The detailed experimental procedure is given in Additional file 1. To obtain GO sheets, graphite oxide was dispersed into distilled water (0.5 g L−1) and ultrasonicated for 1 h at ambient condition. The solution was then chilled to ≈ 5°C in an ice bath. Meanwhile, a titanium precursor composed of 1.5 mL TBT, 7.21 mL EG, and 1.14 mL HAc was also chilled to ≈ 5°C in an ice bath. The mixture was then added dropwise into the chilled GO aqueous solution
under vigorous stirring. Subsequently, the GO-TiO2 stock solution was transferred into a 200-mL Teflonlined stainless steel autoclave and was heated at 180°C for 8 h. The greyish-black precipitate was harvested by centrifugation (5,000 rpm, 30 min) and was washed with
ethanol several times to remove undecorated TiO2 particles, unreacted chemicals, and residual EG. Finally, the product was dried in an air oven at 60°C overnight before characterization.