p-n异质结型光催化剂BiOBr/NaBiO_3的制备与可见光催化活性

Preparation,Characterization and Visible-light Photocatalytic Activities of p-n Heterojunction BiOBr/NaBiO_3 Composites

采用化学蚀刻法在NaBiO3表面利用HBr与NaBiO3的反应原位沉积BiOBr,制备了异质结型光催化剂.利用X射线粉末衍射仪(XRD)、紫外-可见漫反射光谱仪(UV-Vis DRS)和扫描电子显微镜(SEM)等对其相结构、微观形貌和光吸收性能进行了表征.光催化实验结果表明,BiOBr/NaBiO3在可见光下可以有效降解罗丹明B(RhB)溶液,当BiOBr与NaBiO3的摩尔比为40.1%时,BiOBr/NaBiO3具有最大催化活性.通过不同牺牲剂的加入及荧光实验结果推测了该异质结型材料光催化过程中光生载流子的传输方向及活性物种.研究结果表明,BiOBr/NaBiO3催化活性的增强主要归结为两者之间形成了有效的异质结,其内建电场能够促进光生载流子的分离,同时h+在光催化降解过程中是主要的活性物种.

BiOBr/NaBiO3 heterostructures were synthesized by a simple chemical etching method using hydrobromic acid as etching agent to react with NaBiO3. X-ray powder diffraction （XRD）, UV-Vis diffuse reflectance spectra（ UV-Vis DRS） and scanning electron microscope（SEM） were employed to study the phase structures, morphologies and optical properties of the samples. The as-prepared samples exhibited more efficient photocatalytic activities than pure NaBiO3 and BiOBr for the degradation of Rhodamine B （RhB） under visible light irradiation, which could be attributed to the efficient separation of electron-hole pairs caused by the formation of BiOBr/NaBiO3 heterojunction. Terephthalic acid photoluminescence（TA-PL） probing test and radicals scavenger experiments demonstrated that h＋ was the dominant reactive species while the effect of · OH and · O2 was negligible. A possible transfer process of photogenerated carriers was proposed based on the band structures of NaBiO3 and BiOBr and the experimental results.