Surfactant-Free Mixed-Valence ReO₃ Nanocubes for Solar Light Photocatalytic Applications

Mixed-valence ReO 3 nanocubes were successfully synthesized using a simple wet chemical approach without a surfactant. Their UV–vis spectrum exhibits broad absorption from 250 nm to near-IR due to enhanced surface plasmon resonance and mixed-valence oxidation states. The photocatalytic activity of the surfactant-free mixed-valence ReO 3 nanocubes (MVReO 3 SF-NCs) was assessed by observing the photodegradation of methyl orange (MO) under UV-cut- (vis/NIR, >420 nm) and artificial sunlight, demonstrating great improvement compared to surfactant-anchored mixed-valence ReO 3 nanoparticles (MVReO 3 SA-NPs) or TiO 2 (P25). Additionally, ReO 3 SF-NCs outperform ReO 3 SA-NPs and TiO 2 in rhodamine B photodegradation under vis/NIR light irradiation. The results highlight the important roles of the mixed-valence oxidation state, localized surface plasmon resonance, and clean catalyst surfaces of ReO 3 SF-NCs in improving their photocatalytic activity under solar light and vis/NIR light, suggesting the potential use of ReO 3 SF-NCs as a highly efficient solar light photocatalyst for various photocatalytic applications including water splitting for H 2 generation, CO 2 conversion, environmental remediation, and even solar cells via a wide range of solar light harvesting.