Sol-gel synthesis of photoactive PtO/Bi2WO6 nanocomposites for improved photoreduction of Hg (II) ions under visible illumination

Abstract

Heterostructure semiconductor photocatalysts have attracted much research interest for wastewater remediation under visible irradiation. The current study describes synthesizing and characterizing novel nanocomposites based on a mesoporous Bi2WO6 with variation PtO amount through a sol-gel procedure. The effect of PtO content on structural, optical, and photocatalytic features was thoroughly discussed. The Hg(II) ions photocatalytic reduction was utilized to evaluate the performance of the constructed heterojunctions under visible irradiation, in the presence of formic acid as a hole scavenger. The most efficient 1.5wt% PtO/Bi2WO6 nanocomposite demonstrated 100% reduction within 60 min with the greatest photoreduction rate constant (0.062 min−1), which was approximately 5.16 folds greater than pristine Bi2WO6 (0.012 min−1). The enhanced efficiency of the developed heterojunctions in the photoreduction of Hg(II) ions could be attributed to the incorporating 1.5wt% PtO, which increases the light-harvesting, decrease the bandgap (Eg) to 2.23 eV, boost the isolation and mobility of the photoexcited carriers. Utilizing a 1.6 g/L of 1.5wt% PtO/Bi2WO6 nanocomposite demonstrated complete photoreduction efficiency after 40 min and outstanding stability after five cycles without losing their photocatalytic activity. This study offers a cost-effective method of producing Bi2WO6 -based nanocomposites with remarkable ability in wastewater remediation.