Ferrites/carbon allotropes nanocomposites for photocatalytic applications: A review

Metal ferrites have low bandgap (E_g) values between 1.8 and 2.9 eV so that they can absorb visible light. They are applied in lithium batteries, supercapacitor electrodes, electronic and magnetic devices, and photocatalysis thanks to their significant electrical conductivity and magnetic properties. Being magnetic allows metal ferrites to be recycled. Metal ferrites, however, can aggregate due to the magnetic interactions of their particles that reduce their effective surface area. Metal ferrites have low stability in highly acidic media. All these demerits are added to the electron-hole recombination problem. Various supports were investigated to anchor metal ferrites to minimize these problems. These supports include biopolymers, conductive polymers, and carbon-based supports. Carbon-based supports have surface oxygen-containing groups, extended sp² π-conjugation system, and highly porous scaffolds, and they are highly stable in extremely acidic and basic media. Carbon supports anchor metal ferrites via their surface oxygenated functional groups to retard metal ferrites aggregation and accept the conduction band electrons of metal ferrites via their π-bonds system. Composing carbon supports with metal ferrites acquires these supports magnetic properties that ease the composite reuse. In this review, we will explore the different applications of composites of metal ferrites with various carbon allotropes as photocatalysts.