Low-cost and scalable preparation,high photocatalytic activity,and convenient recycle of Zn O nanopowders(NPs)would determine their practical application in purifying wastewater.In this contribution,ZnO NPs were scalably synthesized via the simple reaction of Zn powder with H_2O vapor in autoclave.The structural,morphological and optical properties of the samples were systematically characterized by X-ray diffraction,scanning electron microscopy,Fourier transform infrared spectra,transmission electron microscopy,Micro-Raman,photoluminescence,and ultraviolet-visible spectroscopy.The as-prepared Zn O NPs are composed of nanoparticles with 100–150 nm in diameter,and have a small Brunauer-Emmett-Teller surface area of 6.85 m^2/g.The formation of Zn O nanoparticles is relative to the peeling of H_2 release.Furthermore,the product has big strain-stress leading to the red-shift in the band gap of product,and shows a strong green emission centered at 515 nm revealing enough atomic defects in Zn O NPs.As a comparison with P25,the obtained dust gray Zn O NPs have a strong absorbance in the region of 200–700 nm,suggesting the wide wave-band utilization in sunlight.Based on the traits above,the Zn O NPs show excellent photocatalytic activity on the degradation of rhodamine B(Rh-B)under solar light irradiation,close to that under UV irradiation.Importantly,the Zn O NPs could be well recycled in water due to the quick sedimentation in themselves in solution.The low-cost and scalable preparation,high photocatalytic activity,and convenient recycle of Zn O NPs endow themselves with promising application in purifying wastewater.
