Synergistic Effect of Double-Shelled and Sandwiched TiO2@Au@C Hollow Spheres with Enhanced Visible-Light-Driven Photocatalytic Activity

A novel approach for the fabrication of double-shelled, sandwiched, and nanostructured hollow spheres was proposed, using hydrotherm reaction and calcination. The negatively charged nanoparticles (e.g., Au, Ag, and Pt) could be adsorbed successively onto the positively charged hollow spheres (e.g., TiO2, ZnO, and ZrO2). The resulted nanocomposites (TiO2@Au, as a proof-of-concept) were dispersed in glucose solution under hydrothermal conditions. After calcination, uniform double-shelled and sandwiched TiO2@Au@C hollow spheres were obtained and Au nanoparticles were sandwiched between the shell wall of TiO2 and C. The samples were characterized by SEM, TEM, XRD, XPS, BET, and UV–vis DRS. The photocatalytic activity for the degradation of 4-nitroaniline was in the order of TiO2@Au@C > TiO2@C > TiO2/Au > P25. The visible-light photodegradation rate of 92.65% for 4-nitroaniline was achieved by TiO2@Au@C, which exhibited an increase of 75% compared to Degussa P25 TiO2. Furthermore, no deactivation occurred duri...