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Catalytic removal of trace methane emission over supported Pd catalysts has drawn much attention over the years. For practical application, high activity, excellent thermal stability and outstanding water resistance are always desirable. Herein, we report a facile route for simultaneously improving the activity, stability and water resistance of the zeolite supported Pd catalyst through the combination of reduction-deposition Pd loading and support dealumination. This combination strategy leads to highly dispersed and stable PdO nanoparticles with strong interaction with the Beta support, rich active Pdn+ (0

The fast Li-ion pathways in crystals contribute to superionic conductivity-extraordinarily high ionic conductivity-of the Li10GeP2S12 (LGPS) structure. Composition tuning is expected to improve the conductivity. The phase behavior, microstructure, and ion dynamics of a series of solid solutions of xLi4GeS4-yLi3PS4 (4/1 ≥ x/y ≥ 1/2) were studied by multiple 7Li and 31P solid-state NMR methods. Li10GeP2S12 (Ge/P = x/y = 1/2) is the smallest x/y of the disordered LGPS structure. When the Ge/P ratio increases, the room-temperature Li ionic conductivity first increases to a maximum around x/y = 1/1.2 and then decreases. Meanwhile, a disordered LGPS structure transforms into an ordered LGPS' structure synchronously with conductivity reduction. The Li4GeS4-Li3PS4 phase diagram with the order-disorder structure transition was reconstructed accordingly. Both ordered LGPS' and disordered LGPS exhibit similar two-dimensional (2D) and one-dimensional (1D) Li diffusion paths. But the disordered LGPS structure is conducive to fast ionic conductivity, rooted in its fast 2D Li+ diffusion in the ab-plane rather than 1D diffusion along the c-axis. Two high-temperature relaxation processes are observed in the LGPS' structure, suggesting heterogeneous 2D jumps of rapid and slow rates, whereas only a single homogeneous 2D jump process was found in the LGPS structure. Our findings provide insight into understanding the relationship between structure order (or disorder) and ionic conductivity of superionic materials, offering guidelines for optimizing ionic conductivity for extensive solid electrolyte materials rather than LGPS materials.

In order to utilize the leaked electrons from emission layer (EML) and simultaneously enhance the performance of the quantum dot light-emitting diodes (QLEDs), a blue thermally activated delayed fluorescence (TADF) material, 10,10'-(4,4-Sulfonylbis(4,1-phenylene))bis(9,9-dimethyl-9,10-dihydroacridine) (DMAC-DPS), was inserted as an interlayer between hole transport layer (HTL) and quantum dot (QD) EML. In the TADF inserting layer, the leaked electrons from the EML can form excitons with the injected holes from the HTL, followed by energy transfer from the TADF material to the QD EML. The TADF inserting layer is also expected to promote the hole injection from HTL to EML and to alleviate the electron accumulation situation at QD/HTL interface. Therefore, compared with standard QLED without TADF inserting layer, the utilization of electrons in the QLEDs with TADF interlayer are enhanced and the charge carriers are more balance in QD EML. These benefits enable a 1.17-fold increment for current efficiency (from 8.9 cd/A to 10.44 cd/A) and 1.41-fold improvement for maximum luminance (from 44781 cd/m2 to 63458 cd/m2) in the optimal QLED employing 5 nm TADF interlayer.

Triboelectric nanogenerators (TENGs) have been in spotlight for their excellent capability to drive miniature electronics. Herein, we report a sophisticated double-helix-structured triboelectric nanogenerator (DHS-TENG) enhanced with positive charge traps for self-powered temperature sensing and smart-home control system. The DHS-TENG increases the charge density on the contact surfaces by taking advantage of the ferroelectric characteristics of polyvinylidene fluoride (PVDF). In addition, the flexible double-helix-structure endows DHS-TENG with excellent elastic property as it has no external supporting materials. The reported DHS-TENG, with the dimensions of 3 cm × 3 cm × 5 cm and a light weight of 10 g, can deliver a peak output power of 9.03 mW under a loading resistance of 4 MΩ. It also delivers an enhanced output performance of 460 V, 140 μA and 400 nC under a constant contact force of 40 N. Furthermore, the DHS-TENG is capable of powering 120 green LEDs and enabling a temperature sensor to work properly. In particular, the DHS-TENG demonstrates the capability of successful remote data transmission for application in smart-home control systems within 10 meters.

