from the linear responses of magnetization to the fluctuant temperature. Using this method, a tiny temperature change (<0.1 °C) of organisms can be detected accurately and sensitively, which shows great potential in body temperature monitoring for humans and mammals.
Chemical vapor deposited (CVD) diamond as a burgeoning multi-functional material with tailored quality and characteristics can be artificially synthesized and controlled for various applications. Correspondingly, the application-related “grade” concept associated with materials choice and design was gradually formulated, of which the availability and the performance are optimally suited. In this review, the explicit diversity of CVD diamond and the clarification of typical grades for applications, i.e., from resplendent gem-grade to promising quantum-grade, were systematically summarized and discussed, according to the crystal quality and main consideration of ubiquitous nitrogen impurity content as well as major applications. Realizations of those, from quantum-grade with near-ideal crystal to electronic-grade having extremely low imperfections and then to optical, thermal as well as mechanical-grade needing controlled flaws and allowable impurities, would competently fulfill the multi-field application prospects with appropriate choice in terms of cost and quality. Exceptionally, wide range defects and impurities in the gem-grade diamond (only indicating single crystal), which are detrimental for technology applications, endows CVD crystals with fancy colors to challenge their natural counterparts.
Yolk–shell and hollow structures are powerful platforms for controlled release, confined nanocatalysis, and optical and electronic applications. This contribution describes a fabrication strategy for a yolk–shell nanoreactor (NR) using a post decoration approach. The widely studied yolk–shell structure of silica-coated TiO2 (TiO2@SiO2) was used as a model. At first, anatase TiO2 spheres were prepared, and subsequently were given a continuous coating of carbonaceous and silica layers. Finally, the carbonaceous layer was removed to produce a yolk–shell structure TiO2@SiO2. By using an in-situ photodeposition method, Pt-encased spheres (Pt-TiO2@SiO2) were synthesized with Pt nanoparticles grown on the surface of the TiO2 core, which contained void spaces suitable for use as NRs. The NR showed enhanced hydrogen production with a rate of 24.56 mmol·g−1·h−1 in the presence of a sacrificial agent under simulated sunlight. This strategy holds the potential to be extended for the synthesis of other yolk–shell photocatalytic NRs with different metal oxides.
The wastewater treatment is a challenging research area to reduce the increasing pressure on limited fresh water resources. Amongst several techniques adopted and practiced, adsorption is one of the most effective and sustainable eco-friendly processes. In recent years, MXene nanomaterials, a new family of transition metal carbides, have gained increasing attention as the potential adsorbent for pollutants due to their unique features such as large surface area with abundant active sites and hydrophilicity. A wide range of pollutants viz. heavy metal ions, organic dyes, radionuclides, and toxic gas molecules have been sensed by 2D MXenes. An inclusive understanding on the adsorptive behavior of MXene-based materials is needed to explain the removal mechanism and effects of different adsorption parameters. This review gives a general overview on recent research progress on MXene materials with special reference to their applications for the adsorptive removal of different pollutants. The general trends in the synthesis of MXenes, their stability and different factors affecting the adsorption process along with the main challenges in understanding the full potential of MXenes for environmental applications are discussed.
A novel hierarchical structure of bimetal sulfide FeS2@SnS2 with the 1D/2D heterostructure was developed for high-performance sodium-ion batteries (SIBs). The FeS2@SnS2 was synthesized through a hydrothermal reaction and a sulphuration process. The exquisite 1D/2D heterostructure is featured with 2D SnS2 nanoflakes anchoring on the 1D FeS2 nanorod. This well-designed FeS2@SnS2 provides shortened ion diffusion pathway and adequate surface area, which facilitates the Na+ transport and capacitive Na+ storage. Besides, the FeS2@SnS2 integrates the 1D/2D synthetic structural advantages and synthetic hybrid active material. Consequently, the FeS2@SnS2 anode exhibits high initial specific capacity of 765.5 mAh·g−1 at 1 A·g−1 and outstanding reversibility (506.0 mAh·g−1 at 1 A·g−1 after 200 cycles, 262.5 mAh·g−1 at 5 A·g−1 after 1400 cycles). Moreover, the kinetic analysis reveals that the FeS2@SnS2 anode displays significant capacitive behavior which boosts the rate capacity.
