Abstract:

In this paper, nano ZnO with different photoresponsive capacities were successfully synthesized by three different methods: polyacrylamide gel method （PGM）, gamma ray irradiation-assisted polyacrylamide gel method （GRIAPGM） and carbon particle assisted polyacrylamide gel method （CPAPGM）. The ZnO sunscreens synthesized by PGM and GRIAPGM are pure hexagonal ZnO with space group P63mc （186）. However, the ZnO nanoparticles synthesized by CPAPGM contains not only hexagonal ZnO but also a small amount of carbon diffraction peak. The average grain size of ZnO nanoparticles synthesized by PGM, GRIAPGM and CPAPGM are 23.86, 22.73 and 26.47 nm, respectively, and the optical band gap （E_g） values are 3.15, 3.18 and 3.01 eV, respectively. The E_g value of ZnO nanoparticles decreases with the increase of grain size. The ZnO nanoparticles synthesized by CPAPGM have the widest photoresponse, which can respond to visible light due to the presence of carbon-related impurities. However, the particles of ZnO nanoparticles synthesized by GRIAPGM are small and spherical, and the particle size is uniform. It has the highest UV optical absorption coefficient, which can be potentially applied in the field of ultraviolet shielding materials.

Key words: polyacrylamide gel method, ZnO, optical band gap