CuO photoelectrodes synthesized by the sol-gel method for water splitting

International audienceCuO is an attractive photocatalytic material for water splitting due to its high earth abundance and low cost. In this paper, we report the deposition of CuO thin films by sol–gel dip-coating process. Sol deposition has attractive advantages including low-cost solution processing and uniform film formation over large areas with a fairly good control of the film stoichiometry and thickness. Pure CuO phase was obtained for calcination temperatures higher than 360 °C in air. The CuO photocurrents for hydrogen evolution depend on the crystallinity and the microstructure of the film. Values of −0.94 mA cm−2 at pH = 8 and 0 V vs. RHE were achieved for CuO photoelectrodes annealed at 400 °C under air. More interestingly, the stability of the photoelectrode was enhanced upon the sol–gel deposition of a TiO2 protective layer. In this all sol–gel CuO/TiO2 photocathode, a photocurrent of −0.5 mA cm−2 is achieved at pH = 7 and 0 V vs. RHE with a stability of ~100% over 600 s

Engineering n-p junction for photo-electrochemical hydrogen production.

International audienceThe generation of hydrogen from water and sunlight offers a promising approach for producing scalable and sustainable carbon free fuels. One of the challenges of solar-to-fuel technology is the design of efficient, long-lasting and low-cost photocathodes, which are responsible for absorbing sunlight and driving catalytic hydrogen evolution. We report on the protection of a Cu/Cu2O/CuO photoelectrode against photocorrosion by a 200-300 nm-thick BaTiO3 perovskite layer, deposited using the sol-gel method. This photoelectrode mediates H2 production with a current density of ∼3.1 mA cm-2 at 0 V versus RHE under 3 Sun irradiation and in a pH = 6 aqueous electrolyte. While the unprotected Cu/Cu2O/CuO photoelectrodes show a rapid decay of activity, the BaTiO3-protected photoelectrodes exhibit ∼10% current decay over 20 min

Nanostructured ceria based thin films (<= 1 mu m) As cathode/electrolyte interfaces

International audienceGadolinium doped cerium oxide (CGO: Ce0.9Gd0.1O2-delta) films were used as an oxygen anion diffusion layer at the cathode/electrolyte interface of Solid Oxide Fuel Cells (SOFCs), between LSCF (lanthanum strontium cobalt ferrite) and YSZ (yttria-stabilized zirconia). Thin (similar to 100 nm) and thick (similar to 700 nm) mesoporous CGO layers were synthesized through a sol-gel process including organic template coupled with the dip-coating method. Structural and microstructural characterizations were performed, highlighting a well-bonded crystalline CGO nanoparticles network which delineates a 3-D inter-connected mesoporous network. Their electrical behaviors were investigated by impedance spectroscopy analysis of YSZ/mesoporous-CGO/LSCF half-cell. Anode-supported SOFCs, operating at 800 degrees C, with either dense or mesoporous CGO dip-coated interlayers were also fabricated [NiO-YSZ anode/YSZ/CGO/LSCF cathode]. The impact of the mesoporous CGO interlayers on SOFCs performances was investigated by galvanostatic analysis and compared to the behavior of a dense CGO interlayer. The polarization curves revealed an enhancement in the electrical performance of the cell, which is assigned to a decrease of the polarization resistance at the cathode/electrolyte interface. The integrity and connectivity of the CGO nanoparticles bonded network facilitates O2- transport across the interface. (C) 2012 Elsevier Inc. All rights reserved