The attractive photoelectrochemical (PEC) water splitting for hydrogen fuels always requires new semiconductors, which provide stronger visible light absorption with suitable band positions. Sn(II) complex oxides are expected to offer such new possibilities. In this work, a quaternary (Sn–Ta–W–O) Tetragonal Tungsten Bronze type Sn(II) oxide (Sn-TTB) and its photoanodes are reported for the first time. Results indicate that Sn-TTB has a bandgap of 1.85 eV with intense absorption up to 600 nm and the flat-band potential at −0.10 V vs. RHE. The IPCE of its photoanode is 10 times higher than that of the pyrochlore polymorph, owing to its better light absorption and higher carrier density. Experiments and calculations suggest strong interaction between Sn(II) ions and the W/TaO6 skeleton, facilitating the delocalization of charge carriers. Such an exploration indicates that the structural engineering of Sn(II) oxide may provide more exciting opportunities for solar energy conversion materials.
In the present study, metal-organic framework Cu-BTC-supported Sn (II)-substituted Keggin heteropoly nanocomposite (Sn1.5PW/Cu-BTC) was successfully prepared by a simple impregnation method and applied as a novel nanocatalyst for producing biodiesel from oleic acid (OA) through esterification. The nanocatalyst was characterized by Fourier transform infrared spectrometry (FTIR), wide-angle X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption-desorption, thermogravimetrics (TG), and NH3-temperature-programmed desorption (NH3-TPD). Accordingly, the synthesized nanocatalyst with a Sn1.5PW/Cu-BTC weight ratio of 1 exhibited a relatively large specific surface area, appropriate pore size, and high acidity. Moreover, an OA conversion of 87.7% was achieved under optimum reaction conditions. The nanocatalyst was reused seven times, and the OA conversion remained at more than 80% after three uses. Kinetic study showed that the esterification reaction followed first-order kinetics, and the activation energy (Ea) was calculated to be 38.3 kJ/mol.
Kai Wang,Gaofeng Teng,Jinlong Yang,Rui Tan,Yandong Duan,Jiaxin Zheng,Feng Pan
We report Sn(II) and Sn(IV) self-selective dual-doping, respectively, on Fe and Si sites of Li2FeSiO4 nanocrystals due to the steric and electronic structure effects of Sn(II,IV). Combined with experimental studies and theoretical calculations, we investigate the structure–property relationship of tin doped Li2FeSiO4 as the cathode material for high performance Li-ion batteries, in which the dual-doping enhances the electronic conductivity and lithium-ion diffusion coefficient. The doped sample with 5% Sn(IV) source shows the best electrochemical performance due to the improved electronic conductivity and Li-ion diffusivity. Density functional theory (DFT) calculations also reveal that tin dual-doped Li2FeSiO4 has better electronic conductivity and lower voltage of delithiation than that of the undoped Li2FeSiO4, which is in accordance with our experimental results.
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