# Composite Material Formation Based on Biochar and Nickel (II)-Copper (II) Ferrites

## TL;DR

This paper explores the creation of a composite material using biochar and nickel-copper ferrites, which shows high catalytic activity in breaking down methyl orange.

## Contribution

The study introduces a novel composite material with enhanced catalytic properties due to a defective structure from the Jahn–Teller effect.

## Key findings

- Replacing copper with nickel in ferrites decreases unit cell parameters and cation-anion distances systematically.
- The composite forms a porous film on biochar, enhancing catalytic activity for methyl orange degradation in 30 minutes.
- Mixed nickel-copper ferrite increases reaction rates due to a defective structure from the Jahn–Teller effect.

## Abstract

This paper studies the formation process of a composite material based on an organic substance, biochar from sunflower husks, and an inorganic substance, nickel (II)-copper (II) ferrites of the composition CuxNi1−xFe2O4 (x = 0.0; 0.5; 1.0). The obtained materials were characterized by X-ray phase analysis, scanning electron microscopy, and FTIR spectroscopy. It is shown that when replacing copper (II) cations with nickel (II) cations, the average parameters and volume of the unit cell gradually decrease, and the cation–anion distances in both the tetrahedral and octahedral spinel grids also decrease with regularity. The oxide materials were found to form a film on the surface of biochar, repeating its porous structure. The obtained materials exhibit high catalytic activity in the methyl orange decomposition reaction under the action of hydrogen peroxide in an acidic medium; the degradation of methyl orange in an aqueous solution occurs 30 min after the start of the reaction. This result may be associated with the formation of the Fenton system during the oxidation–reduction process. A significant increase in the reaction rate in the system containing mixed nickel–copper ferrite as a catalyst may be associated with the formation of a more defective structure due to the Jahn–Teller effect manifestation, which creates additional active centers on the catalyst surface.