Improved photoelectrode performance of chemical solution-derived Bi(2)O(3) crystals via manipulation of crystal characterization

Three-dimensional Bi(2)O(3) crystals with various morphologies were successfully synthesized on F-doped tin oxide substrates with and without homoseed layers via chemical bath deposition (CBD) routes. The structural analysis reveals that control of the pH value of the reaction solution resulted in as-grown Bi(2)O(3) crystals with nanosheet and plate morphologies. A lower pH value of the reaction solution engendered formation of a porous sheet-like morphology of Bi(2)O(3); by contrast, a higher pH value of the reaction solution is favorable for formation of solid Bi(2)O(3) plates on the substrates. Furthermore, a sputter coated Bi(2)O(3) seed layer with dual α- and β-Bi(2)O(3) phases plays an important role in the CBD-derived Bi(2)O(3) crystallographic structures. The Bi(2)O(3) crystals formed via CBD processes without a sputter coated Bi(2)O(3) homoseed layer demonstrated a high purity in β-Bi(2)O(3) phase; those grown with a homoseed layer exhibited a dual α/β phase. The photoactive performance results show that construction of an α/β-Bi(2)O(3) homojunction in the CBD-derived Bi(2)O(3) crystals substantially improved their photoactive performance. Comparatively, the porous Bi(2)O(3) nanosheets with a dual α/β-Bi(2)O(3) phase demonstrated the highest photoactive performance among various Bi(2)O(3) crystals in this study. The superior photoactivity of the porous α/β-Bi(2)O(3) nanosheets herein is attributed to their high light absorption capacity and photoinduced charge separation efficiency. The experimental results in this study provide a promising approach to design CBD-derived Bi(2)O(3) crystals with desirable photoelectric conversion functions via facile morphology control and seed layer crystal engineering.