Titanium Dioxide Nanoparticles Doped with Iron for Water Treatment via Photocatalysis: A Review

Abstract

Iron-doped titanium dioxide nanoparticles are widely employed for photocatalytic applications under visible light due to their promising performance. Nevertheless, the manufacturing process, the role of Fe³⁺ ions within the crystal lattice of titanium dioxide, and their impact on operational parameters are still a subject of controversy. Based on these assumptions, the primary objective of this review is to delineate the role of iron, ascertain the optimal quantity, and elucidate its influence on the main photocatalysis parameters, including nanoparticle size, band gap, surface area, anatase-rutile transition, and point of zero charge. Moreover, an optimized synthesis method based on comprehensive data and insights from the existing literature is proposed, focusing exclusively on iron-doped titanium oxide while excluding other dopant variants.

Keywords: doping; iron; nanoparticles; photocatalysis; titanium dioxide.

Figure 1

Schematic representation of the photochemical activation of titanium dioxide and the formation of radical species responsible for the oxidative degradation of organic pollutants.

Figure 2

Number of publications on doped titanium dioxide with different transition metals for photocatalytic applications.

Figure 3

Size of TiO₂ nanoparticles as the amount of iron used for different syntheses [38,48,51,52,53,54,55,56,57,58,59].

Figure 4

SEM micrography of based-TiO₂ samples doped with different amounts of iron: (a) 5%, (b) 15%, (c) 25%, (d) 35% [56].

Figure 5

Band gap of titanium oxide doped with iron at varying Fe/Ti ratio [6,31,38,48,51,56,61,68,69,70,71,72,73,74,75,76,77,78].

Figure 6

BET surface area of iron-doped TiO₂ nanoparticles at varying Fe/Ti ratio [22,31,51,52,53,54,56,57,58,59,62,71,74,84,86,87,88,89,90,91,92].

Figure 7

Surface area of Fe-doped titania samples prepared by impregnation (IM) and co-precipitation (CP) methods at different calcination temperatures [29].

Figure 8

% of rutile phase in TiO₂ as a function of iron content and calcination temperature [37,41,43,101,102,103,104].

Figure 9

A possible optimized synthesis strategy to produce iron-doped titania nanoparticles for photocatalytic purposes.