Boosting photocatalytic performance of cubic Co2SnO4-MnO2@g-C3N5 ternary composites: Analysis of morphology, degradation ability of tetracycline hydrochloride and fragments pathway mechanism

Abstract

The increasing prevalence of tetracycline contaminants poses a profound threat to biodiversity in both aquatic and terrestrial ecosystems worldwide. To address this issue, the current study presents an innovative degradation approach using a ternary composite photocatalyst of Co2SnO4/MnO2 encapsulated with g-C3N5 synthesized via a hydrothermal method. This research describes the first report on the use of Co2SnO4/MnO2@g-C3N5 heterostructures for the photodegradation of tetracycline hydrochloride. A comprehensive characterization of the nanocomposites was performed using XRD, FTIR, SEM (including EDX and mapping), TEM, BET, XPS, and DRS-UV analyses, which confirmed their crystalline structure and revealed a morphology of Co2SnO4 nanocubes and MnO2 nanorods on the g-C3N5 layers. Photocatalytic experiments under visible light illumination showed that with an optimum catalyst loading of 40 mg/L and an initial tetracycline concentration of 5 μM, the composite achieved a degradation efficiency of 93.22 % within 75 min, following pseudo-first order kinetics. The degradation process was predominantly driven by hydroxyl radicals, as confirmed by scavenger studies. The reusability tests was confirmed the stability of the catalyst, which maintained high efficiency over four cycles. A degradation pathway was proposed based on LC-MS analysis of the reaction intermediates. This study confirms that Co2SnO4/MnO2@g-C3N5 composites (ratio 50:30:20) outperform comparative photocatalysts under similar conditions, providing a viable and environmentally benign solution for tetracycline remediation in wastewater.