Ethanol-Mediated 2D Growth of Cu2O Nanoarchitectures on Nanoporous Cu Templates in Anhydrous Ethanol

Abstract

Two types of cupric oxide (Cu2O) nanoarchitectures (nanobelts and nanopetal networks) have been achieved via immersion nanoporous copper (NPC) templates in anhydrous ethanol. NPC templates with different defect densities have been prepared by dealloying amorphous Ti60Cu40 ribbons in a mixture solution of hydrofluoric acid and polyvinylpyrrolidone (PVP) with different ratios of HF/PVP. Both a water molecule reactant acting as OH− reservoir and the ethanol molecule serving as stabilizing or capping reagent for inhibiting the random growth of Cu2Oplayed a role of the formation of 2-dimensional Cu2O nanoarchitectures. Cu2O nanobelts are preferred to form in anhydrous ethanol on the NPC templates from Ti60Cu40 ribbons dealloying in the solution with low HF concentration and small addition of PVP; and Cu2O nanopetals are tended to grow in anhydrous ethanol from the NPC templates from Ti60Cu40 ribbons dealloying in the solution with high HF concentration and large addition of PVP. With increasing the immersion time in anhydrous ethanol, Cu2O nanopetals united together to create porous networks about 300 nm in thickness. The defect sites (i.e., twin boundary) on nanoporous Cu ligaments preferentially served as nucleation sites for Cu2O nanocrystals, and the higher defect density leads to the formation of uniform Cu2O layer. Synergistic effect of initial microstructure of NPC templates and stabilizing agent of ethanol molecule results in different Cu2O nanoarchitectures.

Fabrication and Photocatalytic Activity of Cu2O Nanobelts on Nanoporous Cu Substrate

“…Furthermore, the formation of Cu 2 O nanostructures was controlled by the substrate, solvent, reductant, treatment time, dissolved oxygen and so on [24][25][26]. Different from reported Cu 2 O [36] nanowires or Cu 2 O nanocubes [37], belt-shaped nanostructured Cu 2 O along the NP Cu substrate was synthesized in the research, which might be attributed to the existence of dehydrated ethanol molecules serving as a stabilizing agent by orientated growth of Cu 2 O species [26]. The Cu 2 O octahedral was synthesized controllable by adjusting ammonia solution and NaOH solution [38].…”

“…The shapes of Cu 2 O nanostructures were affected by the stabilizing agent and the ratio of the reagents [38]. Cu 2 O nanobelts in width of several tens to several hundred nanometers were grown against the NP Cu template [26,27,32]. It was believed that Cu 2 O species nucleated preferentially at lamellar defects during the rearrangement of Cu adatoms, which was caused by the synthesis effect of geometrical structure of NP Cu, local pH, diffusion of ions and water molecules.…”

“…Cu 2 O preferentially forms in an alkaline solution because OHinduced reduction reaction of Cu 2? cations to Cu ? cations [39,40] [26][27][28], so that the nanobelts can only grow in the two-dimensional direction of the porous surface. The nanobelts are getting wider and more with increasing immersion time in dehydrated ethanol, which is attributed to more adsorption of dissolved oxygen in dehydrated ethanol to the nanoporous surface.…”

“…. Cu 2 O nanobelts are considered to be grown from the Cu 2 O species during immersion in dehydrated ethanol [26,27]. The present combination of dealloying solutions and immersion in dehydrated ethanol led to the formation of the Cu 2 O nanobelts on NP Cu substrate.…”

“…So far, different types of Cu 2 O in nanostructure have been fabricated by different methods, such as solid-state reaction [24] and electrochemical method [25]. Most recently, a novel type of Cu 2 O nanobelt on NP Cu substrate (Cu 2 O@NP Cu) is synthesized by simply chemical treatment of NP Cu substrate [26,27], which is expected to exhibit excellent photocatalytic performance.…”