One-Step Preparation of Graphene-Supported Anatase TiO₂ with Exposed {001} Facets and Mechanism of Enhanced Photocatalytic Properties

Abstract

Anatase TiO2 nanosheets supported on reduced graphene oxide (RGO) were synthesized via a one-step, solvothermal method. During the solvothermal step, graphene oxide (GO) was reduced to RGO, and, subsequently, anatase TiO2 with 73.7% exposed {001} facets was grown in situ on the surfaces of the RGO nanosheets. Compared with pure TiO2, the RGO/TiO2 hybrid nanocomposite had improved photoactivity as a result of effective photoinduced electron transfer from TiO2 to the RGO acceptor through interfacial interactions. Trapping tests showed that the oxidation of dye molecules proceeded for about 22% through the reaction with (•)OH radicals, and the remaining 78% occurred via direct interactions with holes. The holes left in TiO2 crystals were the main reason for the enhanced photocatalytic properties of the RGO/TiO2 composite. This paper not only reports the fabrication of highly active photocatalysts but also gives deeper insight into the photocatalytic mechanism of carbon/TiO2 composites.

Mechanism of Versatile Catalytic Activities of Quaternary CuZnFeS Nanocrystals Designed by a Rapid Synthesis Route

“…We show the visible light induced catalytic degradation of seven organic dyes namely Methylene blue (MB), Malachite green (MG), Eriochrome Black-T (EBT), Rhodamine B (RhB), Methyl red (MR), Rhodamine 6G (Rh6G) and Cumarine-480 by the H-CZIS NCs. [33][34][35] In addition, we show that the hydrogenation of 4-nitrophenol (4-NP) and 4-nitroaniline (4-NA) by sodium borohydride becomes signifi cantly fast in presence of H-CZIS NCs. [36][37][38] Since NP and its derivatives are major refractory organic pollutants, the conversion into Aminophenol (AP) holds importance considering its uses as corrosion inhibitor in paints, applications in several analgesic and antipyretic drugs and dyeing agent for fur and feathers.…”

“…[ 65 ] small 2014, DOI: 10.1002/smll.201402837 For further support of the reaction pathways, we have examined the effect of radical scavengers on the degradation process. [ 34,[66][67][68] Addition of • OH radical scavengers (methanol and butanol) slow down the degradation process of MB ( Figure 6 a). [ 34,66,67 ] When 17 M methanol is used as reaction medium, the degradation rate is found to decrease since the formation of…”

“…[ 67,68 ] However, addition of hole scavengers (ethylenediaminetetraacetic acid, EDTA and ammonium oxalate) have no infl uence on the MB degradation rate (Figure 6 a). [ 34,66,67 ] Since, direct oxidation of H 2 O by photo excited holes in VB is unfavourable due to large negative redox potential ( E 0 H 2 O/ • OH = −6.82 eV) compared to VB of H-CZIS ( Figure 5 c and 5 e). [ 61,62 ] In addition, N 2 was purged to perform MB degradation test in oxygen free atmosphere.…”

“…[ 34,68 ] Unfortunately, hyperfi ne peaks of the adduct is surpassed by a broad peak in the range of 3405 to 3530 gauss ( Figure S23, supporting information). However, the formation of…”

Fabrication of graphene–TiO2 nanocomposite with improved photocatalytic degradation for acid orange 7 dye under solar light irradiation

“…Owing to this, decreased electron-hole recombination occurred. TiO 2 surface contains photo-generated electrons stucked directly by the dissolved oxygen to give reactive oxygen species, which react with water to give hydroxyl radicals, which is a strong oxidant towards degradation of AO7 [26][27][28]. A schematic illustration of the mechanism of improved photocatalytic efficiency of the GR-TiO 2 nanocomposites is shown in figure 9.…”