Evolution of a Cu₂O Cube to a Hollow Truncated Octahedron and Their Photocatalytic and Electrocatalytic Activity

Abstract

The structure regulation of cuprous oxide (Cu2O) has been realized from submicrometric cubes to irregular hollow polyhedrons and hollow truncated octahedrons. It is suggested that the evolution of Cu2O exotic morphology and hollow structure are caused by an inside–out Ostwald ripening mechanism in the synthetic system, followed by the induced formation of eight (111) and six (100) planes of a hollow truncated octahedron, while a Cu2O cube with six (100) planes is formed quickly via directed attachment in a weak reduction environment. Photocatalysis of methyl orange indicated that the (111) planes of a hollow truncated octahedron showed higher catalytic activities than the (100) planes of both structures. However, both the (100) and (111) planes in a Cu2O cube or hollow truncated octahedron display high electrocatalytic activities toward the reduction of nitrobenzene. A glassy-carbon electrode modified by Cu2O hollow truncated octahedrons showed that the highest catalytic current was 401.8 μA with the most negative potential at −0.82 V due to the small size and hollow nature among these Cu2O particles. The formation of Cu2O cubes and hollow polyhedrons and their structure–property relationship have been studied on the basis of the experimental data.

Facet-Dependent Cu2O Electrocatalysis for Wearable Enzyme-Free Smart Sensing

“…To further improve the sensing performance of enzyme-free biosensors, a series of excellent electroactive materials (bulk metals, metal oxides, alloys, or carbon nanocomposites) have been developed. , Among them, because of simple preparation, abundant active sites, and various morphologies, cuprous oxide (Cu 2 O) has been widely reported to be suitable. , With the properties of appropriate bandgap (2.17 eV) and a large light absorption coefficient, Cu 2 O can be used as a photocatalyst for multiple photocatalytic reactions, such as photodegradation of methyl orange and methanation of CO 2 . − Owing to the high theoretical specific capacitance and photogenerated current density of Cu 2 O, some groups designed a Cu@Cu 2 O-based photo-assisted supercapacitor and Cu/Cu x O@rGO aerogel-based battery materials, providing new paths to energy storage. Additionally, Cu 2 O has been developed as an ideal active material for gas sensing, for example, NO 2 , , H 2 S, and acetone, resulting from the p-type semiconducting behaviors.…”

Well-defined Cu2O photocatalysts for solar fuels and chemicals

“…Therefore, researchers must address these crucial points before claiming that Cu 2 O nanocubes are a highly active photocatalyst for different reactions. [156][157][158][159][160][161] A recent study showed that when Cu 2 O nanocrystals with truncated nanocube morphology were used for the photocatalytic Sonogashira reaction in the presence of the K 2 CO 3 and CO 2 atmosphere, a CuO layer was formed in the exposed crystal surface. 161 Another fascinating hybrid photocatalyst where the Cu 2 O nanocube was decorated with SnO 2 nanoparticles showed a unique post-illumination photocatalytic "memory" effect, which means it can still be catalytically active in the dark aer the illumination was switched off for a certain period of time.…”

Controlled Synthesis and Uniform Anchoring of Hollow CuxO Nanocubes on Carbon Nanofiber for Enhanced Se(S)–Se(S) Bond Activation

“…The nanomaterials with hollow interiors have gained considerable attention over the past decade due to their promising features such as large specific areas, low density, excellent charge/mass transport, high permeability, and most importantly, the void effect. − As a result, they have a variety of potential applications, such as in drug delivery, , sensors, , batteries, ,, and catalysts. − In the construction of materials with hollow spaces, template-assisted synthesis has been very popular, which involves the adsorption of nanoparticles or polymerization on hard templates such as polymeric or inorganic silica surfaces, followed by removal of the template via calcinations or dissolving with solvents. − However, the associated disadvantages, such as surface functionalization, template removal, and poor mechanical strength of the spherical shell, may restrict its further use in large-scale applications. Template-free approaches can also be used to produce materials with void space through different physicochemical techniques such as Ostwald ripening, − Kirkendall effect, − oriented assembly, , galvanic replacement, , and oxidative etching. − It should be noted that the majority of these approaches led to nanoproducts with spherical morphology and polycrystalline structures , excluding some reports on single-crystal metal oxide nanocubes. − Copper metal with different hollow nanostructures has been receiving much attention owing to its unusual properties and promising applications in diverse fields. − However, there are only a few reports on hollow nanocubes. ,− Hence, it still remains a great challenge to overcome multistep preparation routes, and the need for a simple and environmentally friendly approach for the preparation of hollow CuO ...…”