CeO₂系の二段階水分解反応におけるレーザ表面粗面化の効果検証

抄録

In order to investigate the effect of surface roughening due to laser irradiation in two-step thermochemical water-splitting with CeO₂ system, we irradiated reactive ceramics of CeO₂-NiO system and formed groove-like structures on the surface of these samples using the two types of lasers, such as a CW laser (λ=1070nm) and a nanosecond (Ns) pulsed-laser (λ=532nm). We observed structural and characteristic changes after laser irradiation and thermochemical cycling, and estimated the amount of the syngas (H₂ and O₂ gases) during thermochemical cycling. The following findings can be derived from the experimental results. (1) The surface of the samples irradiated by a CW laser became much smoother and its color changed from milky white to blue, while the sample surface after Ns pulsed-laser irradiation was almost the same as that before laser irradiation. (2) Glass-like material was observed on the surface of the sample after thermochemical cycling, and groove-like structures partly changed into melted-like structures. (3) The amount of the syngas from the all of the irradiated samples was markedly higher than that from the unirradiated samples only at the early stage of thermochemical cycling. This reduction after a few cycles would result from the sintering of CeO₂ samples under high temperature and from the separation of inorganic adhesive used as a binder. (4) Even though with lower surface area, the samples by Ns pulsed-laser irradiation emitted more H₂ gas than those of other samples, because they have no a melted-like and smooth surface.