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In this work, a photoelectrochemical (PEC) aptasensor for detecting kanamycin (KAN) was designed based on an aptamer modified Bi/BiOBr/titania nanorod array (TiO2 NRA). Bi/BiOBr was loaded onto the TiO2 NRA via a one-pot solvothermal method using glucose as a reductant. The p–n heterojunction structure constructed from chrysanthemums like BiOBr and the TiO2 NRA improves the electron transfer rate. Combined with metal Bi with the surface plasmon resonance (SPR) effect, it further increases the absorption range of visible light and enhances the light response performance of the PEC aptasensor. The KAN aptamer is fixed to the Bi/BiOBr/TiO2 NRA photoelectric material through the C＝N structure. Once the aptamer precisely captures KAN molecules, photocurrent changes are generated to realize the detection of KAN. The designed PEC aptasensor shows good detection performance in the linear response range of 1 pM–200 nM, and the detection limit is 0.7 pM (S/N = 3). The aptasensor was applied to the determination of KAN in milk with satisfactory results. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNT)–cerium oxide (CeO2) nanocomposites were fabricated successfully by one-pot microwave hydrothermal growth of regular CeO2 nanoparticles with a size of 8 nm on hydroxyl-functionalized multi-walled CNTs. These nanocomposite photocatalysts demonstrated an acid orange (AO7) photocatalytic degradation efficiency of above 90% under solar-simulated light irradiation for 3 h, which was much higher than that of the pure CeO2 nanoparticles. The enhanced photocatalytic activity was observed to mainly originate from the ˙O2− and hole traps, while the hydroxyl radical ˙OH played a secondary role. [ABSTRACT FROM AUTHOR]

Practical applications of lithium–sulfur batteries have been impeded by their poor cycling stability that results from the "shuttling" of polysulfides. Herein, we demonstrate a new strategy for developing a hierarchical phosphorus-doped graphene/carbon nanofiber/sulfur aerogel (PGCNF/S) with "network" morphologies, in which sulfur spheres are wrapped with graphene sheets and carbon nanofibers (PGCNFs) with "net" structures and this carbon matrix has greatly improved the electrochemical performances of sulfur spheres. PGCNF nets ensure a uniform loading of sulfur spheres that leads to a high sulfur mass loading of 85 wt%. Also, the good porous structures achieved with this PGCNF/S cathode can provide sufficient space for volume expansion of active sulfur spheres. Due to its structural advantages, this binder-free PGCNF/S cathode exhibits a specific capacity of 1360 mA h g−1 at 0.1C, and a high areal capacity of 21.5 mA h cm−2 based on a high sulfur mass loading of 15.8 mg cm−2. Furthermore, a long term cycling stability of 600 cycles has been achieved by this PGCNF/S cathode with an average coulombic efficiency of ∼99.8%. This work highlights a broadly adaptable strategy of "network" structures for developing scalable and high-energy density electrode materials for energy storage devices. [ABSTRACT FROM AUTHOR]

Recently, flexible metacomposites with negative permittivity have triggered extensive interest owing largely to their promising applications in areas such as sensors, cloaking, and wearable and flexible electronic devices. In this paper, flexible silver nanowire/carbon fiber felt (AgNW/CFF) metacomposites with weakly negative permittivity were fabricated by adjusting their composition and microstructure. Along with the formation of a conductive AgNW network, the resulting composites gradually presented metal-like behavior. Interestingly, weakly negative permittivity with a small absolute value (as low as about 6.4) and good flexibility were observed in the composites with 3.7 wt% AgNWs. The one-dimensional silver nanowires contribute to reducing the overall electron density of the resulting composites, which is responsible for the weakly negative permittivity. As the AgNWs increased, the Drude-like negative permittivity got stronger owing to the enhancement of the electron density. Further investigation from the perspective of microelectronics revealed that the negative permittivity is dependent on the inductive characteristic. The proposed design strategy for AgNW/CFF composites with tunable negative permittivity opens up a new approach to flexible metacomposites. [ABSTRACT FROM AUTHOR]

In this study, carbon dot-sensitized Ti3+ self-doped TiO2 dual-phase (TiO2−x/CDs) composite photocatalytic systems were successfully constructed using a low-temperature hydrothermal method. The TiO2−x photocatalyst showed improved photocatalytic activities for the removal of Cr6+ and RhB under visible light. Remarkably, RhB (10 mg L−1) and Cr6+ (40 mg L−1) solutions were degraded completely in 30 and 120 min, respectively, by the composite photocatalyst (1 g L−1) under visible-light irradiation. These results were much better than those of commercial P25. This fascinating photocatalytic performance was attributed to the improved photogenerated electron–hole separation efficiency from the synergistic effects of rutile and anatase, and the reduced photogenerated charge carrier recombination and facilitated visible-light absorption from the introduced CDs. This study provides a promising approach for the treatment of real wastewater using sunlight. [ABSTRACT FROM AUTHOR]

