TiO2-Graphene Quantum Dots Nanocomposites for Photocatalysis in Energy and Biomedical Applications

Abstract

The focus of current research in material science has shifted from “less efficient” single-component nanomaterials to the superior-performance, next-generation, multifunctional nanocomposites. TiO2 is a widely used benchmark photocatalyst with unique physicochemical properties. However, the large bandgap and massive recombination of photogenerated charge carriers limit its overall photocatalytic efficiency. When TiO2 nanoparticles are modified with graphene quantum dots (GQDs), some significant improvements can be achieved in terms of (i) broadening the light absorption wavelengths, (ii) design of active reaction sites, and (iii) control of the electron-hole (e−-h+) recombination. Accordingly, TiO2-GQDs nanocomposites exhibit promising multifunctionalities in a wide range of fields including, but not limited to, energy, biomedical aids, electronics, and flexible wearable sensors. This review presents some important aspects of TiO2-GQDs nanocomposites as photocatalysts in energy and biomedical applications. These include: (1) structural formulations and synthesis methods of TiO2-GQDs nanocomposites; (2) discourse about the mechanism behind the overall higher photoactivities of these nanocomposites; (3) various characterization techniques which can be used to judge the photocatalytic performance of these nanocomposites, and (4) the application of these nanocomposites in biomedical and energy conversion devices. Although some objectives have been achieved, new challenges still exist and hinder the widespread application of these nanocomposites. These challenges are briefly discussed in the Future Scope section of this review.

Photocatalysis and Li-Ion Battery Applications of {001} Faceted Anatase TiO2-Based Composites

“…These carbon-based materials have the following characteristic which make them an ideal candidate for coupling with TiO2-001 materials [29]. There is a cornucopia of examples that explore carbon-based, material-based nano composites which could advance fabrication photocatalysis and Li-ion battery anode Some of them are discussed in detail in the application section of this review [31,[86][87][88].…”

Recent Advances in Biocatalysis and Metabolic Engineering

“…Graphene quantum dots (GQDs), a nanostructured material with high surface area and surface energy, have attract great interest in catalytic reactions due to their special physiochemical characteristics [20]. Glucose oxidation reaction (GOR) is a very common redox reaction performed by many electrochemical conversion devices [21].…”

Editorial Catalysts: Special Issue on Recent Advances in TiO2 Photocatalysts

“…This inexpensive, stable, and non-toxic catalyst provides very good removal efficiency. The heterogeneous photocatalytic process, as well as new TiO 2 -based materials applied in biomedical fields, energy storage, and energy conversion devices, can contribute to improving the quality of the natural environment [9][10][11]. High-efficiency TiO 2 -based photocatalysts are also successfully used in photocatalytic water splitting and photoconversion, providing a low-cost and environmentally friendly production method of clean fuels [12,13].…”

“…Three review papers were accepted for this Special Issue which focused on the improvement of visible light photoactivity of TiO 2 . Bokare and co-workers presented an excellent overview of TiO 2 nanoparticle modifications with graphene quantum dots (GQDs) and its potential for energy and biomedical applications [9]. The authors discussed in depth the synthesis of TiO 2 -GQD nanocomposites with regard to structural characteristics and their photocatalytic mechanisms.…”

“…The authors discussed in depth the synthesis of TiO 2 -GQD nanocomposites with regard to structural characteristics and their photocatalytic mechanisms. The high potential of TiO 2 -GQD nanocomposites has been shown in the context of the photocatalytic degradation of micropollutants, H 2 production from water splitting, and dye-sensitized solar cells, as well as biomedical applications including drug delivery, biosensing, tissue engineering, and applications as contrasting agents in bioimaging [9]. Assessing improvements in photoelectrochemical performance in environmental, energy, and catalytic applications of carbon-doped TiO 2 was the main goal of Hua and co-workers' review paper [17].…”