Investigating the spectral characteristic and humification degree of dissolved organic matter in saline-alkali soil using spectroscopic techniques

Soil samples were collected from the areas surrounding Wuliangsuhai Lake in China. Dissolved organic matter （DOM） was extracted from the samples and characterized by fluorescence and UV-Vis spectra. Spectral properties and humification degree of DOM were studied. The results indicated that both humic- and protein- like fluorophores were present in the DOM spectra, and the former was the dominant component. The analysis of humification （HIX） and r （A, C） indices revealed that the maximum humification degree in three agricultural soils （AAF, ASC, and ASW） was presented in the second soil layer （20-40 cm）. However, the humification degree of the two Halophytes soils （SSE and GKF） decreased with increasing depth. One index, I344/270, showed that humification degree increased gradually with an increasing proportion of humic-like acid. There was a significant positive correlation between humification degree （HIX） and aromaticity （SUVA254）, indicating that a higher aromaticity corresponded to a higher humification degree. Land use was an important factor responsible for the major difference of cation exchange capacity （CEC） in different soils, which led to a higher CEC value in the second soil layer for the three agricultural soils. CEC values and humification degree had the same trend for all five soils. The correlation analysis showed that there was a significant positive correlation between HIX and CEC,and a negative correlation between the r （A, C） index and CEC, indicating that humification degree increases gradually with increasing CEC values.

In-situ construction of amorphous/crystalline contact Bi_(2)S_(3)/Bi_(4)O_(7) heterostructures for enhanced visible-light photocatalysis

Constructing a heterojunction photocatalyst is a significant method to enhance photocatalytic activity because it can promote the separation of photogene rated carriers.Herein,amorphous/crystalline contact Bi_(2)S_(3)/Bi_(4)0_(7) heterostructure was successfully synthesized by in-situ sulfidation of Bi407.The amorphous Bi_(2)S_(3) is diffused on the surface of Bi_(4)0_(7) rod,enhancing the visible light response and improving the transport of photogene rated carriers.Various characterizations confirm that the rapid separation of photogene rated carriers leads to increased photocatalytic performance.The optimized Bi_(2)S_(3)/Bi_(4)O_(7) heterostructure photocatalyst(BiS-0.15) exhibits the highest Cr(Ⅵ) reduction(0.01350 min^(-1)) and RhB oxidation(0.08011 min^(-1)) activity,which is much higher than that of pure Bi_(4)0_(7) and mixture under visible light irradiation.This work provides new insights into the construction of efficient novel photocatalysts.

A review on metal-organic frameworks for photoelectrocatalytic applications

Semiconductor-based photoelectrocatalytic processes have attracted considerable research interest for solar energy collection and storage.Photoelectrocatalysis is a heterogeneous photocatalytic process in which a bias potential is applied to a photoelectrode,and thus the photoelectrocatalytic performance is closely related to the photoelectrode prepared by semiconductors.Among various semiconductors,metal-organic frameworks(MOFs)have attracted more and more attention because of their unique properties such as optical properties and adjustable structure.Herein,a comprehensive review on different MOFs(Ti-based,Zn-based,Co-based,Fe-based,Cu-based,and mixed metal-based MOFs)for heterogeneous photoelectrocatalysis is carried out and,in particular,the application of this technique for CO2 conversion and water splitting is discussed.In addition,the challenges and development prospects of MOFs in photoelectrocatalysis are also presented.