The role of CuO nanoparticles decorating TiO 2 nanotubes (TNT) thin film photoanodes in the behavior of photoelectrocatalytic (PEC) cells for water splitting reaction is investigated. CuO is present mainly as small nanoparticles of few nanometer decorating the internal walls of the TiO 2 nanotubes. Their presence improves i) the photocurrent behavior, ii) the H 2 generation rate by water splitting in a full PEC device (without application of a bias) and iii) the solar-to-hydrogen (STH) efficiency. The increase is about 20% with respect to parent TNT photoanodes using open spectrum light from a solar simulator and about 50% increase using AM 1.5G filtered light from a solar simulator. An STH efficiency over 2% in the full PEC cell is observed in the best conditions. IPCE (incident photon to current conversion efficiency) measurements clearly evidence that the presence of CuO nanoparticles induce an enhanced IPCE in the 300-340 nm region. The increase in the performances in water splitting is mainly associated to the transient generation of a p-n junction between the Cu x O nanoparticles and TNT upon illumination, which enhances photocurrent density by promoting charge separation.

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Here, we report on the enhanced electro-catalytic conversion of CO 2 to fuels using Cu and Fe nanofoams (NF) electro-deposited on different substrates which include Cu, Fe, Al, Ti, Fe-Cr-Ni alloy, Al grid/mesh, carbon-fibre based gas diffusion layer (GDL). Metal oxide based porous dendrite like structures were formed on these substrates with varying structural and catalytic properties. Also, we communicate the novel Fe nanofoam structures and preparation via electro-deposition techniques on GDL, Ti substrates. The nano-foam deposited on the metal substrates formed the working electrode and were tested for their catalytic performance on CO 2 reduction in the liquid phase cell prototype designed in the laboratory. The best net fuel productivity value attained was 313 μmol/hr.cm 2 per gram of catalyst. Also, we found that changing the substrate alters the foam structures and thereby, effecting the performance of the CO 2 reduction reaction. The CO 2 to fuels dependence on the substrate was also studied, to determine the true fuel productivity of the nanofoams. In-addition a time dependent fuel production study was also performed. To have a better comparison for different catalysts, all the reactions were performed at fixed conditions. But, for chosen nanofoam based catalytic electrodes, tests were performed at their respective reduction potentials observed from cyclic voltammetry and high faradaic efficiencies (F.E.) were achieved, ranging from -42 % to 83 % for Cu NF with the best case F.E. for formic acid improved by 50% compared to literature and for Fe NFs, its 92 % to 95 % with high faradaic selectivity towards acetic acid.