X-ray powder diffraction (XRD) pattern was carried out on a Rigaku Dmax-γA X-ray diffractometer with CuKα radiation (λ=1.54178 Å). The morphology of nanocrystalline ZrB2 was observed from transmission electron microscopy (TEM) images taken with a Hitachi H-800 transmission electron microscope. X-ray photoelectron spectra (XPS) were recorded on a VGESCALAB MKII X-ray photoelectron spectrometer, using non-monochromatized MgKα X-rays as the excitation source. The UV–vis absorption spectrum was recorded on a Shimadzu UV-2410PC UV–vis spectrophotometer. Thermogravimetric analysis (TGA) was collected with a Shimadzu-50 thermoanalyzer apparatus under air.