Structural, photocatalytic and photoelectrochemical properties of porous ZnO nanosheets prepared by air cold plasma.

Porous ZnO nanosheets with different thickness were prepared on zinc substrate by air cold plasma for photocatalytic degradation and photoelectrochemical water splitting. The ZnO nanosheets consisted of nanocrystallines with high-density oxygen-related defects characterized by the strong red luminescence. The UV absorption tended to be saturated as the thickness increased, and the saturation occurred at a thickness of about 2.3 µm. Under UV irradiation, the nanosheets with thickness of 2.3 µm showed the highest photocatalytic activity (and higher than P25 TiO2) in degradation of gaseous ethyl acetate, ascribed to the highest content of oxygen vacancies and oxygen interstitials. Due to the excellent UV-vis absorption ability and the effective transfer of photogenerated carriers, the ZnO nanosheets with thickness of 3.3 µm showed a photocurrent density as high as 0.22 mA cm-2 at -0.28 V (vs Ag/AgCl) under AM 1.5 G 100 mW cm-2.