Constructive Interfacial Charge Carrier Separation of a p‑CaFe₂O₄@n-ZnFe₂O₄ Heterojunction Architect Photocatalyst toward Photodegradation of Antibiotics

Charge dynamics across the interfacial junction of p–n heterostructures leading to effective charge separation along with notable photodurability are essential preconditions to achieve high photocatalytic activity. The p-CaFe₂O₄@n-ZnFe₂O₄ (CFO@ZFO) heterojunction has been successfully synthesized by a simple solution combustion method followed by the ultrasonication technique. XRD and HRTEM studies confirmed the effective interaction and formation of the CFO@ZFO heterojunction. The loading of CFO over ZFO selectively enhanced the intensity of the (111) plane of active ZFO, leading to greater crystallinity and a suitable heterojunction which triggers the photocatalytic reaction. The result shows that a 40% loading of CFO on ZFO makes it the flagship photocatalyst. The impedance and PL spectra of 40ÏO@ZFO confirmed the low electron–hole recombination in comparison to the neat materials. Bode phase analysis showed that the lifetime exciton in 40ÏO@ZFO is 1.35 times superior to that of pure ZFO. The heterostructure results in enhancement of the photocurrent in the anodic direction, i.e. 6.6 mA/cm², which is nearly 2 times greater that of the neat materials. The 40ÏO@ZFO shows the best activity toward degradation of 20 ppm tetracycline and ciprofloxacin, i.e. 89.5% and 78%, respectively, in 1 h. The efficient charge separation at the interface, low charge transfer resistance, formation of heterostructures, and high value of synergy factor are collectively responsible for the best activity in 40ÏO@ZFO.