Skillful arrangement of the active sites with stable dispersion and desired chemical states on the support surface is vital for their powerful application in catalysis, but remains a daunting challenge. Herein, we present a unique redispersion strategy for well dispersing and stabilizing IrO2/Ir active sites over TiO2 as an advanced catalyst for low temperature CH4 oxidation. The as-designed Ir/TiO2 with a 1 wt.% Ir loading amount exhibits a (>)99 % CH4 conversion and excellent durability at a temperature as low as 320 °C, which ranges among the best of state-of-the-art methane combustion catalysts. Various characterizations and DFT calculations were performed to reveal the redispersion mechanism and understand the reason for the enhanced performance. The superior performance is related to the proper chemical state of complex IrO2/Ir active sites and their ultrafine and stable dispersion, all relating to the strong metal-support interaction (SMSI) induced redispersion process. Such SMSI assisted active sites redispersion strategy provides useful guidance for the rational design of efficient Ir-based and other noble metal catalysts.

Solution-processed blue quantum dot light-emitting diodes (QLEDs) suffer from low device efficiency, whereas the balance of electron and hole injection is critical for obtaining high efficiency. Herein, synergistical double hole transport layers (D-HTLs) are employed, which use poly(9-vinylcarbazole) (PVK) stacked on poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(4,4'-(N-(4-butylphenyl) (TFB). The fabrication of D-HTLs is achieved by using dimethyl formamide (DMF) as the solvent for PVK, with which the underlying TFB layer almost remains unwashed and undamaged during the spin-coating process of PVK layer. TFB/PVK D-HTLs form the stepwise energy level for hole injection, which reduces the hole injection barrier and favors the carrier balance in the emission layer (EML). The optimized blue QLED with TFB/PVK D-HTLs shows a maximum external quantum efficiency (EQE) of 13.7%, which is 3-fold enhancement compared to that of the control device with single TFB HTL. The enhancement of the QLED performance can be attributed to the improvement of surface morphology and charge injection balance for the stepwise D-HTLs based QLEDs. This work manifests the positive effect on performance boost by selecting appropriate solvents towards stepwise D-HTLs formation and paves the way to fabricate highly efficient all-solution processed light emitting diodes.

Triboelectric nanogenerators (TENGs) have demonstrated as an effective way to harvest mechanical energy to drive small electronics. The density of triboelectric charges generated on contact surfaces between two distinct materials is a critical factor for dictating the output power. Herein, we demonstrate the unusual ability of ferroelectric materials to enhance the output performance of the triboelectric nanogenerators (TENG) by taking advantage of the dipole moment in the documents. The output voltage ranged from 100 V to 215 V under a constant contact force of 40 N. This work not only provides a new method of enhancing output power of TENGs but also offers an insight into charge transfer in contact electrification by investigating dipole-moment-induced effects on the electrical output of TENGs.

Highly efficient, all-solution processed inverted quantum dot light-emitting diodes (QLEDs) are demonstrated by employing 1,3,5-tri(m-pyrid-3-yl-phenyl)benzene (TmPyPB) layer as electron blocking layer. Electron injection from ZnO electron transport layer to quantum dots (QDs) emission layer (EML) can be adjusted by thickness of TmPyPB layer, enabling the balanced charge carriers in QDs EML. With optimal thickness of this TmPyPB adjuster, 59.7% increment in the device current efficiency (from 8.2 to 13.1 cd A−1) and 46.2% improvement in the maximum luminance (from 31916 to 46674 cd m−2) are achieved, compared with those of the control QLED which has double hole transport layer structure. On the other hand, we find luminescence quenching process, which often happens at the interface of ZnO nanoparticles and QDs, is not obvious in our QLEDs, in which the ZnO layer is fabricated in precursor method, and this conclusion is verified through Time Resolution Photoluminescence test. In a word, this strategy provides a direction for optimizing charge carrier balance in all-solution processed inverted QLED.

The photostability issue of CsPbX3 (X = Cl, Br, I) quantum dots (QDs) is one of the key origins for the degradation of their luminescence performance, which hinders their application in lighting and displays. Herein, we report a new method combining doping and ligand engineering, which effectively improves the photostability of CsPbBr3 QDs and the performance of QD light-emitting diodes (QLEDs). In this method, ZnBr2 is doped into CsPbBr3 QDs to reduce surface anion defects; didodecyldimethyl ammonium bromide (DDAB) and tetraoctylammonium bromide (TOAB) hybrid ligands, which have strong adsorption with QDs, are employed to protect the surface and enhance the conductivity of QD layer in QLEDs. The photoluminescence (PL) and transmission electron microscopy measurements prove the effectively improved photostability of CsPbX3 QDs. Moreover, reduced defects and improved conductivity by doping and hybrid ligands treatment also enable the improved electroluminescence performance of CsPbX3 QDs. The maximum luminance and external quantum efficiency of the QLED with optimized CsPbX3 QDs are 3518.9 cd m−2 and 5.07%, which are 3.6 and 2.1 times than that of the control device, respectively. Combining doping and hybrid ligands makes perovskite QDs have an extremely promising prospect in future applications of high-definition displays, high-quality lighting, as well as solar cells.

