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Selective semi-hydrogenation of phenylacetylene to styrene is a crucial step in the polystyrene industry. Although Pd-based catalysts are widely used in this reaction due to their excellent hydrogenation activity, the selectivity for styrene remains a great challenge. Herein, we designed a mesoporous silica stabilized Pd-Ru@ZIF-8 (MS Pd-Ru@ZIF-8) nanoreactor with novel Pd and Ru single site synergistic catalytical system for semi-hydrogenation of phenylacetylene. The nanoreactor exhibited a superior performance, achieving 98% conversion of phenylacetylene and 96% selectivity to styrene. Turnover frequency (TOF) of nanoreactor was up to as high as 2,188 h⁻¹, which was 25 times and 5 times more than the single metal species catalysts, mesoporous silica stabilized Pd@ZIF-8 nanoreactor (MS Pd@ZIF-8), and mesoporous silica stabilized Ru@ZIF-8 nanoreactor (MS Ru@ZIF-8). This catalytic activity was attributed to the synergistic effect of Pd and Ru single site anchored strongly into the framework of ZIF-8, which reduced the desorption energy of styrene and increased the hydrogenation energy barrier of styrene. Importantly, since the ordered mesoporous silica was introduced into the nanoreactor shell to stabilize ZIF-8, MS Pd-Ru@ZIF-8 showed excellent reusability and stability. After the five cycles, the catalytical activity and selectivity still remained. This work provides insights for a synergistic catalytic system based on single-site active sites for selective hydrogenation reactions.

Molecular ferroelectrics have captured immense attention due to their superiority over inorganic oxide ferroelectrics, such as environmentally friendly, low-cost, flexible, foldable. However, the mechanisms of ferroelectric switching and phase transition for the molecular ferroelectrics are still missing, leaving the development of novel molecular ferroelectrics less efficient. In this work, we have provided a methodology combining molecular dynamics (MD) simulation on a polarized force field named polarized crystal charge (PCC) and enhanced sampling technique, replica-exchange molecular dynamics (REMD) to simulate such mechanisms. With this procedure, we have investigated a promising molecular ferroelectric material, (R)/(S)-3-quinuclidinol crystal. We have simulated the ferroelectric hysteresis loops of both enantiomers and obtained spontaneous polarization of 7/8 \mu C cm-2 and a corresponding coercive electric field of 15 kV cm-1. We also find the Curie temperature as 380/385 K for ferro-/para-electric phase transition of both enantiomers. All of the simulated results are highly compatible with experimental values. Besides of that, we predict a novel Curie temperature of about 600 K. This finding is further validated by principal component analysis (PCA). Our work would significantly promote the future exploration of multifunctional molecular ferroelectrics for the next generation of intelligent devices.

Using a Cu 2+ -dependent DNA ligation DNAzyme, a portable and sensitive biosensor for Cu 2+ detection based on personal glucose meters (PGMs) has been developed. In the presence of Cu 2+ , the DNAzyme catalyzed the ligation of nucleophilic attack of the phosphorus center of DNA1 by the hydroxyl group on DNA2 and forming a phosphodiseter bond. By introducing DNA-invertase conjugates and capture-DNA modified magnetic beads (MBs), the ligation product can hybridize with them and form invertase-functionalized MBs, which can be separated easily. The presence of invertase can convert sucrose to glucose and can be read out by the PGMs. With this method, a detection limit of 1 nM could be achieved. Moreover, the method exhibited excellent metal ion selectivity and there was almost no effect of biological complex to the detection performance, which suggested our method can be successfully applied to in biological process researches, drug discovery, and clinic diagnostics.

Combined with atomic force microscope (AFM), micro-Raman spectroscope, cross-section transmission electron microscope (TEM) and high resolution electron microscope (HREM) analyses, the surface morphology and structures of a-Si:H/a-SiN x :H multilayers (MLs), irradiated by excimer laser through the phase shifting mask grating, are investigated. It is found that Si nanocrystallites (nc-Si) are formed within the initial a-Si:H sublayers, and the size of the grains can be controlled due to the constrained crystallization effect. And it is possible to use this laser interference crystallization (LIC) method to get the periodic distribution of nc-Si in both transverse and longitudinal direction.

Electron transport mechanisms in lateral tantalum granular oxide-metal tunnel junctions have been investigated at low temperatures that range from 30 to 300 K. Fowler–Nordheim tunneling was determined to be the dominant temperature-independent conducting mechanism at high field, while direct tunneling appeared in the low field regime. All the nonlinear current-voltage curves were well fitted by Simmons’ equation with barrier thickness, height, and tunneling area treated as variables. The temperature-dependent current transport can be described by variable range hopping and Coulomb blockade.