Chemical hydrogen storage ammonia borane has attracted extensive attention as a method of efficient utilization of hydrogen energy. The high‐efficiency catalysts are the main factor restricting the hydrogen production of ammonia borane. In this paper, the synergistic effect of Co and CoOx supported on graphene (named Co?CoOx@GO‐II) promotes the efficient hydrogen production of ammonia borane, and its catalytic hydrogen production rate can reach 5813 mL min?1 gCo?1 at 298 K, the corresponding TOF is 15.33 min?1. After five stability tests, Co?CoOx @GO‐II maintained 65% of its original catalytic performance. The synergy of metal and metal oxide and the defects in the atomic arrangement ensure the catalytic activity, the large specific surface area of graphene ensures the dispersion and fixation. This strategy may provide a possibility to design high‐performance transition metal catalysts. 相似文献
Cd-doped In2O3 was synthesized by a facile solvothermal, template-free preparation method. The phase structure and properties were characterized by various methods. The surface of Cd-doped In2O3 became coarse compared with that of pure In2O3, according to the scanning electron microscopeimages, which enhanced the ability to absorb the gas. The electron paramagnetic resonance showed that the Cd-doped In2O3 can generate more defects and oxygen vacancies. By measuring the gas sensitivity, the response of Cd-doped In2O3 was 1.6 times than that of pure In2O3. Thus, Cd-doped In2O3 can promote gas-sensing performance compared with pure In2O3. 相似文献
Considering the problems of high costs, low catalytic activity and selectivity in the metal-based catalysts for CO2 electroreduction, we apply boron-containing metal-free B2S sheet as an alternative to the traditional metal-based catalysts. Reaction energy calculations identify the preferred “Formate” pathway for CO2 conversion to CH3OH on B2S, in which the thermodynamic energy barrier obtained by using the Computational Hydrogen Electrode model is 0.57 eV, and the kinetic energy barrier obtained by searching the transition states is 1.18 eV. Another possible reaction pathway, “RWGS+CO-hydro”, is suppressed and the hydrogen evolution reaction (HER) side reaction is nonspontaneous. Compared to Cu(211) with the highest catalytic activity among all transition metals, B2S sheet exhibits a better catalytic activity with a lower overpotential for CO2 reduction and a better selectivity that suppresses the non-target reaction. 相似文献
Traumatic brain injury (TBI) is one of the most dangerous acute diseases resulting in high morbidity and mortality. Current methods remain limited with respect to early diagnosis and real-time feedback on the pathological process. Herein, a targeted activatable fluorescent nanoprobe (V&A@Ag2S) in the second near-infrared window (NIR-II) is presented for in vivo optical imaging of TBI. Initially, the fluorescence of V&A@Ag2S is turned off owing to energy transfer from Ag2S to the A1094 chromophore. Upon intravenous injection, V&A@Ag2S quickly accumulates in the inflamed vascular endothelium of TBI based on VCAM1-mediated endocytosis, after which the nanoprobe achieves rapid recovery of the NIR-II fluorescence of Ag2S quantum dots (QDs) owing to the bleaching of A1094 by the prodromal biomarker of TBI, peroxynitrite (ONOO−). The nanoprobe offers high specificity, rapid response, and high sensitivity toward ONOO−, providing a convenient approach for in vivo early real-time assessment of TBI. 相似文献
We used dynamic Monte Carlo simulations to investigate the crystallization kinetics of flat-on lamellar polymer crystals in variable thickness films. We found that the growth rates linearly reduced with decreasing film thickness for the films thinner than a transition thickness dt, while they were constant for the films thicker than dt. Moreover, the mean stem lengths (crystal thickness) we calculated decreased with film thickness in a similar way to the growth rates, and the intramolecular crystallinities we calculated confirmed the film thickness dependence of the crytsal thickness. Besides, the crystal melting rates in thin films were calculated and increased with decreasing film thickness. We proposed a new interpretation on the film thickness dependence of the crystal growth rate in thin films, suggesting that it is dominated by the crystal thickness in terms of the driving force term (l–lmin) expressed by Sadler, rather than the chain mobility based on experiments. The crystal thickness can determine whether a crystal grows or melts in a thin film at a fixed temperature, indicating the reversibility between the crystal growth and melting. 相似文献
