Copper Nanoflower Assembled by Sub-2 nm Rough Nanowires for Efficient Oxygen Reduction Reaction: High Stability and Poison Resistance and Density Functional Calculations.

The copper nanoflowers, assembled by sub-2 nm rough nanowires with high catalytic active (200) facets, are prepared by a prompt and simple method with cetyltrimethylammonium bromide (CTAB) as a capping agent. The CTAB plays a vital role in the synthesis process, whereas the copper nanorod arrays assembled by copper nanoparticles are obtained without CTAB. The copper nanoflowers are used as catalysts in oxygen reduction reactions and exhibit excellent electrocatalytic activity, which shows nearly the same activity compared with the commercial Pt/C catalyst, attributing to the nanoflower-exposed higher catalytic active (200) facets. Furthermore, the nanoflowers can avoid methanol-poison effect and show better long-term operation stability. The density functional theory was used to calculate the atom energy of Cu(100) facets and Cu(111) facets. Both of O2 dissociation and H2O activation on the facets are very easy. However, the difference between Cu(100) facets and Cu(111) facets is the adsorption and dissociation energy of O2, and the adsorption and activation of oxygen molecule is much easier on Cu(100) facets than on Cu(111) facets because of the more open nature of (100) facets.