Abstract
Photocatalysis is a multifunctional phenomenon that can be employed for energy applications such as H2 production, CO2 reduction into fuels, and environmental applications such as pollutant degradations, antibacterial disinfection, etc. In this direction, it is not an exaggerated fact that TiO2 is blooming in the field of photocatalysis, which is largely explored for various photocatalytic applications. The deeper understanding of TiO2 photocatalysis has led to the design of new photocatalytic materials with multiple functionalities. Accordingly, this paper exclusively reviews the recent developments in the modification of TiO2 photocatalyst towards the understanding of its photocatalytic mechanisms. These modifications generally involve the physical and chemical changes in TiO2 such as anisotropic structuring and integration with other metal oxides, plasmonic materials, carbon-based materials, etc. Such modifications essentially lead to the changes in the energy structure of TiO2 that largely boosts up the photocatalytic process via enhancing the band structure alignments, visible light absorption, carrier separation, and transportation in the system. For instance, the ability to align the band structure in TiO2 makes it suitable for multiple photocatalytic processes such as degradation of various pollutants, H2 production, CO2 conversion, etc. For these reasons, TiO2 can be realized as a prototypical photocatalyst, which paves ways to develop new photocatalytic materials in the field. In this context, this review paper sheds light into the emerging trends in TiO2 in terms of its modifications towards multifunctional photocatalytic applications.
Highlights
Since the observation of an enhanced electrolysis of water (H2 O) molecules into H2 and O2 usingTiO2 as photo-anode and Pt as cathode under UV light irradiation, [1] the research on TiO2 is gaining significant momentum towards its ‘photocatalytic’ process, which is coined later on
We have essentially focused on the versatile modifications of TiO2 such as morphology modifications, doped TiO2, hetero-junctions, Z-scheme, plasmonic, ferroelectric/perovskite, chalcogenides, metal–organic frameworks, carbon-based TiO2, defective TiO2, etc
Considering the PC process in TiO2, the VB and CB level of TiO2 lies at +2.9 and −0.3 eV, respectively, which leads to the band gap energy of 3.2 eV
Summary
Since the observation of an enhanced electrolysis of water (H2 O) molecules into H2 and O2 using. In 1977, Schrauzer and Guth reported the Pt/Rh metal modified-TiO2 powders for the photocatalytic splitting of water molecules [2]. Followed by such pioneering work in the field, a range of semiconducting materials have been explored for the photocatalytic properties towards various photocatalytic applications [3,4,5,6,7,8,9,10,11,12]. Catalysts 2019, 9, 680 because of its photocatalytic efficiency as its conduction band has been positioned in the appropriate negative potential, which is the favorable band edge position for redox reactions [26] Despite such merits and reliable properties, TiO2 lacks in some of the other specific crucial properties for photocatalysis, such as wide bang gap energy, rapid charge recombination, insufficient transportation, etc. TiO2 towards developing various photocatalytic systems as a whole, which can be prototyped using other materials
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