BiPO_4稀土掺杂改性及其可见光光催化性能

BiPO_4 doped with rare-earth and its photocatalytic property under visible light irradiation

以Bi(NO_3)_3·5H_2O、NH_4H_2PO_4和稀土氧化物为原料,在乙二醇介质中采用溶剂热法制备了不同稀土元素(Ln=Sm、Pr、Tb)掺杂的Bi PO4光催化剂(记为Bi PO4-Ln,包含Bi PO4-Sm、Bi PO4-Pr和Bi PO_4-Tb)。通过X-射线衍射法(XRD)、扫描电子显微镜(SEM)、X-射线光电子能谱(XPS)和紫外可见漫反射光谱(UV-Vis DRS)对制备的催化剂进行了表征。以染料罗丹明B(rhodamine B,Rh B)及小分子水杨酸(salicylic acid,SA)为目标化合物,研究了在可见光激发下(λ≥420 nm)Bi PO4-Ln对目标污染物的光催化降解特性,结果表明,Bi PO4-Ln相较纯Bi PO4,其光吸收范围从紫外光扩大到可见光区域,在3种Bi PO_4-Ln催化剂中,Bi PO4-Sm对Rh B的吸附能力最强且其光催化活性较强,通过测定其在可见光下降解Rh B过程中产生的活性物种,发现Bi PO4-Ln在氧化降解Rh B的过程中主要涉及到·OH及O-2·的氧化机理。

Rare-earth-doped BiPO4 catalysts were prepared by a solvothermal method in ethylene glycol using bismuth nitrate pentahydrate, ammonium dihydrogen phosphate, and oxides of rare earth elements as the raw materi- als. The as-prepared catalysts were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, X-ray photoelectron spectroscopy （XPS）, and UV-Vis diffuse reflectance spectroscopy （UV-Vis DRS）. The photocat- alytic activities of the samples were evaluated by the degradation of rhodamine B （RhB） and salicylic acid （SA） un- der visible-light irradiation. It was found that the presence of rare earth elements in the host BiPO4 could broaden the absorption region from UV to visible light. Among the rare-earth-doped samples, the BiPO4-Sm catalyst showed the highest adsorption property and photocatalytic activity. The active species were investigated during the degradation of RhB by BiPO4-Sm, and the results showed that superoxide and hydroxyl radicals were the main oxide species.