| Summary: | Efficient utilization of visible light for photocatalytic hydrogen production is one of the most important issues to address. This report describes a facile approach to immobilize visible-light sensitizers on TiO<sub>2</sub> surfaces. To effectively utilize the sensitization of Sn(IV) porphyrin species for photocatalytic hydrogen production, perfluorosulfonate polymer (Nafion) matrix coated-TiO<sub>2</sub> was fabricated. Nafion coated-TiO<sub>2</sub> readily adsorbed <i>trans</i>-diaqua[<i>meso</i>-tetrakis(4-pyridinium)porphyrinato]tin(IV) cation [(TPy<i><sup>H</sup></i>P)Sn(OH<sub>2</sub>)<sub>2</sub>]<sup>6+</sup> via an ion-exchange process. The uptake of [(TPy<i><sup>H</sup></i>P)Sn(OH<sub>2</sub>)<sub>2</sub>]<sup>6+</sup> in an aqueous solution completed within 30 min, as determined by UV-vis spectroscopy. The existence of Sn(IV) porphyrin species embedded in the Nafion matrix coated on TiO<sub>2</sub> was confirmed by zeta potential measurements, UV-vis absorption spectroscopy, TEM combined with energy dispersive X-ray spectroscopy, and thermogravimetric analysis. Sn(IV)-porphyrin cationic species embedded in the Nafion matrix were successfully used as visible-light sensitizer for photochemical hydrogen generation. This photocatalytic system performed 45% better than the uncoated TiO<sub>2</sub> system. In addition, the performance at pH 7 was superior to that at pH 3 or 9. This work revealed that Nafion matrix coated-TiO<sub>2</sub> can efficiently produce hydrogen with a consistent performance by utilizing a freshly supplied cationic Sn(IV)-porphyrin sensitizer in a neutral solution.
|
|---|