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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−1. 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. [ABSTRACT FROM AUTHOR]

In this paper, we report the synthesis of iron silicide and β-iron disilicide nanowires with chemical vapor deposition; remarkably, the latter has drawn much attention but has seldom been achieved. We also propose the formation mechanisms for the two phases. To investigate the effects of the growth parameters on compositions and morphologies of the iron silicide nanowires, we changed and studied the reaction time, substrate temperature, position of samples, and pressure. The reaction concentration was found to be altered by all of the parameters; thus, we observed different nanowires in terms of morphologies and compositions with scanning electron microscopy. To confirm the growth direction and crystal structure of the nanowires, we conducted x-ray diffraction and high-resolution transmission electron microscopy studies. With the potential of being utilized as circuit elements in electronic devices for Schottky barriers, ohmic contacts, and interconnection among silicon-based transistors, the silicide work at nanoscale is beneficial for nanoelectronics. Understanding the effects of these growth parameters facilitates the control of nanowire growth with better quality. [ABSTRACT FROM AUTHOR]