CuO nanostructures: Synthesis, characterization, growth mechanisms, fundamental properties, and applications

Au-BiVO4 heterogeneous nanostructures have been successfully prepared through in situ growth of gold nanoparticles on BiVO4 microtubes and nanosheets via a cysteine-linking strategy. The experimental results reveal that these Au-BiVO4 heterogeneous nanostructures exhibit much higher visible-light photocatalytic activities than the individual BiVO4 microtubes and nanosheets for both dye degradation and water oxidation. The enhanced photocatalytic efficiencies are attributed to the charge transfer from BiVO4 to the attached gold nanoparticles as well as their surface plasmon resonance (SPR) absorption. These new heteronanostructures are expected to show considerable potential applications in solar-driven wastewater treatment and water splitting.

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Preparation of Au-BiVO4 heterogeneous nanostructures as highly efficient visible-light photocatalysts.

Cu2O–Au nanoframes with different nanolayer thicknesses of Cu2O were prepared, and their photocatalytic properties in aqueous solutions were studied. Cu2O semiconductor excitation leads to electron–hole separation. In aqueous solution, the hole is known to oxidize water to produce hydroxyl radicals whose concentration (and that of the holes) can be monitored by the rate of the degradation of dissolved methylene blue dye. The exciton lifetime is determined by femtosecond techniques and is determined by electron–hole recombination which depends on the rates of a number of competing processes such as, electron or hole transfer to an acceptor such as a gold nanoframe and/or the electron or hole trapping processes at the Cu2O–Au nanoframe interface. We measured the exciton lifetime as a function of the average Cu2O–Au layer separation. A good correlation was found between the rate of the photocatalytic degradation of methylene blue and the exciton lifetime. The exciton lifetime is found to increase as the Cu2O...

Following Charge Separation on the Nanoscale in Cu2O–Au Nanoframe Hollow Nanoparticles

Shape-dependent catalysis and sensing behaviours are primarily focused on nanocrystals enclosed by low-index facets, especially the three basic facets ({100}, {111}, and {110}). Several novel strategies have recently exploded by tailoring the original nanocrystals to greatly improve the catalysis and sensing performances. In this Review, we firstly introduce the synthesis of a variety of Cu2O nanocrystals, including the three basic Cu2O nanocrystals (cubes, octahedra and rhombic dodecahedra, enclosed by the {100}, {111}, and {110} facets, respectively), and Cu2O nanocrystals enclosed by high-index planes. We then discuss in detail the three main facet-controlled synthetic strategies (deposition, etching and templating) to fabricate Cu2O-based nanocrystals with heterogeneous, etched, or hollow structures, including a number of important concepts involved in those facet-controlled routes, such as the selective adsorption of capping agents for protecting special facets, and the impacts of surface energy and active sites on reaction activity trends. Finally, we highlight the facet-dependent properties of the Cu2O and Cu2O-based nanocrystals for applications in photocatalysis, gas catalysis, organocatalysis and sensing, as well as the relationship between their structures and properties. We also summarize and comment upon future facet-related directions.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1002/advs.201500140

Facet-Controlled Synthetic Strategy of Cu2O-Based Crystals for Catalysis and Sensing.

Hybrid Cu2O-based heterogeneous nanostructures possess novel synergistic properties that arise from the integrated interaction between the disparate components, thereby showing promising potential for various important applications including solar cells, carbon monoxide oxidation, photocatalysts, field emission, sensors, templates and so on. With the rapid progress in nanomaterials science and nanotechnology, hybrid Cu2O-based heterogeneous nanostructures with well-controlled compositions, shapes and sizes have been rationally designed and synthesized. This review attempts to summarize the important advances in the development of different types of hybrid Cu2O-based heterogeneous nanostructures, such as hybrid Cu2O–metal nanostructures, hybrid Cu2O–metal oxide nanostructures and hybrid Cu2O–carbon nanostructures. The correlations between the improved performances and interfacial structures of the hybrid Cu2O-based heterogeneous nanostructures are discussed based on some important and representative examples. Several key scientific issues and perspective research directions in this field are also given.

Recent advances in hybrid Cu2O-based heterogeneous nanostructures

M/Cu2O (M = Ag, Au) heterogeneous nanocrystals are successfully prepared by depositing noble metal nanoparticles onto the surfaces of Cu2O octahedral nanocrystals through a simple photocatalytic process. The samples are characterized by means of X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX). The influence of the light source and solution temperature on the deposition of noble metal (taking Ag as an example) nanoparticles has been studied. The experimental results show that visible light is more favorable for the deposition of Ag nanoparticles onto Cu2O nanocrystals, and a solution temperature of more than 30 °C can prevent the erosion of Cu2O. The photocatalytic properties of the prepared M/Cu2O heterogeneous nanocrystals are studied, showing enhanced photocatalytic activities.

Yanling Sun

Papers

Photocatalytic synthesis of M/Cu2O (M = Ag, Au) heterogeneous nanocrystals and their photocatalytic properties