Nh4 2tif6

MC of high purity was purchased from Alfa Aesar. GO (>99%) was bought from ACS Material. H₃BO₃ (>99.5%), (NH₄)₂TiF₆ (>99.9%) and ethanol (>99.8%) were acquired from Sigma. TiO₂ was acquired from Evonik (so-called P25), which contains 77.1% anatase, 15.9% rutile and 7% of amorphous TiO₂. Milli-Q water was attained from an Advantage A10 system (Millipore).

(NH₄)₂TiF₆, H₃BO₃ and PEG 400 were obtained from Sigma-Aldrich (Gillingham, UK). All chemicals were used without further purification.

The synthesis of the photocatalytic composites was carried out by the liquid phase deposition method (LPD), as previously reported [6 (link)]. Briefly, the precursors, ammonium hexafluorotitanate (IV), (NH₄)₂TiF₆ (99%, Sigma-Aldrich, St. Louis, MO, USA), and H₃BO₃ (0.1 and 0.3 mol L⁻¹, respectively) were added to a 100 mg L⁻¹ suspension of GO, rGO, rGONS, or rGOB. The carbon loading was maintained at ~3.5 wt%. The mixture was heated in a silicon bath at 60 °C for 5 h under dynamic stirring. The precipitate was filtrated under a vacuum, washed repeatedly with distilled water, and dried at 80 °C for 8 h. Finally, the obtained solid was treated under N₂ flow in an oven at 200 °C, 5 °C min⁻¹ for 2 h. Bare TiO₂ (referred as TiO₂) was also synthetized following the same methodology, without the addition of any graphene derivative. The TiO₂ composites prepared with GO, rGO, rGONS, and rGOB are denoted, as GO-T, rGO-T, rGONS-T, and rGOB-T, respectively.