Direct Synthesis of Controlled-Size Nanospheres inside Nanocavities of Self-Organized Photopolymerizing Soft Oxometalates [PW12O40]n(n=1100-7500)

A Molecular CO2 Reduction Catalyst Based on Giant Polyoxometalate {Mo368}

Photocatalytic CO2 reduction in water is one of the most attractive research pursuits of our time. In this article we report a giant polyoxometalate {Mo368} based homogeneous catalytic system, which efficiently reduces CO2 to formic acid with a maximum turnover number (TON) of 27,666, turnover frequency (TOF) of 4,611 h-1 and external quantum efficiency of the reaction is 0.6%. The catalytic system oxidizes water and releases electrons, and these electrons are further utilized for the reduction of CO2 to formic acid. A maximum of 8.3 mmol of formic acid was observed with the loading of 0.3 μmol of the catalyst. Our catalyst material is also stable throughout the reaction. The starting materials for this experiment are CO2 and H2O and the end products are HCOOH and O2. The formic acid formed in this reaction is an important H2 gas carrier and thus significant in renewable energy research.

pH-induced phase transition and crystallization of soft-oxometalates (SOMs) into polyoxometalates (POMs): a study on crystallization from colloids

In this work, we demonstrate a simple approach for growing 1D (one-dimensional) inorganic chains of K(C₆H₁₆N)₃Mo₈O₂₆·H₂O polyoxometalates (POMs) from its colloidal soft-oxometalate (SOM) phase through the variation of pH. The structure is composed mainly of a 1D inorganic chain with a β-Mo₈O₂₆^4- binding node linked using K⁺ via Mo-O-K linkages, which results in a cuboctahedral geometry for the K⁺ ions. Crystal structure and Hirshfeld surface studies reveal the role of triethylammonium cations in restricting the growth of the 1D chain into 2D/3D (two-/three-dimensional) structures. During the nucleation process from the heterogeneous SOM phase, some of the intermolecular interactions in the dispersion phase are retained in the crystal structure, which was evidenced from residual O...O interactions. The crystallization of the species from its colloidal form as a function of pH was studied by the use of Raman spectroscopy and it was found that the increase in volume fraction of the β-Mo₈O₂₆^4- species in the crystallizing colloidal mixture with the decrease in pH is responsible for the nucleation. This was monitored by time-dependent DLS (dynamic light scattering) measurement and zeta-potential studies, revealing the co-existence of both the crystal and the colloidal forms at pH 3-2. This brings us to the conclusion that in the crystallization of POMs, the colloidal SOM phase precedes the crystalline POM phase which occurs via a phase transition. This work could open up avenues for the study of POM formation from the stand-point of colloidal chemistry and SOMs.

Selective light driven reduction of CO2 to HCOOH in water using a {MoV9}n (n = 1332-3600) based soft-oxometalate (SOM)

A soft-oxometalate (SOM) based on Mo and V i.e. {MoV₉} in their highest oxidation state reduces CO₂ to HCOOH selectively in water. Catalysis initiates without the use of any photosensitizer and solvent water acts as the sacrificial electron donor which gets oxidized to generate oxygen. Electrons and protons released in this process reduce CO₂ to HCOOH.

Softoxometalate [{K6.5Cu(OH)8.5(H2O)7.5}0.5@{K3PW12O40}]n (n = 1348-2024) as an Efficient Inorganic Material for CO2 Reduction with Concomitant Water Oxidation

An immediate challenge for chemists is to devise different methods to trap chemical energy using light by reduction of carbon dioxide to a transportable fuel. To reach this goal the major obstacle lies in finding a suitable material that is abundant and possesses catalytic power to effect such reduction reaction and perform this reduction reaction without using any external photosensitizer. Here we report for the first time a softoxometalate based on a {[K_6.5Cu(OH)_8.5(H₂O)_7.5]_0.5[K₃PW₁₂O₄₀]} metal oxide framework which is stable in reaction conditions that effectively performs photochemical CO₂ reduction reaction in water with a very high turnover number of 613 and TOF of 47.15 h^-1. We observe that during this reaction water gets oxidized to oxygen, while the electrons released directly go to CO₂ reducing it to formic acid. A detailed account of the characterization of the catalyst along with that of products of this reaction is reported.

Autonomous movement in mixed metal based soft-oxometalates induced by CO2evolution and topological effects on their propulsion

Exploiting the intrinsic acidic nature of mixed-metal soft-oxometalates (SOMs) motility is induced using bicarbonate as fuel.

A newly designed softoxometalate [BMIm]2[DMIm][α-PW12O40]@hydrocalumite that controls the chain length of polyacrylic acid in the presence of light

We have controlled the radical as well as cationic polymerization of acrylic acid using [BMIm]₂[DMIm][α-PW₁₂O₄₀]@hydrocalumite (SOM 2) as a photocatalyst.