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 40%CFO@ZFO confirmed the low electron-hole recombination in comparison to the neat materials. Bode phase analysis showed that the lifetime exciton in 40%CFO@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 40%CFO@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 40%CFO@ZFO.