There is a growing demand for stretchable strain sensors because of their potential applications in various emerging fields, such as human motion detection, health monitoring, wearable electronics, and soft robotic skin. Recently, strain sensors based on flexible conductive polymer composites (FCPCs) composed of conductive materials and a stretchable elastomer have received intensive attention owing to their high stretchability, good flexibility, excellent durability, tunable strain sensing behaviors, and ease of processing. Here, we systematically summarize the recent progress of stretchable strain sensors based on FCPCs. This review covers the classification and sensing mechanisms as well as the influence of multiple factors on the sensing behaviors of FCPC based strain sensors with detailed examples. [ABSTRACT FROM AUTHOR]

For effective hydrogen generation with remarkable durability, carbon nanotubes (CNTs) grown on Ni nanofibers and their post hydroxylation treatment engendered active Ni nanofiber catalysts an efficient decomposition of hydrous hydrazine with a turnover frequency (TOF) of 19.4 h−1 and an activation energy down to 51.05 KJ mol−1. [ABSTRACT FROM AUTHOR]

An efficient hydrogen evolution reaction (HER) depends essentially on high-performing electrocatalysts. The aggregation of catalysts normally deteriorates their activity and stability. In this study, a two-step route was used to synthesize surface intercalated well-dispersed spherical MoS2xSe2(1−x) nanocatalysts. The resulting catalysts present a highly active and stable performance towards the HER with an overpotential of −143 mV at 10 mA cm−2, and a Tafel slope of 53.8 mV dec−1. The mechanism for the enhanced HER was analyzed and was attributed to three factors: (i) large numbers of defects and edge active sites arising from the coexistence of S and Se elements; (ii) enhanced electric conductivity arising from the phase transition from the semiconducting 2H-phase to metallic 1T-phase during the intercalation process; and (iii) enlarged contact areas between active sites and electrolyte caused by the increased surface roughness due to the surface intercalation. This work not only deepens our understanding of the improved HER performance of surface intercalated catalysts, but also provides novel strategies for preparing durable electrocatalysts through surface engineering. [ABSTRACT FROM AUTHOR]

Conductive Nb12O29 hierarchical microspheres with nanosheet shells were synthesized based on a hydrothermal process and a high-temperature hydrogen reduction treatment. The obtained materials demonstrated comprehensively good electrochemical properties, including a significant pseudocapacitive contribution, safe operating potential, high reversible capacity, superior initial coulombic efficiency, increased rate capability, and durable cycling stability. [ABSTRACT FROM AUTHOR]

Piezoelectric materials and devices have drawn extensive attention for energy harvesting due to their excellent electromechanical conversion properties. With increasing concerns about environmental problems in traditional lead-based piezoelectric materials, it is imperative to develop lead-free piezoelectric alternatives. This paper is intended to give a brief review on the most recent advances in both inorganic (with an emphasis on piezoelectric ceramics and ZnO nanostructures) and organic (i.e. polyvinylidene difluoride (PVDF) and its copolymers and their composites, and biopolymers) lead-free piezoelectric materials. State-of-the-art piezoelectric devices, namely, nanogenerators, sensors, and transducers, are also introduced with detailed examples. Finally, the challenges and perspectives of lead-free piezoelectric materials and devices are given. [ABSTRACT FROM AUTHOR]

Lightweight conductive porous graphene/thermoplastic polyurethane (TPU) foams with ultrahigh compressibility were successfully fabricated by using the thermal induced phase separation (TISP) technique. The density and porosity of the foams were calculated to be about 0.11 g cm−3 and 90% owing to the porous structure. Compared with pure TPU foams, the addition of graphene could effectively increase the thickness of the cell wall and hinder the formation of small holes, leading to a robust porous structure with excellent compression property. Meanwhile, the cell walls with small holes and a dendritic structure were observed due to the flexibility of graphene, endowing the foam with special positive piezoresistive behaviors and peculiar response patterns with a deflection point during the cyclic compression. This could effectively enhance the identifiability of external compression strain when used as piezoresistive sensors. In addition, larger compression sensitivity was achieved at a higher compression rate. Due to high porosity and good elasticity of TPU, the conductive foams demonstrated good compressibility and stable piezoresistive sensing signals at a strain of up to 90%. During the cyclic piezoresistive sensing test under different compression strains, the conductive foam exhibited good recoverability and reproducibility after the stabilization of cyclic loading. All these suggest that the fabricated conductive foam possesses great potential to be used as lightweight, flexible, highly sensitive, and stable piezoresistive sensors. [ABSTRACT FROM AUTHOR]

