Latest ArticlesMaximizing solar energy utilization is a persistent challenge in photo catalysis, which determines sustainable solar-driven photocatalytic process. Photo thermal-coupled photo catalysis is considered as a promising solution to tackle the issues of sustainable energy scarcity and environmental pollution by harvesting the full-spectrum solar energy. Herein, a highly efficient photo thermal-accelerated photo catalysis system is elaborately established, in which the assembled carbonized stick/Nb2C MXene evaporator can heat water into vapor and the integrated g-C3N4 photocatalyst further enables high-efficiency photocatalytic hydrogen production. The designed hyperboloid wood-based architecture possesses a multiphase interface of water steam/catalyst/hydrogen to reduce the transport resistance of hydrogen gas in liquid and ultimately maximize the output of hydrogen energy. Consequently, this coupled photothermal-photocatalytic system achieves a stable solar evaporation rate of 2.16 kg m-1 h-1 under one sun irradiation and highly efficient hydrogen-evolving rate of 3096 µmol g-1 h-1. This work paves a way to explore the improvement of photocatalytic hydrogen production by synergic photothermal effect for potential applications in renewable solar energy utilization and hydrogen production.
Single-atom catalysts were widely used to treat atmospheric pollution and alleviate energy crises through photocatalysis. However, how to prevent the aggregation of single atoms during the preparation and catalytic processes remained a great challenge. Herein, a novel ultrathin two-dimensional porphyrin-based single-atom photocatalyst Ti-MOF (abbreviated as TMPd) obtained through a simple hydrothermal synthesis strategy was used for photocatalytic hydrogen evolution and NO removal, in which the single-atom Pd tightly anchored in the center of porphyrin to ensure single-atom Pd stable existence. Compared with most reported MOFs-based photocatalysts, the TMPd showed an excellent hydrogen evolution rate (1.32 mmol g−1 h−1) and the NO removal efficiency (62%) under visible light irradiation. Aberration-corrected high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) and synchrotron-radiation-based X-ray absorption fine-structure spectroscopy (XAFS) proved that pd in TMPd existed in an isolated state, and the atomic force microscope (AFM) proved the ultrathin morphology of TMPd. DFT calculations had demonstrated that single-atom Pd could serve as the active center and more effectively achieve electron transfer, indicating that single-atom Pd played a vital role in photocatalytic hydrogen evolution. In addition, a possible photocatalytic pathway of NO removal was proposed based on ESR and in-situ infrared spectra, in which the catalysts anchored with single-atom Pd could produce more active substances and more effectively oxidize NO to NO2− or NO3−. The results suggested that coordinating single-atom metal species as the active site in the center of porphyrin could be a feasible strategy to obtain various ultrathin porphyrin-based single-atom photocatalysts to acquire excellent photocatalytic performance further.
Highly selective and remotely communicable nitrogen dioxide (NO2) sensing may contribute to future Internet of Things in environmental monitoring. However, room-temperature NO2 sensing materials such as carbon materials is still less than satisfactory due to their insensitive interaction with target gas. Here, polyethylene imine functionalized three-dimensional (3D) carbon framework (PEI/C framework) has been developed for enhanced selective NO2 sensing, via combined template synthesis and subsequent doping. Typically, the 3D PEI/C framework is observed porous shape with irregular coating. Beneficially, the response of C framework to NO2 increases while those of interfering gases decrease after being functionalized with PEI. Remarkably, the sensor prototypes show a 100 ppb-concentration detection limit at room temperature. Theoretically, such excellent NO2 sensing is attributed to the large specific surface ratio of porous 3D PEI/C framework, in which PEI serves as an active layer for target NO2, while a passivated one for interfering gases. Practically, such PEI/C framework sensor prototype is simulated for NO2 sensing device and communicated with a smartphone, showing great potential in future intelligent environmental monitoring.
Hydrogen-bonded organic frameworks (HOFs) are a promising candidate for optical sensing, but the lack of effective design strategies poses significant challenges to the construction of HOFs for organic acid sensing. In this work, the first HOF for organic acid sensing is reported by constructing a multiple-pyridine carbazole-based dense HOF, namely HOF-FJU-206, from a tripyridine-carbazole molecular 3,6-bis(pyridin-4-yl)-9-(4-(pyridin-4-yl)phenyl)-9H-carbazole (CPPY) with carbazole center for luminescence, pyridyl sites for its responsive of hydrogen proton, and narrow channels in the dense framework for the diffusion of hydrogen protons. HOF-FJU-206 exhibits differential responsively fluorescence sensing and recovery properties to formic, acetic, and propionic acids with different molecular sizes and pKa value (acid dissociation constant). The dissociation degree of various acids can be determined by analyzing the slope of changes in both peak wavelength and intensity of in-situ fluorescence, which easily enables the dual-corrective recognition of different acids. The varying degree of protonation at pyridine sites is proved to be the reason for differential sensing of various acids, as demonstrated by 1H NMR spectra, X-ray photoelectron spectroscopy (XPS) characterization, and modeling studies.
