A Template-Free Solution Route for the Synthesis of Well-Formed One-Dimensional Zn2GeO4 Nanocrystals and Its Photocatalytic Behavior

Well-defined Zn2GeO4 hexagonal nanorods and nanofibers with high aspect ratios have been readily realized in high yield via a simple and general hydrothermal synthesis method free of any surfactant or template. Field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectrometry (EDX), powder X-ray diffraction (XRD), and ultraviolet-visible light diffuse reflectance spectroscopy (UV-vis DRS) revealed a unique hexagonal-prism-shaped one-dimensional (1-D) structure, surface features, anisotropic crystal growth, and crystal phase of Zn2GeO4. Detailed investigations indicated that the prismatic Zn2GeO4 nanocrystals are uniform single crystal with the longitudinal direction along the [001] and were dominated by (110) and (110) surfaces. The addition of increasing amounts of NaOH was found to facilitate the morphology transition from a hexagonal nanorod shape to a hexagonal fiber shape. As an important wide-band-gap photocatalyst, the products of regular Zn2GeO4 nanocrystals with a hexagonal 1-D structure exhibit superior photocatalytic activities for the photocatalytic decomposition of water-methanol solution to hydrogen under UV irradiation.