Doubling the photocatalytic performance of SnO2 by carbon coating mixed-phase particles

In this work, carbon-coated mixed-phase (tetragonal/orthorhombic) SnO2 photocatalysts were successfully fabricated with a chemical precipitation method, followed by a facile hydrothermal process. This material exhibits the highest activity during photocatalytic methyl orange and phenol degradation, and the degradation rate constant is almost 3 times than that of pure tetragonal SnO2. The enhancement of photocatalytic activity could be mainly attributed to the synergistic effect among tetragonal SnO2, orthorhombic SnO2 and carbon (serves as a charge transfer mediator), which was found to lead to more efficient separation of photogenerated electron–hole pairs. Phase junctions in mixed-phase SnO2 were beneficial to the separation of photogenerated electrons and holes and carbon further facilitated the charge transfer between tetragonal and orthorhombic SnO2 nanoparticles. This study may provide a method for other mixed-phase semiconductors with promising performance for potential applications in environmental protection.