Rare earth-doped upconversion nanoparticles (UCNPs) have promising potentials in biodetection due to their unique frequency upconverting capability and high detection sensitivity. This paper reports an improved UCNPs-based fluorescence probe for dual-sensing of Aflatoxin B1 (AFB1) and Deoxynivalenol (DON) using a magnetism-induced separation and the specific formation of antibody-targets complex. Herein, the improved UCNPs, which were namely NaYF4:Yb/Ho/Gd and NaYF4:Yb/Tm/Gd, were systematically studied based on the optimization of reaction time, temperature and the concentration of dopant ions with simultaneous phase and size controlled NaYF4 nanoparticles; and the targets were detected using the pattern of competitive combination assay. Under an optimized condition, the advanced fluorescent probes revealed stronger fluorescent properties, broader biological applications and better storage stabilities compared to traditional UCNPs-based ones; and ultrasensitive determinations of AFB1 and DON were achieved under a wide sensing range of 0.001–0.1 ng ml−1 with the limit of detection (LOD) of 0.001 ng ml−1. Additionally, the applicability of the improved nanosensor for the detection of mycotoxins was also confirmed in adulterated oil samples. 相似文献
Organic optoelectronics are promising technologies for energy conversion. However, the electrode interlayer, a key material between active layers and conducting electrodes that controls the transport of charge carriers in and out of devices, is still a chemical challenge. Herein, we report a class of porous organic polymers with tunable work function as hole‐ and electron‐selective electrode interlayers. The network with organoborane and carbazole units exhibits extremely low work‐function‐selective electron flow; while upon ionic ligation and electro‐oxidation, the network significantly increases the work function and turns into hole conduction. We demonstrate their outstanding functions as anode and cathode interlayers in energy‐converting solar cells and light‐emitting diodes. 相似文献
In recent years, many investigations on the anthocyanins of the fresh Lycium ruthenicum Murray fruits have been reported; while few studies about dried fruits have been published. In this study, chemical profile of dried fruits was illustrated by a high-performance liquid chromatography–tandem mass spectrometry method, which provided evidence for the certain identification of the main anthocyanins. Among these compounds, nine of them were selected as marker compounds for the semiquantitative evaluation, using a simple and reliable method by high-performance liquid chromatography–photodiode array detection (HPLC–DAD), with the combination of chromatographic fingerprint analysis. Separation was achieved on a C18 ODS 80TS QA analytical column with linear gradient elution of acetonitrile and 10% formic acid and 0.1% trifluoroacetic acid (TFA) aqueous solution. Our results showed that the contents of anthocyanins of dried L. ruthenicum Murray from different origins were different. We also inferred the anthocyanin compositions of dried L. ruthenicum Murray through analyzing the UV spectrum, retention time, elution order, and MS data. Finally, eight kinds of anthocyanin compositions were identified and different from the anthocyanins in fresh L. ruthenicum Murray. In a word, this study may provide experimental data in further development and utilization of L. ruthenicum Murray. 相似文献
This paper provides a biomaterial derived from zwitterionic polymer for controlling macrophage phagocytosis of bacteria. A series of zwitterionic copolymers, named DMAPS‐co‐AA, are synthesized with 3‐dimethyl (methacryloyloxyethyl) ammonium propane sulfonate (DMAPS) and acrylic acid (AA). The biocompatibility of DMAPS‐co‐AA copolymers can be adjusted by adjusting the DMAPS‐content or pH value. As the DMAPS‐content increases, the biocompatibility of zwitterionic copolymer increases. The zwitterionic copolymers with DMAPS content above 30 wt% have higher biocompatibility. Moreover, the biocompatibility also increases significantly as the pH increases from 3.4 to 7.2. By adjusting the pH above 5.8, the zwitterionic copolymer with lower DMAPS‐content also shows higher biocompatibility. Importantly, after incubation with the DMAPS‐co‐AA copolymer solutions at different pH values, phagocytosis behavior of macrophage RAW264.7 cells can also be adjusted. The phagocytosis of bacteria is enhanced at pH = 7.2. Thus, it is proposed that zwitterionic copolymers can be used for controlling phagocytosis of bacteria.