Kao Yuan-Tse, Yang Shu-Meng, Lu Kuo-Chang
Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan.
Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 701, Taiwan.
Materials (Basel). 2019 Apr 3;12(7):1106. doi: 10.3390/ma12071106.
In this study, an efficient method to synthesize CuO-CuS core-shell nanowires by two-step annealing process was reported. CuO nanowires were prepared on copper foil via thermal oxidation in a three-zone horizontal tube furnace. To obtain larger surface area for photocatalytic applications, we varied four processing parameters, finding that growth at 550 °C for 3 h with 16 °C/min of the ramping rate under air condition led to CuO nanowires of appropriate aspect ratio and number density. The second step, sulfurization process, was conducted to synthesize CuO-CuS core-shell nanowires by annealing with sulfur powder at 250 °C for 30 min under lower pressure. High-resolution transmission electron microscopy studies show that a 10 nm thick CuS shell formed and the growth mechanism of the nanowire heterostructure has been proposed. With BET, the surface area was measured to be 135.24 m²·g. The photocatalytic properties were evaluated by the degradation of methylene blue (MB) under visible light irradiation. As we compared CuO-CuS core-shell nanowires with CuO nanowires, the 4-hour degradation rate was enhanced from 67% to 89%. This could be attributed to more effective separation of photoinduced electron and hole pairs in the CuO-CuS heterostructure. The results demonstrated CuO-CuS core-shell nanowires as a promising photocatalyst for dye degradation in polluted water.
在本研究中，报道了一种通过两步退火工艺合成CuO-CuS核壳纳米线的有效方法。通过在三区卧式管式炉中进行热氧化，在铜箔上制备了CuO纳米线。为了获得更大的光催化应用表面积，我们改变了四个工艺参数，发现空气条件下以16℃/min的升温速率在550℃下生长3小时可得到具有合适长径比和数密度的CuO纳米线。第二步，硫化过程，是在较低压力下于250℃用硫粉退火30分钟以合成CuO-CuS核壳纳米线。高分辨率透射电子显微镜研究表明形成了10nm厚的CuS壳层，并提出了纳米线异质结构的生长机制。通过BET测量，表面积为135.24m²·g。通过在可见光照射下亚甲基蓝（MB）的降解来评估光催化性能。当我们将CuO-CuS核壳纳米线与CuO纳米线进行比较时，4小时的降解率从67%提高到了89%。这可归因于CuO-CuS异质结构中光生电子和空穴对的更有效分离。结果表明CuO-CuS核壳纳米线是一种用于污染水中染料降解的有前景的光催化剂。
