Synthesis and enhanced photocatalytic activity of regularly shaped Cu2O nanowire polyhedra

Abstract

A series of unique nanowire superstructures, Cu 2 O nanowire polyhedra, have been synthesized through a cost-effective hydrothermal route. Three types of nanowire polyhedra, namely octahedra, concave octahedra, and hexapods, were formed in high morphological yields (90%) by reducing cupric acetate with o-anisidine or o-phenetidine in the presence of carboxylic acids. The architectures of these Cu 2 O nanowire polyhedra were examined by electron microscopy, which revealed ordered, highly aligned Cu 2 O nanowires within the polyhedral outlines. The growth of the Cu 2 O nanowire polyhedra is controlled by the orientation and growth rates of the nanowire branches which are adjusted by addition of carboxylic acids. Compared to the Cu 2 O samples reported in the recent literature, the Cu 2 O nanowire octahedra exhibit notably enhanced photocatalytic activities for dye degradation in the presence of H 2 O 2 under visible light, probably due to the high-density charge carriers photoexcited from the branched nanowires with their special structures. Additionally, the discussion in the recent literature of the photocatalytic activity of Cu 2 O in the absence of H 2 O 2 for direct photodegradation of dyes seems questionable.

Cu2O-Au nanocomposites with novel structures and remarkable chemisorption capacity and photocatalytic activity

“…This suggests that chemisorbed AO 7 is in the azo form ( Fig. S- [16,38]. de Jongh et al [7] reported that Cu 2 O is not an effective photocatalyst for water splitting but could reduce dissolved oxygen to H 2 O 2 , and Shi et al [16] recently proposed that the formation of H 2 O 2 in this way is responsible for the photodegradation of dye molecules over Cu 2 O.…”

“…S- [16,38]. de Jongh et al [7] reported that Cu 2 O is not an effective photocatalyst for water splitting but could reduce dissolved oxygen to H 2 O 2 , and Shi et al [16] recently proposed that the formation of H 2 O 2 in this way is responsible for the photodegradation of dye molecules over Cu 2 O. Meanwhile, involvement of the so-called semiconductormediated photodegradation (SMPD) mechanism [50], in which absorption of light by the chemisorbed dye molecule generates an excited state from which it injects an electron into the conduction band of a semiconductor and is thereby oxidized, cannot be ruled out.…”

“…Recently the application of Cu 2 O crystal as photocatalyst in 949 water splitting and organic contamination degradation under visible light illumination has been explored [6][7][8][9][10][11][12][13][14][15][16], but these systems still need further investigation. Hara et al [6] first reported the photocatalytic decomposition of water into H 2 and O 2 on Cu 2 O under visible light irradiation, but de Jongh et al [7] pointed out that Cu 2 O could be a promising material not just for direct photochemical water splitting but-in conjunction with a suitable redox system-as a p-type photoelectrode in an electrochemical photovoltaic cell.…”

“…Later Hara et al [8] also observed the generation of metallic Cu during water splitting on Cu 2 O and proposed that a redox reaction between Cu and Cu 2 O may be responsible for H 2 and O 2 formation in the Cu 2 O-catalyzed overall water splitting. Cu 2 O nanocrystals have also been reported to be active in the photodegradation of various dye molecules under visible light illumination [10][11][12][13][14][15], but Shi et al [16] recently reported that Cu 2 O nanowire polyhedra only exhibited photocatalytic activity for dye photodegradation in the presence of H 2 O 2 under visible light irradiation.…”

The effect of different exposed facets on the photoelectrocatalytic degradation of o-chlorophenol using p-type Cu 2 O crystals

“…The synthesis of Cu 2 O micro or nanostructures with controllable morphologies has been developed [14,15], including nanocubes [15,16], octahedra [15,16], polyhedral morphology [17], hollow structures [18] and nanowires [19], and many growth mechanisms have been proposed. These Cu 2 O microcrystals were generally synthesized by hydrothermal methods in the presence of different capping reagents (e.g., surfactant [20], ascorbic acid or hydrazine hydrate [16], and acetic acid [17]).…”