Crystal-Plane-Dependent Etching of Cuprous Oxide Nanoparticles of Varied Shapes and Their Application in Visible Light Photocatalysis

Abstract

We report a simple, facile, surfactant-free chemical route to fabricate morphologically different Cu2O nanoparticles such as octahedron, truncated octahedron, hollow octahedron, cube, and sphere by varying the hydrolyzing agents, complexing agent, and reducing agents. Then the componential and morphological evolution of Cu2O nanoparticles have been studied independently, employing different etching agents such as aqueous NaOH, triethylamine (TEA), and oxalic acid solution. Particles of varied shapes and compositions resulted from the etching, and those particles were characterized by different physical methods. The oxidative dissolution of morphologically different Cu2O nanoparticles with different etching agents depends on the exposed crystal planes. During oxidative dissolution in aqueous oxalic acid solution, it is realized that the stability of the (100) crystal plane is higher than that of the (111) crystal plane. Among all the etching reagents used, only oxalic acid exhibits shape transformation of the as-prepared Cu2O nanoparticles. Oxalic acid etching causes the formation of cubes and hollow cubes as etching products with a 50% reduction of edge length compared to that of octahedral, truncated octahedral, and hollow octahedral Cu2O nanoparticles. But ill-defined cubes are always obtained as the etching products with a 40% reduction of size compared to that of Cu2O cubes and spheres. As-prepared Cu2O nanoparticles and chemically etched products exhibit facet-dependent photocatalytic activity under visible light irradiation where mineralization of congo red takes place. Experimentally it has been concluded that photocatalytic activity of different particles bears a close relationship with exposed crystal planes, surface area, and particle size for congo red degradation. Interestingly, NaOH-etched product with hollow octahedral morphology bearing many (111) facets demonstrates the highest photocatalytic activity.

Photoionization cross section of1sorthoexcitons in cuprous oxide

“…By studying the relative temporal positioning of the pump and probe pulse, features associated with polariton dynamics [13] are obtained. Absorption of near infrared light in excited cuprous oxide might possibly be useful for energy capture in a normally transparent region of photovoltaic [37][38][39][40] or photocatalytic devices [41][42][43][44].…”

Facet-dependent nonenzymatic glucose sensing properties of Cu2O cubes and octahedra

“…In the experiment, n = 1, D = 6.73 Â 10 À6 cm 2 s À1 , 23 V = 100 mV s À1 , and the calculated effective surface areas of the cubic and octahedral Cu 2 O-Nafion-GCE electrodes are 0.126 cm 2 and 0.142 cm 2 (Fig. A possible mechanism for the oxidation of glucose on the Cu 2 O-Nafion-GCE electrodes is follows: 24 Cu(I) + OH À -Cu(II) + e (2) Cu(II) + OH À -Cu(III) + e Moreover, based on the CV curves, it can be found that the current gradually increased from +0.3 V to +0.8 V, which corresponds to the Cu 2+ /Cu 3+ redox couple, 19 indicating that Cu 2 O crystals enable the electron transfer between the glucose and the GCE electrode.…”

Thermosensitive Cu2O–PNIPAM core–shell nanoreactors with tunable photocatalytic activity

“…[39][40][41] This in turn leads to a higher concentration of hydroxyl radicals close to the nanocubes surface, which are the active species in the process of photodegradation of MO. 42,43 As our reaction is fully surface-controlled, the total rate is directly proportional to the surface concentration of the hydroxyl radicals, and thus increases. In detail, ESR spin trapping with DMPO was employed 44 to detect the concentration of hydroxyl radicals in illuminated solutions for pure Cu2O nanocubes as well as for Cu2O@PNIPAM core-shell nanoparticles.…”