Yoon Hyun, Mali Mukund G, Choi Jae Young, Kim Min-woo, Choi Sung Kyu, Park Hyunwoong, Al-Deyab Salem S, Swihart Mark T, Yarin Alexander L, Yoon Sam S
⊥Petrochemicals Research Chair, Department of Chemistry, College of Science, King Saud University, Riyadh 11451, Saudi Arabia.
%Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, Illinois 60607, United States.
Langmuir. 2015 Mar 31;31(12):3727-37. doi: 10.1021/acs.langmuir.5b00486. Epub 2015 Mar 17.
We demonstrate, for the first time, electrostatically sprayed bismuth vanadate (BiVO4) thin films for photoelectrochemical water splitting. Characterization of these films by X-ray diffraction, Raman scattering, and high-resolution scanning electron microscopy analyses revealed the formation of nanotextured pillar-like structures of highly photoactive monoclinic scheelite BiVO4. Electrosprayed BiVO4 nanostructured films yielded a photocurrent density of 1.30 and 1.95 mA/cm(2) for water and sulfite oxidation, respectively, under 100 mW/cm(2) illumination. The optimal film thickness was 3 μm, with an optimal postannealing temperature of 550 °C. The enhanced photocurrent is facilitated by formation of pillar-like structures in the deposit. We show through modeling that these structures result from the electrically-driven motion of submicron particles in the direction parallel to the substrate, as they approach the substrate, along with Brownian diffusion. At the same time, opposing thermophoretic forces slow their approach to the surface. The model of these processes proposed here is in good agreement with the experimental observations.
我们首次展示了用于光电化学水分解的静电喷涂钒酸铋（BiVO₄）薄膜。通过X射线衍射、拉曼散射和高分辨率扫描电子显微镜分析对这些薄膜进行表征，结果表明形成了具有高光活性的单斜白钨矿型BiVO₄纳米纹理柱状结构。在100 mW/cm²光照下，静电喷涂的BiVO₄纳米结构薄膜分别对水和亚硫酸盐氧化产生的光电流密度为1.30和1.95 mA/cm²。最佳薄膜厚度为3μm，最佳退火后温度为550°C。沉积物中柱状结构的形成促进了光电流的增强。我们通过建模表明，这些结构是由亚微米颗粒在接近基板时沿平行于基板的方向的电驱动运动以及布朗扩散产生的。同时，相反的热泳力减缓了它们向表面的靠近。这里提出的这些过程的模型与实验观察结果高度吻合。
