Mechanism Of The Synthesis And Enhanced Photocatalytic Performance Of BiPO₄ And Its Composites

Photocatalysis,which can effectively utilize the infinite sunlight to degrade pollutants or produce hydrogen and oxygen,is considered as a promising technology.The special PO₄^3-group of BiPO₄ causes photogenerated electron-hole pairs high separation efficiency,and strong oxidation ability.However,BiPO₄ can't respond to visible light and react with visible light in sunlight.As a result,we focused on the above problems and the following researches were carried out:?1?The crystal forms,morphologies,properties and degradation mechanism of BiPO₄ were investigated by changing the hydrothermal reaction temperature and reaction time.When the reaction time and temperature were changed,the crystal form and the morphology of BiPO₄ changed accordingly.In this paper,the degradation performance of monoclinic BiPO₄ was the best and the mineralization rate of which was 100%.?2?BiVO₄/BiPO₄ 0 D/1 D composite photocatalyst was prepared by hydrothermal-ultrasonic in situ growth method,and Rhodamine B was decomposed under visible light.BiVO₄ and BiPO₄ formed close interfacial interaction,and 30 wt%BiVO₄/BiPO₄ composite photocatalyst showed the highest photocatalytic activity,the degradation degree of which was 8.3 times and 6.3 times of pristine BiPO₄ and BiVO_4,respectively.In the process of degradation,BiVO₄/BiPO₄ showed 100%mineralization ability and transformed Rh B into H₂O and CO₂.The composite also showed an excellent cycling stability.BiVO₄ and BiPO₄ form heterojunctions,so that the composite photocatalyst can effectively inhibit photo-induced carrier recombination.?3?Eosin Y/BiPO₄ dye sensitized composite photocatalyst was prepared by hydrothermal-immersion stirring method,and the two formed close interfacial interaction.The optimum degradation efficiency of Eosin Y/BiPO₄ is 41.4 times than that of pure BiPO₄ as well as showing excellent cyclic stability.In addition,Eosin Y/BiPO₄ exhibited 100%mineralization ability during degradation.The band gap of Eosin Y and BiPO₄ matches well,and electrons play a major role in the whole degradation process.Moreover,Eosin Y sensitized on the surface of BiPO₄ can effectively accelerate the separation and migration of photogenerated carriers.