Novel Urchin-like CuO Synthesized by a Facile Reflux Method with Efficient Olefin Epoxidation Catalytic Performance

CuO is an important transition metal oxide with a narrow bandgap ( E g = 1.2 eV). CuO has been used as a catalyst, a gas sensor, in anode materials for Li ion batteries. CuO has also been used to prepare high temperature superconductors and magnetoresistance materials. In this paper, CuO with urchin-like morphologies has been synthesized via a simple reflux method. The reflux method has advantages over other solution-based techniques, such as ease of operation, safety, and high yield (95%). XRD results showed pure tenorite CuO was produced. FE-SEM exhibited an urchin-like morphology of CuO, which is composed of aggregates of nanosized strips. HR-TEM showed that the strips were single crystals with the lattice fringe of 2.3 Å, which corresponds to (111). DSC and TGA results suggested that as-synthesized CuO had high thermal stability. Time-dependent experiments were conducted to illustrate the evolution of the urchin-like morphology and crystal phase formation of CuO. The effects of copper sources and precipitators on the phase and morphology of the products were studied. As-synthesized CuO showed much better catalytic performance, increased yield (from 64.3% to 89.5%) for olefin epoxidation than commercial CuO and CuO prepared by thermal decomposition of copper hydroxide.