The O3-Na0.85Ni0.2Fe0.4Mn0.4O2 layered oxide cathode material possesses the advantages of high specific capacity, low cost, and simple synthesis. However, sluggish kinetics and complicated phase transition caused by the large size difference between Na+ and tetrahedral gaps lead to poor rate and cycling performance. Therefore, a scalable and feasible strategy was proposed to modulate local chemical environment by introducing Mg2+ and B3+ into O3-Na0.85Ni0.2Fe0.4Mn0.4O2, which can distinctly improve kinetic transport rate as well as electrochemical performance. The capacity retention of O3-(Na0.82Mg0.04)(Ni0.2Fe0.4Mn0.4)B0.02O2 (NFMB) increases from 43.3% and 12.4% to 89.5% and 89.0% at 1 C and 3 C after 200 cycles, respectively. Moreover, the electrode still delivers high rate capacity of 93.9 mAh/g when current density increases to 10 C. Mg2+ ions riveted on Na layer act as a "pillar" to stabilize crystal structure and inhibit structural change during the desodiumization process. B3+ ions entering tetrahedral interstice of the TM layer strengthen the TM-O bond, lower Na+ diffusion energy barrier and inhibits the slip of TM layer. Furthermore, the assembled full batteries with the modified cathode material deliver a high energy density of 278.2 Wh/kg with commercial hard carbon as anode. This work provides a strategy for the modification of high-performance SIB layered oxide materials to develop the next-generation cost-effective energy storage grid systems.
The clustered regularly interspersed short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) system is an RNA-guided platform for highly efficient and specific genome targeting in diverse organisms, which has been exploited for various applications in gene manipulation. Compared with the constantly active CRISPR/Cas9 function, conditional control of its activity can improve the performance of the system with reduced side effects and high spatiotemporal precision. The pH-responsive triplex RNA was successful used in CRISPR-derived RNA/trans-activating crRNA (crRNA/tracrRNA) of CRISPR/Cas9, thus affecting RNA/dead Cas9 (dCas9) complex to target DNA in vitro and in vivo. This design of triplex RNA opens a new window towards the broad involvement of eukaryotic cells for conditional control of CRISPR/Cas9 function.
Catalytic C-H activation-initiated annulation reactions have emerged as a versatile strategy for the efficient construction of diverse ring structural units and complex cyclic molecules in synthetic chemistry. Herein, we describe a new Rh(Ⅲ)-catalyzed C-H activation-initiated transdiannulation reaction of N, N-dimethyl enaminones with gem-difluorocyclopropenes in the presence of H2O, enabling a facile and oxygen transfer access to ring-fluorinated tricyclic γ-lactones with a 6-5 ring-junction tetrasubstituted stereocenter. This approach features bond-forming/annulation efficiency, good functional group tolerance and complete regioselectivity, which may include a complex process consisting of Rh(Ⅲ)-catalyzed C(sp2)H activation, cyclic alkene insertion, defluorinated ring-opening of gem-difluorocyclopropane, intramolecular oxygen transfer, intramolecular cyclization and oxidative hydration.
Organic electrode materials (OEMs) have attracted substantial attention for aqueous zinc-ion batteries (AZIBs) due to their advantages in relieving resource and environmental anxiety. However, the potential of OEMs is plagued by their low achievable capacity and high solubility. Here, we have proposed a new concept of "co-coordination force" and designed a rigid-flexible coupling crystalline polymer that can overcome the abovementioned limitations. The obtained crystalline polymer (BQSPNs) with multiredox centres makes the BQSPNs exist intermolecular hydrogen bonds (HB) among -C=O, -C=N, and -NH and consequently exhibits transverse two-dimensional arrays and longitudinal π-π stacking structure. Additionally, in-situ FTIR, Raman, variable temperature FTIR spectra, and 2D nuclear overhauser effect spectroscopy (NOESY) well capture the existence and evolution process of HB during the electrochemistry reaction process of BQSPNs, uncovering the effect of HB in stabilizing the structure and promoting the reaction kinetics. As a result, the BQSPNs with rationally designed "co-coordination force" deliver a high capacity of 459.6 mAh/g and a stable cycling lifetime for more than 100,000 cycles at 10 A/g in AZIBs. Our results disclose the HB effect and provide a brand-new strategy for high-performance OEMs design.
On-surface Ullmann-type reaction, or the dehalogenated coupling, is arguably the most pivotal reaction in on-surface synthesis for the fabrications of carbon nanostructures. Hitherto, the vast majority of works rely on activating the C-Br bond of aryl bromide which has a moderate bond dissociation energy. The C-Cl bond of aryl chloride has a higher dissociation energy and requires much higher thermal energy to break the bond. In this study, we have explored the on-surface photo-induced dechlorination and achieved the activation of three distinct aryl chlorines on the Au(111) surface with mild temperatures. This work enriches our understanding of on-surface photo-induced reactions and highlights the potential of photochemistry in realizing unconventional reactions.
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