We report TiO2 branched nanostructure photoelectrodes for dye-sensitized solar cells (DSSCs). The TiO2 branch-type nanoparticle is synthesized by means of a seeding method with TiO2 nanowire as a seed. During the seeding process, the TiO2 nanostructure is evolved from a nanowire (NW) to nanobranch (NB) shape. It is also found that rutile TiO2-NB shows such a three-dimensional structure with branches grown along backbones of rutile TiO2-NW as confirmed by high-resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD) analysis. In photocurrent−voltage measurements, short-circuit current density, and cell efficiency of TiO2-NW and TiO2-NB increase from 6.25 to 12.18 mA/cm2 and increase from 2.6 to 4.3%, respectively, due to both increased specific surface area and roughness factor.
We report Pt-Pd nanoparticles synthesized by means of a polyol process with glycerol as a reducing agent. The Pt-Pd nanoparticles exhibit dominantly exposed {111} facets in octahedral shape with complete alloy formation between Pt and Pd. Furthermore, the octahedral Pt-Pd alloy catalysts show improved catalytic activity and stability in methanol electrooxidation.
Doped carbon nanomaterials as nonprecious metal catalysts for oxygen reduction reaction (ORR) in polymer electrolyte membrane fuel cells have received intensive attraction.The improvement of ORR performance for the doped porous carbon nanostructures with high specific surface areas is mainly attributed to multi-doped electrochemical active sites provided by the metallic (Fe, Co) and non-metallic species (N, B, and S). Here, we prepared porous iron/nitrogen doped carbon nanostructured materials via a simple synthesis process using silicate beads (500 and 50 nm diameter) as templates in the presence of 5,10,15,20-tetrakis(4-methoxyphenyl)-21H,23H porphyrin (TMPP) or 5,10,15,20-tetrakis(4-methoxyphenyl)-21H,23H-porphyrin iron(III) chloride (FeTMPP). The resulting samples exhibited a bimodal porous structure, homogeneous heteroatomic doping, and a fairly large specific surface area. In particular, the sample prepared using both 500 and 50 nm silicate beads with FeTMPP (FeTMPP-C-500/50) exhibited much improved ORR performance in an acid solution. The enhanced ORR properties of FeTMPP-C-500/50 could result from the fairly large specific surface area, mixed macro-/meso-porous structure, high crystallinity, and co-doping of metal and nitrogen.
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