Constructing binary heterojunctions is an important strategy to improve the photocatalytic performance of graphitic carbon nitride(g‐C3N4).In this paper,a novel g‐C3N4 nanosheet‐based composite was constructed via ...Constructing binary heterojunctions is an important strategy to improve the photocatalytic performance of graphitic carbon nitride(g‐C3N4).In this paper,a novel g‐C3N4 nanosheet‐based composite was constructed via in situ growth of bismuth oxyiodide(BiOI)nanoplates on the surface of g‐C3N4 nanosheets.The crystal phase,microstructure,optical absorption and textural properties of the synthesized photocatalysts were analyzed by X‐ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),ultraviolet‐visible(UV‐vis)diffuse reflectance spectroscopy(DRS),and nitrogen adsorption‐desorption isotherm measurements.The BiOI/g‐C3N4 nanosheet composite showed high activity and recyclability for the photodegradation of the target pollutant rhodamine B(RhB).The conversion of RhB(20 mg L?1)by the photocatalyst was nearly 100%after 50 min under visible‐light irradiation.The high photoactivity of the BiOI/g‐C3N4 nanosheet composite can be attributed to the enhanced visible‐light absorption of the g‐C3N4 nanosheets sensitized by BiOI nanoplates as well as the high charge separation efficiency obtained by the establishment of an internal electric field between the n‐type g‐C3N4 and p‐type BiOI.Based on the characterization and experimental results,a double‐transfer mechanism of the photoinduced electrons in the BiOI/g‐C3N4 nanosheet composite was proposed to explain its activity.This work represents a new strategy to understand and realize the design and synthesis of g‐C3N4 nanosheet‐based heterojunctions that display highly efficient charge separation and transfer.展开更多
The coherence method is always used to describe the discontinuity and heterogeneity of seismic data. In traditional coherence methods, a linear correlation coefficient is always used to measure the relationship betwee...The coherence method is always used to describe the discontinuity and heterogeneity of seismic data. In traditional coherence methods, a linear correlation coefficient is always used to measure the relationship between two random variables （i.e., between two seismic traces）. However, mathematically speaking, a linear correlation coefficient cannot be applied to describe nonlinear relationships between variables. In order to overcome this limitation of liner correlation coefficient. We proposed an improved concordance measurement algorithm based on Kendall＇s tau. That mainly concern the sensitivity of the liner correlation coefficient and concordance measurements on the waveform. Using two designed numerical models tests sensitivity of waveform similarity affected by these two factors. The analysis of both the numerical model results and real seismic data processing suggest that the proposed method, combining information divergence measurement, can not only precisely characterize the variations of waveform and the heterogeneity of an underground geological body, but also does so with high resolution. In addition, we verified its effectiveness by the actual application of real seismic data from the north of China.展开更多
文摘Constructing binary heterojunctions is an important strategy to improve the photocatalytic performance of graphitic carbon nitride(g‐C3N4).In this paper,a novel g‐C3N4 nanosheet‐based composite was constructed via in situ growth of bismuth oxyiodide(BiOI)nanoplates on the surface of g‐C3N4 nanosheets.The crystal phase,microstructure,optical absorption and textural properties of the synthesized photocatalysts were analyzed by X‐ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),ultraviolet‐visible(UV‐vis)diffuse reflectance spectroscopy(DRS),and nitrogen adsorption‐desorption isotherm measurements.The BiOI/g‐C3N4 nanosheet composite showed high activity and recyclability for the photodegradation of the target pollutant rhodamine B(RhB).The conversion of RhB(20 mg L?1)by the photocatalyst was nearly 100%after 50 min under visible‐light irradiation.The high photoactivity of the BiOI/g‐C3N4 nanosheet composite can be attributed to the enhanced visible‐light absorption of the g‐C3N4 nanosheets sensitized by BiOI nanoplates as well as the high charge separation efficiency obtained by the establishment of an internal electric field between the n‐type g‐C3N4 and p‐type BiOI.Based on the characterization and experimental results,a double‐transfer mechanism of the photoinduced electrons in the BiOI/g‐C3N4 nanosheet composite was proposed to explain its activity.This work represents a new strategy to understand and realize the design and synthesis of g‐C3N4 nanosheet‐based heterojunctions that display highly efficient charge separation and transfer.
基金supported by the Major Programs of National Natural Science Foundation of China(No.41390454)the Major Research Plan of the National Natural Science Foundation of China(No.91330204)
文摘The coherence method is always used to describe the discontinuity and heterogeneity of seismic data. In traditional coherence methods, a linear correlation coefficient is always used to measure the relationship between two random variables （i.e., between two seismic traces）. However, mathematically speaking, a linear correlation coefficient cannot be applied to describe nonlinear relationships between variables. In order to overcome this limitation of liner correlation coefficient. We proposed an improved concordance measurement algorithm based on Kendall＇s tau. That mainly concern the sensitivity of the liner correlation coefficient and concordance measurements on the waveform. Using two designed numerical models tests sensitivity of waveform similarity affected by these two factors. The analysis of both the numerical model results and real seismic data processing suggest that the proposed method, combining information divergence measurement, can not only precisely characterize the variations of waveform and the heterogeneity of an underground geological body, but also does so with high resolution. In addition, we verified its effectiveness by the actual application of real seismic data from the north of China.
