Few Layer Graphene/TiO₂ Composites for Enhanced Solar-Driven H₂ Production from Methanol

Abstract

Here is presented the elaboration of Few Layer Graphene/TiO 2 photocatalytic composites (FLG/TiO 2 ) with FLG loadings from 0.5 to 11 wt.%. Contrary to commonly used (reduced) graphene oxide obtained by long and harsh conditions synthesis, FLG was synthesized by simple, fast, efficient and eco-friendly exfoliation method. The enhancement of defective/functionalized sites density for attachment of TiO 2 species was achieved via calcination process at 450 °C. The nanocomposites were evaluated toward H 2 production from methanol under artificial solar light irradiation, without the use of a co-catalyst. It was observed that the best activities are provided by the composites with the lowest loading: 0.5 and 1.0 wt.% FLG/TiO 2 that are 2-3 times more efficient than reference and commercial TiO 2 . The photocatalytic activity of the composites was correlated to their surface area, morphological, structural, optical properties and kinetics of free electron mobility properties. The enhanced activity is attributed to higher surface area, better photogenerated charges separation thanks to electrons' delocalization and trapping onto graphene layers well interfaced with TiO 2 nanoparticles, but also to additional FLG visible light absorption properties and charge carriers' generation. The impact of enhanced FLG edges defects/functionalities is reflected as well via selected analysis and hydrogen generation.

On the evolution of oxidative etching of few layer graphene (FLG) in FLG /TiO2 nanocomposites. Interfacial dipole signature and chemical shift in C1s X-ray photoemission spectra

“…The fact that the charge transfer in the present composites occurs is somehow confirmed earlier via enhanced photocatalytic activity and in general, it is well established in this type of hybrids [9,10].…”

“…The synthesis of FLG, FLG', TiO2 and their composites were detailed previously [10,18,19]. In brief, FLG and FLG' were obtained via exfoliation of expanded graphite in water in the presence of bio-surfactant (bovine serum albumin) with help of mixing-assisted sonication.…”

“…According to their main abilities, TiO2-graphene composites are principally synthesized and investigated in view of photocatalytic applications. The first role of graphene is to accept and transport the charge formed via interactions of TiO2 with photons, and consequently reduce the recombination of created electron-hole pairs [7][8][9][10]. Most of such hybrids contains graphene oxide (GO) or reduced graphene oxide (rGO) possessing highly defected carbon lattice substituted by oxygen groups.…”

2D/2D g-C3N4/1T-MoS2 Nanohybrids as Schottky Heterojunction Photocatalysts for Nuclear Wastewater Pretreatment

“…As an increasingly mature application, nuclear power technology can even completely replace fossil fuels to meet future energy needs. − However, a large amount of nuclear wastewater will be generated during the nuclear fuel cycle process, including nuclear facility decommissioning, equipment maintenance, accident treatment, etc. , Researchers have developed various methods to remove or extract uranium ions in wastewater. − Unfortunately, this type of wastewater contains not only radioactive elements but also various organic substances, including alkyl glycosides, xanthan gum, oxalic acid, citric acid, and tannic acid (TA) . In addition, the industrial electroplating wastewater was also found to contain TA .…”

Green Light Photoelectrocatalysis with Sulfur-Doped Carbon Nitride: Using Triazole-Purpald for Enhanced Benzylamine Oxidation and Oxygen Evolution Reactions

“…[61] The latter is the 002 diffraction plane, characteristic for graphitic materials. [22,44,62] A qualitative study of the crystal size and dspace was performed to further exploit XRD data by understanding of the atomic layer disposition on the C3N4 in-plane. Considering that the studied materials are heterogeneous, supported by SEM, this analysis is valid knowing that XRD is an average measurement of the heptazine unit repetition.…”