Department of Civil and Environment Engineering, University of Ulsan, Daehakro 93, Namgu, Ulsan 44610, Republic of Korea.
Department of Civil and Environment Engineering, University of Ulsan, Daehakro 93, Namgu, Ulsan 44610, Republic of Korea.
J Colloid Interface Sci. 2019 Jan 15;534:37-46. doi: 10.1016/j.jcis.2018.08.095. Epub 2018 Aug 28.
Monoclinic bismuth vanadate (c-BVO) was prepared via simple calcination of solvothermally processed tetrahedral BiVO. The physicochemical and morphological properties of c-BVO demonstrated the successful synthesis of the photoactive monoclinic phase from the tetrahedral phase, which has low photoactivity properties. The photoactivities of c-BVO were investigated using the photodegradation of methylene blue (MB) and photoelectrochemical (PEC) measurements in acidic (pH = 2.5), neutral (pH = 6.5) and basic (pH = 9.5) media. The photocatalytic activity of c-BVO was increased with increasing pH, achieved 99% MB degradation in the basic condition, compared with 70 and 45% in the neutral and acidic media, respectively. Although the tetrahedral BiVO showed mainly adsorption with negligible photodegradation, c-BVO demonstrated both good adsorption and photodegradation activities. The PEC results indicated that the photocurrent density was affected by both pH and applied voltage. Impedance measurements showed faster charge transfer in the neutral condition than in the acidic and basic electrolytes. The incident photon conversion efficiency (IPCE) showed very low activity for tetrahedral BiVO, but in comparison it was enhanced by 20- and 10-fold for c-BVO in the visible and simulated solar light, respectively.
四方相 BiVO 通过溶剂热法处理后煅烧制备出单斜相 BiVO（c-BVO）。c-BVO 的物理化学和形态特性表明，成功地从四方相合成出具有低光活性的单斜相光活性相。通过在酸性（pH=2.5）、中性（pH=6.5）和碱性（pH=9.5）介质中用光降解亚甲基蓝（MB）和光电化学（PEC）测量来研究 c-BVO 的光活性。随着 pH 的增加，c-BVO 的光催化活性增加，在碱性条件下达到 99%的 MB 降解，而在中性和酸性介质中分别达到 70%和 45%。虽然四方相 BiVO 主要表现为吸附作用，光降解作用可以忽略不计，但 c-BVO 同时表现出良好的吸附和光降解活性。PEC 结果表明，光电流密度受 pH 和外加电压的影响。阻抗测量表明，中性条件下的电荷转移速度比在酸性和碱性电解质中更快。瞬态光电压（IPCE）表明四方相 BiVO 的活性非常低，但相比之下，在可见光和模拟太阳光下，c-BVO 的活性分别增强了 20 倍和 10 倍。
