Highly Efficient UV–Visible Photocatalyst from Monolithic 3D Titania/Graphene Quantum Dot Heterostructure Linked by Aminosilane

Abstract

without self-degradation. [3] Despite its high photocatalytic reactivity, limitations such as the presence of few active sites in the thinfilm form, limited use of the solar spectrum due to its wide bandgap (3.2 eV for anatase), and relatively inefficient charge separation have hampered the entry of TiO 2 into real applications. [4] So far, various approaches to increase its reaction sites by increasing the specific surface area, [5] to reduce the bandgap through hetero-atom doping, [5d,6] and to retard charge recombination by inducing charge separation or spin-orbit coupling using transition metal have been carried out to improve the photocatalytic efficiency of TiO 2 . [7] Numerous synthetic strategies for these approaches have been well-established and developed in their respective areas, but the overall effect is tempered when the catalyst design only addresses one of these limitations. Therefore, it is essential to develop a rational design that can simultaneously overcome all of the limitations to further enhance the TiO 2 photocatalyst efficiency.Recently, our group has reported the fabrication of N-doped 3D nanostructured TiO 2 in monolithic form by utilizing proximity-field nanopatterning (PnP) and atomic layer deposition (ALD) methods, demonstrating the enhanced photocatalytic activity of the material under visible irradiation, which is produced by the improved surface area and reduced bandgap (2.75 eV), along with great reusability without any recollection process. [5a,d] The N-doping of the periodically nanostructured TiO 2 is carried out through a simple thermal annealing and enables the 3D TiO 2 to take visible light-driven activity, which is difficult to obtain by the nanostructuring effect alone. However, the doping method, known as the most common method of increasing the visible absorption of TiO 2 , inevitably provides intermediate states within the TiO 2 bandgap. These additional states are likely to serve as recombination sites for the photogenerated electron-hole (e-h) pairs. [6b,8] As the recombination sites of e-h pairs adversely affect the charge separation, minimizing the charge recombination is also necessary to enhance the photocatalytic activity.To enhance the visible light activity of TiO 2 without generating intermediate states from the doping, heterostructuring As rapidly growing environmental pollution demands the development of efficient photocatalytic materials, tremendous attention has been drawn to TiO 2 , a widely used photocatalytic material with cost-effectiveness, stability, and outstanding reactivity. To maximize its photocatalytic efficiency by enhancing the photogenerated charge separation, lowering the intrinsically large bandgap (3.2 eV) of TiO 2 is a key problem to be overcome. Herein, a new design is reported for an efficient photocatalyst realized by heterostructuring a 3D nanostructured TiO 2 monolith (3D TiO 2 ) and graphene quantum dots (GQDs) through using 3-aminopropyltriethoxysilane (APTES) as a linker. The incorporation of APTES between the TiO 2 /GQD i...

CsPbBr3 Nanocrystal Induced Bilateral Interface Modification for Efficient Planar Perovskite Solar Cells

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