Nano zinc oxide and nano titanium oxide are two important and widely used physical sunscreens. Their principle of shielding ultraviolet rays is to absorb and scatter ultraviolet rays. Because they are all N-type semiconductors, the band gap of rutile nano-titanium oxide is 3.0 eV, and the band gap of nano-zinc oxide is 3.2 eV. When irradiated by ultraviolet rays, electrons in the valence band can absorb ultraviolet rays and be excited to the conduction band, and at the same time generate hole-electron pairs, so they have the function of absorbing ultraviolet rays. In addition, the particle size of nano-zinc oxide and nano-titanium oxide is much smaller than the wavelength of ultraviolet rays, and nano-particles can scatter ultraviolet rays acting on them in all directions, thereby reducing the intensity of ultraviolet rays in the irradiation direction.

But nano zinc oxide is different from nano-titanium oxide in shielding ultraviolet rays.

Figure 1 shows the absorbance of nano zinc oxide（1） and nano titanium dioxide （2） (the mass fraction of nano-powder is 5%) to ultraviolet light of different wavelengths

It can be seen from Figure 1 that below 330m, the shielding ability of nano-titanium dioxide to ultraviolet rays is significantly higher than that of nano-zinc oxide. At the same concentration, the absorbance of the nano-titanium oxide system is about twice that of the nano-zinc oxide system. In the range of 330 nm to 355 nm, the ultraviolet shielding ability of nano titanium oxide is still higher than that of nano zinc oxide, but in the wavelength of 355 nm to 380 nm, the ultraviolet shielding ability of nano zinc oxide is higher than that of nano titanium dioxide.

SAT NANO can supply nano zinc oxide and nano titanium dioxide powder, 30nm, 50nm, 100nm. if you have any enquiry, please feel free to contact us at admin@satnano.com