Fabrication of Ti/black TiO2-PbO2 micro/nanostructures with tunable hydrophobic/hydrophilic characteristics and their photoelectrocatalytic performance

Abstract

Herein, a novel Ti/black TiO2-PbO2 micro/nanostructured photoanode with tunable hydrophobic/hydrophilic characteristics was fabricated via the facile hydrothermal strategy. The tunable hydrophobic/hydrophilic feature of black TiO2/PbO2 architecture is realized by changing loadings of flower-like PbO2 microspheres. Interestingly, the density functional theory (DFT) calculations demonstrated that H2O molecules prefer to adsorb on the surface of black TiO2 nanosheets, and easier to form hydroxyl radicals on the surface of PbO2. Thus, a cooperation action between black TiO2 and PbO2 regarding the generation of hydroxyl radical (·OH) by water photoelectrolysis occurs as follows: the black TiO2 nanosheet layer can be acted as the supply station of water and rapidly transfer the water molecules to neighboring PbO2 (acted as generation center of hydroxyl radical) to generate hydroxyl radical. Obviously, the division of labor and cooperation between black TiO2 and PbO2 is helpful to improve the generation efficiency of hydroxyl radical. Furthermore, the constructed black TiO2-PbO2 architectures have large electroactive areas, low charge transfer resistance, and high separation efficiency of induced carriers. The black TiO2-PbO2 micro/nanostructure obtained under optimum conditions (Ti/black TiO2-PbO2-180 min) has the highest PEC removal rate of dye (86.24%); an enhancement of approximate 30% is achieved as compared with that of pure black TiO2 (65.20%). These new findings not only make Ti/black TiO2-PbO2 a more attractive photoanode but, most significantly, also provide promising strategy for designing photoanode.