Controlled Fabrication of Photoactive Copper Oxide鈥揅obalt Oxide Nanowire Heterostructures for Efficient Phenol Photodegradation
详细信息 查看全文
- 作者：Wenwu Shi ; Nitin Chopra
- 刊名：ACS Applied Materials & Interfaces
- 出版年：2012
- 出版时间：October 24, 2012
- 年：2012
- 卷：4
- 期：10
- 页码：5590-5607
- 全文大小：1415K
- 年卷期：v.4,no.10(October 24, 2012)
- ISSN：1944-8252
文摘
Fabrication of oxide nanowire heterostructures with controlled morphology, interface, and phase purity is critical for high-efficiency and low-cost photocatalysis. Here, we have studied the formation of copper oxide鈥揷obalt nanowire heterostructures by sputtering and subsequent air annealing to result in cobalt oxide (Co3O4)-coated CuO nanowires. This approach allowed fabrication of standing nanowire heterostructures with tunable compositions and morphologies. The vertically standing CuO nanowires were synthesized in a thermal growth method. The shell growth kinetics of Co and Co3O4 on CuO nanowires, morphological evolution of the shell, and nanowire self-shadowing effects were found to be strongly dependent on sputtering duration, air-annealing conditions, and alignment of CuO nanowires. Finite element method (FEM) analysis indicated that alignment and stiffness of CuO鈥揅o nanowire heterostructures greatly influenced the nanomechanical aspects such as von Mises equivalent stress distribution and bending of nanowire heterostructures during the Co deposition process. This fundamental knowledge was critical for the morphological control of Co and Co3O4 on CuO nanowires with desired interfaces and a uniform coating. Band gap energies and phenol photodegradation capability of CuO鈥揅o3O4 nanowire heterostructures were studied as a function of Co3O4 morphology. Multiple absorption edges and band gap tailings were observed for these heterostructures, indicating photoactivity from visible to UV range. A polycrystalline Co3O4 shell on CuO nanowires showed the best photodegradation performance (efficiency 50鈥?0%) in a low-powered UV or visible light illumination with a sacrificial agent (H2O2). An anomalously high efficiency (67.5%) observed under visible light without sacrificial agent for CuO nanowires coated with thin (5.6 nm) Co3O4 shell and nanoparticles was especially interesting. Such photoactive heterostructures demonstrate unique sacrificial agent-free, robust, and efficient photocatalysts promising for organic decontamination and environmental remediation.