A Detailed Investigation on The Photothermal Properties of SnFe₂O₄ as a Photocatalyst for Wastewater Treatment

SnFe₂O₄ is a magnetic semiconductor with a spinel crystal structure. Due to its relatively narrow bandgap of less than 2.0 <i>e</i>V, SnFe₂O₄ holds promising potential for achieving a full spectral response to the solar radiation with enhanced energy utilization. However, research on its photothermal effects has been limited so far. In this study, we successfully synthesized narrow-bandgap SnFe₂O₄ (1.62 <i>e</i>V) via hydrothermal synthesis. Using Chlorotetracycline (CTC) as a model antibiotic pollutant, we investigate the photothermal properties of SnFe₂O₄ in various catalytic modes. Thermal catalytic experiments at different temperatures, photocatalytic experiments with various light wavelengths, and photothermal catalytic experiments under simulated solar light were conducted to evaluate the photoexcitation and thermal excitation properties.<br/>Our findings reveal that SnFe₂O₄ efficiently utilizes different spectral regions of sunlight: photothermally activated under UV and visible light and mainly thermally excited under near-infrared light. Furthermore, CTC degradation experiments have shown that SnFe2O4 can degrade CTC effectively under real outdoor sunlight. Even under cloudy weather conditions, SnFe₂O₄ retains catalytic activity if the ambient temperature can be kept at higher than 35°C. Therefore, this narrow-bandgap catalyst possesses the remarkable capability to enhance solar energy utilization significantly. Thus, it is believed to promise the design of a full solar spectrum photocatalyst for wastewater treatment.