Fang Su

Two New Armtype Polyoxometalates Grafted on Titanium Dioxide Films: Towards Enhanced Photoelectrochemical Performance.

Two new carboxyethyltin-functionalized polyoxometalates (POMs) were successfully obtained and confirmed with physicochemical and spectroscopic methods including X-ray crystallography. The lowest unoccupied molecular orbitals of both compounds are higher in energy than that of TiO2 , and the optical band gaps of these compounds are smaller than that of TiO2 . Grafting them onto a TiO2 film created two kinds of novel photoanode materials that showed significantly enhanced photovoltaic and photocurrent responses, as well as improved photoelectrooxidation activities for methanol relative to that shown by a single TiO2 film. Further, P2 W15 -Co-SnR produced the largest photocurrent by exploring the photoelectric activities of a series of carboxyethyltin POM derivatives. This work provides new insight into the photoelectrochemical functionalization of POM-based organic-inorganic hybrids.

Two Keggin sandwich-type tungstophosphates modified by open-chain carboxyethyltin groups and transition metals

Two new polyoxometalates containing [PW9O34]9− (abbreviated as PW9) subunits, carboxyltin groups and transition metal ions, namely K10[Mn2{Sn(CH2)2COO}2[(B-α-PW9O34)2]·14H2O (1) and Na8K2 [Zn2{Sn(CH2)2COO}2[(B-α-PW9O34)2]·13H2O (2), were successfully assembled in aqueous solutions by a routine synthetic method, and fully characterized. They represent the first single crystal examples of open-chain carboxyethyltin group-modified Keggin sandwich-type tungstophosphates. Their important structural features are two open-chain carboxyethyltin moieties attached on the PW9 dimer, forming arm-type polyoxometalates. Furthermore, the fluorescence properties, electrocatalytic and oxidation catalytic activities were evaluated. More interestingly, the fluorescence quenching of 1/2-doped TiO2 was clearly observed, which means that the two compounds may be excellent components of photocatalytic materials.

Extended visible photosensitivity of carboxyethyltin functionalized polyoxometalates with common organic dyes enabling enhanced photoelectric performance

A kind of broad spectral responsive photoelectrode has been assembled from open-chain carboxyethyltin functionalized Dawson sandwich-type polyoxometalates (POMs) [{Sn(CH2)2COO}2M2(P2W15O56)2]16− (SnR-M-P2W15, M = Mn, Co, Cu and Zn) and organic dyes such as rhodamine B (RhB) and methylene blue (MB) through the layer-by-layer (LBL) self-assembly method. SnR-M-P2W15 shows strong adsorption towards RhB and MB. The adsorption capacity of SnR-Co-P2W15 towards RhB and MB reached 217.36 and 288.76 mg g−1 in 10 min, respectively. Compared to Keggin sandwich-type open-chain carboxyethyltin–POM and closed-ring carboxyethyltin–POM derivatives such as [Zn2{Sn(CH2)2COO}2[(PW9O34)2]10− (SnR-Zn-PW9) and [K3{Sn(CH2)2COO}2(PW9O34)2]11− (SnR-PW9), and the parent POMs [M4(H2O)2(P2W15O56)2]16− (M-P2W15, M = Mn, Co, Cu and Zn), SnR-M-P2W15-based photoelectrodes showed significantly enhanced photocurrent owing to their greater visible light harvesting. Also, the photoelectric performances of LBL multilayer films can be adjusted by controlling the number of deposited layers, adsorbed dye types and incorporated transition metal ions in the POMs.