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Graham Bjerrum posted an update 12 hours, 41 minutes ago
A series of nanoparticles (NPs) with different Au content was successfully encapsulated into metal organic framework ZIF-8 with highly porous structure through room-temperature crystallization. X-ray diffraction, Fourier transform infrared spectroscopy, N2 adsorption and transmission electron microscopy were carried out to characterize the obtained Au@ZIF-8 heterogeneous catalytic material comprehensively. Au NPs were dispersed uniformly in the ZIF-8 and the Au NP diameter was 5-6 nm. The crystal structure of ZIF-8 was unchanged when compared with that before Au loading. It was found that the Au content plays an important role in the hydrogenation reaction. The obtained Au@ZIF-8 exhibited high hydrogenation activity to nitrophenol and excellent selectivity to aminophenol. The recyclability of the Au@ZIF-8 catalysts showed excellent catalytic performance and great stability in the recycling reaction.We apply the non-equilibrium molecular dynamics approach (NEMD) to study thermal rectification in a hybrid graphene-carbon nitride system ([Formula see text]) under a series of positive and negative temperature gradients. In this study, the effects of temperature difference, between two baths (ΔT), and sample size on thermal rectification are investigated. Our simulation results indicate positive correlation between thermal rectification and temperature difference for ΔT > 60 K, and high thermal rectification values, up to around 50% for ΔT = 100 K. Furthermore, this behavior remains practically consistent among different sample lengths. The underlying mechanism leading to a preferable direction for phonons is calculated using phonon density of states (DOS) on both sides of the [Formula see text] interface, and the contributions of in-plane and out-of-plane phonon modes in total thermal rectification are also explored.1D ZnO nanostructures have been widely explored due to their potential applications in ultraviolet (UV) region photodetectors because of their unique structural and optoelectronic properties. However, a large number of surface defect states leading to a noticeable dark current hinders their practical applications in UV photodetection. In this work, we have shown improved ZnO/Al2O3 core-shell microrod photodetectors, whose performance is significantly enhanced by defect passivation and the introduction of trap states by atomic layer deposition grown thin amorphous Al2O3 shell layer, as evidenced by steady-state and transient photoluminescence investigations. The photodetectors demonstrated suppressed dark current and increased photocurrent after capping the Al2O3 layer. Specifically, the ZnO/Al2O3 core-shell microrod photodetector exhibited a photoresponsivity as high as 0.019 A/(W cm-2) with the dark current as low as ∼1 × 10-11 A, and a high I light/I dark ratio of ∼104 under relatively weak light illumination (∼10 μW cm-2). The results presented in this work provide valuable pathways to boost the performance of 1D ZnO microrod-based photodetectors for future practical applications.Motivated by interesting physical and chemical properties created by doping and topological quantum state, we perform the density functional theory and the Boltzmann transport equation to systematically investigate the geometric structures, stabilities, electronic structures, thermal conductivities and thermoelectric properties for Sb and its oxidations (Sb2O and SbO). The predicted lattice thermal conductivity (k L ) of Sb is 11.6 nW K-1 at 300 K, but it would fall drastically when introducing O atoms. This is mainly attributed to the strong anharmonic interactions by adding O atoms, and few contributions are from the decreasing phonon group velocities caused by the compressed phonon spectrum. SbO has been proven as a topological insulator with a relatively large topological band gap (E g ) ∼ 0.156 eV, and meanwhile its carrier mobilities (345.78 cm2/Vs for electrons) and scattering time (44.27 × 10-14 s for electrons) are also rather high among all 2D materials, exhibiting the excellent thermoelectric performance. The calculated maximum thermoelectric figure of merit ([Formula see text]) of the three Sb films for optimum n-type doping are close to each other at 300 K, but with an increasing temperature, the [Formula see text] of Sb for optimum n-type doping climbs quickly and can reach up to 0.73 at 700 K, which is far higher than others. More interestingly, the [Formula see text] of SbO can be increased sharply at 300 K after considering spin-orbit coupling (SOC) 0.50 for optimum p-type doping and 0.41 for optimum n-type doping. However, only the tiny changes in the [Formula see text] of Sb can be found before and after considering SOC. Our research reveals how the doping and the topological quantum state affect thermoelectric performances, providing reference to design and search high [Formula see text] thermoelectric materials in future.Silver phosphate (Ag3PO4, APO) has attracted intense attention as a visible-light-driven photocatalyst, but its large-scale application is limited by severe charge recombination and inevitable photo-corrosion. SBE-β-CD Various rational APO-based heterostructures composed of APO nanoparticles (NPs) and band-matched semiconductor support are designed to address the above issues. Nevertheless, the size, density, stability, and dispersion of APO NPs are critical challenges for the photocatalytic performance of APO-based photocatalysts. Here, three-dimensional (3D) self-assembled TiO2 hierarchical spheres (THS) prepared by a simple one-step hydrothermal method are employed as innovative support, and ultrafine high-density APO NPs with an average size of about 3 nm are successfully deposited and uniformly dispersed throughout THS to form hierarchical THS/APO composites. The novel THS/APO microstructure provides abundant reactive sites for photocatalytic reactions and promotes the photogenerated charge separation and transfer due to the ultrafine size of APO NPs and the TiO2/APO Type-II heterojunction. As a result, the THS/APO composites show significant improvement in photocatalytic activity and stability in methylene blue (MB) degradation. The reaction constant of THS/APO composites far exceeds that of either THS or APO, roughly 16 and 7 times higher than that of THS and APO under full-spectrum light, and 41 and 4 times higher under visible light. Our results strongly suggest new insights into the low-cost, large-scale application of high-efficiency APO-based photocatalyst.