Enhanced Photocatalytic Hydrogen Evolution from Water Splitting on Ta2O5/SrZrO3 Heterostructures Decorated with CuxO/RuO2 Cocatalysts.

Photocatalytic H2 generation by water splitting is a promising alternative for producing renewable fuels. This work synthesized a new type of Ta2O5/SrZrO3 heterostructure with Ru and Cu (RuO2/CuxO/Ta2O5/SrZrO3) using solid-state chemistry methods to achieve a high H2 production of 5164 µmol g-1 h-1 under simulated solar light, 39 times higher than that produced using SrZrO3. The heterostructure performance is compared with other Ta2O5/SrZrO3 heterostructure compositions loaded with RuO2, CuxO, or Pt. CuxO is used to showcase the usage of less costly cocatalysts to produce H2. The photocatalytic activity toward H2 by the RuO2/CuxO/Ta2O5/SrZrO3 heterostructure remains the highest, followed by RuO2/Ta2O5/SrZrO3 > CuxO/Ta2O5/SrZrO3 > Pt/Ta2O5/SrZrO3 > Ta2O5/SrZrO3 > SrZrO3. Band gap tunability and high optical absorbance in the visible region are more prominent for the heterostructures containing cocatalysts (RuO2 or CuxO) and are even higher for the binary catalyst (RuO2/CuxO). The presence of the binary catalyst is observed to impact the charge carrier transport in Ta2O5/SrZrO3, improving the solar to hydrogen conversion efficiency. The results represent a valuable contribution to the design of SrZrO3-based heterostructures for photocatalytic H2 production by solar water splitting.

Color Tuning of Electrochromic TiO2 Nanofibrous Layers Loaded with Metal and Metal Oxide Nanoparticles for Smart Colored Windows.

Co-axial electrospinning was applied for the structuring of non-woven webs of TiO2 nanofibers loaded with Ag, Au, and CuO nanoparticles. The composite layers were tested in an electrochromic half-cell assembly. A clear correlation between the nanoparticle composition and electrochromic effect in the nanofibrous composite is observed: TiO2 loaded with Ag reveals a black-brown color, Au shows a dark-blue color, and CuO shows a dark-green color. For electrochromic applications, the Au/TiO2 layer is the most promising choice, with a color modulation time of 6 s, transmittance modulation of 40%, coloration efficiency of 20 cm2/C, areal capacitance of 300 F/cm2, and cyclic stability of over 1000 cycles in an 18 h period. In this study, an unexplored path for the rational design of TiO2-based electrochromic device is offered with unique color-switching and optical efficiency gained by the fibrous layer. It is also foreseen that co-axial electrospinning can be an alternative nanofabrication technique for smart colored windows.