Study On The Synthesis And Photocatalytic Activity Of BiVO₄ Photocatalysts

The global energy crisis and environment pollution have attracted tremendously attentions. The synthesis and applications of visible-light photocatalysts with high utilization efficiency of solar energy to split water into hydrogen or degrade organic pollutant has become a hot research covering materials science, chemistry and environmental science. BiV04, as a kind of photocatalytic materials under visible light, has obtained more attentions due to its narrow gap and higher catalytic activity.In the present work, two various methods were applied for preparing BiVO4 particles, and the correspongding microstructure, growth process and the light-visible photocatalytic property were also investigated. Firstly, under hydrothermal conditions, crystalline bismuth vanadate (BiV04) microtubes were synthesized successfully with isopropanol as the organic inducer. The results indicated that as-prepared microtubes had a monoclinic structure with a side length of ca.1 um and a wall thickness of ca.100-150nm. Investigation on the phase and morphology of samples with the amount of isopropanol and time showed that the well-crystalline BiVO4 microtubes could be obtained by hydrothermal treated for 1h with adding 20% isopropanol. Furthermore, isopropanol played a significant role in the process of preparing BiVO4 particles. The BiVO4 particles with square micotubes and comb-like shape could be obtained respectively as the existence of isopropanol or not. The BiVO4 microtubes exhibite higher photocatalytic activity under visible light irradiation, causing the 99% degradation of rhodamin B after visible light irradiated for 4h.Crystalline bismuth vanadate (BiVO4) spindly microtubes were ionothermally synthesized in the deep eutectic solvent (DES) of choline chloride/urea mixtures with Bi(NO3)3·5H2O and NH4VO3 as raw materials. The crystalline monoclinic BiVO4 spindly microtubes with the length of 10-15μm, the diameter of ca.1.5μm and the wall thickness of 200nm, were obtained at 150℃treated for 15h. The BiVO4 spindly microtubes were characterized by XRD, SEM and UV-Vis spectrophotometer. Additionally, more attentions were taken for the pH value effect on the phase and morphology of samples, leading to the formation of the monoclinic BiVO4 samples with rod, spindly microtubes, microtubes and needle shapes. A much higher photocatalytic activity of the spindly microtubes were found in comparison with other samples for degradation of rhodamine B under visible light irradiation, causing the 93% degradation of rhodamin B after visible light irradiated for 4.5h.