Perovskites with flexible structures and excellent redox properties have attracted considerable attention in industry, and their denitration activities can be further improved with metal substitution. In order to investigate the effect of Ce and Cu substitution on the physicochemical properties of perovskite in NH 3 -SCR system, a series of La 1- x Ce x Mn 1- y Cu y O 3 ( x = 0, 0.1, y = 0, 0.05, 0.1, 0.2, 0.4) catalysts were prepared by citrate sol-gel method and employed for NO removal in the simulated flue gas, and the physical and chemical properties of the catalysts were studied using XRD, SEM, BET, XPS, DRIFT characterizations. The Ce substitution on A-site cation of LaMnO 3 can improve the denitration activity of the perovskite catalyst, and La 0.9 Ce 0.1 MnO 3 displays NO conversion of 86.7% at 350 °C. The characterization results indicate that the high denitration activity of La 0.9 Ce 0.1 MnO 3 is mainly attributed to the larger surface area, which contributes to the adsorption of NH 3 and NO. Besides, the appropriate Cu substitution on B-site cation of La 0.9 Ce 0.1 MnO 3 can further improve the denitration activity of perovskite catalyst, and La 0.9 Ce 0.1 Mn 0.8 Cu 0.2 O 3 displays the NO conversion of 91.8% at 350 °C. Although the specific surface area of La 0.9 Ce 0.1 Mn 0.8 Cu 0.2 O 3 is lower than La 0.9 Ce 0.1 MnO 3 , the Cu active sites and the Ce 3+ contents are more developed, making many reaction units formed on the catalyst surface and redox properties of catalyst improved. In addition, strong metal interaction (Ce 4+ + Mn 2+ + Cu 2+ ↔ Ce 3+ + Mn 3+ /Mn 4+ + Cu + ) and high concentrations of chemical adsorbed oxygen and lattice oxygen both strengthen the redox reaction on catalyst surface, thus contributing to the better denitration activity of La 0.9 Ce 0.1 Mn 0.8 Cu 0.2 O 3 . Therefore, appropriate cerium and copper substitution will markedly improve the denitration activity of La-Mn perovskite catalyst. We also reasonably conclude a multiple reaction mechanism during NH 3 -SCR denitration process basing on DRIFT results, which includes the Eley-Rideal mechanism and Langmuir-Hinshelwood mechanism., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

This study aims to investigate the enhanced low temperature denitration activity and promotional mechanism of a cerium-based catalyst through copper modification. In this paper, copper and cerium oxides were supported on TiO 2 -ZrO 2 by an impregnation method, their catalytic activity tests of selective catalytic reduction (SCR) of NO with NH 3 were carried out and their physicochemical properties were characterized. The CuCe/TiO 2 -ZrO 2 catalyst shows obviously enhanced NH 3 -SCR activity at low temperature (<300 °C), which is associated with the well dispersed active ingredients and the synergistic effect between copper and cerium species (Cu 2+ + Ce 3+ ↔ Cu + + Ce 4+ ), and the increased ratios of surface chemisorbed oxygen and Cu + /Cu 2+ lead to the enhanced low-temperature SCR activity. The denitration reaction mechanism over the CuCe/TiO 2 -ZrO 2 catalyst was investigated by in situ DRIFTS and DFT studies. Results illustrate that the NH 3 is inclined to adsorb on the Cu acidic sites (Lewis acid sites), and the NH 2 and NH 2 NO species are the key intermediates in the low-temperature NH 3 -SCR process, which can explain the promotional effect of Cu modification on denitration activity of Ce/TiO 2 -ZrO 2 at the molecular level. Finally, we have reasonably concluded a NH 3 -SCR catalytic cycle involving the Eley-Rideal mechanism and Langmuir-Hinshelwood mechanism, and the former mechanism dominates in the NH 3 -SCR reaction., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

An efficient hydrogen evolution reaction (HER) depends essentially on high-performing electrocatalysts. The aggregation of catalysts normally deteriorates their activity and stability. In this study, a two-step route was used to synthesize surface intercalated well-dispersed spherical MoS 2x Se 2(1-x) nanocatalysts. The resulting catalysts present a highly active and stable performance towards the HER with an overpotential of -143 mV at 10 mA cm -2 , and a Tafel slope of 53.8 mV dec -1 . The mechanism for the enhanced HER was analyzed and was attributed to three factors: (i) large numbers of defects and edge active sites arising from the coexistence of S and Se elements; (ii) enhanced electric conductivity arising from the phase transition from the semiconducting 2H-phase to metallic 1T-phase during the intercalation process; and (iii) enlarged contact areas between active sites and electrolyte caused by the increased surface roughness due to the surface intercalation. This work not only deepens our understanding of the improved HER performance of surface intercalated catalysts, but also provides novel strategies for preparing durable electrocatalysts through surface engineering.

Conductive Nb12O29 hierarchical microspheres with nanosheet shells were synthesized based on a hydrothermal process and a high-temperature hydrogen reduction treatment. The obtained materials demonstrated comprehensively good electrochemical properties, including a significant pseudocapacitive contribution, safe operating potential, high reversible capacity, superior initial coulombic efficiency, increased rate capability, and durable cycling stability.