CaSnO3 nanorod-decorated Bi2WO6 nanosheets as a stable heterojunction photocatalyst for improved photocatalysis and nitrite sensing

Abstract

Significant global concerns about the environment include the removal of various organic dye contaminants and the detection of toxic nitrite (NO₂⁻). Herein, we developed a novel composite that combines an inorganic perovskite-based alkaline earth stannate (CaSnO₃) with aurivillius oxide (Bi₂WO₆). These components were synthesized by combustion and hydrothermal methods, respectively. The composite was designed for the photocatalytic degradation of methylene blue (MB) and electrochemical sensing of nitrite. The prepared composite was systematically characterized using various analytical techniques to verify its elemental composition and morphology and to determine the particle size and band gap. CaSnO₃/Bi₂WO₆ exhibited a remarkable 92.5% degradation of the carcinogenic MB dye under UV light over approximately 180 minutes. Importantly, it was observed that the designed nanocomposite did not exhibit photo-corrosion properties as the degradation of MB occurred even at pH 11. Furthermore, the CaSnO₃/Bi₂WO₆-modified glassy carbon electrode (GCE) demonstrated excellent electrocatalytic activity, with an obtained limit of detection (LOD) of 0.9 μM. In this work, the CaSnO₃/Bi₂WO₆ nanocomposite shows promising potential for efficient photocatalytic dye degradation and electrochemical sensing of nitrite, with the added advantage of avoiding photo-corrosion even under alkaline conditions.