| Photocatalytic technology is driven by solar energy.The main reaction products are CO2 and H2O,which play an important role in protecting the environment and saving energy.However,most single photocatalysts are easy to recombine electron-hole pairs,and have low photocatalytic activity under visible light.They are usually modified by elemental doping,semiconductor recombination and precious metal deposition to improve their photocatalytic properties.In this paper,AgBr/g-C3N4 and Ag/AgBr/Ag3VO4 composite photocatalysts were prepared on the basis of AgBr.Methyl orange?MO?was used as the target pollutant to evaluate the photocatalytic performance,and its photocatalytic degradation mechanism was studied.The main research contents are as follows:?1?The AgBr/g-C3N4 composites were prepared and analyzed by XRD,SEM,XPS,UV-Vis and PL.The results show that AgBr and g-C3N4 are completely coupled together to form a heterogeneity.The effect of different mass ratios between AgBr and g-C3N4 on visible light photocatalytic activity was investigated.The results show that the degradation rate of AgBr/g-C3N4 with mass ratio of 4:1 is 93.44%when it degrades MO,which is significantly higher than that of single photocatalyst.At the same time,the effects of temperature and pH on the photocatalytic properties of the composites were investigated.The results show that pH is the main factor affecting the photocatalytic performance.As the pH increases,the photocatalytic activity of the composites increases first and then decreases.The active substance capture test showed that·O2—is the main active material,and the enhancement of photocatalytic activity mainly stems from the formation of the interface between AgBr and g-C3N4 to enhance the separation of electron-hole pairs.?2?Ag/AgBr/Ag3VO4 composites were prepared by continuous precipitation method.The composition,morphology and photoelectric properties of the composites were characterized and analyzed by XRD,SEM,XPS,UV-vis and PL.The influence of different mass ratios of AgBr and Ag3VO4 on visible light catalytic activity was investigated.It was found that the composite material with a mass ratio of 5:1 had the best photocatalytic effect after 20 min of visible light??>420 nm?irradiation.The degradation rate of MO reached 98.6%,and the degradation efficiency was 2.2 and96.5 times that of Ag/AgBr and Ag3VO4,respectively.System research of the composite materials in the preparation of system temperature,photoreduction time and pH of light on its photocatalytic performance,the results showed that the change of pH caused the change of composition and morphology of the composite,so that the photocatalytic activity increased first and then decreased with the increase of pH,while the temperature and photoreduction time had little effect on the photocatalytic performance.In addition,the capture experiments of active substances showed that h+and·O2—were the main active substances in the reaction,while the results of PL and electrochemical performance tests showed that the enhancement of photocatalytic activity was mainly attributed to the effective separation of electron-hole pairs.It is found that the photocatalytic activity of Ag/AgBr/Ag3VO4 is better than that of AgBr/g-C3N4,which is mainly due to the introduction of Ag0phase in Ag/AgBr/Ag3VO4 composite.Ag0 enhances the absorption of visible light,and the electron-hole pair separates faster in the three-phase composite,making Ag/AgBr/Ag3VO4 exhibit superior activity. |
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