Carbon-coated TiO₂ fibers were synthesized as core–shell structured supports for highly dispersed Pt nanoparticles. The catalyst samples were characterized by XRD, Raman, TGA, SEM, TEM and EDX. Performance of methanol oxidation was evaluated in aqueous H₂SO₄ solutions with methanol by cyclic voltammetry and chronoamperometry. The TiO₂ nanofibers were coated with carbon shells mostly between 5 and 10 nm in thickness. Platinum nanoparticles around 2 nm were evenly deposited onto the as-synthesized carbon-coated TiO₂ fibers, denoted as Pt–TiO₂/C. Electrochemical experiments showed that the peak current density of methanol oxidation in the forward scan was significantly increased by 7.3 and 2.5 times on Pt–TiO₂/C compared with those of Pt–TiO₂ and Pt–C (Vulcan XC-72), respectively. Furthermore, the Pt–TiO₂/C electro-catalyst exhibited a lower onset potential and slower current decay than Pt–C, suggesting higher catalytic activity and better stability. In photo-electrochemical experiments, the electro-catalytic and photo-catalytic properties of Pt–TiO₂/C have been synergistically coupled to boost the performance of methanol oxidation. Under UV irradiation, the total peak current density of methanol oxidation on Pt–TiO₂/C is enhanced 2.5 times as that in the dark. In brief, the cooperation between Pt, carbon shell and TiO₂ support promotes methanol oxidation on Pt–TiO₂/C with and without UV illumination.

A novel metal–semiconductor nanocomposite with stable metal nanoparticles and efficient photocatalytic performance has been prepared. It consists of highly dispersed ∼2 nm platinum (Pt) nanoparticles loaded on mesoporous and bicrystalline TiO₂ fibers (Pt/mb-TiO₂). Due to the well organized porous Pt/TiO₂ nanoarchitecture, rate of photodegradation of CHCl₃ was nearly doubled compared to both P25 and Pt/P25. And in photocatalytic production of H₂ (with methanol as an electron donor), Pt/mb-TiO₂ presented much more stable activity than Pt/P25. In a 20 h H₂ production, Pt nanoparticles on P25 agglomerated and grew remarkably from 2.0 ± 0.5 nm to 4.5 ± 2.5 nm, while Pt nanoparticles on mb-TiO₂ changed slightly from 2.0 ± 0.5 nm to 2.2 ± 0.5 nm. Moreover, the loss ratio of Pt on P25 is 36%, which is much larger than that of 7% on mb-TiO₂. The efficient charge transfer in the interfaces of Pt/TiO₂(B) and TiO₂(B)/anatase was discussed. We concluded that the high photocatalytic performance of Pt/mb-TiO₂ can be attributed to stable Pt nanoparticles supported on the mesoporous masonry frameworks of TiO₂ and efficient charge transfer in the interfaces.

Nanocrystals from non-toxic, earth abundant materials have recently received great interest for their potential large-scale application in photovoltaics and photocatalysis. Here, we report for the first time on the shape-controlled and scalable synthesis of phase-pure pyrite (FeS₂) nanocrystals employing the simple, inexpensive, thermal reaction of iron–oleylamine complexes with sulfur in oleylamine. Either dendritic nanocrystals (nanodendrites) or nanocubes are obtained by adjusting the iron-oleylamine concentration and thereby controlling the nucleus concentration and kinetics of the nanocrystal growth. Pyrite nanodendrites are reversibly assembled by washing with toluene and redispersed by adding the ligand oleylamine. The assembly–redispersion-process is accompanied by an increased absorption in the red/near-infrared spectral region for the aggregated state. This increased low-energy absorption is due to interactions between the closed-packed nanocrystals. High-concentration nanodendrite dispersions are used to prepare pyrite thin films with strong broadband extinction in the visible and near-infrared. These films are attractive candidates for light harvesting in all inorganic solar cells based on earth abundant, non-toxic materials as well as for photocatalytic applications.