Optical and Photocatalytic Properties of Spinel ZnCr 2 O 4 Nanoparticles Synthesized by a Hydrothermal Route

In this paper, a simple hydrothermal route has been developed to synthesize ZnCr 2 O 4 nanoparticles. Experimental results show that the as‐prepared ZnCr 2 O 4 nanoparticles have an average particle size of <5 nm. The ZnCr 2 O 4 nanoparticles have a direct band gap about 3.46 eV and exhibit blue emission in the range of 300–430 nm, centered at 358 nm when excited at 220 nm. Furthermore, the nanoparticles show apparent photocatalytic activities for the degradation of methylene blue under UV light irradiation.