In this paper, solution-processed blue organic light-emitting devices (OLEDs) with high efficiency and high luminance are realized. A blue thermally activated delayed fluorescence (TADF) material, 4CzFCN, is used as the emitting material. A host material with high hole mobility, mCP, and an electron transport material with high electron mobility and lower LUMO level, B4PyMPM, are employed to increase the electron density and balance the carrier distribution inside the emission layer. As a result, a luminance of 7625.0 cd/m2, a current efficiency of 49.3 cd/A, and an external quantum efficiency of up to 24% are obtained. To the best of our knowledge, these values are superior to the highest values reported for this material in the literatures.

The fabrication of highly efficient organic light-emitting diodes (OLEDs) by solution processes has become a hot research point due to the low production cost, high material utilization ratio and simple fabrication process. Herein, highly efficient, solution-processed red phosphorescent organic light-emitting diodes (PhOLEDs) using chlorobenzene (CB) and isopropanol (IPA) as mixed solvents are proposed. It is found that both the roughness and the defect states of emission layer (EML) prepared with mixed solvents are reduced. Thereby, the electroluminescence performance of PhOLEDs are enhanced compared with that of the ones with pure CB as the solvent. With CB:IPA ratio of 5:1, the current efficiency and the external quantum efficiency of device reach 27.1 cd/A and 17.2 %, respectively. These results prove that the use of IPA can improve the device performance even if it is not able to dissolve the organic materials, which breaks the limitation of the use of alcohol solvent in solution-processed OLEDs.

The marine environment monitoring system is of considerable significance to the sea development. However, the power-supply issue of the sensor nodes in the system is a crucial consideration all the time. Here, a chaotic pendulum triboelectric-electromagnetic hybridized nanogenerator integrated with the power management circuit to power the wireless sensing nodes by scavenging wave energy has been proposed. The physical design of the harvester utilized the virtue of low working frequency and high electromechanical conversion efficiency characteristics of the chaotic pendulum. To verify the utility and applicability of the hybridized nanogenerators, several experimental scenarios were selected, the maximum output power of TENG can reach 15.21 μW and the EMG is up to 1.23 mW as triggered by the water wave. The hybridizied nanogenerator can light up about 100 LEDs. Moreover, the self-powered wireless sensing node distant transmission has been realized, and data transmission capability exceeds 300 m. This study provides a new direction of scavenging low-frequency vibrations from the environment of marine, also in the aerospace and industry.

Highly efficient, all-solution processed inverted quantum dot light-emitting diodes (QLEDs) with high performance are demonstrated by employing poly(9-vinlycarbazole) (PVK) as additional hole transport layer (HTL) and doping it with a blue thermal activated delay fluorescent (TADF) material, 4,5-bis(carbazol-9-yl)-1,2-dicyanobenzene (2CzPN). This PVK: 2CzPN composite layer not only optimizes hole injection, but also utilizes the leaked electrons to enhance device luminance by energy transfer process from 2CzPN to quantum dots (QDs). These benefits enable a 20-fold increment for the device current efficiency (from 0.523 cd/A to 11 cd/A) and a 9.9-fold improvement for the maximum luminance (from 3220 cd/m2 to 35352 cd/m2), compared with those of the standard QLED with poly[(9, 9-dioctylfluorenyl-2,7-diyl)-alt-(4,4'-(N-(4-butylphenyl) (TFB) single HTL. In comparison with the QLED with TFB/pristine PVK double HTLs, the device performance of the optimal QLED with PVK: 2CzPN additional HTL are still 40.8% and 61.7% higher in luminance and current efficiency, respectively.

Quantum dot light-emitting diodes (QLEDs) have been widely recognized as one of the potential candidates for next-generation displays. In QLEDs, unbalanced carrier distribution (lacking holes) is an essential factor limiting device efficiency. Herein, we propose the solvent treatment of hole transporting layer (HTL) and quantum dot (QD) emission layer (EML) to enhance hole injection from HTL and reduce the defects in QD EML. Scanning Kelvin probe microscopy measurements reveal that the surface potential of HTL is lowered by solvent treatment with dimethyl formamide (DMF), which is due to the formation of an interface dipole layer between QD EML and HTL, and thus the hole injection barrier from HTL to QD EML is reduced. Furthermore, steady and transient photoluminescence (PL) measurements reveal that the DMF treated QD film, in comparison with the standard QD film, exhibits higher PL intensity and reduced non-radiative recombination induced by the defects. These improvements result in a 25% boost in the current efficiency of the QLEDs with DMF treated QD EML as compared to the QLED with unmodified EML, leading to a high current efficiency of 14.81 cd/A and a maximum brightness of 113 373 cd/m2. Furthermore, the solvent treatment enables the QLEDs possessing sub-bandgap turn-on voltage, which is 1.8 V (the optical bandgap of 2.1 eV) for the QLEDs with DMF treated QD EML.