Cu single atoms embedded on hollow g-C_(3)N_(4)nanospheres with enhanced charge transfer and separation for efficient photocatalysis

Establishing an effective charge transfer mechanism in carbon nitride(g-C_(3)N_(4))to enhance its photocatalytic activity remains a limiting nuisance.Herein,the combination design of a single Cu atom with hollow g-C_(3)N_(4)nanospheres(Cu-N_(3)structure)has been proven to offer significant opportunities for this crucial challenge.Moreover,this structure endows two pathways for charge transfer in the reaction,namely,the N atoms in the three-dimensional planar structure are only bonded with a single Cu atom,and charge transfer occurs between the plane and the layered structure due to the bending of the interlayered g-C_(3)N_(4)hollow nanospheres.Notably,Cu-N_(3)and hollow nanosphere structures have been certified to greatly enhance the efficiency of photogenerated carrier separation and transfer between the layers and planes by ultrafast spectral analysis.As a result,this catalyst possesses unparalleled photocatalytic efficiency.Specifically,the hydrogen production rate up to 2040μmol h^(−1) g^(−1),which is 51 times that of pure C_(3)N_(4)under visible light conditions.The photocatalytic degradation performance of tetracycline and oxidation performance of benzene is also expressed,with a degradation rate of 100%,a conversion of 97.3%and a selectivity of 99.9%.This work focuses on the structure-activity relationship to provide the possibilities for the development of potential photocatalytic materials.

Adsorption–desorption behavior of atrazine on agricultural soils in China

Adsorption and desorption are important processes that affect atrazine transport,transformation,and bioavailability in soils.In this study,the adsorption–desorption characteristics of atrazine in three soils（laterite,paddy soil and alluvial soil） were evaluated using the batch equilibrium method.The results showed that the kinetics of atrazine in soils was completed in two steps：a＂fast＂ adsorption and a ＂slow＂ adsorption and could be well described by pseudo-second-order model.In addition,the adsorption equilibrium isotherms were nonlinear and were well fitted by Freundlich and Langmuir models.It was found that the adsorption data on laterite,and paddy soil were better fitted by the Freundlich model;as for alluvial soil,the Langmuir model described it better.The maximum atrazine sorption capacities ranked as follows：paddy soil 〉 alluvial soil 〉 laterite.Results of thermodynamic calculations indicated that atrazine adsorption on three tested soils was spontaneous and endothermic.The desorption data showed that negative hysteresis occurred.Furthermore,lower solution pH value was conducive to the adsorption of atrazine in soils.The atrazine adsorption in these three tested soils was controlled by physical adsorption,including partition and surface adsorption.At lower equilibrium concentration,the atrazine adsorption process in soils was dominated by surface adsorption;while with the increase of equilibrium concentration,partition was predominant.

Constructing built-in electric field in graphitic carbon nitride hollow nanospheres by co-doping and modified in-situ Ni_(2)P for broad spectrum photocatalytic activity

The construction of built-in electric field is generally considered as an effective strategy to enhance photocatalytic performance due to its significant role in charge separation.Herein,a built-in electric field within g-C_(3)N_4 hollow nanospheres co-doped with sulfur and oxygen and modified in-situ Ni_(2)P is proposed.Ni_(2)P/SO-HC_(3)N_4 exhibits significantly enhanced board spectrum photocatalytic properties for hydrogen precipitation(5.21 mmol h^(-1)g^(-1))and photocatalytic Cr(VI)reduction without the use of noble metal.It also achieves high photocatalytic sterilization activity and remarkable stability when used to completely inactivate E.coli(10~7)in 60 min under Vis-NIR light irradiation.The enhanced performance is attributed to the formation of a curved hollow sphere structure,which promotes the electron transfer between the inner and outer layers.In addition,co-doping inhibits the recombination of photogenerated carriers,and the built-in electric field recombined with Ni_(2)facilitates the electron transfer between the composite interfaces.This design strategy demonstrates an original method of devising multifunctional photocatalysts with enhanced activity and stability.