31 research outputs found
Hierarchical DSSC structures based on single walled TiO2 nanotube arrays reach back-side illumination solar light conversion efficiency of 8%
In the present work we introduce a path to the controlled construction of
DSSCs based on hierarchically structured single walled, self-organized TiO2
layers. In a first step we describe a simple approach to selectively remove the
inner detrimental shell of anodic TiO2 nanotubes (NTs). This then allows
controlled well-defined layer-by-layer decoration of these TiO2-NT walls with
TiO2 nanoparticles (this in contrast to conventional TiO2 nanotubes). We show
that such defined multiple layered decoration can be optimized to build dye
sensitized solar cells that (under back-side illumination conditions) can yield
solar light conversion efficiencies in the range of 8 %. The beneficial effects
observed can be ascribed to a combination of three factors : 1) improved
electronic properties of the single walled tubes themselves, 2) a further
improvement of the electronic properties by the defined TiCl4 treatment, and 3)
a higher specific dye loading that becomes possible for the layer-by-layer
decorated single walled tubes.Comment: arXiv admin note: text overlap with arXiv:1610.0643
Pt Single Atoms on TiO 2 PolymorphsâMinimum Loading with a Maximized Photocatalytic Efficiency
For more than 20 years, Pt/TiO represents the benchmark photocatalyst/co-catalyst platform for photocatalytic hydrogen (H) generation. Here, single atom (SA) Pt is decorated on different polymorphs of TiO (anatase, rutile, and the mixed phase of P25) using a simple immersion anchoring approach. On P25 and anatase, Pt SAs act as highly effective co-catalyst for pure water splitting with a photocatalytic H evolution activity (4600 ”mol h g)âon both polymorphs, SA deposition yields a significantly more active photocatalyst than those decorated with classic Pt nanoparticles or conventional SA deposition approaches. On rutile, Pt SAs provide hardly any co-catalytic effect. Most remarkable, for P25, the loading of Pt SAs from precursor solution with a very low concentration (<1 ppm Pt) leads already to a maximized co-catalytic effect. This optimized efficiency is obtained at 5.3 Ă 10 atoms ”m (at macroscopic loading of 0.06 at%)âfor a higher concentration of Pt (a higher density of SAs), the co-catalytic efficiency is significantly reduced due to H/O recombination. The interactions of the SA Pt with the different polymorphs that lead to this high co-catalytic activity of SA Pt at such low concentrations are further discussed
Effect of Salt Concentration in WaterâInâSalt Electrolyte on Supercapacitor Applications
Electrical doubleâlayer supercapacitors offer numerous advantages in the context of energy storage; however, their widespread use is hindered by the high unit energy cost and low specific energy. Recently, waterâinâsalt (WIS) electrolytes have garnered interest for use in energy storage devices. Nevertheless, their direct application in highâpower devices is limited due to their high viscosity. In this study, we investigate the WIS Lithium bis(trifluoromethanesulfonyl)Imide (LiTFSI) electrolyte, revealing a high specific capacitance despite its elevated viscosity and restricted ionic conductivity. Our approach involves nuclear magnetic resonance (NMR) analysis alongside electrochemical analyses, highlighting the pronounced advantage of the WIS LiTFSI electrolyte over the WIS LiCl electrolyte at the molecular level. The NMR analysis shows that the LiTFSI electrolyte ions preferentially reside within the activated carbon pore network in the absence of an applied potential, in contrast to LiCl where the ions are more evenly distributed between the inâpore and exâpore environments. This difference may contribute to the difference in capacitance between the two electrolytes observed during electrochemical cycling