Natural hematite ore composited with ZnO nanoneedles for energy applications

Natural hematite ore is used as a novel photocatalyst for visible photocatalyst and also for advanced fuel cell applications. The hematite was composited with needle-shaped ZnO via a hydrothermal approach. This hematite-based system exhibits excellent photodegradation for methelyene blue within 40 min when the hematite is hybridized with wurzite-structured ZnO under visible light irradiation. The hybrid heterojunction was characterized by the transmission electron microscopy, ultraviolet-visible diffuses reflectance spectra, cyclic voltammetry, and AC impedance spectroscopy. The photocatalytic activity of the heterojunction was evaluated by the photodegradation of MB dye. The high photocatalytic activity observed under visible light is discussed on basis of the coupling of the hybrid heterojunction band structure. On the other hand, hematite ore and its composites were also used for advanced fuel cells. At 550 °C, 182 mW cm−2 and 580 mW cm−2 were achieved for fuel cells using raw hematite and composite with ZnO as the electrolytes, respectively. The heterostructure energy band alignment is proposed. These results demonstrate that the natural composites for next-generation functional semiconductor-ionic materials can influence the multi-utilization of natural resources, thereby affecting the environment and energy sustainability.