Layered double hydroxide helps LaFeO3 photocatalyst activate peroxymonosulfate to efficiently degrade dyes

Photocatalysis is recognized as an environmentally benign technology for water treatment, yet its limited efficiency has impeded its wider application. Combining it with persulfate oxidation - a technique known for rapid reaction kinetics and potent contaminant removal capabilities - may enhance the efficacy of photocatalysis. However, the development of highly efficient catalysts for the synergistic effect of photocatalysis and persulfate oxidation remains challenging. To this end, we report a novel catalyst consisting of layered double hydroxides (LDH) and lanthanum ferrite (LFO). This LDH@LFO catalyst not only effectively combines photocatalysis and persulfate oxidation, but also establishes a p-n heterojunction. Optical and photoelectrochemical analysis shows that the catalyst significantly improves the photogenic carrier separation. We performed a thorough study to understand the influence of various factors on the catalysts’ performance, e.g., reaction systems, LFO loading, photocatalyst dosage, peroxymonosulfate (PMS) and dye concentration, pH value, coexisting anions, catalyst reusability and applicability. Under optimal conditions, the catalyst achieved a 93 % reduction of the dye AR27 in 20 min, enhancing the degradation rate by at least 1.6-fold compared to conventional photocatalysis or persulfate oxidation alone. Investigations into the mechanism, through batch comparison tests, oxygen species quenching assays and electron paramagnetic resonance, have illuminated the essential roles of 1O2 and h+ etc., with Co and Fe redox cycles on LDH critical for PMS activation. Overall, this research illustrates the design of a heterojunction photocatalyst for efficiently mitigating environmental pollution.