Wongee Chun

Facile fabrication and photoelectrochemical properties of a CuO nanorod photocathode with a ZnO nanobranch protective layer

In this study, the photoelectrochemical properties of CuO/ZnO photoelectrodes fabricated with nanorod and film structures were investigated and compared, and the effect of surface morphology on their photoelectrochemical performance was discussed in detail. The experimental results demonstrated that the CuO/ZnO photoelectrode with nanorod structures showed superior photoelectrochemical properties compared to that of the photoelectrode with the film structure. The electrochemical impedance analysis and UV-vis spectroscopy results confirmed that the hierarchical nanorod-like structure of the CuO/ZnO photoelectrode was advantageous for effective light absorption, and reduced charge transfer resistance at the electrode/electrolyte interface. At the same time, the ZnO layer effectively contributed to the suppression of photocorrosion in the CuO, and the photoelectrodes with a ZnO layer demonstrated 82.13% better stability in photoelectrochemical conditions.

Performance Analysis on Solar Tracking Daylighting Systems Using Different Types of Solar Collectors: Parabolic Dish vs. Fresnel Lens

This paper presents the effect of solar collectors on the performance of solar tracking daylighting systems. A series of measurements were made for two different types of solar collectors mounted on double axis solar trackers: Parabolic dish concentrator and Fresnel Lens. Indoor light levels were measured at different locations of an office space (longitude: 126.33 E, latitude 33.45 N) as photo sensors were placed on a task plane 80 cm above the floor. To accurately monitor the applicability of the systems, measurements were performed under clear and overcast sky conditions with the roll-screen (on the south window) in the down position. Comparing the illuminance data, the system with Fresnel lens outperformed that of parabolic dish concentrator. On clear days, the former delivered the light levels of 400~600 lux on the task plane whereas the latter recorded 100~200 lux. Depending on the amount of cloud cover, on overcast days, illuminance readings fluctuated to some extent.