Study On The Modification And Photodegradation Mechanism Of Graphite Carbon Nitride Photocatalyst

With the thorough development of industrialization,dilemma such as energy depletion and environment pollution and so on,have been increasingly exposed.Sustainable development has became the common concern worldwide.Photocatalysis,considered as an ideal solution to cope with energy and environment issues,has became one of the most widely investigated scientific field.Photocatalyst is the core of photocatalysis.In this work,we have investigated the modification of g-C₃N₄,such as heterojunction construction with Bi₂WO₆and（K,Fe）co-doping.Details are listed as follows:A 2D/2D Z-scheme visible-light-driven Bi₂WO₆/Porous-g-C₃N₄with enhanced adsorption and photodegradation was successfully attained by an ultrasonication-assisted chemisorption method.Its physicochemical properties were systematically characterized.The adsorptive and photocatalytic activities were determined by Rh B decoloration experiments.The results show that Bi₂WO₆/Porous-g-C₃N₄-15 exhibits the highest adsorption capacity and photocatalytic activity,which is 2.55 and 3.31 times of that of Bi₂WO₆,and 2.58 and 1.46 times of that of Porous-g-C₃N₄.The adsorption enhancement was proved by BET and Zeta potential characterizations.The adsorption enhancement can not only help to remove Rh B directly,but also accelerate the initial step of photodegradation,which is of great importance in dyes removal.A Z-scheme mechanism was proposed,and particularly investigated through theoretical analyses and active species trapping experiments comparison on Bi₂WO₆and Bi₂WO₆/Porous-g-C₃N₄.P-type（K,Fe）co-doped g-C₃N₄was synthesized under self-generated NH₃atmosphere and displayed improved photocatalysis performances.Its physicochemical properties were systematically characterized.The reducing atmosphere,self-generated NH₃,strongly affects photocatalytic performances and causes a downshift of the band alignments.The photo-current response and Mott-Schottky plots show that the as-synthesized（K,Fe）co-doped g-C₃N₄is of P-type and has a boosted current density.Photocatalytic activity evaluation in Rh B solution could be well fitted by zero-order kinetic.Photocatalytic mechanism was investigated based on trapping experiments,suggesting a synergistic effect between low E_VBand p-type behaviors.