Carbonaceous-TiO2 composite photocatalysts through reactive direct current magnetron sputtering on powdered graphene for environmental applications

•Powdered graphene was coated with TiO2 by DC magnetron sputtering.•Deposition of TiO2 on graphene does not cause damage to its structure.•Photocatalytic effect on methylene blue degradation and inactivation of E.coli. An efficient photocatalytic composite material was produced by coating graphene powder with TiO2 using reactive pulsed direct-current magnetron sputtering. High-quality graphene powder with a thickness consisting of 6–10 layers was obtained by liquid-phase exfoliation of natural graphite. The process variables included the working pressure (0.7, 1.2, and 1.5 Pa), coating time (1, 2, 4, and 8 h), and graphene mass (0.1, 0.5, and 1.0 g). Raman spectroscopy, scanning electron microscopy coupled to energy dispersive spectroscopy, and X-ray photoelectron spectroscopy were used to characterize the graphene-TiO2 nanocomposites. The results of the characterization showed efficient TiO2 deposition with anatase and rutile crystallographic structures on the powdered graphene. Additionally, it was verified that the graphene was not damaged during the coating process, thereby maintaining its unique conductive and mechanical properties. The produced material exhibited photocatalytic activity for methylene blue degradation and Escherichia coli inactivation under UV light.