Role of hydroxylation modification on the structure and property of reduced graphene oxide/TiO2 hybrids

The structure model and enhancement mechanism of hydroxylation treatment on adsorbability and photocatalytic activity [Display omitted] •Highly-hydroxylated TiO2/rGO hybrids can be obtained by UV pre-excitation and microwave method.•Surface hydroxylation induces many defects (Ti3+, O vacancy and Ti-OH) and changes color into yellow.•Hydroxylation expands the light absorption up to about 600nm and benefits to adsorb organic dyes.•ESR reveals the self-accumulation of hydroxyl radicals under the irradiation of UV and visible light.•The photoinduced defects and rGO/TiO2@OH-TiO2 heterojunctions enable the excellent applicability. To extend the spectra response of TiO2 and enhance its photocatalytic activity, surface modification and catalyst supporter have attracted great attention. In this report, a simple and versatile approach has been developed to hydroxylate the reduced graphene oxide/TiO2 hybrids (OH-rGO/TiO2) by UV-microwave method, and the enhanced mechanisms of hydroxylation were analyzed in details. Experimental results show that TiO2 nanocrystals@OH-TiO2 heterojunctions formed on rGO sheets in situ by UV/H2O2 process. Hydroxylation not only can induce many surface defects (Ti3+, O vacancy and Ti-OH) on the surface of TiO2, but also change the color into yellow and strengthen the interaction between rGO and TiO2. OH-rGO/TiO2 hybrids showed excellent durability for high-concentration dyes, and exhibited strong adsorbability and photocatalytic activity. These enhancements are attributed to the excellent property of rGO and surface defects of TiO2 induced by hydroxylation, which expand the light absorption up to 600nm, benefit to the self-dispersion of hybrids, and improve the adsorption dynamic and charge transfer with lower carrier’s recombination.