Preparation And Photocatalytic Activities Of Potassium Niobate System Photocatalysts

In the 21st century,energy shortage has become one of the major factors hindering social and economic development.Hydrogen is regarded as an ideal substitute for traditional fossil fuels due to its high calorific value and zero pollution.Therefore,photocatalytic technology,which can convert low-density solar energy to high-density hydrogen and offer a cost-effective and eco-friendly process to generate hydrogen,is believed to be an ideal way to solve the energy issue,through photocatalyst while.KNbO3 has excellent application potential due to it is high stability,non-toxicity and high activity in hydrogen evolution.However,the wide bandgap of KNbP3 and low photocarrier separation efficiency limit its light utilization and photocatalytic activity.In order to improve the photocatalytic activity of KNbO3,the following approaches were designed and performed:1.Carbon-doped KNbO3 photocatalyst was synthesized for the first time via a simple combination of hydrothermal and post-calcination processes with glucose as the carbon source.C-KNbO3 sample calcined at 350? displayed the highest hydrogen generation rate of 211?mol�g-l h-1.which is 42 times higher than that of pure KNbO3.XRD,XPS,FT-IR,Raman,SEM analysis indicated that the doped carbon mainly substites for the position of NdS+.The doped carbon leads to the generation of oxygen vacancies which improves the separation efficiency and subsequently results in the enhanced photocatalytic activity;2.In order to further enhance the separation efficiency and photocatalytic activity,a narrow bandgap semiconductor MOS2 was decorated on carbon-doped KNbO3 via hydrothermal method to fabricate a heterojunction structure.The efficient.photocatalytic hydrogen production was realized on the MoS2/C-KNbO3 composite under simulated sunlight irradiation in the present of methanol and chloroplatinic acid.The optimal composite presents a H2 production rate of 1300 ?mol�g-1,h-1,which reaches 260 times that of pure KNbO3;3.High efficient KNbO3/g-C3N4 composite was prepared via a simple milling-calcination method.The synergistic effect of g-C3N4 with KNbO3 overcomes the drawbacks of low visible light utilization and low separation efficiency of KNbO3.Under visible light irradiation,the photocatalytic hydrogen production rate for the optimal KNbO3/g-C3N4 composite is 180 umol�g.-1�h-1,which is about 3.0 times that of pristine g-C3N4.