{Mo72Fe30} Nanoclusters for the Visible-Light-Driven Photocatalytic Degradation of Organic Dyes

The photocatalytic efficiency of ecofriendly Keplerate {Mo72Fe30} nanoclusters in degradation of hazardous organic dyes such as rhodamine B (RhB) under visible/solar light is exploited. A higher photoremoval activity was observed for amorphous {Mo72Fe30} than its crystalline counterparts and other Keplerates. The greater specific surface area (SBET) and, particularly, pore volume (VBJH) of the amorphous {Mo72Fe30} cluster than those of its rhombohedral crystal (3- and 28-fold for SBET and VBJH, respectively) as well as negative charges on its surface (ζ = −16.2 mv) are important factors for such a superiority. The negative effect of increasing the pH of the solution on the removal rate along with scavenging experiments and photoluminescence (PL) study excluded the involvement of OH• in photodegradation process. Instead, an electron transfer from the excited dye (RhB*) to the POM producing RhB+·, and reduced POM (POM–) is postulated as a possible mechanism for photoassisted degradation of dye under visible light. The nanocluster proved to be a recyclable photocatalyst with high durability as evidenced by FT-IR, Raman, XRD, EDX, and XPS spectral data.