Facile Strategy to Fabricate Uniform Black TiO2Nanothorns/Graphene/Black TiO2Nanothorns Sandwichlike Nanosheets for Excellent Solar-Driven Photocatalytic Performance

Uniform black TiO2 nanothorns/graphene/black TiO2 nanothorns sandwichlike nanosheets (denoted as G@BTN) are fabricated through facile solvothermal approach and subsequent surface hydrogenation, in which the black TiO2 nanothorns vertically grow on the surface of two sides of graphene and form the sandwichlike structure. The rational control of hydrolysis and condensation of Ti precursors results in a uniform coating of amorphous TiO2 seeds, which then vertically grow in TiO2 nanothorns. After surface hydrogenation, the resultant G@BTN materials, with uniform sandwichlike configuration and narrow band gap of approximately 2.81 eV, can extend the photoresponse from the ultraviolet to the visible-light region and exhibit an excellent solar-driven photocatalytic performance for the degradation of the highly toxic pesticide atrazine (99 %). The first-order rate constant (k) of G@BTN (0.863 h−1) is about three times as high as that of black TiO2 nanothorns (0.287 h−1), which implies the significant role of the introduction of graphene for improving the photocatalytic performance. The high solar-driven photocatalytic performance is ascribed to the formed Ti3+ in frameworks and surface disorders enhancing the absorption of solar light, and the sandwichlike structure favoring the separation and transportation of photogenerated charge carriers.