Abstract
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.
Highlights
In recent years, organic pollutants released from industries have caused major environmental damages; various contaminant treatments are being researched, including absorption [1,2], electrolysis [3], chemical flocculation [4], and photocatalytic degradation [5,6,7,8,9,10,11,12]
Cu ions would diffuse along grain boundaries, leading to Cupric oxide (CuO) nanowire growth on CuO grains
CuO nanowires grew slowly owing to the low mobility of Cu ions and insufficient stress generation to drive the grain boundary diffusion
Summary
Organic pollutants released from industries have caused major environmental damages; various contaminant treatments are being researched, including absorption [1,2], electrolysis [3], chemical flocculation [4], and photocatalytic degradation [5,6,7,8,9,10,11,12]. Among these treatment techniques, photocatalytic degradation is a low-cost, environmentally friendly, and sustainable method for the removal of organic pollutants. The most popular photocatalyst, TiO2 , only works under UV light, which is less than 5% of solar energy on the Earth’s surface; the photocatalytic applications
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