Modification strategies of TiO₂ for potential applications in photocatalysis: a critical review

Abstract

TiO 2 has received tremendous attention owing to its potential applications in the field of photocatalysis for solar fuel production and environmental remediation. This review mainly describes various modification strategies and potential applications of TiO 2 in efficient photocatalysis. In past few years, various strategies have been developed to improve the photocatalytic performance of TiO 2 , including noble metal deposition, elemental doping, inorganic acids modification, heterojunctions with other semiconductors, dye sensitization and metal ion implantation. The enhanced photocatalytic activities of TiO 2 -based material for CO 2 conversion, water splitting and pollutants degradation are highlighted in this review.

Synthesis and Surface Modification of TiO2-Based Photocatalysts for the Conversion of CO2

“…To overcome limitations and drawbacks, many researches have suggested to employ hybrid systems which combine two or more of these different modification techniques [40]. The advantages and disadvantages of the main modification strategies along with the performance results from the most important CO 2 photoreduction studies are summarized in Tables 1 and 2 below [19,26,37,[88][89][90]. Further details on the pros and cons of the mentioned TiO 2 surface modification techniques are discussed in the following individual Sections 3.1-3.5…”

Preparation and Characterization of Photoactive Anatase TiO2 from Algae Bloomed Surface Water

“…Moreover, the substitutional and interstitial doping of impurities from the feed water can significantly affect the particle size of the prepared TiO 2 NPs [24,47]. For instance, the high Ca (large atomic radius when comparing Ti) content (see Table 2) in A-TiO 2 crystal might have contributed towards the enhancement of crystal size through substitutional doping [32]. Table 2 demonstrates the elemental composition of the prepared A-Residue and A-TiO 2 from EDX analysis along with the estimated BET specific surface area (S BET ).…”

“…Castro and Durán [53] reported that Ca doping on TiO 2 at a very low concentration (<3 wt.%) could reduce the band energy gap of TiO 2 and enhance the photodegradation of methyl orange under solar irradiation. However, the doped Ca of substantial amount can act as recombination site for e -/h + pair generated during photodegradation (see Figure 1) and might cause a reduced level of photoactivity [32]. Similarly, Wang et al [54] illustrated that a certain amount (2 atomic%-4 atomic%) of Cl as the dopant in TiO 2 could activate TiO 2 under visible light, and the extent of light absorption within the UV range can get reduced, so as the photoactivity.…”

“…TiO 2 is an n-type semiconductor, whose conduction band (CB) and valence band (VB) are at an energy level of −0.03 eV and 2.9 eV, respectively, which results in the band energy gap of 3.2 eV [23,32]. Hence, during the solar irradiation of TiO 2 , when the energy of the incident photon (E p ) is equivalent to the band energy gap (E gap ), it gets absorbed.…”

Caracterização de reator fotoquímico para aplicações em processos oxidativos avançados

“…Os mecanismos de ação dos POAs são diversos, mas destacam-se aqueles capazes de formar agentes altamente oxidantes (radicais livres) e que apresentam maior eficiência para degradação destes contaminantes (Boczkaj & Fernandes, 2017). Neste aspecto, a fotocatalise heterogênea tem sido amplamente investigada, uma vez que semicondutores fotoativos apresentam capacidade para geração destes radicais livres (Humayun, Raziq, Khan, & Luo, 2018).…”