Liang-Sheng Qiang

Self-assembly of two supramolecular indium(III) metal–organic frameworks for reversible iodine capture and large band gap change semiconductor behavior

Under self-assembly, a novel polydentate benzimidazole ligand 2-(quinoline-2-yl)-benzimidazole (2-QLBM) and two In(III) compounds, [In(2-Hqlca)2Cl3·3H2O] (1) and {[In(2-QLBM)(2-qlca)Cl2]2·CH3CN·2H2O} (2) (2-Hqlca = 2-quinolinecarboxylic acid) have been synthesized and characterized. Both the In(III) compounds are driven by noncovalent interactions to assemble into supramolecular metal–organic frameworks (MOFs). Considering 2-QLBM and 2-Hqlc ligands with different geometrical structures, compound 1 possesses a (66)-dia network with a channel diameter of about 1.856 A, and compound 2 displays a (3,4)-connected topology network with the Schlafli symbol of (63)(65·8), whose channel diameter is about 3.683 A. Owing to large voids in the framework, 2 can serve as a host for reversible encapsulation of iodine corresponding to the 1.52 molecules of iodine per formula unit with a fast response and high sensitivity. Upon irradiation with UV light, the two compounds display tunable fluorescence emission from blue to yellow by varying the temperature. Moreover, the absorption spectra demonstrate that the band gaps of compounds 1 and 2 are 3.71 and 3.58 eV, respectively. When adsorbing iodine into the framework, the host structure of 2 is relatively perturbed by the presence of guests and exerts a remarkable influence on the band size and gap state.

Nickel silicotungstate-decorated Pt photocathode as an efficient catalyst for triiodide reduction in dye-sensitized solar cells

A new type of polyoxometalate material, K6SiW11O39Ni(H2O)·xH2O (denoted as SiW11Ni), was successfully synthesized and introduced to a dye-sensitized solar cell (DSSC) with modified traditional Pt as a novel composite counter electrode. The new counter electrode showed superior electrochemical catalytic activity for the reduction of I3- to I- in analysis utilizing a Tafel-polarization curve, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The DSSC assembled with the SiW11Ni/Pt photocathode exhibited an enhanced performance (7.03%) under the standard AM 1.5G illumination compared to the DSSC with a pristine Pt photocathode (6.65%). Furthermore, the DSSC based on the SiW11Ni/Pt photocathode had an increased light-harvesting efficiency and was very stable. The results demonstrate that SiW11Ni/Pt is an alternative and highly efficient counter electrode for dye-sensitized solar cells. Moreover, the facile design strategy is promising for fabricating efficient and inexpensive composite counter electrode catalysts for DSSCs.