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 (V BJH) of the amorphous {Mo72Fe30} cluster than those of its rhombohedral crystal (3- and 28-fold for SBET and V BJH, 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.

Catalytic activity of amorphous {Mo72Fe30} nanoclusters as a safe Keplerate polyoxometalate in aerobic synthesis of benzimidazoles was described.

In this work, the effect of Keggin polyoxometalates encapsulated in Keplerate {Mo72Fe30} shell (K shell) on the visible light-assisted catalase-like activity (H2O2 dismutation) of the resulting core–shell clusters PMo12@K, SiMo12@K, and BW12@K was investigated. Superior photodismutation activity of PMo12@K compared to that of K shell and two other core–shell clusters was discovered. The homogeneity of PMo12@K and its improved oxidative stability, increased redox potential, and reduced band gap caused by a synergistic effect between the Keplerate shell and Keggin core seem reasonable to explain such a superiority. The light-dependent photocatalytic performance of PMo12@K evaluated by action spectra revealed a maximum apparent quantum efficiency (AQY) at 400 nm, demonstrating the visible light-driven photocatalytic reaction. A first-order rate constant of 2 × 10–4 s–1 and activation energy of 108.8 kJ mol–1 alongside a turnover frequency of 0.036 s–1 and a total turnover number of up to ∼3800 approved the effective photocatalytic activity and improved the oxidative stability of PMo12@K. A nonradical photocatalytic mechanism through a Fe–OOH intermediate was proposed. Thus, the structure, optical activity, and oxidative stability of a host Keplerate-type nanocluster can be tuned significantly by encapsulation of a guest, like “cluster-in-cluster” structures, which opens the scope for introducing new visible light-sensitive hierarchical nanostructures.

The photocatalytic efficiencies of bimetallic MOFs for the reductive removal of Cr(vi) were explored. The catalysts revealed higher performance compared to the corresponding single-metal MOFs, highlighting the synergistic effect between the two metal ions.