Controlled preparation of M(Ag, Au)/TiO through sulfydryl-assisted method for enhanced photocatalysis.

Here a simple and effective method was explored to fabricate M/TiO (M = Ag, Au) composites, which required neither pre-treatment of TiO nor any additives as reducing agent. Using amorphous TiO spheres functionalized with SH groups as starting materials, the noble metallic ions (Ag, Au) can be adsorbed by TiO due to their special affinity with SH groups, which is beneficial to the uniform dispersion of metallic ions on the surface of TiO. Then the adsorbed ions were reduced to form noble metal nanoparticles by heating process (95 °C) directly without additive as reduction agent. Meanwhile, the amorphous TiO was transformed into anatase phase during the heating process. Thus, the transformation of TiO along with the reduction of noble metallic ions (Ag, Au) was simultaneously carried out by heating. The XRD patterns proved the formation of anatase TiO after heating. The characterizations of XPS and TEM proved the formation of Ag and Au nanoparticles on the surface of TiO. The element mapping indicated that Ag nanoparticles are dispersed uniformly on the surface of TiO. The photocatalytic activity of the composites has been investigated by the degradation of methyl orange under visible light irradiation. The results showed that when Ag/TiO (2.8 wt%) was used as photocatalyst, about 98% of the MO molecules were degraded in 70 min.