1 3
Topics in Current Chemistry (2020) 378:6
(auto)combustion, vapour deposition, laser ablation or flame spray pyrolysis methods have been also reported (Figs. 4, 5) [13–16].
For applications in photocatalysis or photo-Fenton processes, the specific surface
area exposed, the crystallinity as well as the possibility to tune the intrinsic properties of the ferrites (such as the surface redox properties, the bandgap values or the
light absorption profile) are the main criteria to be considered for selecting the synthesis method. The cationic or anionic mono- or bisubstitution within the defined
structure of the ferrites is an elegant and powerful way to tailor those properties.
Further, as far as the catalysts need to operate in a manner consistent with the constraints of industrial implementation, whether it concerns liquid or gas-phase applications, the synthesis method should allow the ferrite catalyst to be immobilized
on macroscopic supports. In addition, since most of the methods require a thermal
treatment for increasing the crystallinity of the ferrite materials, the methods enabling a lower temperature to be achieved are preferred because they do not impact
too strongly on the specific surface area. Therefore, the chemical syntheses in solution remain the preparation methods of choice, among which co-precipitation,
sol–gel methods and thermal methods are the most popular ones.
1.2.1 Co‑precipitation Method
The co-precipitation is a very common and fast synthesis method consisting in
favouring the simultaneous precipitation of insoluble or low solubility products
Fig. 5 Schematic diagrams depicting microemulsion-based syntheses. a Typical reverse micelle system, which is a water-in-oil microemulsion where the polar head groups of the surfactants creating the
aqueous core reside towards the inside, whereas the organic tails of the surfactant molecules are directed
towards the outside. b One-microemulsion synthesis method. c Two-microemulsion synthesis method in
which the microemulsions carrying the separate reactants are mixed together in the appropriate ratio.
Reproduced with permission from Ref. [17]. Copyright Royal Society of Chemistry
113
Reprinted from the journal
Topics in Current Chemistry (2020) 378:6
(auto)combustion, vapour deposition, laser ablation or flame spray pyrolysis methods have been also reported (Figs. 4, 5) [13–16].
For applications in photocatalysis or photo-Fenton processes, the specific surface
area exposed, the crystallinity as well as the possibility to tune the intrinsic properties of the ferrites (such as the surface redox properties, the bandgap values or the
light absorption profile) are the main criteria to be considered for selecting the synthesis method. The cationic or anionic mono- or bisubstitution within the defined
structure of the ferrites is an elegant and powerful way to tailor those properties.
Further, as far as the catalysts need to operate in a manner consistent with the constraints of industrial implementation, whether it concerns liquid or gas-phase applications, the synthesis method should allow the ferrite catalyst to be immobilized
on macroscopic supports. In addition, since most of the methods require a thermal
treatment for increasing the crystallinity of the ferrite materials, the methods enabling a lower temperature to be achieved are preferred because they do not impact
too strongly on the specific surface area. Therefore, the chemical syntheses in solution remain the preparation methods of choice, among which co-precipitation,
sol–gel methods and thermal methods are the most popular ones.
1.2.1 Co‑precipitation Method
The co-precipitation is a very common and fast synthesis method consisting in
favouring the simultaneous precipitation of insoluble or low solubility products
Fig. 5 Schematic diagrams depicting microemulsion-based syntheses. a Typical reverse micelle system, which is a water-in-oil microemulsion where the polar head groups of the surfactants creating the
aqueous core reside towards the inside, whereas the organic tails of the surfactant molecules are directed
towards the outside. b One-microemulsion synthesis method. c Two-microemulsion synthesis method in
which the microemulsions carrying the separate reactants are mixed together in the appropriate ratio.
Reproduced with permission from Ref. [17]. Copyright Royal Society of Chemistry
113
Reprinted from the journal