Hydrothermally grown α-MoO3 microfibers for photocatalytic degradation of methylene blue dye

Abstract Adsorption and photodegradation efficiency of α-MoO3 microfibers towards methylene blue (MB) dye in the aqueous solution were reported. To obtain high-quality α-MoO3 microfibers, an aqueous solution of (NH4)6Mo7O24∙4H2O and citric acid was hydrothermally treated (180 °C, 12 h) in the presence of HNO3. The possible growth mechanism of microfibers in the hydrothermal reaction is explained. XRD and TEM studies provide shreds of evidence that microfibers have crystallized in a pure orthorhombic phase and grown up in the direction of [001]. The structural bonding between molybdenum and oxygen constituent elements of microfibers was further confirmed by XPS, FTIR, and Raman techniques. The estimated optical band gap of α-MoO3 microfibers (Eg = 2.68 eV) lies in the visible region, making them suitable candidates for visible light photocatalytic application. MB adsorption and degradation capacity of microfibers were performed in the dark and light, respectively. The photocatalytic properties revealed that 90% MB dye was degraded within 120 min illumination. Moreover, the good photocatalytic recycling capability of α-MoO3 microfibers makes them a promising photocatalyst to eliminate organic pollutants from water.