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Unraveling the Interfacial Charge Migration Pathway at the Atomic Level in a Highly Efficient Z-Scheme Photocatalyst
No full textA highly efficient Z-scheme photocatalytic system constructed with 1D CdS and 2D CoS2 exhibited high photocatalytic hydrogen-evolution activity of 5.54 mmol h(-1) g(-1) with an apparent quantum efficiency of 10.2 % at 420 nm. More importantly, its interfacial charge migration pathway was unraveled: The electrons are efficiently transferred from CdS to CoS2 through a transition atomic layer connected by Co-S-5.8 coordination, thus resulting in more photogenerated carriers participating in surface reactions. Furthermore, the charge-trapping and charge-transfer processes were investigated by transient absorption spectroscopy, which gave an estimated charge-separation yield of approximately 91.5 % and a charge-separated-state lifetime of approximately (5.2 +/- 0.5) ns in CdS/CoS2. This study elucidates the key role of interfacial atomic layers in heterojunctions and will facilitate the development of more efficient Z-scheme photocatalytic systems
Metagenomic Analysis of the Diversity of DNA Viruses in the Surface and Deep Sea of the South China Sea
No full textA metagenomic analysis of the viral community from five surface and five deep sea water (>2000 m below the surface, mbs) samples collected from the central basin of the South China Sea and adjacent Northwest Pacific Ocean during July-August 2017 was conducted herein. We builded up a South China Sea DNA virome (SCSV) dataset of 29,967 viral Operational Taxonomic Units (vOTUs), which is comparable to the viral populations from the original Tara Ocean and Malaspina expeditions. The most abundant and widespread viral populations were from the uncultivated viruses annotated from the viral metagenomics. Only 74 and 37 vOTUs have similarity with the reported genomes from the cultivated viruses and the single-virus genomics, respectively. The community structures of deep sea viromes in the SCSV were generally different from the surface viromes. The carbon flux and nutrients (PO4 and NOx) were related to the surface and deep sea viromes in the SCSV, respectively. In the SCSV, the annotated vOTUs could be affiliated to the cultivated viruses mainly including Pelagibacter (SAR11) phage HTVC010P, Prochlorococcus phages (P-GSP1, P-SSM4, and P-TIM68), Cyanophages (MED4-184 and MED4-117) and Mycobacterium phages (Sparky and Squirty). It indicated that phage infection to the SAR11 cluster may occur ubiquitously and has significant impacts on bathypelagic SAR11 communities in the deep sea. Meanwhile, as Prochlorococcus is prominently distributed in the euphotic ocean, the existence of their potential phages in the deep sea suggested the sedimentation mechanism might contribute to the formation of the deep sea viromes. Intriguingly, the presence of Mycobacterium phages only in the deep sea viromes, suggests inhabitance of endemic viral populations in the deep sea viromes in the SCSV. This study provided an insight of the viral community in the South China Sea and for the first time uncovered the deep sea viral diversity in the central basin of the South China Sea
Intense X-ray isolated attosecond pulse generation by using low-intensity chirped pulse combined with a UV seeding pulse
No full textWe theoretically investigate intense isolated attosecond pulse (IAP) generation from high-order harmonic generation (HHG) driven by a low-intensity chirped pulse combined with a UV seeding pulse. The results show that, driven by a two-color chirped pulse, the harmonic cutoff can be remarkably extended and a spectral continuum in X-ray region can be obtained. Moreover, as the pulse duration increases or the delay time of the two pulses changes, a larger harmonic cutoff can be found. Further, with the introduction of a UV seeding pulse, the efficiency of HHG can be enhanced by three orders of magnitudes due to the UV resonance ionization. Moreover, as the UV pulse intensity increases, the enhanced ratio of HHG yield can be further improved. The enhancement of HHG yield is related to the pulse duration and delay time of the UV pulse. For instance, when adding a shorter duration UV pulse, the enhancement of HHG is dependent on the delay time of the UV pulse. However, when adding a longer duration UV pulse, the HHG enhancement is not very sensitive to the delay time of the UV pulse. Finally, the obtained spectral continuum supports the generation of intense IAP with the duration of 36 as
