The development of low-cost,abundant,and efficient non-metal catalysts has always been a research focus on photocatalytic hydrogen evolution reactions.Boron nitride nanosheet(BNNS),which is a promising non-metallic tw...The development of low-cost,abundant,and efficient non-metal catalysts has always been a research focus on photocatalytic hydrogen evolution reactions.Boron nitride nanosheet(BNNS),which is a promising non-metallic two-dimensional material,possesses remarkable properties.However,its inherently wide bandgap significantly limits their potential for visible-light-responsive catalysis,and conventional chemical methods struggle to overcome this limitation.In this study,we employed high-energy ionizing radiation to precisely regulate defect formation in BNNS at ambient temperature and pressure.The results showed that gamma-ray radiation markedly enhanced the efficiency of photocatalytic hydrogen production of the irradiated BNNS with increasing absorbed dose.The maximum hydrogen production rate of the samples reached 1033.7μmol/(g·h),which represents an increase of almost two orders of magnitude compared to commercial BNNS.The structural characterization also confirmed that the introduction of three-boron-center defects results in forming intermediate energy levels and improving the charge carrier separation efficiency of BNNS.This transformation converts BNNS from a wide bandgap semiconductor to a visible-light-responsive catalyst.This work not only provides a novel approach for the application of BNNS in visible-light photocatalysis,but also demonstrates the unique role of radiation technology in quantitatively regulating defects and improving catalytic activity.展开更多
Because gamma-ray bursts （GRBs） trace the high-z universe, there is an appreciable probability for a GRB to be gravitational lensed by galaxies in the universe. Herein we consider the gravitational lensing effect of...Because gamma-ray bursts （GRBs） trace the high-z universe, there is an appreciable probability for a GRB to be gravitational lensed by galaxies in the universe. Herein we consider the gravitational lensing effect of GRBs contributed by the dark matter halos in galaxies. Assuming that all halos have the singular isothermal sphere （SIS） mass profile in the mass range 101~h 1Mo 〈 M 〈 2×10^13h^-1M and all GRB samples follow the intrinsic redshift distribution and luminosity function derived from the Swift LGRBs sample, we calculated the gravitational lensing probability in BATSE, Swift/BAT and Fermi/GBM GRBs, re- spectively. With an derived probability result in BATSE GRBs, we searched for lensed GRB pairs in the BATSE5B GRB Spectral catalog. The search did not find any convincing gravitationally lensed events. We discuss our result and future obser- vations for GRB lensing observation.展开更多
文摘The development of low-cost,abundant,and efficient non-metal catalysts has always been a research focus on photocatalytic hydrogen evolution reactions.Boron nitride nanosheet(BNNS),which is a promising non-metallic two-dimensional material,possesses remarkable properties.However,its inherently wide bandgap significantly limits their potential for visible-light-responsive catalysis,and conventional chemical methods struggle to overcome this limitation.In this study,we employed high-energy ionizing radiation to precisely regulate defect formation in BNNS at ambient temperature and pressure.The results showed that gamma-ray radiation markedly enhanced the efficiency of photocatalytic hydrogen production of the irradiated BNNS with increasing absorbed dose.The maximum hydrogen production rate of the samples reached 1033.7μmol/(g·h),which represents an increase of almost two orders of magnitude compared to commercial BNNS.The structural characterization also confirmed that the introduction of three-boron-center defects results in forming intermediate energy levels and improving the charge carrier separation efficiency of BNNS.This transformation converts BNNS from a wide bandgap semiconductor to a visible-light-responsive catalyst.This work not only provides a novel approach for the application of BNNS in visible-light photocatalysis,but also demonstrates the unique role of radiation technology in quantitatively regulating defects and improving catalytic activity.
基金supported by the National Basic Research Program of China(Grant No. 2014CB845800)the National Natural Science Foundation of China (Grant No. 11373012)
文摘Because gamma-ray bursts （GRBs） trace the high-z universe, there is an appreciable probability for a GRB to be gravitational lensed by galaxies in the universe. Herein we consider the gravitational lensing effect of GRBs contributed by the dark matter halos in galaxies. Assuming that all halos have the singular isothermal sphere （SIS） mass profile in the mass range 101~h 1Mo 〈 M 〈 2×10^13h^-1M and all GRB samples follow the intrinsic redshift distribution and luminosity function derived from the Swift LGRBs sample, we calculated the gravitational lensing probability in BATSE, Swift/BAT and Fermi/GBM GRBs, re- spectively. With an derived probability result in BATSE GRBs, we searched for lensed GRB pairs in the BATSE5B GRB Spectral catalog. The search did not find any convincing gravitationally lensed events. We discuss our result and future obser- vations for GRB lensing observation.
